Axsome Therapeutics (AXSM) 10-K 12 Mar 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Mar. 06, 2020	Jun. 28, 2019
Document and Entity Information [Abstract]
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Entity Registrant Name	AXSOME THERAPEUTICS, INC.
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Interactive Data Current	Yes
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		37,075,422
Entity Public Float			$ 675
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0001579428
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash	$ 219,966,167	$ 13,968,742
Prepaid and other current assets	413,095	1,246,360
Total current assets	220,379,262	15,215,102
Equipment, net	30,623	51,832
Other assets	139,875	112,345
Total assets	220,549,760	15,379,279
Current liabilities:
Accounts payable	10,943,325	3,687,245
Accrued expenses and other current liabilities	10,949,128	3,843,299
Loan payable, current portion	2,602,292	3,291,394
Total current liabilities	24,494,745	10,821,938
Loan payable, long-term	17,332,626	3,619,420
Total liabilities	41,827,371	14,441,358
Stockholders' equity:
Preferred stock, $0.0001 par value per share (10,000,000 shares authorized, none issued and outstanding at December 31, 2019 and December 31, 2018, respectively)
Common stock, $0.0001 par value per share (150,000,000 shares authorized, 36,933,217 and 30,087,213 shares issued and outstanding at December 31, 2019 and December 31, 2018, respectively)	3,693	3,009
Additional paid-in capital	354,614,189	108,485,219
Accumulated deficit	(175,895,493)	(107,550,307)
Total stockholders' equity	178,722,389	937,921
Total liabilities and stockholders' equity	$ 220,549,760	$ 15,379,279

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	36,933,217	30,087,213
Common stock, shares outstanding	36,933,217	30,087,213

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating expenses:
Research and development	$ 53,647,067	$ 23,495,055	$ 19,957,616
General and administrative	13,598,030	9,351,522	7,206,691
Total operating expenses	67,245,097	32,846,577	27,164,307
Loss from operations	(67,245,097)	(32,846,577)	(27,164,307)
Interest and amortization of debt discount (expense)	(1,239,537)	(1,127,305)	(1,340,199)
Tax credit	139,448	217,418	207,114
Change in fair value of warrant liabilities		2,791,000	(646,000)
Net loss	$ (68,345,186)	$ (30,965,464)	$ (28,943,392)
Net loss per common share, basic and diluted	$ (2.01)	$ (1.15)	$ (1.27)
Weighted average common shares outstanding, basic and diluted	34,020,257	26,883,656	22,764,606

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($)	Common Stock	Additional paid-in capital	Accumulated deficit	Total
Beginning balance at Dec. 31, 2016	$ 1,916	$ 69,210,986	$ (47,641,451)	$ 21,571,451
Balance (in shares) at Dec. 31, 2016	19,158,417
Stock-based compensation		2,072,210		2,072,210
Exercise of warrants	$ 13	167,881		167,894
Exercise of warrants (in shares)	129,149
Issuance of common stock upon exercise of options	$ 9	316,710		316,719
Issuance of common stock upon exercise of options (in shares)	88,922
Issuance of common stock upon financing	$ 611	21,531,730		21,532,341
Issuance of common stock upon financing (in shares)	6,116,504
Net loss			(28,943,392)	(28,943,392)
Ending balance at Dec. 31, 2017	$ 2,549	93,299,517	(76,584,843)	16,717,223
Balance (in shares) at Dec. 31, 2017	25,492,992
Stock-based compensation		1,754,974		1,754,974
Exercise of warrants	$ 10	131,693		131,703
Exercise of warrants (in shares)	101,310
Issuance of common stock upon exercise of options	$ 29	380,293		380,322
Issuance of common stock upon exercise of options (in shares)	278,925
Issuance of warrants upon debt financing		37,842		37,842
Issuance of common stock upon financing	$ 421	12,880,900		12,881,321
Issuance of common stock upon financing (in shares)	4,213,986
Net loss			(30,965,464)	(30,965,464)
Ending balance at Dec. 31, 2018	$ 3,009	108,485,219	(107,550,307)	$ 937,921
Balance (in shares) at Dec. 31, 2018	30,087,213			30,087,213
Stock-based compensation		6,115,160		$ 6,115,160
Exercise of warrants	$ 10	249,826		249,836
Exercise of warrants (in shares)	97,541
Issuance of common stock upon exercise of options	$ 25	1,143,816		$ 1,143,841
Issuance of common stock upon exercise of options (in shares)	252,773			252,773
Issuance of warrants upon debt financing		387,000		$ 387,000
Issuance of common stock upon financing	$ 649	238,233,168		238,233,817
Issuance of common stock upon financing (in shares)	6,495,690
Net loss			(68,345,186)	(68,345,186)
Ending balance at Dec. 31, 2019	$ 3,693	$ 354,614,189	$ (175,895,493)	$ 178,722,389
Balance (in shares) at Dec. 31, 2019	36,933,217			36,933,217

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net loss	$ (68,345,186)	$ (30,965,464)	$ (28,943,392)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	6,115,160	1,754,974	2,072,210
Amortization of debt discount	649,993	375,635	470,521
Change in fair value of warrants		(2,791,000)	646,000
Depreciation	37,330	48,935	42,557
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	833,265	32,058	102,143
Other assets	(27,530)	75,607	(75,131)
Accounts payable	7,256,080	251,789	(645,717)
Accrued expenses and other current liabilities	7,105,829	1,163,765	(140,843)
Net cash used in operating activities	(46,375,059)	(30,053,701)	(26,471,652)
Cash flows from investing activities
Purchases of equipment	(16,121)	(32,696)	(9,898)
Net cash used in investing activities	(16,121)	(32,696)	(9,898)
Cash flows from financing activities
Payment of debt issuance costs		(25,997)
Procceds from issuance of common stock upon financing, net	238,233,817	12,881,321	23,677,341
Proceeds from issuance of term loan	20,000,000
Repayment of principal on term loan	(7,238,889)	(3,333,333)	(277,778)
Proceeds from issuance of common stock upon exercise of options	1,143,841	380,322	316,719
Proceeds issuance of common stock upon exercise of warrants	249,836	131,703	167,894
Net cash (used in) provided by financing activities	252,388,605	10,034,016	23,884,176
Net (decrease) increase in cash	205,997,425	(20,052,381)	(2,597,374)
Cash at beginning of period	13,968,742	34,021,123	36,618,497
Cash at end of period	219,966,167	13,968,742	34,021,123
Supplemental disclosures of cash flow information:
Interest paid	1,287,506	771,966	865,278
Supplemental disclosures of non-cash financing activity:
Establishment of warrant liabilities in connection with common stock issuance			$ 2,145,000
Issuance of warrants in connection with debt financing	$ 387,000	$ 37,842

