Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2018	Mar. 01, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	Flex Pharma, Inc.
Entity Central Index Key	0001615219
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		18,069,476
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Public Float			$ 9.8

CONSOLIDATED BALANCE SHEETS - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 9,829,624	$ 19,186,036
Restricted cash	126,595	0
Marketable securities	0	14,129,723
Accounts receivable	9,939	10,385
Inventory	186,920	431,891
Prepaid expenses and other current assets	162,088	777,102
Total current assets	10,315,166	34,535,137
Property and equipment, net	74,460	331,040
Restricted cash	0	126,595
Total assets	10,389,626	34,992,772
Current liabilities:
Accounts payable	342,530	2,004,440
Accrued expenses and other current liabilities	764,340	3,712,221
Deferred revenue	0	72,188
Deferred rent, current portion	0	58,821
Total current liabilities	1,106,870	5,847,670
Deferred rent, net of current portion	0	39,214
Total liabilities	1,106,870	5,886,884
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized at December 31, 2018 and December 31, 2017; none issued or outstanding at December 31, 2018 and December 31, 2017	0	0
Common stock, $0.0001 par value; 100,000,000 shares authorized at December 31, 2018 and December 31, 2017, 18,069,476 and 17,972,166 shares issued at December 31, 2018 and December 31, 2017, respectively, and 18,067,392 and 17,797,178 shares outstanding at December 31, 2018 and December 31, 2017, respectively	1,807	1,780
Additional paid-in capital	142,242,224	140,184,630
Accumulated other comprehensive loss	0	(1,247)
Accumulated deficit	(132,961,275)	(111,079,275)
Total stockholders' equity	9,282,756	29,105,888
Total liabilities and stockholders' equity	$ 10,389,626	$ 34,992,772

CONSOLIDATED BALANCE SHEET (PARENTHETICAL) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized (shares)	10,000,000	10,000,000
Preferred stock, issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Common stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (shares)	100,000,000	100,000,000
Common stock, shares issued (shares)	18,069,476	17,972,166
Common stock, shares outstanding (shares)	18,067,392	17,797,178

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	12 Months Ended
CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total revenue	$ 838,142	$ 1,274,499	$ 1,010,663
Costs and expenses:
Cost of product revenue	430,750	506,530	662,747
Research and development	11,908,294	16,989,911	20,378,161
Selling, general and administrative	10,573,321	18,503,684	19,855,987
Total costs and expenses	22,912,365	36,000,125	40,896,895
Loss from operations	(22,074,223)	(34,725,626)	(39,886,232)
Interest income, net	152,006	291,964	393,109
Net loss	(21,922,217)	(34,433,662)	(39,493,123)
Net loss attributable to common stockholders	$ (21,922,217)	$ (34,433,662)	$ (39,493,123)
Net loss per share attributable to common stockholders - basic and diluted (in usd per share)	$ (1.22)	$ (1.99)	$ (2.43)
Weighted-average number of common shares outstanding — basic and diluted (shares)	18,016,841	17,260,626	16,233,985
Net product revenue
Total revenue	$ 826,515	$ 1,260,973	$ 989,918
Other revenue
Total revenue	$ 11,627	$ 13,526	$ 20,745

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($)	12 Months Ended
CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (21,922,217)	$ (34,433,662)	$ (39,493,123)
Other comprehensive gain:
Change in net unrealized gains on available-for-sale securities	1,247	367	23,040
Comprehensive loss	$ (21,920,970)	$ (34,433,295)	$ (39,470,083)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($)	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Preferred stock, shares outstanding, beginning balance at Dec. 31, 2015		0
Equity, beginning balance at Dec. 31, 2015	$ 92,192,408	$ 0	$ 1,574	$ 129,367,978	$ (24,654)	$ (37,152,490)
Common stock, shares outstanding, beginning balance at Dec. 31, 2015			15,741,618
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted common stock (shares)			1,023,664
Vesting of restricted common stock	$ 0		$ 102	(102)
Issuance of common stock from option exercises (shares)	8,516		8,516
Issuance of common stock from option exercises	$ 22,098		$ 2	22,096
Stock-based compensation expense	6,572,963			6,572,963
Unrealized gain on available-for-sale securities	23,040				23,040
Net loss	(39,493,123)					(39,493,123)
Preferred stock, shares outstanding, ending balance at Dec. 31, 2016		0
Equity, ending balance at Dec. 31, 2016	59,317,386	$ 0	$ 1,678	135,962,935	(1,614)	(76,645,613)
Common stock, shares outstanding, ending balance at Dec. 31, 2016			16,773,798
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted common stock (shares)			1,021,804
Vesting of restricted common stock	$ 0		$ 102	(102)
Issuance of common stock from option exercises (shares)	1,576		1,576
Issuance of common stock from option exercises	$ 2,632			2,632
Stock-based compensation expense	4,219,165			4,219,165
Unrealized gain on available-for-sale securities	367				367
Net loss	$ (34,433,662)					(34,433,662)
Preferred stock, shares outstanding, ending balance at Dec. 31, 2017	0	0
Equity, ending balance at Dec. 31, 2017	$ 29,105,888	$ 0	$ 1,780	140,184,630	(1,247)	(111,079,275)
Common stock, shares outstanding, ending balance at Dec. 31, 2017	17,797,178		17,797,178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted common stock (shares)			172,904
Vesting of restricted common stock	$ 0		$ 17	(17)
Issuance of common stock from option exercises (shares)	97,310		97,310
Issuance of common stock from option exercises	$ 118,010		$ 10	118,000
Stock-based compensation expense	1,939,611			1,939,611
Unrealized gain on available-for-sale securities	1,247				1,247
Net loss	$ (21,922,217)					(21,922,217)
Preferred stock, shares outstanding, ending balance at Dec. 31, 2018	0	0
Equity, ending balance at Dec. 31, 2018	$ 9,282,756	$ 0	$ 1,807	$ 142,242,224	$ 0	$ (132,961,275)
Common stock, shares outstanding, ending balance at Dec. 31, 2018	18,067,392		18,067,392

CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($)	12 Months Ended
CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net loss	$ (21,922,217)	$ (34,433,662)	$ (39,493,123)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	228,158	324,548	277,231
Stock-based compensation expense	1,939,611	4,219,165	6,572,963
Amortization and accretion on investments	11,537	(68,139)	16,161
Other non-cash items	20,310	1,781	3,434
Changes in operating assets and liabilities:
Accounts receivable	7,206	1,796	(12,181)
Inventory	227,979	22,241	(454,132)
Prepaid expenses and other current assets	600,121	148,881	(17,409)
Other assets	0	64,800	(64,800)
Accounts payable	(1,661,910)	819,357	309,437
Accrued expenses and other current liabilities	(2,951,420)	1,124,648	746,879
Deferred revenue	0	(16,156)	88,344
Deferred rent	(98,035)	68,542	(9,475)
Other long term liabilities	0	0	(15,442)
Net cash used in operating activities	(23,598,660)	(27,722,198)	(32,052,113)
Investing activities
Purchases of marketable securities	(1,997,751)	(32,987,697)	(38,682,081)
Proceeds from maturities and sales of marketable securities	16,117,184	57,585,413	26,995,324
Purchases of property and equipment	0	(113,498)	(559,378)
Proceeds from sales of property and equipment	4,805	5,344	5,255
Net cash provided by (used in) investing activities	14,124,238	24,489,562	(12,240,880)
Financing activities
Proceeds from exercise of common stock	118,010	2,632	22,098
Net cash provided by financing activities	118,010	2,632	22,098
Net decrease in cash, cash equivalents and restricted cash	(9,356,412)	(3,230,004)	(44,270,895)
Cash, cash equivalents and restricted cash at beginning of period	19,312,631	22,542,635	66,813,530
Cash, cash equivalents and restricted cash at end of period	9,956,219	19,312,631	22,542,635
Supplemental cash flow information
Property and equipment purchases included in accounts payable	$ 0	$ 0	$ 7,100

Organization and operations	12 Months Ended
Organization and operations	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and operations	Organization and operations The Company Flex Pharma Inc. (the “Company”) is a biotechnology company that was previously focused on developing innovative and proprietary treatments for muscle cramps, spasms and spasticity associated with severe neurological conditions. In June 2018, the Company announced that it was ending the Company's ongoing Phase 2 clinical trials of the Company's lead drug product candidate, FLX-787, in patients with motor neuron disease, or MND, primarily with amyotrophic lateral sclerosis, or ALS, and in patients with Charcot-Marie-Tooth disease, or CMT, due to oral tolerability concerns observed in both studies. The wind-down of the activities associated with these studies was completed in the third quarter of 2018. In 2016, the Company launched its consumer product, HOTSHOT®, to prevent and treat exercise-associated muscle cramps, or EAMCs. The Company continues to market and sell HOTSHOT to endurance athletes who drink it before, during and after exercise to prevent and treat EAMCs. In June 2018, the Company initiated a process to explore a range of strategic alternatives for enhancing stockholder value, including the potential sale or merger of the Company. Wedbush PacGrow was engaged to act as its strategic financial advisor at that time. The Company also announced the restructuring of its organization to reduce the Company's cost structure. In connection with the restructuring plan, the Company reduced its workforce by approximately 60%, with the reduction completed as of September 30, 2018. Following an extensive process of evaluating strategic alternatives for the Company, including identifying and reviewing potential candidates for a strategic acquisition or other transaction, on January 3, 2019, the Company entered into an Agreement and Plan of Merger, or the Merger Agreement, with Salarius Pharmaceuticals, LLC, or Salarius, under which the privately-held Salarius will merge with a wholly-owned subsidiary of the Company. If the merger is completed, the business of Salarius will continue as the business of the combined company. The Company operates as two reportable segments, Consumer Operations and Drug Development. See Note 16 for additional discussion and information on the Company's reportable segments. Liquidity The Company has incurred an accumulated deficit of $132,961,275 from February 26, 2014 (inception) through December 31, 2018. The Company had cash and cash equivalents of $9,829,624 at December 31, 2018. The Company's operating plan assumes limited research and development activities and that the Consumer Operations segment will continue to sell HOTSHOT. In the event that the Company does not complete the merger with Salarius, the Company (i) may elect to pursue a dissolution and liquidation of the Company, (ii) pursue another strategic transaction or (iii) may continue to market HOTSHOT and operate its consumer business. If the Company dissolves and liquidates, the Company's common stockholders may lose their entire investment. The amount of assets available for distribution to the Company's stockholders will depend heavily on the timing of such liquidation as well as the amount of cash that will be needed for commitments and contingent liabilities. Based on the Company's operating plan, the Company believes that its existing cash and cash equivalents will be sufficient to allow the Company to fund its current operating plan for at least 12 months from the date the financial statements are issued. The Company cannot predict the outcome of the merger or whether and to what extent it will resume drug development activities for FLX-787 or other drug product candidates and to what extent it will promote and sell HOTSHOT or other consumer products in the future. Accordingly, it is difficult to predict future cash needs. Management does expect the Company to incur losses for the foreseeable future. The Company's ability to achieve profitability in the future is dependent upon achieving a level of revenues adequate to support the Company's cost structure. The Company may never achieve profitability, and unless and until it does, the Company will continue to need to raise additional capital. If the Company raises funds through the sale of equity or convertible debt securities, the issuance of those securities could result in substantial dilution of the stockholders' ownership in the Company. There can be no assurances, however, that additional funding will be available on terms acceptable to the Company, or at all.

Summary of significant accounting policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of significant accounting policies

Basis of presentation and use of estimates

The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP"). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States GAAP as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company's management evaluates its estimates, which include, but are not limited to, estimates related to inventory write-offs, clinical study accruals, stock-based compensation expense, and amounts of expenses during the reported period. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.

Principles of consolidation

The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries: TK Pharma, Inc., a Massachusetts Securities Corporation, Flex Innovation Group LLC, a Delaware limited liability company which contains the Company's consumer-related operations, and Falcon Acquisition Sub, LLC, a Delaware limited liability company established for purposes of the merger. All significant intercompany balances and transactions have been eliminated in consolidation.

Concentration of risk

The Company outsources the manufacture of HOTSHOT to a single co-packer that produces bottled finished goods. The Company also sources certain raw materials from sole suppliers. A disruption in the supply of materials or the production of finished goods could significantly impact the Company's revenues in the future as alternative sources of raw materials and co-packing may not be available at commercially reasonable rates or within a reasonably short period of time.

In addition, the inventory of HOTSHOT is concentrated in one warehouse location. Any significant disruption to the operation of the warehouse location for any reason, such as a power failure, equipment breakdown, workforce disruption, or natural or similar disasters, could materially adversely affect the Company's product distribution and sales.

Segment information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and assess performance. The Company and the Company's chief operating decision maker, the Company's Chief Executive Officer, and management, view the Company's operations and manage its business as two operating segments, Drug Development and Consumer Operations (see Note 16). The Company operates in one geographic segment, the United States.

Concentrations of credit risk and off-balance sheet risk

Cash and cash equivalents are financial instruments that potentially subject the Company to concentrations of credit risk. The Company held no marketable securities as of December 31, 2018. The Company's cash and cash equivalents are held in accounts at financial institutions that management believes are creditworthy. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to any significant credit risk on these funds. The Company has no financial instruments with off-balance sheet risk of loss.

Revenue

Revenue is comprised of net product revenue and other revenue. Net product revenue includes sales of HOTSHOT bottled finished goods to e-commerce customers, specialty retailers and sports teams, including professional and collegiate teams. Other revenue consists of payments made by customers for expedited shipping and handling. On January 1, 2018, the Company adopted ASU No. 2014-09, Revenue from Contracts with Customers ("ASC 606"), using the modified retrospective method applied to contracts not yet completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under ASC 606, while prior period amounts are not adjusted and are reported in accordance with the Company's historical accounting under ASC Topic 605, Revenue Recognition ("ASC 605").