Nature of Business and Basis of

Nature of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2019
Nature of Business and Basis of Presentation
Nature of Business and Basis of Presentation	Note 1. Axsome Therapeutics, Inc. (“Axsome” or the “Company”) is a clinical-stage biopharmaceutical company developing novel therapies for central nervous system (“CNS”) disorders for which there are limited treatment options. By focusing on this therapeutic area, the Company is addressing significant and growing markets where current treatment options are limited or inadequate. The Company’s core CNS portfolio includes five product candidates, AXS‑05, AXS-07, AXS-09, AXS-12, and AXS-14 which are being developed for multiple indications. The Company aims to become a fully integrated biopharmaceutical company that develops and commercializes differentiated therapies that expand the treatment options available to caregivers and improve the lives of patients living with CNS disorders. The Company was incorporated on January 12, 2012 in the State of Delaware and now has operations in the United States and Australia. The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and include all adjustments necessary for the fair presentation of the Company’s financial position for the periods presented. The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All material intercompany accounts and transactions have been eliminated during the consolidation process. Amendment to Certificate of Incorporation In connection with the completion of the Company’s initial public offering (“IPO”) on November 24, 2015, the Company’s stockholders approved an amended and restated Certificate of Incorporation, in which its authorized capital stock consists of 150,000,000 shares of common stock, par value $0.0001 per share, and 10,000,000 shares of preferred stock, par value $0.0001 per share. Liquidity and Capital Resources The Company has incurred operating losses since its inception, and expects to continue to incur operating losses for the foreseeable future and may never become profitable. As of December 31, 2019, the Company had an accumulated deficit of $175.9 million. The Company’s primary sources of cash have been proceeds from the issuance and sale of its common stock in public offerings. The Company has not yet commercialized any of its product candidates and cannot be sure if it will ever be able to do so. Even if the Company commercializes one or more of its product candidates, it may not become profitable. The Company’s ability to achieve profitability depends on a number of factors, including its ability to obtain regulatory approval for its product candidates, successfully complete any post-approval regulatory obligations and successfully commercialize its product candidates alone or in partnership. The Company may continue to incur substantial operating losses even if it begins to generate revenues from its product candidates. The Company believes its existing cash will be sufficient to fund its anticipated operating cash requirements for at least twelve months following the date of this filing. The actual amount of cash that the Company will need to operate is subject to many factors, including, but not limited to, the timing, design and conduct of clinical trials for its product candidates along with cost to commercialize its product candidates. The Company is dependent upon future financing to provide the cash necessary to execute its current operations, including the commercialization of any of its product candidates. The Company’s common stock is listed on the Nasdaq Global Market and trades under the symbol “AXSM”.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2. Significant Risks and Uncertainties The Company’s operations are subject to a number of factors that can affect its operating results and financial condition. Such factors include, but are not limited to: the results of clinical testing and trial activities of the Company’s product candidates; the Company’s ability to obtain regulatory approval to market its products, if approved; competition from products manufactured and sold or being developed by other companies; the price of, and demand for, Company products, if approved; the Company’s ability to negotiate favorable licensing or other manufacturing and marketing agreements for its products, if approved; and the Company’s ability to raise additional financing. If the Company does not successfully commercialize any of its product candidates, it will be unable to generate recurring product revenue or achieve and maintain profitability. Use of Estimates Management considers many factors in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements if these results differ from historical experience, or other assumptions do not turn out to be substantially accurate, even if such assumptions are reasonable when made. In preparing these financial statements, management used significant estimates in the following areas, among others: stock‑based compensation expense; the determination of the fair value of the warrants; the accounting for research and development costs; and the recoverability of the Company’s net deferred tax assets and related valuation allowance. Foreign Currency Translation Expenses denominated in foreign currency are translated into U.S. dollars at the exchange rate on the date the expense is incurred. Assets and liabilities of foreign operations are translated at period-end exchange rates. The effect of exchange rate fluctuations on translating foreign currency into U.S. dollars is included in the Statements of Operations and is not material to the Company’s financial statements. Segment and Geographic Information Operating segments are defined as components of an enterprise for 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 in assessing performance. The Company views its operations and manages its business as one operating segment, which is the business of developing novel therapies for the management of CNS disorders. Cash Equivalents The Company considers all highly liquid investments that have maturities of three months or less when acquired to be cash equivalents. Cash equivalents are valued at cost, which approximates their fair value. There were no cash equivalents at December 31, 2019 and 2018. Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash. The Company maintains its cash at financial institutions, which at times, exceed federally insured limits. At December 31, 2019, the majority of the Company’s cash was held by one financial institution and the amount on deposit was in excess of Federal Deposit Insurance Corporation insurance limits. The Company has not recognized any losses from credit risks on such accounts since inception. The Company believes it is not exposed to significant credit risk on cash. Fair Value of Financial Instruments Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. Assets and liabilities that are measured at fair value are reported using a three‑level fair value hierarchy that prioritizes the inputs used to measure fair value. This hierarchy maximizes the use of observable inputs and minimizes the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1 —Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 —Inputs other than quoted prices in active markets that are observable for the asset or liability, either directly or indirectly. Level 3 —Inputs that are unobservable for the asset or liability. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying amounts reported in the accompanying consolidated financial statements for accounts payable and accrued expenses approximate their respective fair values due to their short‑term maturities. Debt Issuance Costs The Company incurred third‑party costs in connection with the Company’s term loans as described in Note 6 – Loan and Security Agreement. These costs are classified on the consolidated balance sheet as a direct deduction from the debt liability. The Company amortizes these costs over the term of its debt agreements as interest expense in the consolidated statement of operations. Equipment Equipment consists primarily of computer equipment and is recorded at cost. Equipment is depreciated on a straight‑line basis over its estimated useful life, which the Company estimates to be three years. When equipment is sold or otherwise disposed of, the cost and related accumulated depreciation are removed from the accounts and the resulting gain or loss is included in operating expenses. Research and Development Costs Research and development expenses primarily consist of costs incurred in performing research and development activities, including preclinical studies, clinical trials, manufacturing costs, employee salaries and benefits, stock‑based compensation expense, contract services, including external research and development expenses incurred under arrangements with third parties, such as contract research organizations (“CROs”), facilities costs, overhead costs, depreciation, and other related costs. Generally, research and development costs are expensed as incurred. Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and amortized over the period that the goods are delivered or the related services are performed, subject to an assessment of recoverability. The Company makes estimates of costs incurred in relation to external CROs, and clinical site costs. The Company analyzes the progress of clinical trials, including levels of patient enrollment, invoices received and contracted costs when evaluating the adequacy of the amount expensed and the related prepaid asset and accrued liability. Significant judgments and estimates must be made and used in determining the accrued balance and expense in any accounting period. The Company reviews and accrues CRO expenses and clinical trial study expenses based on work performed and relies upon estimates of those costs applicable to the stage of completion of a study. Accrued CRO costs are subject to revisions as such trials progress to completion. Revisions are charged to expense in the period in which the facts that give rise to the revision become known. With respect to clinical site costs, the financial terms of these agreements are subject to negotiation and vary from contract to contract. Payments under these contracts may be uneven, and depend on factors such as the achievement of certain events, the successful recruitment of patients, the completion of portions of the clinical trial or similar conditions. The objective of our policy is to match the recording of expenses in our financial statements to the actual services received and efforts expended. As such, expense accruals related to clinical site costs are recognized based on our estimate of the degree of completion of the event or events specified in the specific clinical study or trial contract. Income Taxes Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to the differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, operating losses, and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not to be sustained upon examination based on the technical merits of the position as well as consideration of the available facts and circumstances. 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. As of December 31, 2019 and 2018, the Company does not believe any material uncertain tax positions are present. In the event the Company determines that accrual of interest or penalties are necessary in the future, the amount will be presented as a component of income tax expense. Stock‑Based Compensation For stock options issued, the Company estimates the grant date fair value of each option using the Black‑Scholes option pricing model. The Black-Scholes model takes into account the expected volatility of the Company’s common stock, the risk-free interest rate, the estimated life of the option, the closing market price of the Company’s common stock and the exercise price. The estimates utilized in the Black-Scholes calculation involve inherent uncertainties and the application of management judgment. In addition, the Company recognizes expense for equity award forfeitures as they occur. For awards subject to service-based vesting conditions, the Company recognizes stock-based compensation expense on a straight-line basis over the requisite service period, which is generally the vesting term. For awards subject to performance-based vesting conditions, the Company recognizes stock-based compensation expense using the accelerated attribution method when it is probable that the performance condition will be achieved. The expense related to the stock-based compensation is recorded within the financial statement line item the grantee’s cash compensation is recorded in . The Company’s policy upon exercise of stock options is that shares will be issued as new shares drawing on the Company’s 2015 Omnibus Incentive Compensation Plan share pool that was adopted by the stockholders in November 2015. Tax Credit The tax credit represents the receipt by Axsome Therapeutics Australia PTY, LTD, the Company’s Australian subsidiary, of the Australia Tax Incentive Credit, related to the Company’s research and development expenses incurred for its product candidates. These expenses were incurred in prior periods and therefore the grant income was recorded when the funds were received. Basic and Diluted Net Loss per Common Share Basic net loss per share of common stock is computed by dividing net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as convertible notes, warrants, and stock options, which would result in the issuance of incremental shares of common stock. As the impact of these items is anti‑dilutive during periods of net loss, there was no difference between basic and diluted net loss per share of common stock for the years ended December 31, 2019, 2018, and 2017. Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842), which supersedes FASB Topic 840, Leases (Topic 840), requires that assets and liabilities arising under leases be recognized on the balance sheet as well as additional quantitative and qualitative disclosures that provide the amount, timing, and uncertainty of cash flows related to lease agreements. In July 2018, the FASB also issued ASU No. 2018-11, Leases (Topic 842), which provides (1) optional transition method that entities can use when adopting the standard and (2) a practical expedient that permits lessors to not separate nonlease components from the associated lease component if certain conditions are met. The standard is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted upon issuance. The Company elected to use the transition method approved by the FASB in accordance with ASU No. 2018-11, Leases, which allows companies to apply the provisions of the new leasing standard as of January 1, 2019, without adjusting the comparative periods presented by recognizing a cumulative-effect adjustment to the opening balance of retained earnings. The Company applied a policy election to exclude short-term leases from balance sheet recognition and also elected certain practical expedients at adoption. As permitted under these expedients, the Company did not reassess whether existing contracts are or contain leases, the lease classification for any existing leases, initial direct costs for any existing lease and whether existing land easements and rights of way, that were not previously accounted for as leases, are or contain a lease. The Company has adopted this guidance effective January 1, 2019. The Company evaluated its contracts and concluded that the contracts are not leases and do not contain a lease and the adoption of this guidance did not impact its financial statements. In July 2018, the FASB issued ASU No. 2018-09, Codification Improvements , which provides technical corrections, clarifications, and other improvements to several topics in the FASB Accounting Standard Codification. The transition and effective date guidance is based on the facts and circumstances of each amendment. Some of the amendments do not require transition guidance and were effective upon issuance of the ASU. Amendments that do not have transition guidance are effective for annual periods beginning after December 15, 2018. The Company has adopted this guidance effective January 1, 2019 and the adoption of the guidance did not have a material impact on the Company’s financial statements. 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 , which modifies, removes and adds certain disclosure requirements on fair value measurements based on the FASB Concepts Statement, Conceptual Framework for Financial Reporting-Chapter 8: Notes to the Financial Statements. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those years. The Company has adopted this guidance effective January 1, 2019 and the adoption of the guidance did not have a material impact on the Company’s financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12). The new standard simplifies the accounting for income taxes by removing exceptions to the incremental approach for intraperiod tax allocation when there is a loss from continuing operations and income or a gain from other items, to the requirement to recognize a deferred tax liability for equity method investments when a foreign subsidiary becomes an equity method investment, to the ability not to recognize a deferred tax liability for a foreign subsidiary when a foreign equity method investment becomes a subsidiary, and to the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. In addition, the standard requires that an entity recognize a franchise tax that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax, evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction, reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date, and specifying that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements, however, an entity may elect to do so (on an entity-by-entity basis) for a legal entity that is both not subject to tax and disregarded by the taxing authority. ASU 2019-12 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2020. Early adoption is permitted, including adoption in an interim period. The Company is currently evaluating the expected impact of this standard, but does not expect it to have a material impact on its consolidated financial statements upon adoption.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2019
Fair Value Measurements
Fair Value Measurements	Note 3. 2017 Warrants associated with Registered Direct Offering In connection with the Company’s 2017 Registered Direct Offering, the Company issued common stock warrants (“Common Warrants”) to certain investors to purchase an aggregate of 1,783,587 shares of its common stock. The Common Warrants were exercisable at $5.25 per share and expired on December 11, 2018. Additionally, as part of the 2017 Registered Direct Offering, the Company issued warrants (the “Placement Agent Warrants’) to certain investors affiliated with H.C. Wainwright & Co., LLC, the placement agent in the 2017 Registered Direct Offering to purchase an aggregate of 107,015 shares of its common stock. The Placement Agent Warrants were exercisable at $6.6562 and expired on December 11, 2018. The Common Warrants and Placement Agent Warrants (collectively the “2017 Warrants”) were analyzed and it was determined that they required liability treatment. Under ASC 815 Derivatives and Hedging (“ASC 815”), registered common stock warrants that require the issuance of registered shares upon exercise and do not expressly preclude an implied right to cash settlement are accounted for as derivative liabilities. The fair value of the Common Warrants at December 4, 2017, the date these warrants were issued, and December 31, 2017 were determined to be approximately $2,064,000 and $2,683,000, respectively, as calculated using Black-Scholes with the following assumptions: (1) stock price of $5.00 and $5.60, respectively; (2) a risk-free rate of 1.66% and 1.76%, respectively; and (3) an expected volatility of 61% and 62%, respectively. The fair value of the Common Warrants were reported as a warrant liability on the balance sheet and the change in the fair value between December 4, 2017 and December 31, 2017 is reported as a change in fair value of the warrant liability on the statement of operations. The fair value of the Placement Agent Warrants at December 4, 2017, the date these warrants were issued, and December 31, 2017 were determined to be approximately $81,000 and $108,000, respectively, as calculated using Black-Scholes with the following assumptions: (1) stock price of $5.00 and $5.60, respectively; (2) a risk-free rate of 1.66% and 1.76%, respectively; and (3) an expected volatility of 61% and 62%, respectively. The fair value of the Placement Agent Warrants were reported as a warrant liability on the balance sheet and the change in the fair value between December 4, 2017 and December 31, 2017 is reported as a change in fair value of the warrant liability on the statement of operations. The 2017 Warrants associated with 2017 Registered Direct Offering expired on December 11, 2018, and therefore, the warrant liability was zero as of December 31, 2018. There were no financial liabilities measured at fair value on a recurring basis as of December 31, 2019.

Net Loss per Common Share

Net Loss per Common Share	12 Months Ended
	Dec. 31, 2019
Net Loss per Common Share
Net Loss per Common Share	Note 4. The following table sets forth the computation of basic and diluted net loss per common share: Year ended December 31, 2019 2018 2017 Basic and diluted net loss per common share: Net loss $ (68,345,186) $ (30,965,464) $ (28,943,392) Weighted average common shares outstanding—basic and diluted 34,020,257 26,883,656 22,764,606 Net loss per common share—basic and diluted $ (2.01) $ (1.15) $ (1.27) The following potentially dilutive securities outstanding at December 31, 2019, 2018, and 2017 have been excluded from the computation of diluted weighted average shares outstanding, as they would be anti‑dilutive: December 31, 2019 2018 2017 Stock options 3,458,447 2,291,163 2,315,638 Warrants 69,656 123,037 2,099,199 Total 3,528,103 2,414,200 4,414,837

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2019
Accrued Expenses and Other Current Liabilities
Accrued Expenses and Other Current Liabilities	Note 5. At December 31, 2019 and 2018, accrued expenses consisted of the following: December 31, 2019 2018 Research and development $ 8,209,594 $ 2,266,285 Accrued compensation 2,056,356 1,051,401 Other 683,178 525,613 Total $ 10,949,128 $ 3,843,299

Loan and Security Agreement

Loan and Security Agreement	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Loan and Security Agreement	Note 6. Current Term Loan 2019 Term Loan In March 2019, the Company entered into a $24.0 million growth capital term loan facility (the “2019 Term Loan”) with Silicon Valley Bank (“SVB”) and WestRiver Innovation Lending Fund VIII, L.P (“WestRiver”). The two-tranche loan agreement consists of an initial $20.0 million tranche (the “Term A Loan Advance”), which was funded upon closing, with the remaining $4.0 million (the “Term B Loan Advance”) initially available to be drawn, at the Company’s option, subject to the achievement of positive data, on or prior to August 15, 2019 (which was extended to December 31, 2019, in connection with the First Amendment to the 2019 Term Loan, as discussed below), with respect to the Company’s ongoing Phase 2 clinical trial for AXS-12 in narcolepsy, sufficient to submit a Phase 3 protocol to FDA, provided that the Company has not received any objections from the FDA within thirty days after submission of such Phase 3 protocol (the “Milestone Event”). A portion of the first tranche was used to satisfy the Company’s existing obligations under the 2016 Amended Term Loan (as defined below) with SVB, which consisted of $5.6 million in outstanding principal balance and $0.85 million as a final payment fee, and such obligations are considered to be fully repaid and performed. The Term B Loan Advance of $4.0 million was not drawn down by the Company and has since expired. The loan bears interest at an annual rate equal to the greater of (i) seven and one-half of one percent (7.50%) and (ii) two percent (2%) above the Prime Rate. The loan advances mature in February 2023 and initially had an interest-only payment period of 12 months (which was extended to 18 months in connection with the First Amendment to the 2019 Term Loan, as discussed below), extendable to 18 months upon the drawing of the Term B Loan Advance (which is now extendable to 24 months as a result of the First Amendment to the 2019 Term Loan). Principal payments coming due within twelve months have been classified as current liabilities in the accompanying balance sheet. In addition, the Company was initially required to pay a final payment fee of 6.0% of the principal amount extended on the date of repayment of the 2019 Term Loan (which was increased to 6.3% in connection with the First Amendment to the 2019 Term Loan, as discussed below), which is being accreted and amortized into interest expense using the effective interest rate method over the term of the loan. The Company could initially prepay all, but not less than all, of the 2019 Term Loan, subject to a prepayment premium of 3.0% of the outstanding principal if prepaid within one year of the effective date of the loan, 2.0% of the outstanding principal if prepaid after the first anniversary of the effective date but on or prior to the second anniversary of the effective date, and 1.0% of the outstanding principal if prepaid after the second anniversary of the effective date. The 2019 Term Loan is collateralized by a security interest in all of the Company’s assets except intellectual property. The Company’s intellectual property is subject to a negative pledge. First Amendment to the 2019 Term Loan On July 25, 2019 (the “First Amendment Effective Date”), the Company entered into the first amendment to the 2019 Term Loan (the “First Amendment to the 2019 Term Loan”). Under the First Amendment to the 2019 Term Loan, the interest-only monthly payment period was extended to 18 months after the date of the 2019 Term Loan, which may be further extended to 24 months upon receipt by the Company of the Term B Loan Advance. The Company’s ability to draw down the Term B Loan Advance was extended to December 31, 2019, subject to the Company’s achievement of the Milestone Event prior to or on December 31, 2019. The Term B Loan Advance and the Term A Loan Advance (together, the “Loan Advances”) mature on February 1, 2023 (the “Maturity Date”). Pursuant to the 2019 Term Loan, as amended by the First Amendment to the 2019 Term Loan, following the interest-only payment period, the Company will begin making monthly payments of principal in equal monthly installments for 30 consecutive months (provided, that, upon the occurrence of the Milestone Event, the repayment schedule will be decreased to 24 consecutive months) and monthly payments of interest, until the Maturity Date. Interest will accrue on the unpaid principal balance of the outstanding Loan Advances at a floating per annum rate equal to the greater of (i) seven and one-half of one percent (7.50%) and (ii) two percent (2.0%) above the prime rate. The First Amendment to the 2019 Term Loan increased the final payment fee, payable upon the Company’s repayment of the Loan Advances from 6.0% to 6.3% of the original principal amount of the Loan Advances. The Company may prepay all, but not less than all of the Loan Advances, subject to a prepayment fee of 3.0% of any amount prepaid prior to the first anniversary of the First Amendment Effective Date, 2.0% of the amount prepaid if the prepayment occurs after the first anniversary of the First Amendment Effective Date through and including the second anniversary of the First Amendment Effective Date, or 1.0% of the amount prepaid if the prepayment occurs after the second anniversary of the First Amendment Effective Date, but prior to the Maturity Date. These percentages are unchanged from the original 2019 Term Loan. The Company evaluated whether the First Amendment to the 2019 Term Loan entered into in July 2019 represented a debt modification or extinguishment in accordance with ASC 470-50, Debt – Modifications and Extinguishments. As the present value of the cash flows under the terms of the First Amendment to the 2019 Term Loan is less than 10% different from the remaining cash flows under the terms of the 2019 Term Loan, the First Amendment to the 2019 Term Loan was accounted for as a debt modification. Therefore, the unamortized balance of debt discount costs incurred in connection with 2019 Term Loan are being amortized through maturity in February 2023 utilizing the effective interest rate method. Previous Term Loan Prior to the 2019 Term Loan, the Company had a $20.0 million Term Loan Agreement with SVB which was executed in November 2016 (“2016 Original Term Loan”). The three-tranche term loan consisted of an initial $10.0 million tranche triggered upon closing, with the remaining $10.0 million available to be drawn in two $5.0 million tranches, at the Company’s option, subject to the achievement of certain clinical and financial milestones. The Company did not achieve the conditional criteria to access the second and third tranches before the specified dates and the $10.0 million in additional term loan advances subsequently expired. The 2016 Original Term Loan bore interest at an annual rate equal to 4.50% plus the prime rate, which is the greater of 3.50% or the Wall Street Journal prime rate, and was payable monthly. It was set to mature in November 2020 and had an interest-only payment period until December 1, 2017, which was extendable to May 2018 upon the drawing of the second tranche. Because the Company did not achieve the conditional criteria to access the second and third term advances before the specified dates, the $10.0 million in additional term loan advances expired and the Company began to repay principal in December 2017. Following the interest only payment period, the Company began making monthly payments of principal and interest which were to continue until the maturity date. Principal payments coming due within twelve months have been classified as current liabilities in the accompanying balance sheet. In addition, the Company was required to pay a final payment fee of 8.5% of the principal amount extended on the date of repayment of the 2016 Original Term Loan. The Company accrued the final payment fee into interest expense using the effective interest rate method until the entry into the 2019 Term Loan in March 2019, at which time the Company paid SVB $0.85 million in satisfaction of all final payment fee liabilities due under the 2016 Original Term Loan. The Company was permitted to prepay all, but not less than all, of the Original Term Loan subject to a prepayment premium of 3.0% of the outstanding principal if prepaid within two years of the effective date of the loan, 2.0% of the outstanding principal if prepaid during the third year of the loan, and 1.0% of the outstanding principal if prepaid after the third year. The Term Loan was collateralized by a security interest in all of the Company’s assets except intellectual property. The Company’s intellectual property was subject to a negative pledge. In November 2018, the Company amended the 2016 Original Term Loan with SVB to provide an additional $4.0 million growth capital loan. This additional capital was available to be drawn, at Axsome’s option, subject to the achievement of positive results from the Company’s upcoming Phase 2 trial of AXS-12 in narcolepsy sufficient to proceed to a Phase 3 trial. The financial terms for this additional growth capital were more favorable than those of the original term loan. All other terms and conditions from the original term loan agreement remain in place. The additional $4.0 million growth capital loan had to be drawn by May 31, 2019 and would bear interest at an annual rate equal to the greater of the prime rate plus 2.00%, or 7.25%, if drawn. The Company’s obligations under the 2016 Amended Term Loan, along with the ability of the Company to draw down on the additional $4.0 million tranche, were considered performed and completed in connection with the establishment of the 2019 Term Loan. The Company evaluated whether the 2019 Term Loan entered into in March 2019 represented a debt modification or extinguishment in accordance with ASC 470-50, Debt – Modifications and Extinguishments. As the present value of the cash flows under the terms of the 2019 Term Loan is less than 10% different from the remaining cash flows under the terms of the 2016 Original Term Loan and the 2016 Amended Term Loan, the 2019 Term Loan was accounted for as a debt modification. Since the borrowing capacity of the 2019 Term Loan is greater than the borrowing capacity from the 2016 Original Term Loan and the 2016 Amended Term Loan, the unamortized balance of debt discount costs incurred in connection with those loans and additional debt discount costs incurred in connection with entry into the 2019 Term Loan, are being amortized through maturity in February 2023 utilizing the effective interest rate method. The book value of debt approximates its fair value given its short term maturity and variable interest rate. Interest expense was $1,362,500, $751,670, and $869,678 and amortization of the final payment was $436,567, $266,668, and $346,978 for the years ended December 31, 2019, 2018, and 2017, respectively. Long-term debt and unamortized debt discount balances are as follows: December 31, December 31, 2019 2018 Outstanding principal amount $ 20,000,000 $ 6,388,889 Add: accreted liability of final payment fee 404,364 663,459 Less: unamortized debt discount, long term (405,071) (99,595) Less: current portion of long-term debt (2,666,667) (3,333,333) Loan payable, long-term $ $ Current portion of outstanding principal amount Less: current portion of unamortized debt discount Loan payable, current portion $ $ Further information on warrants issued related to the debt financings and amendments are disclosed in Note 8 - Warrants. Amortization of the debt discount in relation to warrants issued in Note 8 - Warrants was $213,426, $108,968, and $123,543 for the year ended December 31, 2019, 2018, and 2017, respectively. Due to the debt modification upon entry of the 2019 Term Loan, the unamortized balance of the deferred debt issuance costs incurred with the 2016 Amended Term Loan will continue to be amortized through maturity in February 2023 along with the debt issuance costs of the 2019 Term Loan utilizing the effective interest rate method. Scheduled Principal Payments on Outstanding Debt, as of December 31, 2019, are as follows: 2020 $ 2,666,667 2021 8,000,000 2022 8,000,000 2023 1,333,333 Total principal payments outstanding $ 20,000,000