Under ASC 605 and through December 31, 2017, revenue was recognized when persuasive evidence of an arrangement existed, delivery of the product occurred, the sales price was fixed or determinable and collectability was reasonably assured. The Company generally provided refunds to e-commerce customers, upon request, within 30 days of delivery. As the Company did not have adequate history to accurately estimate refunds, all e-commerce sales, and their related costs, were deferred and revenue was recognized once the refund period lapsed. This deferral represents total deferred revenue presented on the Company's consolidated balance sheet at December 31, 2017. For specialty retailers and sports teams, the Company did not offer a right of return or refund and revenue was recognized at the time products were delivered to customers. Discounts provided to customers were accounted for as a reduction of product revenue.

Upon the adoption of ASC 606 on January 1, 2018, revenue is recognized when control of the promised goods is transferred to the customer, upon delivery to the customer, in an amount that reflects the consideration to which the Company expects to be entitled to in exchange for those goods. See Note 3 for further discussion of revenue.

Accounts receivable and allowance for doubtful accounts

Accounts receivable are stated at their carrying values, net of any allowances for doubtful accounts. Accounts receivable consist primarily of amounts due from specialty retailers and sports teams, for which collectability is reasonably assured. Receivables are evaluated for collectability on a regular basis and an allowance for doubtful accounts is recorded, if necessary. No allowance for doubtful accounts was deemed necessary at December 31, 2018 and December 31, 2017.

Cost of product revenue

Cost of product revenue includes the cost of raw materials utilized to produce HOTSHOT, co-packing fees, repacking fees, in-bound freight charges and warehouse and transportation costs incurred to bring HOTSHOT finished goods to salable condition. All other costs incurred after this condition is met are considered selling costs and included in selling, general and administrative expenses. Cost of product revenue also includes write-offs for inventory that has become obsolete, has a cost basis in excess of its estimated realizable value, or exceeds projected sales, as well as depreciation expense related to manufacturing equipment purchased to support production and royalty amounts payable to certain of the Company's founders on HOTSHOT sales.

Inventory

The Company launched HOTSHOT in the second quarter of 2016 and began capitalizing inventory costs associated with HOTSHOT in the first quarter of 2016, when it was determined that the inventory costs had probable future economic benefit. Inventory is stated at the lower of cost or estimated net realizable value, on a first-in, first-out ("FIFO") basis.

The Company outsources the manufacture of HOTSHOT to a co-packer. Inventory at December 31, 2018 includes raw materials available for future production runs, as well as finished goods.

The Company periodically analyzes its inventory levels and writes down inventory that has become obsolete, has a cost basis in excess of its estimated realizable value, or exceeds projected sales. Estimates of excess inventory consider factors such as inventory levels, production requirements, projected sales and the estimated shelf-lives of inventory components. Inventory write-offs are recorded as a component of cost of product revenue.

Advertising expense

Advertising expense consists of media and production costs related to print and digital advertising. All advertising is expensed as incurred. Total advertising expenses are included in selling, general and administrative and were approximately $822,000, $3,566,000 and $2,936,000 for the years ended December 31, 2018, December 31, 2017 and December 31, 2016, respectively.

Shipping and handling costs

Shipping and handling costs related to the movement of inventory to the Company's co-packer and from the co-packer to the Company's third-party warehousing and fulfillment partners is capitalized as inventory and expensed as a cost of product revenue when revenue is recognized. Shipping and handling costs to move finished goods from the Company's warehousing and third-party fulfillment partners to customer locations are included in selling, general and administrative expense in the consolidated statement of operations, and were approximately $98,000, $261,000 and $170,000 for the years ended December 31, 2018, December 31, 2017 and December 31, 2016, respectively.

Restructuring-related costs

The Company records employee termination costs in accordance with ASC Topic 712, Compensation - Nonretirement and Postemployment Benefits ("ASC 712"), if the termination benefits are paid as part of an ongoing benefit arrangement, which includes benefits provided as part of the Company's established severance policy or as part of an executive employment agreement. The Company accrues employee termination costs associated with an on-going benefit arrangement if the obligation is attributable to prior services rendered, the rights to the benefits have vested, the payment is probable, and the Company can reasonably estimate the liability. The Company accounts for employee termination benefits that represent a one-time benefit in accordance with ASC Topic 420, Exit or Disposal Cost Obligations ("ASC 420"). Upon communication of the termination to the employee, the Company expenses these costs over the employee’s future service period, if any.

Restructuring-related costs are recorded within research and development expenses and selling, general and administrative expenses on the Company's consolidated statement of operations. Liabilities associated with the Company's restructuring activities are recorded as a component of accrued expenses and other current liabilities on its consolidated balance sheet. See Note 9 for additional information on the Company's current restructuring plan.

Property and equipment

Property and equipment are stated at cost, less accumulated depreciation. Maintenance and repairs that do not improve or extend the lives of the respective assets are expensed to operations as incurred, while costs of major additions and betterments are capitalized. Upon disposal, the related cost and accumulated depreciation is removed from the accounts and any resulting gain or loss is included in the results of operations. Depreciation is recorded, once assets are placed in service, using the straight-line method over the estimated useful lives of the respective assets, which are as follows:



Asset type	Estimated useful life
Computers and computer equipment	3 years
Laboratory equipment	3 years
Manufacturing equipment	3 years
Website development costs	1-2 years

Impairment of long-lived assets

The Company evaluates long-lived assets for potential impairment when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparing the book values of the assets to the expected future net undiscounted cash flows that the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the book value of the assets exceed their fair value. The Company has not recognized any impairment losses through December 31, 2018.

Research and development expense

Research and development costs are charged to expense as incurred in performing research and development activities. The costs include employee compensation costs, clinical study costs, external consultant costs, regulatory costs and facilities and overhead costs. Facilities and overhead costs have primarily included the allocation of insurance, rent, utility and office-related expenses attributable to research and development personnel. The Company records payments made to outside vendors in advance of services performed or goods being delivered for use in research and development activities as prepaid expenses, which are expensed as services are performed or goods are delivered.

Stock-based compensation expense

The Company accounts for its stock-based compensation awards to employees and directors in accordance with FASB ASC Topic 718, Compensation-Stock Compensation ("ASC 718"). ASC 718 requires all stock-based payments to employees, including grants of employee stock options, to be recognized in the statement of operations based on their grant date fair values. Compensation expense related to awards to employees with service conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term. Compensation expense related to awards to employees with performance conditions is recognized based on grant date fair value over the remaining service period when management determines that achievement of the milestone is probable. Management evaluates when the achievement of a performance-based milestone is probable based on the relative satisfaction of the performance conditions as of the reporting date.

In July 2018, the Company adopted ASU 2018-07, Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. Prior to the adoption of ASU 2018-07, the Company accounted for stock-based compensation arrangements with non-employees based upon the fair value of the consideration received or the equity instruments issued, whichever is more reliably measurable, in accordance with the provisions of FASB ASC Topic 505-50, Equity-Based Payments to Non-Employees. The measurement date for non-employee awards were generally the date performance of services required from the non-employee is complete, resulting in periodic adjustments to stock-based compensation expense during the vesting period for changes in the fair value of the awards. Stock-based compensation costs for non-employee service awards were recognized as services were provided, which was generally the vesting period, on a straight-line basis. The unvested portion of the awards was subject to re-measurement over the vesting period. Following the adoption of ASU 2018-07, the Company accounts for stock granted to non-employees in accordance with ASC 718 in the same manner as employee awards described above. The adoption did not have a material impact on the condensed consolidated financial statements and therefore a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year was not required.

The Company estimates the fair value of its stock options using the Black-Scholes option pricing model, which requires the input of subjective assumptions, including (a) the expected stock price volatility, (b) the expected term of the award, (c) the risk-free interest rate, (d) expected dividends and (e) the estimated fair value of the Company's common stock on the measurement date. Due to the lack of significant trading history for the Company's common stock, it has based its estimate of expected volatility on the historical volatility of a group of similar companies that are publicly traded. When selecting the public companies on which it has based its expected stock price volatility, the Company selected companies with comparable characteristics, including enterprise value, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected term of the stock-based awards. The Company computes historical volatility data using the volatility for the selected companies' shares during the equivalent period of the calculated expected term of the stock-based awards. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. Due to the lack of Company specific historical option activity, the Company has estimated the expected term of its employee stock options using the "simplified" method, whereby, the expected term equals the arithmetic average of the vesting term and the original contractual term of the option. The expected term for non-employee awards is the remaining contractual term of the option. The risk-free interest rates are based on the U.S. Treasury securities with a maturity date commensurate with the expected term of the associated award. The Company has never paid and does not expect to pay dividends in the foreseeable future.

The Company does not apply a forfeiture rate to stock-based compensation expense and accounts for forfeitures as they occur.

Income taxes

Income taxes are recorded in accordance with FASB ASC Topic 740, Income Taxes ("ASC 740"), which provides for deferred taxes using an asset and liability approach. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial reporting and the tax reporting basis of assets and liabilities and are measured using the enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax assets will be realized. The Company has evaluated available evidence and concluded that the Company may not realize the benefit of its deferred tax assets; therefore, a valuation allowance has been established for the full amount of the deferred tax assets.

The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. As of December 31, 2018 and December 31, 2017, the Company did not have any significant uncertain tax positions. The Company's practice is to recognize interest and/or penalties related to income tax matters in income tax expense.

Net loss per share attributable to common stockholders

Basic net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period, determined using the treasury stock method and the if-converted method, for convertible securities, if inclusion of these is dilutive.

For years ended December 31, 2018, December 31, 2017 and December 31, 2016, the Company has excluded the effects of all potentially dilutive shares from the weighted-average number of common shares outstanding as their inclusion in the computation for each period would be anti-dilutive due to the net loss per share incurred by the Company.

Comprehensive loss

Comprehensive loss is the change in equity of a company during a period from transactions and other events and circumstances, excluding transactions resulting from investments by owners and distributions to owners. Comprehensive loss includes net loss and the change in accumulated other comprehensive loss for the period. Accumulated other comprehensive loss consisted entirely of unrealized gains and losses on available-for-sale marketable securities for the years ended December 31, 2018, December 31, 2017 and December 31, 2016.

Recent accounting pronouncements

In May 2014, the FASB issued ASC 606 which supersedes the revenue recognition requirements in ASC 605 and requires entities to recognize revenue when control of the promised goods or services is transferred to customers at an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. The Company adopted ASC 606 as of January 1, 2018 using the modified retrospective transition method. See Note 3 for further details.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) ("ASU 2016-02"). The ASU requires lessees to recognize the assets and liabilities on their balance sheet for the rights and obligations created by most leases and continue to recognize expenses on their income statements over the lease term. It will also require disclosures designed to give financial statement users information on the amount, timing and uncertainty of cash flows arising from leases. In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases. This ASU is intended to clarify, or correct unintended application of the guidance outlined in ASU No. 2016-02. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements. This ASU is intended to address comparative reporting requirements for initial adoption. The guidance is effective for annual reporting periods beginning after December 15, 2018, and interim periods within those years. Based on the Company's evaluation of the effect of this standard, the Company does not expect the adoption of this guidance to have a material effect on its consolidated financial statements and related disclosures.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). ASU 2016-15 clarifies how entities should classify certain cash receipts and cash payments on the statement of cash flows with the objective of reducing the existing diversity in practice related to eight specific cash flow issues. The Company retrospectively adopted ASU No. 2016 in the first quarter of 2018, retrospectively, which did not impact the Company's condensed consolidated financial statements or disclosures.

In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (“ASU 2016-18”). ASU 2016-18 requires entities to show the changes in the total of cash, cash equivalents, restricted cash and restricted cash equivalents in the statement of cash flows. As a result, entities are no longer required to present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents in the statement of cash flows. When cash, cash equivalents, restricted cash and restricted cash equivalents are presented in more than one line item on the balance sheet, the new guidance requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. The Company adopted ASU No. 2016-18 in the first quarter of 2018, retrospectively, resulting in a change to the presentation of restricted cash on the condensed consolidated statement of cash flows.

The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the condensed consolidated balance sheets that sum to the total of such amounts in the condensed consolidated statements of cash flows:



	December 31, 2018		December 31, 2017
Cash and cash equivalents	$	9,829,624	$	19,186,036
Restricted cash	126,595		126,595
Cash, cash equivalents and restricted cash shown on the condensed consolidated statement of cash flows	$	9,956,219	$	19,312,631

In May 2017, the FASB issued ASU No. 2017-09, Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”), to provide clarity and reduce diversity in practice, cost and complexity when applying the guidance of Topic 718. The guidance is effective for fiscal years beginning after December 15, 2017 and interim periods within those years. Early adoption is permitted, and the guidance should be applied prospectively. The Company adopted ASU 2017-09 in the first quarter of 2018, which did not impact the Company's condensed consolidated financial statements or disclosures.

In June 2018, the FASB issued ASU 2018-07. This ASU is intended to simplify aspects of share-based compensation issued to non-employees by making the guidance consistent with the accounting for employee share-based compensation. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within that year. Early adoption is permitted, but not before an entity has adopted ASC 606, and the guidance should be applied using a modified retrospective transition approach. The Company early adopted ASU 2018-07 on July 1, 2018 and revalued its unvested nonemployee awards as of the July 1, 2018 adoption date. The adoption did not have a material impact on the condensed consolidated financial statements and therefore a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year was not required.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”). This ASU modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement. The guidance is effective for annual reporting periods beginning after December 15, 2019, and interim periods within those years. Early adoption is permitted. The Company is currently evaluating the impact of ASU 2018-13 on its consolidated financial statements and disclosures.

The Company believes that the impact of other recently issued standards that are not yet effective will not have a material effect on its consolidated financial position or results of operations upon adoption.