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2019
Stockholders' Equity
Stockholders' Equity	Note 7. Stockholders’ Equity Capital Structure In October 2017, the Company entered into the Sales Agreement with SVB Leerink, pursuant to which the Company may sell up to $30 million in shares of its common stock from time to time through SVB Leerink, acting as its sales agent, in one or more at-the-market offerings. In January 2019, the Company raised approximately $25.8 million in gross proceeds through the sale of 3,164,015 shares under the Sales Agreement. Upon completion of this final sale, the Sales Agreement was automatically terminated, SVB Leerink received a commission of 3.0% of the gross proceeds for all shares sold under the Sales Agreement. In December 2017, the Company completed the Registered Direct Offering, whereby it sold an aggregate of $9.5 million worth of units (“Units”) at a purchase price of $5.325 per Unit with each Unit consisting of (i) one share of the Company’s common stock, and (ii) a Common Warrant at an exercise price equal to $5.25 per share. The Company sold an aggregate of 1,783,587 Units for gross proceeds of approximately $9.5 million and net proceeds of approximately $8.8 million, net of underwriting discounts and offering expenses. Additionally, the Company issued 107,015 Placement Agent Warrants. The Company incurred issuance costs associated with the Units offering of $745,856, which included $81,000 related to issuance of 107,015 Placement Agent Warrants, of which, $583,768 was allocated to the common stock sold and was recorded as a reduction to equity. The remaining amount was allocated to the Common Warrants and was expensed. The Placement Agent Warrants have the same terms as the Common Warrants, except for the exercise price of $6.6562 per share. The Common Warrants priced at $5.25 and Placement Agent Warrants priced at $6.6562 utilized the 2016 Shelf Registration Statement for a total of $9.4 million and $712,313. On September 27, 2018, the Company entered into a purchase agreement with certain institutional and accredited investors (collectively, the “RDO Investors”) for the sale by the Company directly to the RDO Investors of an aggregate of 2,966,667 shares of the Company’s common stock, at a purchase price of $3.00 per share (the “2018 Registered Direct Offering”), for gross proceeds of approximately $8.9 million. The 2018 Registered Direct Offering closed on October 1, 2018, and the Company received net proceeds of approximately $8.8 million, after deducting transaction expenses. The 2,966,667 shares of common stock sold in the 2018 Registered Direct Offering were offered and sold by the Company directly to the RDO Investors, without a placement agent, underwriter, broker or dealer, pursuant to a prospectus supplement to the 2016 Shelf Registration Statement. In May 2019, the Company entered into the May 2019 Sales Agreement with SVB Leerink, pursuant to which the Company may sell up to $50 million in shares of the Company’s common stock from time to time through SVB Leerink, acting as the Company’s sales agent, in one or more at-the-market offerings utilizing the 2016 Shelf Registration Statement. SVB Leerink is entitled to receive a commission of 3.0% of the gross proceeds for any shares sold under the May 2019 Sales Agreement. The Company received approximately $20.1 million in gross proceeds through the sale of 942,285 shares, of which net proceeds were approximately $19.5 million during the year ended December 31, 2019. Due to expiration of the 2016 Shelf Registration Statement, at the Company’s option, the shares that were unsold under the May 2019 Sales Agreement, may be rolled over to the December 2019 Sales Agreement (see below). In December 2019, the Company entered into the December 2019 Sales Agreement with SVB Leerink, pursuant to which the Company may sell up to $80 million in shares of the Company’s common stock from time to time through SVB Leerink, acting as the Company’s sales agent, in one or more at-the-market offerings utilizing the 2019 Shelf Registration Statement. SVB Leerink is entitled to receive a commission of 3.0% of the gross proceeds for any shares sold under the December 2019 Sales Agreement. The Company received approximately $7.3 million in gross proceeds through the sale of 89,390 shares, of which net proceeds were approximately $7.1 million during the quarter ended December 31, 2019. In December 2019, the Company completed an underwritten public offering, whereby the Company sold 2,300,000 shares of our common stock at a public offering price of $87.00 per share. The Company received gross proceeds of approximately $200.1 million and net proceeds of approximately $187.1 million, net of underwriting discounts and offering expenses. The holders of shares of common stock are entitled to one vote for each share of common stock held at all meetings of stockholders and written actions in lieu of meetings. The holders of shares of common stock are entitled to receive dividends, if and when declared by the board of directors. Shelf Registration Statement On December 5, 2019, the Company filed an automatic shelf registration statement (“2019 Shelf Registration”) with the Securities and Exchange Commission (“SEC”) for the issuance of common stock, preferred stock, warrants, rights, debt securities and units. It became effective upon filing with the SEC and is currently the Company’s only active shelf registration. Through the date of this report, the Company has issued common stock of approximately $207.4 million pursuant to such shelf registration statement. In the future, the Company may also periodically offer unlimited number of these securities in amounts, prices and terms to be announced when and if the securities are offered. At the time any of the securities covered by the 2019 Shelf Registration Statement are offered for sale, a prospectus supplement will be prepared and filed with the SEC containing specific information about the terms of any such offering. Equity Incentive Plans The Company had granted stock options under its 2013 Equity Compensation Plan (the "2013 Plan"), which was adopted for employees and consultants for the purpose of advancing the interests of the Company's stockholders by enhancing its ability to attract, retain and motivate persons who are expected to make important contributions to the Company. In November 2015, t he 2015 Omnibus Incentive Compensation Plan (the “2015 Plan”) was adopted by the Company’s stockholders . The 2015 Plan is the successor to the Company's 2013 Plan. In conjunction with the adoption of the 2015 Plan, no additional grants were made from the 2013 Plan and options from the 2013 Plan remain outstanding. As of December 31, 2019, there were 3,388,926 shares available for future grant under the 2015 Plan. Stock Options The following table summarizes stock option activity as of December 31, 2019: Weighted Weighted average Aggregate Number average contractual intrinsic of shares exercise price term value Outstanding at December 31, 2018 2,282,636 5.06 Granted 1,484,352 Exercised (252,773) Forfeited (55,768) Expired — — Outstanding at December 31, 2019 3,458,447 10.19 8.0 322,229,820 Vested and expected to vest at December 31, 2019 3,449,778 10.21 8.0 321,347,251 Exercisable at December 31, 2019 1,861,890 7.23 6.5 178,992,676 The fair value of each stock option grant is estimated on the date of grant using the Black‑Scholes option pricing model. The expected term of the Company’s stock options has been determined utilizing the “simplified” method as described in the SEC’s Staff Accounting Bulletin No. 107 relating to stock‑based compensation. The simplified method was chosen because the Company has limited historical option exercise experience due to its short operating history. The risk‑free interest rate is based on the U.S. Treasury yield in effect at the time of grant for a period approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. Expected volatility is based on historical volatilities of similar entities within the Company’s industry which were commensurate with the Company’s expected term assumption. The relevant data used to determine the value of the stock option grants for the years ended December 31, 2019, 2018, and 2017 is as follows: Black-Scholes option valuation assumptions 2019 2018 2017 Risk-free interest rates 1.4 - 2.7 % 2.0 - 3.1 % 1.6 - 2.2 % Dividend yield — — — Volatility - 91 % - 87 % - 77 % Weighted average expected term 5.00 - 6.13 years 3.66 - 6.13 years 3.50 - 6.12 years The weighted average grant date fair value of options granted was $12.49, $1.99, and $3.06 per option for the years ended December 31, 2019, 2018 and 2017, respectively. As of December 31, 2019, there was $14.9 million of total unrecognized compensation cost related to non‑vested stock options which is expected to be recognized over a weighted average period of 3.3 years. These amounts do not include 15,269 options outstanding as of December 31, 2019, which are performance‑based and vest upon the achievement of certain corporate milestones. Stock‑based compensation will be measured and recorded if and when it is probable that the milestone will occur. Stock‑based compensation expense recognized for the years ended December 31, 2019, 2018, and 2017 was as follows: 2019 2018 2017 Research and development $ 1,584,165 $ 391,946 $ 613,629 General and administrative 4,530,995 1,363,028 1,458,581 Total $ 6,115,160 $ 1,754,974 $ 2,072,210 Performance‑Based Awards During the year ended December 31, 2019, the Company issued 4,500 performance-based awards at an exercise price of $16.71, to employees that vest upon completion of certain clinical events. During the year ended December 31, 2018, the Company issued 19,000 performance-based awards at an exercise price of $2.18, to employees that vest upon completion of certain clinical events. During the year ended December 31, 2017, the Company issued 20,650 performance-based awards, with a weighted average exercise price of $5.70, to employees that vest upon completion of certain clinical events. For awards granted to employees with performance conditions, no expense will be recognized, and no measurement date can occur, until the occurrence of the event is probable. For awards granted to non‑employees, the Company will recognize the lowest aggregate amount within the range of potential values as expense until the measurement date is established. For the years ended December 31, 2019, 2018, and 2017, the Company recognized $88,835, $1,587, and $59,424, respectively, as expense related to performance‑based awards.