Subsequent events

The Company considers events or transactions that occur after the balance sheet date but prior to the issuance of the consolidated financial statements for potential recognition or disclosure in the consolidated financial statements. Subsequent events have been evaluated through the date these consolidated financial statements were issued for potential recognition or disclosure in the consolidated financial statements (see Note 19).

Revenue from contracts with customers

12 Months Ended

Dec. 31, 2018

Revenue from Contract with Customer [Abstract]

Revenue from contract with customers

Revenue from contracts with customers

Adoption of ASC Topic 606, "Revenue from Contracts with Customers"

On January 1, 2018, the Company adopted ASC 606 using the modified retrospective method applied to contracts not yet completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under ASC 606, while prior period amounts are not adjusted and are reported in accordance with the Company's historical accounting under ASC 605.

The primary impact of the adoption of ASC 606 related to the timing of revenue recognized for e-commerce sales, due to e-commerce refund rights. Under ASC 606, the Company recognizes revenue when control of the promised good is transferred to the customer and reflects the consideration to which the Company expects to be entitled to receive in exchange for the good. This has resulted in accelerated revenue recognition for e-commerce sales, as under ASC 605, all revenue and related costs were deferred and recognized once the refund period lapsed.

The cumulative effect of applying the new guidance to all contracts that were not completed as of January 1, 2018 was recorded as an adjustment to accumulated deficit of approximately $40,000 as of the adoption date, which was primarily the result of reducing deferred revenue by approximately $70,000 and deferred cost of product revenue and selling fees by approximately $30,000, that were recorded on the consolidated balance sheet at December 31, 2017. The Company would have recognized approximately $44,000 of additional total revenue during the twelve months ended December 31, 2018, respectively, if the Company had continued to recognize revenue under ASC 605.

The adoption of ASC 606 did not impact income taxes, as the Company fully reserves its net deferred tax assets. Therefore, the change to the Company's net deferred tax asset position due to adoption was offset by a corresponding change to the valuation allowance.

Revenue recognition

Revenue includes sales of HOTSHOT bottled finished goods to e-commerce customers, specialty retailers and sports teams, including professional and collegiate teams. Revenue also consists of payments made by customers for expedited shipping and handling.

The Company expenses fulfillment costs as incurred because the amortization period would be less than one year in accordance with the ASC 606 practical expedient.

In accordance with ASC 606, the Company applies the following steps to recognize revenue for the sale of bottled finished goods that reflects the consideration to which the Company expects to be entitled to receive in exchange for the promised goods:


1.	Identify the contract with a customer

A contract with a customer exists when the Company enters into an enforceable contract with a customer. The contract is based on either the acceptance of standard terms and conditions on the websites for e-commerce customers, or the execution of terms and conditions contracts with specialty retailers and sports teams. These contracts define each party's rights, payment terms and other contractual terms and conditions of the sale. The Company applies judgment in determining the customer’s ability and intention to pay, which is based on a variety of factors including the customer’s historical payment experience and, in some circumstances, published credit and financial information pertaining to the customer.


2.	Identify the performance obligations in the contract

Performance obligations promised in a contract are identified based on the goods that will be transferred to the customer that are both capable of being distinct and are distinct in the context of the contract, whereby the transfer of the goods is separately identifiable from other promises in the contract. The Company has concluded the sale of bottled finished goods and related shipping and handling are accounted for as a single performance obligation.


3.	Determine the transaction price

The transaction price is determined based on the consideration to which the Company will be entitled to receive in exchange for transferring goods to the customer. For sales through June 18, 2018, the Company offered refunds to e-commerce customers, upon request, within 30 days of delivery. For sales subsequent to June 18, 2018, the Company now offers refunds to e-commerce customers, upon request, within 14 days of delivery. The Company estimates the amount of potential refunds at each reporting period using a portfolio approach of historical data, adjusted for changes in expected customer experience, including seasonality and changes in economic factors, as necessary. For specialty retailers and sports teams, the Company does not offer a right of return or refund and revenue is recognized at the time products are delivered to customers.

Discounts provided to customers are accounted for as an element of the transaction price and as a reduction to revenue, and were approximately $38,000, $278,000, $135,000 and for the twelve months ended December 31, 2018, December 31, 2017, and December 31, 2016, respectively.

Revenue is presented net of taxes collected from customers and remitted to governmental authorities.


4.	Determine the satisfaction of performance obligation

Revenue is recognized when control of the bottled finished goods is transferred to the customer. Control of the bottled finished goods is transferred at a point in time, upon delivery to the customer. The period of time between the satisfaction of the performance obligation and when payment is due from the customer is not significant.

Concentrations of credit risk

The Company had no customers that represented greater than 10% of total revenue during the twelve months ended December 31, 2018, December 31, 2017, or December 31, 2016. The vast majority of revenue was generated from sales within the United States.

Fair value measurements

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair value measurements

The Company records cash equivalents and marketable securities at fair value. ASC Topic 820, Fair Value Measurements and Disclosures established a fair value hierarchy for those instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). The hierarchy consists of three levels:

Level 1 – Unadjusted quoted prices in active markets for identical assets or liabilities.

Level 2 – Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, directly or indirectly, for substantially the full term of the asset or liability.

Level 3 – Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability in which there is little, if any, market activity for the asset or liability at the measurement date.

The following table summarizes the cash equivalents and marketable securities measured at fair value on a recurring basis as of December 31, 2018 and December 31, 2017:



	Level 1		Level 2		Level 3		Balance at December 31, 2018
Cash equivalents	$	2,333,771	$	—	$	—	$	2,333,771
	$	2,333,771	$	—	$	—	$	2,333,771



	Level 1		Level 2		Level 3		Balance at December 31, 2017
Cash equivalents	$	5,046,205	$	—	$	—	$	5,046,205
Marketable securities:
U.S. government agency securities	—		8,986,259		—		8,986,259
Commercial paper	—		4,440,689		—		4,440,689
Corporate debt securities	—		702,775		—		702,775
	$	5,046,205	$	14,129,723	$	—	$	19,175,928

Cash equivalents and marketable securities have been initially valued at the transaction price and subsequently valued, at the end of each reporting period, utilizing third-party pricing services or other market observable data. The pricing services utilize industry standard valuation models, including both income and market based approaches and observable market inputs to determine value. The Company's cash equivalents consist of money market funds that are valued based on publicly available quoted market prices for identical securities as of December 31, 2018. After completing its validation procedures, the Company did not adjust or override any fair value carrying amounts of as of December 31, 2018.

The carrying amounts reflected in the consolidated balance sheets for cash, restricted cash, accounts receivable, prepaid expenses and other current assets, accounts payable, accrued expenses and other current liabilities approximate their fair values at December 31, 2018 and 2017, due to their short-term nature.

The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of assets or liabilities between Level 1 and Level 2 during the year ended December 31, 2018 or during the year ended December 31, 2017. The Company had no financial assets or liabilities that were classified as Level 3 at any point during the year ended December 31, 2018 or during the year ended December 31, 2017.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Cash equivalents and marketable securities

12 Months Ended

Dec. 31, 2018

Cash and Cash Equivalents [Abstract]

Cash equivalents and marketable securities

The Company considers all highly liquid investments with maturities of three months or less when purchased to be cash equivalents. Cash equivalents as of December 31, 2018 and December 31, 2017 consisted of money market funds.

The Company held no marketable securities as of December 31, 2018. Marketable securities as of December 31, 2017 consisted of U.S. government agency securities, commercial paper and corporate debt securities. Management determines the appropriate classification of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its marketable securities as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities. Marketable securities are recorded at fair value, with unrealized gains and losses included as a component of accumulated other comprehensive income (loss) in stockholders’ equity and a component of total comprehensive income (loss) in the consolidated statement of comprehensive income (loss), until realized. Realized gains and losses are included in investment income on a specific-identification basis. There were no realized gains on marketable securities during the years ended December 31, 2018 or December 31, 2017.

The Company reviews marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the consolidated statement of operations if the Company has experienced a credit loss, has the intent to sell the marketable security, or if it is more likely than not that the Company will be required to sell the marketable security before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period.

The Company held no marketable securities at December 31, 2018. Marketable securities at December 31, 2017 consisted of the following:



	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
As of December 31, 2017
Current (due within 1 year):
U.S. government agency securities	$	8,987,254	$	38	$	(1,033	)	$	8,986,259
Commercial paper	4,440,689		—		—			4,440,689
Corporate debt securities	703,027		—		(252		)	702,775
Total	$	14,130,970	$	38	$	(1,285	)	$	14,129,723

At December 31, 2017, the Company held six debt securities that were in an unrealized loss position, all of which had been in a continuous loss position for less than 12 months. The aggregate fair value of securities in an unrealized loss position was $8,191,315 at and December 31, 2017. There were no individual securities that were in a significant unrealized loss position as of December 31, 2017. The Company evaluated its securities for other-than-temporary impairment and considered the decline in market value for the securities to be primarily attributable to economic and market conditions. The Company had the intent and ability to hold such securities until recovery. Based on this analysis, these marketable securities were not considered to be other-than-temporarily impaired as of December 31, 2017.

At December 31, 2017, all investments held by the Company were classified as current. Investments classified as current have maturities of less than one year. Investments classified as noncurrent are those that (i) have a maturity greater than one year and (ii) management does not intend to liquidate within the next year, although these funds are available for use and therefore classified as available-for-sale.

Inventory

12 Months Ended

Dec. 31, 2018

Inventory Disclosure [Abstract]

Inventory

Inventory has been recorded at cost as of December 31, 2018 and December 31, 2017. Costs capitalized at December 31, 2018 and December 31, 2017 relate to HOTSHOT finished goods and raw materials available to be used for future production runs.

The following table presents inventory:



	December 31, 2018		December 31, 2017
Raw materials	$	7,247	$	17,411
Finished goods	179,673		414,480
Total inventory	$	186,920	$	431,891

In the second quarter of 2018, the Company wrote off raw materials that are not expected to be used in future production runs, as well as finished goods inventory no longer expected to be used. In 2017, the Company wrote off raw materials not expected to be used in future production runs and expiring finished goods not anticipated to be sold. In 2016, the Company wrote off raw materials purchased for production runs of HOTSHOT that were not expected to be used in future production runs, as well as finished goods not expected to be sold based upon projected sales, estimated product shelf life, the number of units produced and production level requirements.

Write-offs totaled approximately $85,000, $42,000 and $282,000 for the years ended December 31, 2018, December 31, 2017 and December 31, 2016, respectively, and are included in cost of product revenue in the accompanying consolidated statement of operations.

Property and equipment, net

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property and equipment, net

Property and equipment, net consists of the following:



	December 31, 2018			December 31, 2017
Manufacturing equipment	$	421,999		$	421,999
Computers and computer equipment	275,670			311,847
Website development costs	177,886			177,886
Laboratory equipment	—			13,368
Capital in progress	—			28,823
Total property and equipment	875,555			953,923
Accumulated depreciation	(801,095		)	(622,883		)
Property and equipment, net	$	74,460		$	331,040

Capital in progress consists of assets acquired but not yet placed into service. There was no capital in progress at December 31, 2018. At December 31, 2017 capital in progress consisted of computers and computer equipment.

Depreciation expense was $228,158, $324,548 and $277,231 for the years ended December 31, 2018, December 31, 2017, and December 31, 2016, respectively.

In 2018, the Company disposed of computer and computer equipment, laboratory equipment and capital in progress that was sold or no longer in use. Property and equipment disposals, net, for the year ended December 31, 2018 totaled $28,422. The Company received proceeds of $4,805 related to these disposals, resulting in a loss of $23,617, included in research and development expense and selling, general and administrative expense in the accompanying consolidated statement of operations. Disposals in prior years were immaterial.

Accrued expenses and other current liabilities

12 Months Ended

Dec. 31, 2018

Payables and Accruals [Abstract]

Accrued expenses and other current liabilities

Accrued expenses and other current liabilities consist of the following:



	December 31, 2018		December 31, 2017

Payroll and employee-related costs	$	417,997	$	874,246
Professional fees	269,544		227,980
Restructuring-related costs	68,593		—
Consumer product-related costs	5,360		107,595
Research and development costs	2,846		2,502,400
Total	$	764,340	$	3,712,221

Restructuring-related costs

In June 2018, the Company's Board of Directors ("Board") approved a corporate restructuring plan to reduce the Company's cost structure. In connection with the corporate restructuring plan, the Company reduced its workforce by approximately 60%, with the reduction completed as of September 30, 2018.

Also, in June 2018, the Board approved employee retention arrangements and certain increased severance payments related to the corporate restructuring plan, to incentivize certain employees to remain with the Company through a potential sale or merger. As of December 31, 2018, the Company had paid $205,000 in retention bonuses and had paid or accrued approximately $186,000 in severance benefits associated with these arrangements. As of December 31, 2018, cash retention benefits totaling approximately $1,006,000 will be payable to the remaining employees and certain former employees who continue to provide service as consultants, upon the occurrence of a change in control event, including a sale or merger of the Company. Of this total, $603,000 relates to amounts payable to certain employees and former employees who continue to provide service as consultants only upon a change in control event, and $403,000 relates to amounts payable upon a change in control event or at certain timepoints through early 2019 if the individuals are employed by the Company and in good standing at the date of payment, even if a change in control event has not occurred. Upon a change in control event and termination without cause, the remaining employees will be eligible for up to approximately $928,000, in the aggregate, of severance benefits.