Warrants

Warrants	12 Months Ended
	Dec. 31, 2019
Warrants
Warrants	Note 8. Warrants As of December 31, 2019, the Company had outstanding warrants to purchase 69,656 shares of common stock. The following table summarizes warrant activity as of December 31, 2019, 2018, and 2017: Weighted average Warrants exercise price Outstanding at December 31, 2016 337,746 $ 3.06 Issued 1,890,602 5.33 Exercised (129,149) 1.30 Outstanding at December 31, 2017 2,099,199 5.21 Issued 15,750 3.06 Exercised (101,310) 1.30 Expired (1,890,602) 5.33 Outstanding at December 31, 2018 123,037 6.35 Issued 58,334 8.10 Exercised (111,715) 6.73 Outstanding at December 31, 2019 69,656 $ 7.21 In connection with the Company’s new term loan facility with SVB and WestRiver which was completed in March 2019, the Company issued warrants for up to 70,000 shares of the Company’s common stock at a price per share equal to $8.10 based upon usage of the facility and are exercisable until March 4, 2026. The warrants were classified as a component of stockholders' equity. On July 25, 2019, in connection with the First Amendment to the 2019 Term Loan, the March 2019 Warrants were amended to fix the number of shares that may be issued upon exercise of each such March 2019 Warrant at 29,167 shares of common stock, and SVB and WestRiver were issued new warrants (the “July 2019 Warrants”), which would have become exercisable upon funding of the Term B Loan Advance, to purchase 5,750 shares of the Company’s common stock at a price per share equal to $25.71. The July 2019 Warrants replace the portion of the March 2019 Warrants that could originally be earned by SVB and WestRiver upon funding of the Term B Loan Advance. Due to the Company not drawing down on the Term B Loan Advance by December 31, 2019, the July 2019 Warrants have been terminated. I n December 2019, SVB exercised in full its portion of 29,167 warrants it received in connection with the 2019 Term Loan via a cashless exercise. The Company issued SVB 24,185 shares of its common stock in connection with the warrant exercise and did not receive any cash proceeds. As of December 31, 2019, WestRiver’s portion of 29,167 warrants remain outstanding. On November 26, 2018, in connection with the First Amendment to the Loan and Security Agreement, SVB and WestRiver Innovation Lending Fund VIII, L.P. received warrants to purchase 15,750 shares of the Company’s stock at an exercise price of $3.06 per share, which are exercisable for seven years from the date of issuance (“2018 warrants”). The warrants were classified as a component of stockholders' equity. In August 2019, SVB exercised in full its portions of 7,875 warrants it received in connection with the 2016 Amended Term Loan via a cashless exercise. The Company issued SVB 6,969 shares of its common stock in connection with the warrant exercise, and did not receive any cash proceeds. The 2018 warrants have a seven - year term and expire on November 25, 2025. As of December 31, 2019, WestRiver’s portion of 7,875 warrants remain outstanding. In connection with the Registered Direct Offering, which was completed on December 11, 2017, the Company issued Common Warrants and Placement Agent Warrants to purchase 1,783,587 shares and 107,015 shares of common stock, respectively, with an exercise price of $5.25 per share and $6.6562 per share, respectively, which are exercisable from the date of issuance until December 11, 2018 (“2017 warrants”). The Common Warrants and Placement Agent Warrants were classified as warrant liability. See Note 3, “Fair Value Measurements”, for the fair value calculations of the warrant liability. The 2017 warrants had a 1 year term and expired on December 11, 2018. In connection with the Company’s debt financing which was completed on November 9, 2016, the Company issued warrants to purchase 65,228 shares of common stock with an exercise price of $7.41 per share, which are exercisable upon issuance (“2016 warrants”) to SVB and Life Sciences. The warrants were classified as a component of stockholders' equity. In September 2019, SVB exercised its portion of 32,614 warrants it received in connection with the 2016 Original Term Loan via a cashless exercise. The Company issued SVB 24,328 shares of its common stock in connection with the warrant exercise, and did not receive any cash proceeds. The 2016 warrants have a seven-year term and expire on November 8, 2023. As of December 31, 2019, Life Sciences portion of 32,164 warrants remain outstanding. On November 3, 2014, the Company issued warrants to purchase 42,059 shares of common stock with an exercise price of $5.94 per share to the placement agent in connection with the issuance of certain convertible notes from September 2014 through November 2014 (the “September 2014 Notes”), which were exercisable upon issuance (“2014 warrants”). The warrants were initially classified as a liability in the consolidated financial statements, as upon a qualified financing, the warrant price would automatically adjust to a 10% premium to the conversion price of the September 2014 Notes in such mandatory conversion. The initial fair value of the warrant liability was $79,129 which was recorded as a discount to the notes and amortized over the term of the original September 2014 Notes. Upon the note amendment that occurred in September 2015, the discount was included in the carrying amount in the calculation of a loss on extinguishment. In connection with the automatic conversion of the September 2014 Notes upon the close of the Company’s IPO in November 2015, the warrant liability was reclassified to equity. The 2014 warrants had a five-year term and an expiration of November 2, 2019. All 42,059 warrants were exercised in 2019. On October 29, 2013, the Company issued warrants to purchase 230,459 shares of common stock with an exercise price of $1.30 per share to the placement agent in connection with the June 2013 Notes, which were exercisable upon issuance (“2013 warrants”). The warrants were classified as a component of stockholders’ equity. The 2013 warrants had a five-year term. 129,149 warrants and 101,310 warrants were exercised in 2017 and 2018, respectively. The initial fair value of the warrants were estimated using the Black‑Scholes option pricing model with the following assumptions: Black-Scholes option valuation assumptions 2019 warrants 2018 warrants 2017 warrants 2016 warrants 2014 warrants 2013 warrants Risk-free interest rate 2.8 % 3.0 % 1.7 % 1.8 % 1.6 % 1.4 % Dividend yield — — — — — — Volatility 97 % 85 % 61 % 73 % 70 % 64 % Weighted average contractual term 7 years 7 years 1 year 7 years 5 years 5 years

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2019
License Agreements.
License Agreements	Note 9. License Agreements In 2012, the Company entered into three exclusive license agreements with Antecip Bioventures II LLC, or Antecip, an entity owned by Axsome’s Chief Executive Officer and Chairman of the Board, Herriot Tabuteau, M.D., in which it was granted exclusive licenses to develop, manufacture, and commercialize Antecip’s patents and applications related to the development of AXS‑02, AXS‑05, and AXS‑04, a product candidate that is currently in early stage development, anywhere in the world for veterinary and human therapeutic and diagnostic use. Pursuant to the agreements, the Company is required to use commercially reasonable efforts to develop, obtain regulatory approval for and commercialize AXS‑02, AXS‑05, and AXS‑04. Under the terms of the agreements, the Company is required to pay to Antecip a royalty equal to 4.5% for AXS‑02, 3.0% for AXS‑05, and 1.5% for AXS‑04, of net sales of products containing the licensed technology by the Company, its affiliates, or permitted sublicensees. These royalty payments are subject to reduction by an amount up to 50.0% of any required payments to third parties. Unless earlier terminated by a party for cause or by the Company for convenience, the agreements shall remain in effect on a product‑by‑product and country‑by‑country basis until the later to occur of (i) the applicable product is no longer covered by a valid claim in that country or (ii) 10 years from the first commercial sale of the applicable product in that country. Upon expiration of the agreements with respect to a product in a country, the Company’s license grant for that product in that country will become a fully paid‑up, royalty‑free, perpetual non‑exclusive license. If Antecip terminates any of the agreements for cause, or if the Company exercises its right to terminate any of the agreements for convenience, the rights granted to the Company under such terminated agreement will revert to Antecip. To date, the Company has not been required to make any payments to Antecip under any of the license agreements. In January 2020, the Company entered into an exclusive license agreement with Pfizer Inc. See Note 14 – Subsequent Event, for further information.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies
Commitments and Contingencies	Note 10. Commitments and Contingencies Operating Leases The Company’s offices are located in New York, New York. The Company is currently under a short-term lease agreement, which does not qualify for accounting under ASC 842. Rent expense incurred during the years ended December 31, 2019, 2018 and 2017 was $485,548, $315,301, and $307,557.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Taxes
Income Taxes	Note 11. Income Taxes As of December 31, 2019, the Company has U.S. federal net operating loss (“NOL”) carryforwards of approximately $154 million. NOLs amounting to $60 million generated before the 2018 tax year will start expiring beginning 2033, and the NOL of approximately $94 million generated in 2018 and later have an indefinite carryforward period. The NOL carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. NOL carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders, as defined under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, as well as similar state tax provisions. This could limit the amount of NOLs that the Company can utilize annually to offset future taxable income or tax liabilities. The components of the Company’s deferred tax assets and deferred tax liabilities are as follows: December 31, 2019 December 31, 2018 Deferred tax assets: Net federal operating loss carryforward $ 32,299,085 $ 18,911,435 Net foreign operating loss carryforward 59,557 40,927 Net state operating loss carryforward 20,000,317 11,842,460 Non-cash compensation 3,485,519 1,625,560 Research and development credits 10,366,683 7,651,781 Deferred finance costs — 38,578 Interest Expense 985,431 400,946 Charitable Contribution 5,408 5,408 Fixed Assets 11,401 8,595 Accrued expenses 1,200,754 732,958 Deferred tax asset, excluding valuation allowance 68,414,155 41,258,648 Deferred tax liabilities: Deferred finance costs (121,875) — Deferred tax liability, excluding valuation allowance (121,875) — Less valuation allowance (68,292,280) (41,258,648) Net deferred tax assets $ — $ — A valuation allowance is provided for deferred tax assets where the recoverability of the assets is uncertain. The determination to provide a valuation allowance is dependent upon the assessment of whether it is more likely than not that sufficient future taxable income will be generated to utilize the deferred tax assets. Based on the weight of the available evidence, which includes the Company’s historical operating losses and forecast of future losses, the Company provided a full valuation allowance against the deferred tax assets resulting from the tax loss and credits carried forward. Valuation allowance increased $27.0 million, $12.5 million, and $6.7 million, in 2019, 2018, and 2017, respectively, as a result of the increase of the deferred tax assets. There was no income tax expense (benefit) recorded by the Company due to its net loss tax position and full valuation allowance during the years ended December 31, 2019, 2018, and 2017. A reconciliation of income tax expense (benefit) at the statutory federal income tax rate and income taxes as reflected in the consolidated financial statements is as follows: December 31, 2019 December 31, 2018 December 31, 2017 U.S. federal statutory income tax rate 21.0 % 21.0 % 34.0 % State taxes, net of federal benefit 13.5 13.1 10.0 Stock based compensation - Excess tax benefit 1.2 1.1 (1.0) Other permanent differences (0.1) (1.3) (1.9) Tax credit 4.2 6.3 7.7 US Federal tax rate change - tax reform — — (25.4) Change in valuation allowance (39.8) (40.2) (23.4) Effective tax rate — % — % — % The Company is not currently under examination at the federal or state levels and as of the date of the consolidated financial statements, and there were no known assessments. The Company’s U.S. federal and state net operating losses have occurred since its inception in 2012 and as such, tax years subject to potential tax examination could apply from that date because the utilization of net operating losses from prior years opens the relevant year to audit by the IRS and/or state taxing authorities.

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2019
Related-Party Transactions
Related-Party Transactions	Note 12. Related Party Transactions From the Company’s inception, Herriot Tabuteau, M.D. has been the Company’s founder, Chief Executive Officer, Chairman of the Company’s board of directors, and the beneficial owner of more than 5% of the outstanding shares of the Company’s common stock. In connection with the formation of the Company, in January 2012, the Company issued to Antecip Capital LLC, an entity controlled by Dr. Tabuteau, an aggregate of 7,344,500 shares of the Company’s common stock for nominal consideration. The Company is a party to three exclusive license agreements with Antecip Bioventures II LLC, an entity owned by Dr. Tabuteau. See Note 9 – License Agreements for further information regarding the license agreements.

Quarterly Consolidated Financia

Quarterly Consolidated Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2019
Quarterly Consolidated Financial Data (Unaudited)
Quarterly Consolidated Financial Data (Unaudited)	Note 13. Quarterly Consolidated Financial Data (Unaudited) 2019 Mar. 31 June 30 Sept. 30 Dec. 31 Total operating expenses $ 10,421,473 $ 13,448,219 $ 18,947,235 $ 24,428,170 Net loss $ (10,640,376) $ (13,762,214) $ (19,135,612) $ (24,806,984) Net loss per common share, basic and diluted (1) $ (0.32) $ (0.41) $ (0.56) $ (0.71) 2018 Mar. 31 June 30 Sept. 30 Dec. 31 Total operating expenses $ 7,163,210 $ 7,989,593 $ 8,243,459 $ 9,450,315 Net loss $ (4,805,559) $ (8,280,916) $ (8,281,974) $ (9,597,015) Net loss per common share, basic and diluted (1) $ (0.19) $ (0.32) $ (0.31) $ (0.32) (1) Basic and diluted net loss per common share is computed independently for each of the quarters presented. Therefore, the sum of all quarterly basic and fully diluted net loss per common share may not equal the annual basic and diluted net loss per common share.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events
Subsequent Event	Note 14. Subsequent Event In January 2020, the Company entered into an exclusive license agreement with Pfizer Inc. for Pfizer’s clinical and nonclinical data, and intellectual property for reboxetine, the active pharmaceutical ingredient in AXS-12 which the Company is developing for the treatment of narcolepsy. The agreement also provides the Company exclusive rights to develop and commercialize esreboxetine, a new late-stage product candidate now referred to as AXS-14, in the U.S. for the treatment of fibromyalgia. Under the terms of the Agreement, Pfizer received 82,019 shares of the Company’s common stock having a value of $8 million, based on the average closing price of the Company’s common stock for the 10 prior trading days of $97.538, in consideration for the license and rights. Pfizer also received an upfront cash payment of $3 million and will also receive up to $323 million in regulatory and sales milestones, and tiered mid-single to low double-digit royalties on future sales. Pfizer will also have a right of first negotiation on any potential future strategic transactions involving AXS-12 and AXS-14. .

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Summary of Significant Accounting Policies
Significant Risks and Uncertainties	Significant Risks and Uncertainties The Company’s operations are subject to a number of factors that can affect its operating results and financial condition. Such factors include, but are not limited to: the results of clinical testing and trial activities of the Company’s product candidates; the Company’s ability to obtain regulatory approval to market its products, if approved; competition from products manufactured and sold or being developed by other companies; the price of, and demand for, Company products, if approved; the Company’s ability to negotiate favorable licensing or other manufacturing and marketing agreements for its products, if approved; and the Company’s ability to raise additional financing. If the Company does not successfully commercialize any of its product candidates, it will be unable to generate recurring product revenue or achieve and maintain profitability.
Use of Estimates	Use of Estimates Management considers many factors in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements if these results differ from historical experience, or other assumptions do not turn out to be substantially accurate, even if such assumptions are reasonable when made. In preparing these financial statements, management used significant estimates in the following areas, among others: stock‑based compensation expense; the determination of the fair value of the warrants; the accounting for research and development costs; and the recoverability of the Company’s net deferred tax assets and related valuation allowance.
Foreign Currency Translation	Foreign Currency Translation Expenses denominated in foreign currency are translated into U.S. dollars at the exchange rate on the date the expense is incurred. Assets and liabilities of foreign operations are translated at period-end exchange rates. The effect of exchange rate fluctuations on translating foreign currency into U.S. dollars is included in the Statements of Operations and is not material to the Company’s financial statements.
Segment and Geographic Information	Segment and Geographic Information Operating segments are defined as components of an enterprise for 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 in assessing performance. The Company views its operations and manages its business as one operating segment, which is the business of developing novel therapies for the management of CNS disorders.
Cash Equivalents	Cash Equivalents The Company considers all highly liquid investments that have maturities of three months or less when acquired to be cash equivalents. Cash equivalents are valued at cost, which approximates their fair value. There were no cash equivalents at December 31, 2019 and 2018.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash. The Company maintains its cash at financial institutions, which at times, exceed federally insured limits. At December 31, 2019, the majority of the Company’s cash was held by one financial institution and the amount on deposit was in excess of Federal Deposit Insurance Corporation insurance limits. The Company has not recognized any losses from credit risks on such accounts since inception. The Company believes it is not exposed to significant credit risk on cash.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. Assets and liabilities that are measured at fair value are reported using a three‑level fair value hierarchy that prioritizes the inputs used to measure fair value. This hierarchy maximizes the use of observable inputs and minimizes the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1 —Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 —Inputs other than quoted prices in active markets that are observable for the asset or liability, either directly or indirectly. Level 3 —Inputs that are unobservable for the asset or liability. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying amounts reported in the accompanying consolidated financial statements for accounts payable and accrued expenses approximate their respective fair values due to their short‑term maturities.
Debt Issuance Costs	Debt Issuance Costs The Company incurred third‑party costs in connection with the Company’s term loans as described in Note 6 – Loan and Security Agreement. These costs are classified on the consolidated balance sheet as a direct deduction from the debt liability. The Company amortizes these costs over the term of its debt agreements as interest expense in the consolidated statement of operations.
Equipment	Equipment Equipment consists primarily of computer equipment and is recorded at cost. Equipment is depreciated on a straight‑line basis over its estimated useful life, which the Company estimates to be three years. When equipment is sold or otherwise disposed of, the cost and related accumulated depreciation are removed from the accounts and the resulting gain or loss is included in operating expenses.
Research and Development Costs	Research and Development Costs Research and development expenses primarily consist of costs incurred in performing research and development activities, including preclinical studies, clinical trials, manufacturing costs, employee salaries and benefits, stock‑based compensation expense, contract services, including external research and development expenses incurred under arrangements with third parties, such as contract research organizations (“CROs”), facilities costs, overhead costs, depreciation, and other related costs. Generally, research and development costs are expensed as incurred. Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and amortized over the period that the goods are delivered or the related services are performed, subject to an assessment of recoverability. The Company makes estimates of costs incurred in relation to external CROs, and clinical site costs. The Company analyzes the progress of clinical trials, including levels of patient enrollment, invoices received and contracted costs when evaluating the adequacy of the amount expensed and the related prepaid asset and accrued liability. Significant judgments and estimates must be made and used in determining the accrued balance and expense in any accounting period. The Company reviews and accrues CRO expenses and clinical trial study expenses based on work performed and relies upon estimates of those costs applicable to the stage of completion of a study. Accrued CRO costs are subject to revisions as such trials progress to completion. Revisions are charged to expense in the period in which the facts that give rise to the revision become known. With respect to clinical site costs, the financial terms of these agreements are subject to negotiation and vary from contract to contract. Payments under these contracts may be uneven, and depend on factors such as the achievement of certain events, the successful recruitment of patients, the completion of portions of the clinical trial or similar conditions. The objective of our policy is to match the recording of expenses in our financial statements to the actual services received and efforts expended. As such, expense accruals related to clinical site costs are recognized based on our estimate of the degree of completion of the event or events specified in the specific clinical study or trial contract.
Income Taxes	Income Taxes Income taxes are accounted for under the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to the differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, operating losses, and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not to be sustained upon examination based on the technical merits of the position as well as consideration of the available facts and circumstances. 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. As of December 31, 2019 and 2018, the Company does not believe any material uncertain tax positions are present. In the event the Company determines that accrual of interest or penalties are necessary in the future, the amount will be presented as a component of income tax expense.
Stock Based Compensation	Stock‑Based Compensation For stock options issued, the Company estimates the grant date fair value of each option using the Black‑Scholes option pricing model. The Black-Scholes model takes into account the expected volatility of the Company’s common stock, the risk-free interest rate, the estimated life of the option, the closing market price of the Company’s common stock and the exercise price. The estimates utilized in the Black-Scholes calculation involve inherent uncertainties and the application of management judgment. In addition, the Company recognizes expense for equity award forfeitures as they occur. For awards subject to service-based vesting conditions, the Company recognizes stock-based compensation expense on a straight-line basis over the requisite service period, which is generally the vesting term. For awards subject to performance-based vesting conditions, the Company recognizes stock-based compensation expense using the accelerated attribution method when it is probable that the performance condition will be achieved. The expense related to the stock-based compensation is recorded within the financial statement line item the grantee’s cash compensation is recorded in . The Company’s policy upon exercise of stock options is that shares will be issued as new shares drawing on the Company’s 2015 Omnibus Incentive Compensation Plan share pool that was adopted by the stockholders in November 2015.
Tax Credit	Tax Credit The tax credit represents the receipt by Axsome Therapeutics Australia PTY, LTD, the Company’s Australian subsidiary, of the Australia Tax Incentive Credit, related to the Company’s research and development expenses incurred for its product candidates. These expenses were incurred in prior periods and therefore the grant income was recorded when the funds were received.
Basic and Diluted Net Loss per Common Share	Basic and Diluted Net Loss per Common Share Basic net loss per share of common stock is computed by dividing net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as convertible notes, warrants, and stock options, which would result in the issuance of incremental shares of common stock. As the impact of these items is anti‑dilutive during periods of net loss, there was no difference between basic and diluted net loss per share of common stock for the years ended December 31, 2019, 2018, and 2017.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842), which supersedes FASB Topic 840, Leases (Topic 840), requires that assets and liabilities arising under leases be recognized on the balance sheet as well as additional quantitative and qualitative disclosures that provide the amount, timing, and uncertainty of cash flows related to lease agreements. In July 2018, the FASB also issued ASU No. 2018-11, Leases (Topic 842), which provides (1) optional transition method that entities can use when adopting the standard and (2) a practical expedient that permits lessors to not separate nonlease components from the associated lease component if certain conditions are met. The standard is effective for annual and interim periods beginning after December 15, 2018, with early adoption permitted upon issuance. The Company elected to use the transition method approved by the FASB in accordance with ASU No. 2018-11, Leases, which allows companies to apply the provisions of the new leasing standard as of January 1, 2019, without adjusting the comparative periods presented by recognizing a cumulative-effect adjustment to the opening balance of retained earnings. The Company applied a policy election to exclude short-term leases from balance sheet recognition and also elected certain practical expedients at adoption. As permitted under these expedients, the Company did not reassess whether existing contracts are or contain leases, the lease classification for any existing leases, initial direct costs for any existing lease and whether existing land easements and rights of way, that were not previously accounted for as leases, are or contain a lease. The Company has adopted this guidance effective January 1, 2019. The Company evaluated its contracts and concluded that the contracts are not leases and do not contain a lease and the adoption of this guidance did not impact its financial statements. In July 2018, the FASB issued ASU No. 2018-09, Codification Improvements , which provides technical corrections, clarifications, and other improvements to several topics in the FASB Accounting Standard Codification. The transition and effective date guidance is based on the facts and circumstances of each amendment. Some of the amendments do not require transition guidance and were effective upon issuance of the ASU. Amendments that do not have transition guidance are effective for annual periods beginning after December 15, 2018. The Company has adopted this guidance effective January 1, 2019 and the adoption of the guidance did not have a material impact on the Company’s financial statements. 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 , which modifies, removes and adds certain disclosure requirements on fair value measurements based on the FASB Concepts Statement, Conceptual Framework for Financial Reporting-Chapter 8: Notes to the Financial Statements. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those years. The Company has adopted this guidance effective January 1, 2019 and the adoption of the guidance did not have a material impact on the Company’s financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12). The new standard simplifies the accounting for income taxes by removing exceptions to the incremental approach for intraperiod tax allocation when there is a loss from continuing operations and income or a gain from other items, to the requirement to recognize a deferred tax liability for equity method investments when a foreign subsidiary becomes an equity method investment, to the ability not to recognize a deferred tax liability for a foreign subsidiary when a foreign equity method investment becomes a subsidiary, and to the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. In addition, the standard requires that an entity recognize a franchise tax that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax, evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction, reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date, and specifying that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements, however, an entity may elect to do so (on an entity-by-entity basis) for a legal entity that is both not subject to tax and disregarded by the taxing authority. ASU 2019-12 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2020. Early adoption is permitted, including adoption in an interim period. The Company is currently evaluating the expected impact of this standard, but does not expect it to have a material impact on its consolidated financial statements upon adoption.