During the year ended December 31, 2018, the Company recognized expense for restructuring-related activities of approximately $1,366,000 which is comprised of approximately $1,037,000 recorded as termination benefits under ongoing benefit arrangements for terminated employees, approximately $100,000 as one-time termination benefit costs for terminated employees, approximately $214,000 in retention benefits for retained employees and approximately $15,000 of other restructuring related costs, including consulting and legal fees. There are currently no assurances a change in control event will take place. The Company does not consider the payment of severance benefits for retained employees or the payment of retention benefits only payable upon a change in control to be probable for accounting purposes as of December 31, 2018. On January 3, 2019, the Company entered into a Merger Agreement with Salarius. Unless and until the Company's shareholders have approved this specific transaction, the Company's probability assessment regarding a change in control event is not expected to change.

The Company expects to incur between approximately $1,769,000 and $3,354,000 in total costs for its restructuring-related activities, including approximately $1,366,000 that was recorded during 2018, included in the table below and $403,000 related to the annual bonus program that was recorded during 2018, included in payroll and employee-related costs. Based on the Company's current probability assessment regarding a change in control event and termination of retained employees, there are no anticipated charges in 2019. The range noted above includes approximately $603,000 related to retention benefits only payable upon a change in control event and $928,000 of severance benefits only payable upon a change in control event and termination under certain circumstances.

The following table outlines the Company's restructuring activities during the year ended December 31, 2018:



Accrued restructuring balance as of December 31, 2017	$	—
Charges:
Employee termination benefits	1,136,388
Employee retention benefits	214,417
Other	14,995
Payments	(1,297,207		)
Accrued restructuring balance as of December 31, 2018	$	68,593

The Company's accrued restructuring balance as of December 31, 2018 is included as a component of accrued expenses and other current liabilities on the Company's condensed consolidated balance sheet as of December 31, 2018. For the twelve months ended December 31, 2018, approximately $968,000 of the restructuring-related charges are included in research and development expenses and approximately $398,000 are included in selling, general and administrative expenses in the Company's condensed consolidated statement of operations.

For the twelve months ended December 31, 2018, approximately $81,000 of the restructuring-related charges were incurred by the Company's Consumer Operations segment, approximately $968,000 were incurred by the Company's Drug Development segment and the remaining charges of approximately $317,000 related to corporate costs. In total, the Company may incur restructuring-related charges of up to approximately $113,000 and $1,036,000 within the Company's Consumer Operations and Drug Development segments, respectively. The Company may incur up to $2,205,000 of corporate costs that do not relate to a reportable segment.

Commitments and contingencies	12 Months Ended
Commitments and contingencies	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies Lease commitments On April 29, 2014, the Company leased office space in Boston, Massachusetts for its former corporate headquarters. The lease for this office space was scheduled to expire on August 31, 2019 but was terminated on December 13, 2018. The company has no remaining obligations under this lease agreement as of December 31, 2018. On October 21, 2014, the Company leased office space in New York, New York under an operating lease that was originally scheduled to expire on October 31, 2018. In March 2017, the Company commenced a plan to transition its consumer operations from New York to Boston. In connection with this transition, the Company terminated its New York office operating lease and was released from any further obligations in July 2017. In November 2018, the Company leased space at a smaller office facility in Boston, Massachusetts. This lease expires upon at least one month's notice, resulting in minimum future lease payments of $2,350. Rent expense is being recognized on a straight-line basis. The Company recorded approximately $351,000, $522,000 and $337,000 of rent expense for the twelve months ended December 31, 2018, December 31, 2017 and December 31, 2016, respectively. Royalty agreement In March 2014, the Company entered into a royalty agreement with certain of its founders, or collectively the Founders. Under the agreement, the Company agreed to pay the Founders an aggregate royalty of 2% of gross sales of the Company's products in perpetuity. The Company began incurring royalty expense upon commencement of HOTSHOT sales during the second quarter of 2016. The Company recorded approximately $17,000, $25,000 and $20,000 of royalty expense during the twelve months ended December 31, 2018, December 31, 2017 and December 31, 2016, respectively. Royalty amounts owed to the Founders as of December 31, 2018, December 31, 2017 and December 31, 2016 were approximately $3,000, $3,000 and $4,000, respectively. In January 2019, the Founders entered into a royalty agreement with Flex Innovation Group LLC, which, in part, replaces the royalty agreement with Flex Pharma, Inc., described above, related to the sale of over the counter, non-prescription and/or nutritional supplement products. The royalty is payable over twenty years from the date of the agreement, with a 2% royalty due on product sales, as defined in the agreement, for the first ten years and a 1% royalty due for the following ten years. Litigation On March 1, 2019, a written demand was made on the Company by a purported shareholder requesting that additional information, including financial projections and valuation analyses, be made in the Company’s Registration Statement on Form S-4 relating to the proposed merger with Salarius. The demand stated, among other thing, that, if such disclosures are not made within a reasonable period of time, the shareholder intends to file a securities class action lawsuit in federal court. The Company will review the demand letter and respond appropriately. The Company does not have contingency reserves established for any litigation liabilities as of December 31, 2018.

Common stock

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Common stock

As of December 31, 2018, the Company had authorized 100,000,000 shares of common stock, $0.0001 par value per share. Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors. The Company does not intend to declare dividends for the foreseeable future.

Restricted common stock to founders

In March 2014, the Company sold 4,553,415 shares of restricted common stock to the founders of the Company ("recipients"), for $0.0004 per share, for total proceeds of $1,950. In April 2014, based upon anti-dilution provisions granted to the founders, an additional 867,314 shares of restricted common stock were sold to the same founders, after which the anti-dilution provisions were terminated. The restricted common stock vested 25% upon issuance, and the remaining 75% vested ratably over four years, during which time the Company had the right to repurchase the unvested shares held by a recipient if the relationship between such recipient and the Company ceased. Such shares were not accounted for as outstanding until they vested. Unvested restricted common stock awards to non-employees were re-measured at each vest date and each financial reporting date. All restricted common stock sold to the founders of the Company had vested as of December 31, 2018 and is no longer eligible for repurchase.

The following is a summary of restricted common stock activity:



	Number of Shares		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2017	169,654		$	0.10
Issued	—		—
Vested	(169,654	)	0.10
Forfeited	—		—
Unvested at December 31, 2018	—		$	—

The total fair value of shares vested during the twelve months ended 2018, 2017 and 2016 was approximately $725,000, $3,840,000 and $9,646,000 respectively.

Restricted common stock to consultants

There were no shares of restricted common stock granted to non-employee consultants and advisors during 2018 or 2017. During 2016, the Company granted a total of 18,194 of shares of restricted common stock to non-employee consultants and advisors. Such shares are not accounted for as outstanding until they vest. There were 16,110 shares of restricted common stock issued to consultants outstanding as of December 31, 2018. Prior to July 1, 2018, unvested restricted common stock awards to non-employees were re-measured at each vest date and each financial reporting date. On July 1, 2018, the Company adopted ASU 2018-07 using a modified retrospective transition approach. As a result, the Company permanently revalued all unvested stock awards granted to non-employees as of July 1, 2018. The adoption-date fair value did not materially change from the fair value as of June 30, 2018 and therefore, a cumulative-effect adjustment was not required.

The following is a summary of restricted common stock activity:



	Number of Shares		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2017	5,334		$	10.51
Issued	—		—
Vested	(3,250	)	10.16
Forfeited	—		—
Unvested at December 31, 2018	2,084		$	11.05

The total fair value of shares vested during the twelve months ended 2018, 2017 and 2016 was approximately $9,000, $22,000 and $71,000 respectively.

Employee stock purchase plan

As of the December 31, 2018, no shares of common stock have been purchased under the 2015 Employee Stock Purchase Plan (the "ESPP").

Shares reserved for future issuance

The Company has reserved the following number of shares of common stock for future issuance:



	As of December 31,
	2018	2017
Stock-based compensation awards	4,061,397	3,439,820
Vesting of restricted common stock	2,084	174,988
Employee stock purchase plan	713,996	534,274
Total	4,777,477	4,149,082

Stock-based compensation

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-based compensation

In March 2014, the Company adopted the Flex Pharma, Inc. 2014 Equity Incentive Plan (the "2014 Plan"), under which it had the ability to grant incentive stock options ("ISOs"), non-qualified stock options, restricted stock awards, restricted stock units and stock appreciation rights. Terms of stock award agreements, including vesting requirements, were determined by the board of directors, subject to the provisions of the 2014 Plan. For options granted under the 2014 Plan, the exercise price equaled the fair market value of the common stock as determined by the board of directors on the date of grant. No further awards will be granted under the 2014 Plan.

In January 2015, the Company's board of directors adopted, and the Company's stockholders approved, the 2015 Equity Incentive Plan (the "2015 Plan"), which became effective immediately prior to the closing of the Company's IPO. The 2015 Plan provides for the grant of ISOs, nonstatutory stock options, restricted stock awards, restricted stock units, stock appreciation rights, performance-based stock awards and other stock-based awards. Additionally, the 2015 Plan provides for the grant of performance-based cash awards. ISOs may be granted only to the Company's employees. All other awards may be granted to the Company's employees, including officers, and to non-employee directors and consultants. As of December 31, 2018, there were 1,740,416 shares remaining available for the grant of stock awards under the 2015 Plan.

During 2018 and 2016, the Company granted a total of 30,000 and 14,670, respectively, of stock options to non-employee consultants. There were no stock options issued to non-employee consultants during 2017. The options generally vest over a four-year period, and have a contractual term of ten years. The total stock-based compensation expense related to all non-employee stock options for the year ended December 31, 2018, December 31, 2017 and December 31, 2016 was approximately $124,000, $201,000 and $370,000, respectively.

The Company has awarded stock options to its employees, directors, advisors and consultants, pursuant to the plans described above. Stock options subsequent to the completion of the Company's IPO are granted with an exercise price equal to the closing market price of the Company's common stock on the date of grant. Stock options generally vest over one to four years and have a contractual term of ten years. Stock options are valued using the Black-Scholes option pricing model and compensation cost is recognized based on the resulting value over the service period. Prior to July 1, 2018, unvested awards to non-employees were re-measured at each vest date and at each financial reporting date. On July 1, 2018, the Company adopted ASU 2018-07 using a modified retrospective transition approach. As a result, the Company permanently revalued all unvested stock options granted to non-employees as of July 1, 2018. The adoption-date fair value did not materially change from the fair value as of June 30, 2018 and therefore, a cumulative-effect adjustment was not required.

The following table summarizes stock option activity for employees and non-employees for the twelve months ended December 31, 2018:



	Shares		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2017	2,580,491		$	6.65	7.55	$	803,600
Granted	1,517,544		2.74
Exercised	(97,310	)	1.21
Forfeited	(859,543	)	5.76
Expired	(820,201	)	8.19
Outstanding at December 31, 2018	2,320,981		$	4.10	7.61	$	—
Exercisable at December 31, 2018	1,149,927		$	5.53	6.07	$	—
Vested or expected to vest at December 31, 2018	2,320,981		$	4.10	7.53	$	—

During 2018, 2017 and 2016, the Company granted stock options to purchase an aggregate of 1,517,544, 1,059,500, and 763,320 shares of its common stock, respectively. The weighted-average grant date fair value of option awards granted during 2018, 2017 and 2016 were $1.95, $2.80, and $6.35, respectively.

The number of stock options exercised during 2018, 2017 and 2016 were 97,310, 1,576, and 8,516, respectively. The weighted-average exercise price of options exercised during 2018, 2017 and 2016 was $1.21, $1.67, and $2.59, respectively. The total intrinsic value of options exercised during 2018, 2017 and 2016 was $349,974, $2,606, and $64,302, respectively. The intrinsic value is calculated as the difference between the fair value of the Company's common stock and the exercise price of the options at the date of exercise.

The Company estimates the fair value of each stock option award on the grant date using the Black-Scholes option-pricing model based on the following assumptions regarding the fair value of the underlying Common Stock on each measurement date:



	Year Ended December 31, 2018		Year Ended December 31, 2017		Year Ended December 31, 2016
Expected volatility	81.56% to 82.41%		73.87% to 81.04%		71.01% to 74.20%
Risk-free interest rate	2.45% to 2.91%		1.83% to 2.40%		1.23% to 2.40%
Expected term	5.3 - 10 years		5.3 - 9.5 years		5.3 - 10 years
Expected dividend yield	0	%	0	%	0	%

Total stock-based compensation expense recognized for employee and non-employee restricted common stock, and stock options granted to employees and non-employees is included in the Company's consolidated statements of operations and comprehensive loss as follows:



	Year Ended December 31, 2018		Year Ended December 31, 2017		Year Ended December 31, 2016
Research and development	$	705,687	$	1,545,737	$	2,435,565
Selling, general and administrative	1,233,924		2,673,428		4,137,398
Total	$	1,939,611	$	4,219,165	$	6,572,963

Selling, general and administrative expense for the year ended December 31, 2016 included $285,000 related to stock options that were modified in connection with an employee termination agreement.

As of December 31, 2018, there was approximately $2,160,000 of total unrecognized compensation cost related to unvested equity awards. Total unrecognized compensation cost will be adjusted for future changes in employee and non-employee forfeitures, if any. The Company expects to recognize that cost over a remaining weighted-average period of 2.74 years.

In June 2018, the Company extended the three-month post termination exercisability of 877,137 option awards held by six employees and one adviser to one-year post termination. As of December 31, 2018, three of the six employees had been terminated, but continue to provide consulting services. The Company also extended the three-month post termination exercisability of 500,000 option awards held by one employee to three-years post termination. The valuation of these awards did not change as a result of the modification of these awards and as such, the Company did not recognize any additional compensation expense related to the modification.

On June 14, 2018, the Company granted 654,544 stock options, in the aggregate, to seven employees as part of the Company's retention arrangements with these employees. These awards vest monthly over 48 months as the employees provide continuous service, and expense is being recognized over this period. As of December 31, 2018, three of the six employees had been terminated, but continue to provide consulting services and vest in these options. The awards are exercisable for one to three-years post termination depending on the employee to which the stock options were granted. The awards vest in full upon a change in control event and termination under certain circumstances. A change in control event is not currently considered probable for accounting purposes. On January 3, 2019, the Company entered into a Merger Agreement with Salarius. Unless and until the Company's shareholders have approved this specific transaction, the Company's probability assessment regarding a change in control event is not expected to change.