Net Loss per Common Share (Tabl

Net Loss per Common Share (Tables)	12 Months Ended
	Dec. 31, 2019
Net Loss per Common Share
Computation of basic and diluted net loss per common share	Year ended December 31, 2019 2018 2017 Basic and diluted net loss per common share: Net loss $ (68,345,186) $ (30,965,464) $ (28,943,392) Weighted average common shares outstanding—basic and diluted 34,020,257 26,883,656 22,764,606 Net loss per common share—basic and diluted $ (2.01) $ (1.15) $ (1.27)
Schedule of potentially dilutive securities	December 31, 2019 2018 2017 Stock options 3,458,447 2,291,163 2,315,638 Warrants 69,656 123,037 2,099,199 Total 3,528,103 2,414,200 4,414,837

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Accrued Expenses
Schedule of accrued expenses	December 31, 2019 2018 Research and development $ 8,209,594 $ 2,266,285 Accrued compensation 2,056,356 1,051,401 Other 683,178 525,613 Total $ 10,949,128 $ 3,843,299

Loan and Security Agreement (Ta

Loan and Security Agreement (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of outstanding debt and unamortized debt discount balances	December 31, December 31, 2019 2018 Outstanding principal amount $ 20,000,000 $ 6,388,889 Add: accreted liability of final payment fee 404,364 663,459 Less: unamortized debt discount, long term (405,071) (99,595) Less: current portion of long-term debt (2,666,667) (3,333,333) Loan payable, long-term $ $ Current portion of outstanding principal amount Less: current portion of unamortized debt discount Loan payable, current portion $ $
Schedule of principal payments	2020 $ 2,666,667 2021 8,000,000 2022 8,000,000 2023 1,333,333 Total principal payments outstanding $ 20,000,000

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Stockholders' Equity
Schedule of stock option activity	Weighted Weighted average Aggregate Number average contractual intrinsic of shares exercise price term value Outstanding at December 31, 2018 2,282,636 5.06 Granted 1,484,352 Exercised (252,773) Forfeited (55,768) Expired — — Outstanding at December 31, 2019 3,458,447 10.19 8.0 322,229,820 Vested and expected to vest at December 31, 2019 3,449,778 10.21 8.0 321,347,251 Exercisable at December 31, 2019 1,861,890 7.23 6.5 178,992,676
Summary of Black-Scholes option valuation assumptions	Black-Scholes option valuation assumptions 2019 2018 2017 Risk-free interest rates 1.4 - 2.7 % 2.0 - 3.1 % 1.6 - 2.2 % Dividend yield — — — Volatility - 91 % - 87 % - 77 % Weighted average expected term 5.00 - 6.13 years 3.66 - 6.13 years 3.50 - 6.12 years
Schedule of stock-based compensation expense	2019 2018 2017 Research and development $ 1,584,165 $ 391,946 $ 613,629 General and administrative 4,530,995 1,363,028 1,458,581 Total $ 6,115,160 $ 1,754,974 $ 2,072,210

Warrants (Tables)

Warrants (Tables)	12 Months Ended
	Dec. 31, 2019
Warrants
Schedule of warrant activity	Weighted average Warrants exercise price Outstanding at December 31, 2016 337,746 $ 3.06 Issued 1,890,602 5.33 Exercised (129,149) 1.30 Outstanding at December 31, 2017 2,099,199 5.21 Issued 15,750 3.06 Exercised (101,310) 1.30 Expired (1,890,602) 5.33 Outstanding at December 31, 2018 123,037 6.35 Issued 58,334 8.10 Exercised (111,715) 6.73 Outstanding at December 31, 2019 69,656 $ 7.21
Summary of warrant fair value inputs	Black-Scholes option valuation assumptions 2019 warrants 2018 warrants 2017 warrants 2016 warrants 2014 warrants 2013 warrants Risk-free interest rate 2.8 % 3.0 % 1.7 % 1.8 % 1.6 % 1.4 % Dividend yield — — — — — — Volatility 97 % 85 % 61 % 73 % 70 % 64 % Weighted average contractual term 7 years 7 years 1 year 7 years 5 years 5 years

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Taxes
Schedule of components of deferred tax assets	December 31, 2019 December 31, 2018 Deferred tax assets: Net federal operating loss carryforward $ 32,299,085 $ 18,911,435 Net foreign operating loss carryforward 59,557 40,927 Net state operating loss carryforward 20,000,317 11,842,460 Non-cash compensation 3,485,519 1,625,560 Research and development credits 10,366,683 7,651,781 Deferred finance costs — 38,578 Interest Expense 985,431 400,946 Charitable Contribution 5,408 5,408 Fixed Assets 11,401 8,595 Accrued expenses 1,200,754 732,958 Deferred tax asset, excluding valuation allowance 68,414,155 41,258,648 Deferred tax liabilities: Deferred finance costs (121,875) — Deferred tax liability, excluding valuation allowance (121,875) — Less valuation allowance (68,292,280) (41,258,648) Net deferred tax assets $ — $ —
Schedule of income tax rate reconciliation	December 31, 2019 December 31, 2018 December 31, 2017 U.S. federal statutory income tax rate 21.0 % 21.0 % 34.0 % State taxes, net of federal benefit 13.5 13.1 10.0 Stock based compensation - Excess tax benefit 1.2 1.1 (1.0) Other permanent differences (0.1) (1.3) (1.9) Tax credit 4.2 6.3 7.7 US Federal tax rate change - tax reform — — (25.4) Change in valuation allowance (39.8) (40.2) (23.4) Effective tax rate — % — % — %