Income taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income taxes

For the years ended December 31, 2018, December 31, 2017 and December 31, 2016, the Company did not record a current or deferred income tax provision or benefit. The Company's losses before income taxes for the periods presented consisted solely of domestic losses.

On December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118, or SAB 118, to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed, including computations, in reasonable detail to complete the accounting for certain income tax effects of the Tax Reform Act. The Company recognized the provisional tax impacts related to the revaluation of the deferred tax assets and liabilities and included these amounts in its consolidated financial statements for the year ended December 31, 2017. The ultimate impact may differ from these provisional amounts due to, among other things, additional analysis, changes in interpretations and assumptions the Company has made, additional regulatory guidance that may be issued, and actions the Company may take as a result of the Tax Reform Act. In 2018, the Company completed the analysis of the 2017 Tax Act with no material changes.

The following table presents a reconciliation of income tax expense (benefit) computed at the statutory federal income tax rate to the effective income tax rate as reflected in the consolidated financial statements:



	Year Ended December 31, 2018		Year Ended December 31, 2017		Year Ended December 31, 2016
Federal income tax expense at statutory rate	21.0	%	35.0	%	35.0	%
State income tax, net of federal benefit	6.0	%	5.0	%	5.0	%
Permanent differences	(0.1	)%	(0.7	)%	0.0	%
Stock-based compensation	(2.8	)%	(1.9	)%	(2.6	)%
Research credits	2.6	%	2.2	%	1.9	%
Other, net	(1.6	)%	(1.3	)%	(0.1	)%
Payroll tax credit election	(1.1	)%	(0.7	)%	0.0	%
Change in valuation allowance	(24.0	)%	(1.1	)%	(39.2	)%
Deferred rate change	0.0	%	(36.5	)%	0.0	%
Effective tax rate	0.0	%	0.0	%	0.0	%

Deferred income tax assets and liabilities are determined based upon temporary differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse.

The following table presents the significant components of the Company's deferred tax assets and liabilities:



	December 31, 2018			December 31, 2017
Deferred tax assets:
U.S. and state net operating loss carryforwards	$	29,902,019		$	24,744,841
Accruals and other temporary differences	336,229			202,301
Amortization	50,688			35,783
Stock-based compensation	1,220,546			1,591,131
Tax credit carryforward	2,277,428			1,964,189
Total deferred tax assets	33,786,910			28,538,245
Less valuation allowance	(33,786,910		)	(28,533,755		)
Deferred tax assets	—			4,490
Deferred tax liabilities:
Stock-based compensation	—			(4,490		)
Deferred tax liabilities	—			(4,490		)
Net deferred tax assets	$	—		$	—

As of December 31, 2018, the Company has U.S. federal net operating loss carryforwards of approximately $110,900,000 and U.S. state net operating loss carryforwards of approximately $105,400,000 ($8,400,000 tax affected), which are available to reduce future taxable income. The Company also had federal research and development tax credit carryforwards of approximately $1,800,000 and state research and development tax credit carryforwards of approximately $570,000, which may be used to offset future tax liabilities.

The Company's pre-2018 federal loss carryforwards will expire at various dates through 2037. Any federal net operating losses generated in 2018 or after will not expire as a result of the Tax Cuts and Jobs Act. Any state operating loss carryforwards and tax credit carryforwards will expire at various dates through 2038. Under the provisions of the Internal Revenue Code, the net operating loss and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50 percent, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has completed financings since its inception which may have resulted in a change in control as defined by Sections 382 and 383 of the Internal Revenue Code, or the merger with Salarius could result in a change in control. The Company has not conducted an assessment to determine whether there may have been a Section 382 or 383 ownership changes.

ASC 740 requires a valuation allowance to reduce the deferred tax assets reported if, based on the weight of available evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. After considerations of all the evidence, both positive and negative, the Company continues to maintain a valuation allowance for the full amount of the 2018 deferred tax asset because it is more likely than not that the deferred tax asset will not be realized. The valuation allowance increased by approximately $5,250,000 from December 31, 2017 to December 31, 2018, primarily due to an increase in net operating losses.

The Company has no unrecognized tax benefits. Interest and penalty charges, if any, related to uncertain tax positions would be classified as income tax expenses in the accompanying consolidated statement of operations. At December 31, 2018 and 2017, the Company had no accrued interest or penalties related to uncertain tax positions.

Under the Protecting Americans from Tax Hikes Act, enacted in December 2015, certain qualified small businesses may elect to apply up to $250,000 of its federal research and development tax credit against the Social Security portion of its payroll tax liability. The Company elected the $250,000 credit on its 2016 tax return and utilized approximately $22,000 and $156,000 of the credit as a decrease to its payroll tax expense in 2017 and 2018, respectively. The Company elected an additional $250,000 credit on its 2017 tax return.

Segment Information

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Segment Information

Effective as of the second quarter of 2016 and in connection with the launch of HOTSHOT, the Company operates as two reportable segments:


•	The Consumer Operations segment, which reflects the total revenue and costs and expenses related to HOTSHOT and the Company's consumer operations.


•	The Drug Development segment, which reflects the costs and expenses related to the Company's efforts to develop innovative and proprietary drug products; previously to treat muscle cramps, spasms and spasticity associated with severe neurological conditions.

The Company discloses information about its reportable segments based on the way that the Company's Chief Operating Decision Maker, who the Company has identified as the Chief Executive Officer, and management, organizes segments within the Company for making operating decisions and assessing financial performance. The Company evaluates the performance of its reportable segments based on revenue and operating income or loss. The accounting policies of the segments are the same as those described herein as well as those described in Note 2. Corporate and unallocated amounts that do not relate to a reportable segment have been allocated to "Corporate." No asset information has been provided for the Company's reportable segments as management does not measure or allocate such assets on a reportable segment basis.

Information for the Company's reportable segments for the years ended December 31, 2018, December 31, 2017, and December 31, 2016 are as follows:



Year Ended December 31, 2018	Consumer Operations		Drug Development	Corporate	Consolidated
Total revenue	$	838,142	—	—	$	838,142
Loss from operations	$	1,975,792	11,887,108	8,211,323	$	22,074,223
Interest income, net	$	—	—	152,006	$	152,006



Year Ended December 31, 2017	Consumer Operations		Drug Development	Corporate	Consolidated
Total revenue	$	1,274,499	—	—	$	1,274,499
Loss from operations	$	8,877,330	16,715,752	9,132,544	$	34,725,626
Interest income, net	$	—	—	291,964	$	291,964



Year Ended December 31, 2016	Consumer Operations		Drug Development	Corporate	Consolidated
Total revenue	$	1,010,663	—	—	$	1,010,663
Loss from operations	$	10,023,137	19,620,338	10,242,757	$	39,886,232
Interest income, net	$	—	—	393,109	$	393,109

Related parties	12 Months Ended
Related parties	Dec. 31, 2018
Related Party Transactions [Abstract]
Related parties	Related parties Royalty agreement In 2014, the Company entered into a royalty agreement with certain of the Company's founders under which these founders are paid a royalty of 2%, in the aggregate, of gross sales of any product sold by the Company or by any of the Company's licensees for use in the treatment of any neuromuscular disorder, and that uses, incorporates or embodies, or is made using, any of the Company's intellectual property, including any know-how. Upon the launch of HOTSHOT in the second quarter of 2016, the Company's founders began earning royalties under this agreement. Royalty amounts earned by the founders during the years ended December 31, 2018, December 31, 2017 and December 31, 2016 totaled approximately $17,000, $25,000 and $20,000, respectively, including approximately $3,000, $3,000 and $4,000 not yet paid as of year end, respectively. Royalty expense is recorded in cost of product revenue in the consolidated statement of operations. In January 2019, the Founders entered into a royalty agreement with Flex Innovation Group LLC, which, in part, replaces the royalty agreement with Flex Pharma, Inc. described above. The royalty is payable over twenty years from the date of the agreement, with a 2% royalty due on product sales, as defined in the agreement, for the first ten years and a 1% royalty due for the following ten years. License agreement For the period from May 2014 through July 2016, the Company licensed a portion of its office space to ECLDS, LLC, which was controlled by the Company's former Chief Executive Officer. In October 2015, the license agreement was assigned by ECLDS, LLC to a third party, that was not owned by the Company's former Chief Executive Officer, but for which a business relationship existed. In July 2016, the license agreement terminated. Under the terms of the license, the entity charged the same rental rate as that was charged to the Company. During the year ended December 31, 2016, the Company received approximately $32,000 in license fees from the aforementioned related party, and such amounts received have been recorded as a reduction to rent expense.

Quarterly financial information (unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Quarterly financial information (unaudited)



	First Quarter Ended March 31, 2018			Second Quarter Ended June 30, 2018			Third Quarter Ended September 30, 2018			Fourth Quarter Ended December 31, 2018
Net product revenue	$	176,255		$	241,416		$	247,284		$	161,560
Other revenue	2,327			4,086			3,707			1,507
Total revenue	178,582			245,502			250,991			163,067
Costs and expenses:
Cost of product revenue	83,934			179,945			91,937			74,934
Research and development	4,680,181			6,174,589			865,765			187,759
Selling, general and administrative	3,697,287			2,994,649			1,959,872			1,921,513
Total costs and expenses	8,461,402			9,349,183			2,917,574			2,184,206
Loss from operations	(8,282,820		)	(9,103,681		)	(2,666,583		)	(2,021,139		)
Interest income, net	59,593			51,809			28,210			12,394
Net loss	$	(8,223,227	)	$	(9,051,872	)	$	(2,638,373	)	$	(2,008,745	)
Net loss per share attributable to common stockholders — basic and diluted	$	(0.46	)	$	(0.50	)	$	(0.15	)	$	(0.11	)
Weighted-average number of common shares outstanding — basic and diluted	17,893,912			18,037,274			18,066,548			18,067,179



	First Quarter Ended March 31, 2017			Second Quarter Ended June 30, 2017			Third Quarter Ended September 30, 2017			Fourth Quarter Ended December 31, 2017
Net product revenue	$	240,292		$	330,688		$	407,241		$	282,752
Other revenue	2,255			4,835			6,360			76
Total revenue	242,547			335,523			413,601			282,828
Costs and expenses:
Cost of product revenue	79,106			145,325			148,756			133,343
Research and development	3,914,974			4,076,220			4,739,360			4,259,357
Selling, general and administrative	4,594,716			4,990,943			4,934,937			3,983,088
Total costs and expenses	8,588,796			9,212,488			9,823,053			8,375,788
Loss from operations	(8,346,249		)	(8,876,965		)	(9,409,452		)	(8,092,960		)
Interest income, net	77,854			72,342			77,339			64,429
Net loss	$	(8,268,395	)	$	(8,804,623	)	$	(9,332,113	)	$	(8,028,531	)
Net loss per share attributable to common stockholders — basic and diluted	$	(0.49	)	$	(0.51	)	$	(0.54	)	$	(0.46	)
Weighted-average number of common shares outstanding — basic and diluted	16,873,512			17,130,264			17,386,249			17,642,646

The Company would have recognized approximately $18,000, $10,000, $1,000 and $15,000 of additional total revenue during the quarters ended March 31, 2018, June 30, 2018, September 30, 2018 and December 31, 2018, respectively, if the Company had continued to recognize revenue under ASC 605.

Subsequent events

12 Months Ended

Dec. 31, 2018

Subsequent Events [Abstract]

Subsequent events

The Company has completed an evaluation of all subsequent events after the balance sheet date of December 31, 2018 through the date these consolidated financial statements were issued. The Company has concluded that no subsequent events have occurred that require disclosure, except as described below.

Agreement and Plan of Merger

On January 3, 2019, the Company, Merger Sub, and Salarius entered into the Merger Agreement. Pursuant to the Merger Agreement, among other matters, and subject to the satisfaction or waiver of the conditions set forth in the Merger Agreement, Merger Sub will merge with and into Salarius, with Salarius continuing as a wholly owned subsidiary of the Company and the surviving corporation.

The Merger Agreement (i) values the Company at $10.5 million, subject to adjustment, on a dollar-for-dollar basis, based on the Company's net cash balance at the closing of the merger compared to a target net cash of $3.3 million, and (ii) values Salarius at $36.6 million, subject to adjustment, on a dollar-for-dollar basis, based on the sale of Series A Preferred units pursuant to subscription agreements that Salarius entered into prior to the Merger Agreement compared to the target sale of $7.0 million of Series A Preferred units.

At the closing of the merger, each outstanding common unit, profits interest common unit and Series A Preferred unit of Salarius will convert into the right to receive shares of the Company's common stock (subject to the payment of cash in lieu of fractional shares and after giving effect to an anticipated reverse stock split of the Company’s common stock) at the conversion ratio formulae described in the Merger Agreement. Under those formulae, immediately following the effective time of the merger, the Company's current stockholders will own approximately 19.9% of the combined company (on a partially-diluted basis, excluding the effect of certain options, the dividend or distribution of rights and warrants to the Company's current stockholders and the possible issuance of a warrant to Wedbush) and Salarius’ current members will own approximately 80.1% of the combined company (on a partially-diluted basis, excluding the effect of certain options, the dividend or distribution of rights and Warrants to our current stockholders and the possible issuance of a warrant to Wedbush). For purposes of calculating the conversion ratios, the number of outstanding shares of the Company's common stock immediately before the merger takes into account the dilutive effect of approximately 849,610 shares of the Company's common stock underlying options outstanding as of January 3, 2019 that have an exercise price less than or equal to $1.35 per share of our common stock. Approximately 1,447,426 shares of the Company's common stock that underlie options outstanding as of January 3, 2019 have an exercise price greater than $1.35 per share of the Company's common stock.

In addition, at or prior to the closing of the merger, the Company will pay a dividend of or distribute one right per share of common stock to stockholders of record as of a date and time determined by the board of directors. Each right will entitle such stockholders to receive a warrant to purchase shares of the Company's common stock six months and one day following the closing date of the merger.

The warrants will contain customary terms and conditions, provided that the Warrants:


•	will have an exercise price per share of the Company's common stock equal to the fair market value of a share of the Company's common stock on the closing date of the merger (such exercise price subject to appropriate adjustment in the event of any stock dividend, stock split, combination or other similar recapitalization with respect to the Company's common stock);


•	will be immediately exercisable upon receipt, which receipt will be six months and one day following the closing date of the merger;


•	will be exercisable for five years after receipt;


•	will be subject to a cashless exercise, at the Company's option, under certain circumstances; and


•	will be exercisable, in the aggregate, with respect to that number of shares of the Company's common stock equal to the Warrant Aggregate Value (as defined in the Merger Agreement) divided by the value (determined using the Black-Scholes-Merton option pricing formula) of a warrant to purchase a share of the Company's common stock on the closing date of the merger.

The Warrant Aggregate Value generally represents the difference between (i) the Company's value and (ii) the value of the Company’s common stock that the Company’s current stockholders will have in the combined company. Accordingly, the Warrant Aggregate Value will be based in part on the Company’s net cash balance at the time of closing of the merger and adjusted for the amount of additional financing consummated by Salarius at or before the closing of the merger, as further described in the Merger Agreement.

The Merger Agreement contains certain termination rights for both the Company and Salarius, and further provides that, upon termination of the Merger Agreement under specified circumstances, either party may be required to pay the other party a termination fee of $0.35 million, or in some circumstances the Company may be required to reimburse Salarius’ expenses up to a maximum of $0.2 million. In addition, in certain specified circumstances, Salarius may be required to pay us a termination fee of $1.0 million.

Summary of significant accounting policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of presentation

Use of estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company's management evaluates its estimates, which include, but are not limited to, estimates related to inventory write-offs, clinical study accruals, stock-based compensation expense, and amounts of expenses during the reported period. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.

Principles of consolidation

Concentrations of risk, Concentrations of credit risk and off-balance sheet risk

Concentration of risk

Concentrations of credit risk and off-balance sheet risk

Segment information

Revenue

Accounts receivable and allowance for doubtful accounts

Cost of product revenue

Inventory

The Company outsources the manufacture of HOTSHOT to a co-packer. Inventory at December 31, 2018 includes raw materials available for future production runs, as well as finished goods.

Advertising expense

Advertising expense consists of media and production costs related to print and digital advertising. All advertising is expensed as incurred.

Shipping and handling costs

Restructuring-related costs

Property and equipment



Asset type	Estimated useful life
Computers and computer equipment	3 years
Laboratory equipment	3 years
Manufacturing equipment	3 years
Website development costs	1-2 years

Impairment of long-lived assets

Research and development expense

Stock-based compensation expense

The Company does not apply a forfeiture rate to stock-based compensation expense and accounts for forfeitures as they occur.

Income taxes

Net loss per share attributable to common stockholders

Comprehensive loss

Recent accounting pronouncements



	December 31, 2018		December 31, 2017
Cash and cash equivalents	$	9,829,624	$	19,186,036
Restricted cash	126,595		126,595
Cash, cash equivalents and restricted cash shown on the condensed consolidated statement of cash flows	$	9,956,219	$	19,312,631

Subsequent events

Fair value measurements

Level 1 – Unadjusted quoted prices in active markets for identical assets or liabilities.

Summary of significant accounting policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Schedule of cash and cash equivalents



	December 31, 2018		December 31, 2017
Cash and cash equivalents	$	9,829,624	$	19,186,036
Restricted cash	126,595		126,595
Cash, cash equivalents and restricted cash shown on the condensed consolidated statement of cash flows	$	9,956,219	$	19,312,631

Restrictions on cash and cash equivalents



	December 31, 2018		December 31, 2017
Cash and cash equivalents	$	9,829,624	$	19,186,036
Restricted cash	126,595		126,595
Cash, cash equivalents and restricted cash shown on the condensed consolidated statement of cash flows	$	9,956,219	$	19,312,631

Depreciation over estimated useful life

Depreciation is recorded, once assets are placed in service, using the straight-line method over the estimated useful lives of the respective assets, which are as follows:



Asset type	Estimated useful life
Computers and computer equipment	3 years
Laboratory equipment	3 years
Manufacturing equipment	3 years
Website development costs	1-2 years

Property and equipment, net consists of the following:



	December 31, 2018			December 31, 2017
Manufacturing equipment	$	421,999		$	421,999
Computers and computer equipment	275,670			311,847
Website development costs	177,886			177,886
Laboratory equipment	—			13,368
Capital in progress	—			28,823
Total property and equipment	875,555			953,923
Accumulated depreciation	(801,095		)	(622,883		)
Property and equipment, net	$	74,460		$	331,040

Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Summary of cash equivalents and marketable securities measured at fair value on a recurring basis

The following table summarizes the cash equivalents and marketable securities measured at fair value on a recurring basis as of December 31, 2018 and December 31, 2017:



	Level 1		Level 2		Level 3		Balance at December 31, 2018
Cash equivalents	$	2,333,771	$	—	$	—	$	2,333,771
	$	2,333,771	$	—	$	—	$	2,333,771



	Level 1		Level 2		Level 3		Balance at December 31, 2017
Cash equivalents	$	5,046,205	$	—	$	—	$	5,046,205
Marketable securities:
U.S. government agency securities	—		8,986,259		—		8,986,259
Commercial paper	—		4,440,689		—		4,440,689
Corporate debt securities	—		702,775		—		702,775
	$	5,046,205	$	14,129,723	$	—	$	19,175,928

Accrued expenses and other current liabilities (Tables)

12 Months Ended

Dec. 31, 2018

Payables and Accruals [Abstract]

Schedule of accrued expenses

Accrued expenses and other current liabilities consist of the following:



	December 31, 2018		December 31, 2017

Payroll and employee-related costs	$	417,997	$	874,246
Professional fees	269,544		227,980
Restructuring-related costs	68,593		—
Consumer product-related costs	5,360		107,595
Research and development costs	2,846		2,502,400
Total	$	764,340	$	3,712,221

Schedule of other current liabilities

Accrued expenses and other current liabilities consist of the following:



	December 31, 2018		December 31, 2017

Payroll and employee-related costs	$	417,997	$	874,246
Professional fees	269,544		227,980
Restructuring-related costs	68,593		—
Consumer product-related costs	5,360		107,595
Research and development costs	2,846		2,502,400
Total	$	764,340	$	3,712,221

Schedule of restructuring and related costs

The following table outlines the Company's restructuring activities during the year ended December 31, 2018:



Accrued restructuring balance as of December 31, 2017	$	—
Charges:
Employee termination benefits	1,136,388
Employee retention benefits	214,417
Other	14,995
Payments	(1,297,207		)
Accrued restructuring balance as of December 31, 2018	$	68,593

Common stock (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Restricted common stock activity

The following is a summary of restricted common stock activity:



	Number of Shares		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2017	5,334		$	10.51
Issued	—		—
Vested	(3,250	)	10.16
Forfeited	—		—
Unvested at December 31, 2018	2,084		$	11.05

The following is a summary of restricted common stock activity:



	Number of Shares		Weighted-Average Grant Date Fair Value
Unvested at December 31, 2017	169,654		$	0.10
Issued	—		—
Vested	(169,654	)	0.10
Forfeited	—		—
Unvested at December 31, 2018	—		$	—

Shares reserved for future issuance

The Company has reserved the following number of shares of common stock for future issuance:



	As of December 31,
	2018	2017
Stock-based compensation awards	4,061,397	3,439,820
Vesting of restricted common stock	2,084	174,988
Employee stock purchase plan	713,996	534,274
Total	4,777,477	4,149,082

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21553-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
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-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=65877616&loc=d3e177068-122764

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Subparagraph (SX 210.5-02(29))
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Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 235
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-Subparagraph (SX 210.4-08(d))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21488-112644

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-Section S99
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-Subparagraph (SX 210.5-02(27))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21484-112644

Reference 14: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

Stock-based compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of stock option activity

The following table summarizes stock option activity for employees and non-employees for the twelve months ended December 31, 2018:



	Shares		Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2017	2,580,491		$	6.65	7.55	$	803,600
Granted	1,517,544		2.74
Exercised	(97,310	)	1.21
Forfeited	(859,543	)	5.76
Expired	(820,201	)	8.19
Outstanding at December 31, 2018	2,320,981		$	4.10	7.61	$	—
Exercisable at December 31, 2018	1,149,927		$	5.53	6.07	$	—
Vested or expected to vest at December 31, 2018	2,320,981		$	4.10	7.53	$	—

Schedule of fair value assumptions



	Year Ended December 31, 2018		Year Ended December 31, 2017		Year Ended December 31, 2016
Expected volatility	81.56% to 82.41%		73.87% to 81.04%		71.01% to 74.20%
Risk-free interest rate	2.45% to 2.91%		1.83% to 2.40%		1.23% to 2.40%
Expected term	5.3 - 10 years		5.3 - 9.5 years		5.3 - 10 years
Expected dividend yield	0	%	0	%	0	%

Summary of stock-based compensation expense



	Year Ended December 31, 2018		Year Ended December 31, 2017		Year Ended December 31, 2016
Research and development	$	705,687	$	1,545,737	$	2,435,565
Selling, general and administrative	1,233,924		2,673,428		4,137,398
Total	$	1,939,611	$	4,219,165	$	6,572,963

Income taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of effective income tax rate reconciliation



	Year Ended December 31, 2018		Year Ended December 31, 2017		Year Ended December 31, 2016
Federal income tax expense at statutory rate	21.0	%	35.0	%	35.0	%
State income tax, net of federal benefit	6.0	%	5.0	%	5.0	%
Permanent differences	(0.1	)%	(0.7	)%	0.0	%
Stock-based compensation	(2.8	)%	(1.9	)%	(2.6	)%
Research credits	2.6	%	2.2	%	1.9	%
Other, net	(1.6	)%	(1.3	)%	(0.1	)%
Payroll tax credit election	(1.1	)%	(0.7	)%	0.0	%
Change in valuation allowance	(24.0	)%	(1.1	)%	(39.2	)%
Deferred rate change	0.0	%	(36.5	)%	0.0	%
Effective tax rate	0.0	%	0.0	%	0.0	%

Schedule of deferred tax assets and liabilities

The following table presents the significant components of the Company's deferred tax assets and liabilities:



	December 31, 2018			December 31, 2017
Deferred tax assets:
U.S. and state net operating loss carryforwards	$	29,902,019		$	24,744,841
Accruals and other temporary differences	336,229			202,301
Amortization	50,688			35,783
Stock-based compensation	1,220,546			1,591,131
Tax credit carryforward	2,277,428			1,964,189
Total deferred tax assets	33,786,910			28,538,245
Less valuation allowance	(33,786,910		)	(28,533,755		)
Deferred tax assets	—			4,490
Deferred tax liabilities:
Stock-based compensation	—			(4,490		)
Deferred tax liabilities	—			(4,490		)
Net deferred tax assets	$	—		$	—

Segment Information (Tables)

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Schedule of segment reporting information

Information for the Company's reportable segments for the years ended December 31, 2018, December 31, 2017, and December 31, 2016 are as follows:



Year Ended December 31, 2018	Consumer Operations		Drug Development	Corporate	Consolidated
Total revenue	$	838,142	—	—	$	838,142
Loss from operations	$	1,975,792	11,887,108	8,211,323	$	22,074,223
Interest income, net	$	—	—	152,006	$	152,006



Year Ended December 31, 2017	Consumer Operations		Drug Development	Corporate	Consolidated
Total revenue	$	1,274,499	—	—	$	1,274,499
Loss from operations	$	8,877,330	16,715,752	9,132,544	$	34,725,626
Interest income, net	$	—	—	291,964	$	291,964



Year Ended December 31, 2016	Consumer Operations		Drug Development	Corporate	Consolidated
Total revenue	$	1,010,663	—	—	$	1,010,663
Loss from operations	$	10,023,137	19,620,338	10,242,757	$	39,886,232
Interest income, net	$	—	—	393,109	$	393,109

Quarterly financial information (unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Schedule of quarterly financial information



	First Quarter Ended March 31, 2018			Second Quarter Ended June 30, 2018			Third Quarter Ended September 30, 2018			Fourth Quarter Ended December 31, 2018
Net product revenue	$	176,255		$	241,416		$	247,284		$	161,560
Other revenue	2,327			4,086			3,707			1,507
Total revenue	178,582			245,502			250,991			163,067
Costs and expenses:
Cost of product revenue	83,934			179,945			91,937			74,934
Research and development	4,680,181			6,174,589			865,765			187,759
Selling, general and administrative	3,697,287			2,994,649			1,959,872			1,921,513
Total costs and expenses	8,461,402			9,349,183			2,917,574			2,184,206
Loss from operations	(8,282,820		)	(9,103,681		)	(2,666,583		)	(2,021,139		)
Interest income, net	59,593			51,809			28,210			12,394
Net loss	$	(8,223,227	)	$	(9,051,872	)	$	(2,638,373	)	$	(2,008,745	)
Net loss per share attributable to common stockholders — basic and diluted	$	(0.46	)	$	(0.50	)	$	(0.15	)	$	(0.11	)
Weighted-average number of common shares outstanding — basic and diluted	17,893,912			18,037,274			18,066,548			18,067,179



	First Quarter Ended March 31, 2017			Second Quarter Ended June 30, 2017			Third Quarter Ended September 30, 2017			Fourth Quarter Ended December 31, 2017
Net product revenue	$	240,292		$	330,688		$	407,241		$	282,752
Other revenue	2,255			4,835			6,360			76
Total revenue	242,547			335,523			413,601			282,828
Costs and expenses:
Cost of product revenue	79,106			145,325			148,756			133,343
Research and development	3,914,974			4,076,220			4,739,360			4,259,357
Selling, general and administrative	4,594,716			4,990,943			4,934,937			3,983,088
Total costs and expenses	8,588,796			9,212,488			9,823,053			8,375,788
Loss from operations	(8,346,249		)	(8,876,965		)	(9,409,452		)	(8,092,960		)
Interest income, net	77,854			72,342			77,339			64,429
Net loss	$	(8,268,395	)	$	(8,804,623	)	$	(9,332,113	)	$	(8,028,531	)
Net loss per share attributable to common stockholders — basic and diluted	$	(0.49	)	$	(0.51	)	$	(0.54	)	$	(0.46	)
Weighted-average number of common shares outstanding — basic and diluted	16,873,512			17,130,264			17,386,249			17,642,646

Organization and operations (Details)	1 Months Ended	9 Months Ended	12 Months Ended
Organization and operations (Details)	Jun. 30, 2018	Sep. 30, 2018	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Decrease in company workforce (as a percent)	60.00%	60.00%
Number of reportable segments \| segment			2
Accumulated deficit			$ 132,961,275	$ 111,079,275
Cash and cash equivalents			$ 9,829,624	$ 19,186,036

Summary of significant accounting policies - Narrative (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Entity Location [Line Items]
Number of operating segments \| segment									2
Advertising expenses									$ 822,000	$ 3,566,000	$ 2,936,000
Cost of product revenue	$ 74,934	$ 91,937	$ 179,945	$ 83,934	$ 133,343	$ 148,756	$ 145,325	$ 79,106	430,750	506,530	662,747
Shipping and handling
Entity Location [Line Items]
Cost of product revenue									$ 98,000	$ 261,000	$ 170,000
UNITED STATES
Entity Location [Line Items]
Number of geographic segments \| segment									1

Summary of significant accounting policies - Depreciation over estimated useful life (Details)	12 Months Ended
	Dec. 31, 2018
Computers and computer equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Laboratory equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Manufacturing equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Minimum \| Website development costs
Property, Plant and Equipment [Line Items]
Estimated useful life	1 year
Maximum \| Website development costs
Property, Plant and Equipment [Line Items]
Estimated useful life	2 years

Summary of significant accounting policies - Reconciliation of cash, cash equivalents and restricted cash (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Cash and cash equivalents	$ 9,829,624	$ 19,186,036
Restricted cash, current	126,595	0
Restricted cash	0	126,595
Cash, cash equivalents and restricted cash shown on the condensed consolidated statement of cash flows	$ 9,956,219	$ 19,312,631	$ 22,542,635	$ 66,813,530

Revenue from contracts with customers (Details) - USD ($)	3 Months Ended								6 Months Ended		12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Jun. 18, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Increase to retained earnings due to adoption of Topic 606	$ (132,961,275)				$ (111,079,275)				$ (132,961,275)		$ (132,961,275)	$ (111,079,275)
Total revenue	163,067	$ 250,991	$ 245,502	$ 178,582	$ 282,828	$ 413,601	$ 335,523	$ 242,547			838,142	1,274,499	$ 1,010,663
Refund period									14 days	30 days
Discounts to customers											38,000	$ 278,000	$ 135,000
Difference between revenue guidance in effect before and after Topic 606 \| Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Increase to retained earnings due to adoption of Topic 606														$ 40,000
Decrease in deferred revenue														70,000
Decrease in deferred costs from product revenue														$ 30,000
Total revenue	$ (15,000)	$ (1,000)	$ (10,000)	$ (18,000)							$ (44,000)

Restricted cash (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash, current	$ 126,595	$ 0
Restricted cash	0	126,595
Letter of Credit
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash, current	$ 126,595
Restricted cash		$ 126,595

Fair value measurements (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 0	$ 14,129,723
U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		8,986,259
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		4,440,689
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		702,775
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	2,333,771	5,046,205
Total assets at fair value	2,333,771	19,175,928
Fair Value, Measurements, Recurring \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	2,333,771	5,046,205
Total assets at fair value	2,333,771	5,046,205
Fair Value, Measurements, Recurring \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Total assets at fair value	0	14,129,723
Fair Value, Measurements, Recurring \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Total assets at fair value	$ 0	0
Fair Value, Measurements, Recurring \| U.S. government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		8,986,259
Fair Value, Measurements, Recurring \| U.S. government agency securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		0
Fair Value, Measurements, Recurring \| U.S. government agency securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		8,986,259
Fair Value, Measurements, Recurring \| U.S. government agency securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		0
Fair Value, Measurements, Recurring \| Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		4,440,689
Fair Value, Measurements, Recurring \| Commercial paper \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		0
Fair Value, Measurements, Recurring \| Commercial paper \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		4,440,689
Fair Value, Measurements, Recurring \| Commercial paper \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		0
Fair Value, Measurements, Recurring \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		702,775
Fair Value, Measurements, Recurring \| Corporate debt securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		0
Fair Value, Measurements, Recurring \| Corporate debt securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		702,775
Fair Value, Measurements, Recurring \| Corporate debt securities \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities		$ 0

Cash equivalents and marketable securities (Details)	12 Months Ended
Cash equivalents and marketable securities (Details)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) security
Cash and Cash Equivalents [Abstract]
Realized gains on marketable securities	$ 0	$ 0
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		14,130,970
Unrealized Gains		38
Unrealized Losses		(1,285)
Fair Value	$ 0	$ 14,129,723
Number of debt securities held \| security		6
Aggregate fair value of securities in an unrealized loss position		$ 8,191,315
Number of debt securities in a significant unrealized loss position \| security		0
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		$ 8,987,254
Unrealized Gains		38
Unrealized Losses		(1,033)
Fair Value		8,986,259
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		4,440,689
Unrealized Gains		0
Unrealized Losses		0
Fair Value		4,440,689
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		703,027
Unrealized Gains		0
Unrealized Losses		(252)
Fair Value		$ 702,775

Inventory (Details) - USD ($)	12 Months Ended
Inventory (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 7,247	$ 17,411
Finished goods	179,673	414,480
Total inventory	186,920	431,891
Write-off of inventory	$ 85,000	$ 42,000	$ 282,000

Property and equipment, net (Details) - USD ($)	12 Months Ended
Property and equipment, net (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 875,555	$ 953,923
Accumulated depreciation	(801,095)	(622,883)
Property and equipment, net	74,460	331,040
Depreciation expense	228,158	324,548	$ 277,231
Property and equipment disposals	28,422
Proceeds from sales of property and equipment	4,805	5,344	$ 5,255
Loss on disposal of property and equipment	23,617
Manufacturing equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	421,999	421,999
Computers and computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	275,670	311,847
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	177,886	177,886
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	0	13,368
Capital in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 0	$ 28,823

Accrued expenses and other current liabilities - Schedule of accrued expenses and other current liabilities (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Payroll and employee-related costs	$ 417,997	$ 874,246
Professional fees	269,544	227,980
Restructuring-related costs	68,593	0
Consumer product-related costs	5,360	107,595
Research and development costs	2,846	2,502,400
Total	$ 764,340	$ 3,712,221

Accrued expenses and other current liabilities - Narrative (Details) - USD ($)		1 Months Ended	9 Months Ended	12 Months Ended
	Jan. 03, 2019	Jun. 30, 2018	Sep. 30, 2018	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Decrease in company workforce (as a percent)		60.00%	60.00%
Restructuring charges				$ 1,366,000
Corporate restructuring plan
Restructuring Cost and Reserve [Line Items]
Cash retention bonus cost				205,000
Severance benefits				186,000
Cash Retention Bonuses Payable				1,006,000
Cash retention bonuses payable upon change in control				603,000
Cash retention bonuses payable upon employees in good standing				403,000
Severance benefits payable upon change in control and termination without cause				928,000
Ongoing termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges				1,037,000
One-time termination benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges				100,000
Retention benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges				214,417
Other restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring charges				14,995
Scenario, forecast
Restructuring Cost and Reserve [Line Items]
Severance benefits payable upon change in control and termination without cause	$ 928,000
Restructuring charges incurred upon change in control	$ 603,000
Minimum
Restructuring Cost and Reserve [Line Items]
Restructuring charges				1,769,000
Maximum
Restructuring Cost and Reserve [Line Items]
Restructuring charges				3,354,000
Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring charges				968,000
Selling, general and administrative expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges				398,000
Consumer Operations
Restructuring Cost and Reserve [Line Items]
Restructuring charges				81,000
Consumer Operations \| Maximum
Restructuring Cost and Reserve [Line Items]
Restructuring charges				113,000
Drug Development
Restructuring Cost and Reserve [Line Items]
Restructuring charges				968,000
Drug Development \| Maximum
Restructuring Cost and Reserve [Line Items]
Restructuring charges				1,036,000
Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges				317,000
Corporate \| Maximum
Restructuring Cost and Reserve [Line Items]
Restructuring charges				$ 2,205,000

Accrued expenses and other current liabilities - Schedule of restructuring and related costs (Details)	12 Months Ended
	Dec. 31, 2018 USD ($)
Restructuring Reserve [Roll Forward]
Accrued restructuring balance as of December 31, 2017	$ 0
Restructuring charges	1,366,000
Payments	(1,297,207)
Accrued restructuring balance as of December 31, 2018	68,593
Employee severance
Restructuring Reserve [Roll Forward]
Restructuring charges	1,136,388
Retention benefits
Restructuring Reserve [Roll Forward]
Restructuring charges	214,417
Other restructuring
Restructuring Reserve [Roll Forward]
Restructuring charges	$ 14,995

Commitments and contingencies (Details) - USD ($)	1 Months Ended		12 Months Ended
Commitments and contingencies (Details) - USD ($)	Jan. 31, 2019	Mar. 31, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Operating Leased Assets [Line Items]
Future minimum lease payments			$ 2,350
Rent expense			351,000	$ 522,000	$ 337,000
Percent of gross sales due to related parties		2.00%				2.00%
Royalty expense			17,000	25,000	20,000
Royalties payable			$ 3,000	$ 3,000	$ 4,000
Subsequent Event
Operating Leased Assets [Line Items]
Royalty agreement term	20 years
Subsequent Event \| Royalty agreement first ten years
Operating Leased Assets [Line Items]
Percent of gross sales due to related parties	2.00%
Subsequent Event \| Royalty agreement next ten years
Operating Leased Assets [Line Items]
Percent of gross sales due to related parties	1.00%

Common stock - Narrative (Details)		1 Months Ended		12 Months Ended
Common stock - Narrative (Details)	Jun. 14, 2018	Apr. 30, 2014 shares	Mar. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) vote $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) shares
Class of Stock [Line Items]
Common stock, shares authorized (shares)				100,000,000	100,000,000
Common stock, par value (in usd per share) \| $ / shares				$ 0.0001	$ 0.0001
Common stock, number of votes per share \| vote				1
Restricted common stock, vesting period	48 months
Common stock purchased under the 2015 ESPP (shares)				0
Unvested restricted common stock
Class of Stock [Line Items]
Restricted common stock, shares sold		867,314	4,553,415
Restricted common stock, price per share (in usd per share) \| $ / shares			$ 0.0004
Proceeds from sale of restricted common stock to founders \| $			$ 1,950
Restricted common stock, fair value of shares vested \| $				$ 725,000	$ 3,840,000	$ 9,646,000
Restricted common stock, issued (shares)				0
Unvested restricted common stock \| Vests upon issuance
Class of Stock [Line Items]
Restricted common stock, percent vested				25.00%
Unvested restricted common stock \| Vests ratably over four years
Class of Stock [Line Items]
Restricted common stock, percent vested				75.00%
Restricted common stock, vesting period				4 years
Non-employee consultants and advisers \| Unvested restricted common stock
Class of Stock [Line Items]
Restricted common stock, fair value of shares vested \| $				$ 9,000	$ 22,000	$ 71,000
Restricted common stock, issued (shares)				0	0	18,194
Restricted common stock, shares outstanding				16,110

Common stock - Restricted common stock activity (Details) - Unvested restricted common stock - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning balance, unvested (shares)	169,654
Issued (shares)	0
Vested (shares)	(169,654)
Forfeited (shares)	0
Ending balance, unvested (shares)	0	169,654
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning balance, unvested, weighted average grant date fair value (in usd per share)	$ 0.10
Issued, weighted average grant date fair value (in usd per share)	0.00
Vested, weighted average grant date fair value (in usd per share)	0.10
Forfeited, weighted average grant date fair value (in usd per share)	0.00
Ending balance, unvested, weighted average grant date fair value (in usd per share)	$ 0.00	$ 0.10
Non-employee consultants and advisers
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning balance, unvested (shares)	5,334
Issued (shares)	0	0	18,194
Vested (shares)	(3,250)
Forfeited (shares)	0
Ending balance, unvested (shares)	2,084	5,334
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning balance, unvested, weighted average grant date fair value (in usd per share)	$ 10.51
Issued, weighted average grant date fair value (in usd per share)	0.00
Vested, weighted average grant date fair value (in usd per share)	10.16
Forfeited, weighted average grant date fair value (in usd per share)	0.00
Ending balance, unvested, weighted average grant date fair value (in usd per share)	$ 11.05	$ 10.51

Common stock - Shares reserved for future issuance (Details) - shares	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Stock-based compensation awards (shares)	4,061,397	3,439,820
Employee stock purchase plan (shares)	713,996	534,274
Total (shares)	4,777,477	4,149,082
Unvested restricted common stock
Class of Stock [Line Items]
Vesting of restricted common stock (shares)	2,084	174,988

Stock-based compensation - Narrative (Details)		1 Months Ended	12 Months Ended
Stock-based compensation - Narrative (Details)	Jun. 14, 2018 employee shares	Jun. 30, 2018 adviser employee shares	Dec. 31, 2018 USD ($) employee $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, vesting period	48 months
Stock-based compensation expense \| $			$ 1,939,611	$ 4,219,165	$ 6,572,963
Shares granted (shares)	654,544		1,517,544	1,059,500	763,320
Shares granted, weighted-average grant date fair value (in usd per share) \| $ / shares			$ 1.95	$ 2.80	$ 6.35
Shares exercised (shares)			97,310	1,576	8,516
Shares exercised, weighted average exercise price (in usd per share) \| $ / shares			$ 1.21	$ 1.67	$ 2.59
Stock options exercised, intrinsic value \| $			$ 349,974	$ 2,606	$ 64,302
Unrecognized compensation cost \| $			$ 2,160,000
Unrecognized compensation cost, recognition period			2 years 8 months 27 days
Option awards held (shares)			2,320,981	2,580,491
Number of employees granted options \| employee	7
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Post termination exercisability extended period	1 year
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Post termination exercisability extended period	3 years
Non-employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted to non-employee consultants and members of the Scientific Advisory Board (shares)			30,000	0	14,670
Stock options, vesting period			4 years
Stock options, contractual term			10 years
Stock-based compensation expense \| $			$ 124,000	$ 201,000	$ 370,000
Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, contractual term			10 years
Options to purchase common stock \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, vesting period			1 year
Options to purchase common stock \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, vesting period			4 years
2015 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares remaining available for grant of stock awards (shares)			1,740,416
Employee stock option, one-year post termination exercisability
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Post termination exercisability period		3 months
Option awards held (shares)		877,137
Number of employees holding options \| employee		6	6
Number of advisers holding options \| adviser		1
Post termination exercisability extended period		1 year
Number of employees terminated \| employee			3
Employee stock option, three-year post termination exercisability
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Post termination exercisability period		3 months
Option awards held (shares)		500,000
Number of employees holding options \| employee		1
Post termination exercisability extended period		3 years
Selling, general and administrative expenses \| Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense \| $					$ 285,000

Stock-based compensation - Summary of stock option activity (Details) - USD ($)		12 Months Ended
	Jun. 14, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares
Shares outstanding, beginning balance (shares)		2,580,491
Shares granted (shares)	654,544	1,517,544	1,059,500	763,320
Shares exercised (shares)		(97,310)	(1,576)	(8,516)
Shares forfeited (shares)		(859,543)
Shares expired (shares)		(820,201)
Shares outstanding, ending balance (shares)		2,320,981	2,580,491
Shares exercisable (shares)		1,149,927
Shares vested or expected to vest (shares)		2,320,981
Weighted-Average Exercise Price
Shares outstanding, beginning balance, weighted average exercise price (in usd per share)		$ 6.65
Shares granted, weighted average exercise price (in usd per share)		2.74
Shares exercised, weighted average exercise price (in usd per share)		1.21	$ 1.67	$ 2.59
Shares forfeited, weighted average exercise price (in usd per share)		5.76
Shares expired, weighted average exercise price (in usd per share)		8.19
Shares outstanding, ending balance, weighted average exercise price (in usd per share)		4.10	$ 6.65
Shares exercisable, weighted average exercise price (in usd per share)		5.53
Shares vested or expected to vest, weighted average exercise price (in usd per share)		$ 4.10
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding, weighted average remaining contractual term		7 years 7 months 10 days	7 years 6 months 18 days
Exercisable, weighted average remaining contractual term		6 years 26 days
Vested or expected to vest, weighted average remaining contractual term		7 years 6 months 11 days
Outstanding, aggregate intrinsic value		$ 0	$ 803,600
Exercisable, aggregate intrinsic value		0
Vested or expected to vest, aggregate intrinsic value		$ 0

Stock-based compensation - Schedule of fair value assumptions (Details) - Options to purchase common stock	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, minimum	2.45%	1.83%	1.23%
Risk-free interest rate, maximum	2.91%	2.40%	2.40%
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (as a percent)	81.56%	73.87%	71.01%
Expected term	5 years 3 months 18 days	5 years 3 months 18 days	5 years 3 months 18 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility (as a percent)	82.41%	81.04%	74.20%
Expected term	10 years	9 years 6 months	10 years

Stock-based compensation - Summary of stock-based compensation expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share-Based Compensation Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,939,611	$ 4,219,165	$ 6,572,963
Research and development
Employee Service Share-Based Compensation Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	705,687	1,545,737	2,435,565
Selling, general and administrative
Employee Service Share-Based Compensation Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,233,924	$ 2,673,428	$ 4,137,398

Income taxes - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Income taxes - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Increase (decrease) in valuation allowance	$ 5,250
Payroll tax credit	156	$ 22
U.S. Federal
Income Taxes [Line Items]
Net operating loss carryforward	110,900
Research and development tax credit carryforwards	1,800
U.S. State
Income Taxes [Line Items]
Net operating loss carryforward	105,400
Operating loss carryforward tax affected	8,400
Research and development tax credit carryforwards	$ 570

Income taxes - Schedule of effective income tax rate reconciliation (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal income tax expense at statutory rate	21.00%	35.00%	35.00%
State income tax, net of federal benefit (as a percent)	6.00%	5.00%	5.00%
Permanent differences (as a percent)	(0.10%)	(0.70%)	0.00%
Stock-based compensation (as a percent)	(2.80%)	(1.90%)	(2.60%)
Research credits (as a percent)	2.60%	2.20%	1.90%
Other, net (as a percent)	(1.60%)	(1.30%)	(0.10%)
Payroll tax credit election (as a percent)	(1.10%)	(0.70%)	0.00%
Change in valuation allowance (as a percent)	(24.00%)	(1.10%)	(39.20%)
Deferred rate change	0.00%	(36.50%)	0.00%
Effective tax rate	0.00%	0.00%	0.00%

Income taxes - Schedule of deferred tax assets and liabilities (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
U.S. and state net operating loss carryforwards	$ 29,902,019	$ 24,744,841
Accruals and other temporary differences	336,229	202,301
Amortization	50,688	35,783
Stock-based compensation	1,220,546	1,591,131
Tax credit carryforward	2,277,428	1,964,189
Total deferred tax assets	33,786,910	28,538,245
Less valuation allowance	(33,786,910)	(28,533,755)
Deferred tax assets	0	4,490
Deferred tax liabilities:
Stock-based compensation	0	(4,490)
Deferred tax liabilities	0	(4,490)
Net deferred tax assets	$ 0	$ 0

Net loss per share (Details) - shares	12 Months Ended
Net loss per share (Details) - shares	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)	2,323,065	2,755,479	3,353,042
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)	2,320,981	2,580,491	2,156,250
Unvested restricted common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)	2,084	174,988	1,196,792

Segment Information (Details)	3 Months Ended								12 Months Ended
Segment Information (Details)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Segment Reporting [Abstract]
Number of reportable segments \| segment									2
Segment Reporting Information [Line Items]
Total revenue	$ 163,067	$ 250,991	$ 245,502	$ 178,582	$ 282,828	$ 413,601	$ 335,523	$ 242,547	$ 838,142	$ 1,274,499	$ 1,010,663
Loss from operations	2,021,139	2,666,583	9,103,681	8,282,820	8,092,960	9,409,452	8,876,965	8,346,249	22,074,223	34,725,626	39,886,232
Interest income, net	$ 12,394	$ 28,210	$ 51,809	$ 59,593	$ 64,429	$ 77,339	$ 72,342	$ 77,854	152,006	291,964	393,109
Operating Segments \| Consumer Operations
Segment Reporting Information [Line Items]
Total revenue									838,142	1,274,499	1,010,663
Loss from operations									1,975,792	8,877,330	10,023,137
Interest income, net									0	0	0
Operating Segments \| Drug Development
Segment Reporting Information [Line Items]
Total revenue									0	0	0
Loss from operations									11,887,108	16,715,752	19,620,338
Interest income, net									0	0	0
Corporate
Segment Reporting Information [Line Items]
Total revenue									0	0	0
Loss from operations									8,211,323	9,132,544	10,242,757
Interest income, net									$ 152,006	$ 291,964	$ 393,109

Related parties (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
Related parties (Details) - USD ($) $ in Thousands	Jan. 31, 2019	Mar. 31, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Related Party Transaction [Line Items]
Percent of gross sales due to related parties		2.00%				2.00%
Royalty expense			$ 17	$ 25	$ 20
Royalties payable			$ 3	$ 3	4
Affiliated entity
Related Party Transaction [Line Items]
License fees received					$ 32
Subsequent Event
Related Party Transaction [Line Items]
Royalty agreement term	20 years
Subsequent Event \| Royalty agreement first ten years
Related Party Transaction [Line Items]
Percent of gross sales due to related parties	2.00%
Subsequent Event \| Royalty agreement next ten years
Related Party Transaction [Line Items]
Percent of gross sales due to related parties	1.00%

Quarterly financial information (unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Total revenue	$ 163,067	$ 250,991	$ 245,502	$ 178,582	$ 282,828	$ 413,601	$ 335,523	$ 242,547	$ 838,142	$ 1,274,499	$ 1,010,663
Costs and expenses:
Cost of product revenue	74,934	91,937	179,945	83,934	133,343	148,756	145,325	79,106	430,750	506,530	662,747
Research and development	187,759	865,765	6,174,589	4,680,181	4,259,357	4,739,360	4,076,220	3,914,974	11,908,294	16,989,911	20,378,161
Selling, general and administrative	1,921,513	1,959,872	2,994,649	3,697,287	3,983,088	4,934,937	4,990,943	4,594,716	10,573,321	18,503,684	19,855,987
Total costs and expenses	2,184,206	2,917,574	9,349,183	8,461,402	8,375,788	9,823,053	9,212,488	8,588,796	22,912,365	36,000,125	40,896,895
Loss from operations	(2,021,139)	(2,666,583)	(9,103,681)	(8,282,820)	(8,092,960)	(9,409,452)	(8,876,965)	(8,346,249)	(22,074,223)	(34,725,626)	(39,886,232)
Interest income, net	12,394	28,210	51,809	59,593	64,429	77,339	72,342	77,854	152,006	291,964	393,109
Net loss	$ (2,008,745)	$ (2,638,373)	$ (9,051,872)	$ (8,223,227)	$ (8,028,531)	$ (9,332,113)	$ (8,804,623)	$ (8,268,395)	$ (21,922,217)	$ (34,433,662)	$ (39,493,123)
Net loss per share attributable to common stockholders - basic and diluted (in usd per share)	$ (0.11)	$ (0.15)	$ (0.50)	$ (0.46)	$ (0.46)	$ (0.54)	$ (0.51)	$ (0.49)	$ (1.22)	$ (1.99)	$ (2.43)
Weighted-average number of common shares outstanding — basic and diluted (shares)	18,067,179	18,066,548	18,037,274	17,893,912	17,642,646	17,386,249	17,130,264	16,873,512	18,016,841	17,260,626	16,233,985
Net product revenue
Total revenue	$ 161,560	$ 247,284	$ 241,416	$ 176,255	$ 282,752	$ 407,241	$ 330,688	$ 240,292	$ 826,515	$ 1,260,973	$ 989,918
Other revenue
Total revenue	1,507	3,707	4,086	2,327	$ 76	$ 6,360	$ 4,835	$ 2,255	11,627	$ 13,526	$ 20,745
Accounting Standards Update 2014-09 \| Difference between revenue guidance in effect before and after Topic 606
Total revenue	$ (15,000)	$ (1,000)	$ (10,000)	$ (18,000)					$ (44,000)

Subsequent events (Details) - Subsequent Event $ / shares in Units, $ in Thousands	Jan. 03, 2019 USD ($) $ / shares shares
Subsequent Event [Line Items]
Value assigned	$ 10,500
Target net cash	$ 3,300
Rights distributed (shares) \| shares	1
Period to receive warrants to purchase shares	6 months 1 day
Period which warrants are exercisable	5 years
Termination fee payable	$ 350
Termination reimbursement Expense	200
Termination fee receivable	$ 1,000
Combined company
Subsequent Event [Line Items]
Ownership percentage	19.90%
Agreement and plan of merger
Subsequent Event [Line Items]
Exercise price, below threshold (shares) \| shares	849,610
Business Combination, Exercise Price \| $ / shares	$ 1.35
Exercise price, above threshold (shares) \| shares	1,447,426
Salarius
Subsequent Event [Line Items]
Value assigned	$ 36,600
Ownership percentage	80.10%
Preferred Stock
Subsequent Event [Line Items]
Target sale price	$ 7,000

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 40,217
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 40,217

Restricted cash	12 Months Ended
Restricted cash	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Restricted cash	Restricted cash As of December 31, 2018 and December 31, 2017, the Company had $126,595 of restricted cash in the form of a letter of credit. The Company maintained this letter of credit as a security deposit on the lease of its former corporate headquarters in Boston, Massachusetts that was set to expire on August 31, 2019. The Company terminated this lease on December 13, 2018 (see Note 10). The letter of credit was released, and the cash became unrestricted on January 4, 2019.

Preferred stock	12 Months Ended
Preferred stock	Dec. 31, 2018
Equity [Abstract]
Preferred stock	Preferred stock As of December 31, 2018, the Company is authorized to issue 10,000,000 shares of preferred stock ("Preferred Stock") with a par value of $0.0001 per share. The Company has not issued any shares of Preferred Stock as of December 31, 2018.