Quarterly Consolidated Financ_2

Quarterly Consolidated Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Consolidated Financial Data (Unaudited)
Summary of quarterly consolidated financial data	2019 Mar. 31 June 30 Sept. 30 Dec. 31 Total operating expenses $ 10,421,473 $ 13,448,219 $ 18,947,235 $ 24,428,170 Net loss $ (10,640,376) $ (13,762,214) $ (19,135,612) $ (24,806,984) Net loss per common share, basic and diluted (1) $ (0.32) $ (0.41) $ (0.56) $ (0.71) 2018 Mar. 31 June 30 Sept. 30 Dec. 31 Total operating expenses $ 7,163,210 $ 7,989,593 $ 8,243,459 $ 9,450,315 Net loss $ (4,805,559) $ (8,280,916) $ (8,281,974) $ (9,597,015) Net loss per common share, basic and diluted (1) $ (0.19) $ (0.32) $ (0.31) $ (0.32)

Nature of Business and Basis _2

Nature of Business and Basis of Presentation (Details)	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Nov. 24, 2015$ / sharesshares
Number of late-stage candidates in Company's product candidate portfolio | $	5
Common stock, shares authorized | shares	150,000,000	150,000,000
Common stock, par value | $ / shares	$ 0.0001	$ 0.0001
Preferred stock, shares authorized | shares	10,000,000	10,000,000
Preferred stock, par value | $ / shares	$ 0.0001	$ 0.0001
Accumulated deficit | $	$ 175,895,493	$ 107,550,307
IPO
Common stock, shares authorized | shares			150,000,000
Common stock, par value | $ / shares			$ 0.0001
Preferred stock, shares authorized | shares			10,000,000
Preferred stock, par value | $ / shares			$ 0.0001

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)
Segment and Geographic Information
Number of operating segments | segment	1
Cash Equivalents
Cash Equivalents | $	$ 0	$ 0
Equipment
Estimated useful life	3 years

Fair Value Measurements - Recur

Fair Value Measurements - Recurring Basis (Details)	Nov. 26, 2018$ / sharesshares	Dec. 11, 2017$ / sharesshares	Dec. 04, 2017USD ($)$ / sharesshares	Dec. 31, 2019$ / sharesshares	Dec. 31, 2018$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Sep. 27, 2018$ / shares	Dec. 31, 2016$ / shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants issued | shares				58,334	15,750	1,890,602
Share Price						$ 5.325	$ 3
Exercise price of warrants (in dollars per share)				$ 7.21	$ 6.35	$ 5.21		$ 3.06
Common warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants issued | shares	15,750	1,783,587	1,783,587
Fair value | $			$ 2,064,000			$ 2,683,000
Share Price			$ 5			$ 5.60
Exercise price of warrants (in dollars per share)	$ 3.06	$ 5.25	$ 5.25
Common warrants | Risk Free Interest Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants and Rights Outstanding, Measurement Input			1.66			1.76
Warrant measurement input			1.66			1.76
Common warrants | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants and Rights Outstanding, Measurement Input			61			62
Warrant measurement input			61			62
Placement agent warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants issued | shares		107,015	107,015
Fair value | $			$ 81,000			$ 108,000
Share Price			$ 5			$ 5.60
Exercise price of warrants (in dollars per share)		$ 6.6562	$ 6.6562
Placement agent warrants | Risk Free Interest Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants and Rights Outstanding, Measurement Input			1.66			1.76
Warrant measurement input			1.66			1.76
Placement agent warrants | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants and Rights Outstanding, Measurement Input			61			62
Warrant measurement input			61			62

Net Loss per Common Share - Com

Net Loss per Common Share - Computation of Basic and Diluted Net Loss per Common Share (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Basic and diluted net loss per common share:
Net loss	$ (24,806,984)	$ (19,135,612)	$ (13,762,214)	$ (10,640,376)	$ (9,597,015)	$ (8,281,974)	$ (8,280,916)	$ (4,805,559)	$ (68,345,186)	$ (30,965,464)	$ (28,943,392)
Weighted average common shares outstanding, basic and diluted									34,020,257	26,883,656	22,764,606
Net loss per common share, basic and diluted	$ (0.71)	$ (0.56)	$ (0.41)	$ (0.32)	$ (0.32)	$ (0.31)	$ (0.32)	$ (0.19)	$ (2.01)	$ (1.15)	$ (1.27)

Net Loss per Common Share - Pot

Net Loss per Common Share - Potentially Dilutive Securities Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities	3,528,103	2,414,200	4,414,837
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities	3,458,447	2,291,163	2,315,638
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities	69,656	123,037	2,099,199

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Accrued Expenses and Other Current Liabilities
Research and development	$ 8,209,594	$ 2,266,285
Accrued compensation	2,056,356	1,051,401
Other	683,178	525,613
Total	$ 10,949,128	$ 3,843,299

Loan and Security Agreement - A

Loan and Security Agreement - Additional Information (Details)	Jul. 25, 2019installment	Mar. 31, 2019USD ($)tranche	Nov. 30, 2018USD ($)	Nov. 30, 2016USD ($)tranche	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Repayment of principal on term loan					$ 7,238,889	$ 3,333,333	$ 277,778
Interest expense						751,670	869,678
Amortization of debt issuance costs						$ 266,668	$ 346,978
Term Loan
Maximum loan amount				$ 20,000,000
Number of loan tranches | tranche				3
Interest rate basis				3.50%
Interest rate spread				3.50%
Final payment fee, percent of principal				8.50%
Final payment fee		$ 850,000
Prepayment premium, percent of principal, if prepaid within two years				3.00%
Prepayment premium, condition one, term				2 years
Prepayment premium, percent of principal, if prepaid during the third year				2.00%
Prepayment premium, percent of principal, if prepaid after third year				1.00%
Base interest rate				4.50%
Interest expense					1,362,500
Amortization of debt issuance costs					$ 436,567
2019 Term Loan
Maximum loan amount		$ 24,000,000
Number of loan tranches | tranche		2
Interest-only payment period	18 months	12 months
Number of monthly installments | installment	30
Interest rate basis	7.50%	7.50%
Interest rate spread	7.50%	7.50%
Final payment fee, percent of principal	6.30%	6.00%
Prepayment premium, percent of principal, if prepaid within one year	3.00%	3.00%
Prepayment premium, percent of principal, if prepaid during the second year	2.00%	2.00%
Prepayment premium, percent of principal, if prepaid after second year	1.00%	1.00%
2019 Term Loan | Milestone Met
Number of monthly installments | installment	24
2019 Term Loan | Prime Rate
Interest rate basis	2.00%	(2.00%)
Interest rate spread	2.00%	(2.00%)
Term Loan 2019, Tranche One
Loan amount		$ 20,000,000
Final payment fee		850,000
Repayment of principal on term loan		5,600,000
Term Loan 2019, Tranche Two
Remaining credit facility to be drawn		$ 4,000,000
Interest only payment period after drawing of second tranche	24 months	18 months
Term Loan 2016, Tranche One
Loan amount				$ 10,000,000
Term Loan 2016, Tranche Three
Maximum loan amount				5,000,000
Term Loan 2016, Tranche Two and Three
Maximum loan amount				$ 10,000,000
Number of loan tranches | tranche				2
Loan amount				$ 5,000,000
Growth Capital Loan
Loan amount			$ 4,000,000
Maximum | Growth Capital Loan | Prime Rate
Interest rate basis			2.00%
Interest rate spread			2.00%
Base interest rate			7.25%

Loan and Security Agreement - O

Loan and Security Agreement - Outstanding Debt and Unamortized Debt Discount (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Total Outstanding Debt	$ 20,000,000	$ 6,388,889
Add: accreted liability of final payment fee	404,364	663,459
Less: unamortized debt discount, long-term	(405,071)	(99,595)
Less: current portion of long-term debt	(2,666,667)	(3,333,333)
Loan payable, long-term	17,332,626	3,619,420
Current portion of long-term debt	2,666,667	3,333,333
Current portion of unamortized debt discount	(64,375)	(41,939)
Loan payable, current portion	$ 2,602,292	$ 3,291,394

Loan and Security Agreement - W

Loan and Security Agreement - Warrants Issued (Details) - USD ($)	Dec. 05, 2019	Dec. 31, 2019	Sep. 30, 2019	Jan. 31, 2019	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jul. 25, 2019	Mar. 31, 2019	Dec. 31, 2016	Nov. 09, 2016
Exercise price of warrants (in dollars per share)		$ 7.21			$ 5.21	$ 7.21	$ 7.21	$ 6.35	$ 5.21			$ 3.06
Warrants exercised							111,715	101,310	129,149
Shares issued	207,400,000			3,164,015	1,783,587	89,390	942,285
Proceeds from Issuance of Long-term Debt							$ 20,000,000
Warrants issued							58,334	15,750	1,890,602
Amortization of debt discount							$ 649,993	$ 375,635	$ 470,521
Warrants
Amortization of debt discount							$ 213,426	$ 108,968	$ 123,543
Term Loan
Common stock to be issued if warrants are exercised (in shares)													65,228
Exercise price of warrants (in dollars per share)													$ 7.41
Warrants exercised			32,614
Shares issued			24,328
2019 Term Loan
Shares issued		24,185
2019 Term Loan | Warrants
Common stock to be issued if warrants are exercised (in shares)										29,167	70,000
Exercise price of warrants (in dollars per share)											$ 8.10
Warrants exercised		29,167
Term Loan 2019, Tranche Two | Warrants
Common stock to be issued if warrants are exercised (in shares)										5,750
Exercise price of warrants (in dollars per share)										$ 25.71

Loan and Security Agreement - S

Loan and Security Agreement - Schedule of Principal Payments (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
2020	$ 2,666,667
2021	8,000,000
2022	8,000,000
2023	1,333,333
Total principal payments outstanding	$ 20,000,000	$ 6,388,889

Stockholders' Equity - Capital

Stockholders' Equity - Capital Structure (Details)	Dec. 05, 2019shares	Oct. 01, 2018USD ($)	Sep. 27, 2018USD ($)$ / shares	Dec. 31, 2019USD ($)$ / sharesshares	Aug. 31, 2019shares	May 31, 2019USD ($)	Jan. 31, 2019USD ($)shares	Dec. 31, 2017USD ($)$ / sharesshares	Oct. 31, 2017USD ($)	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2019USD ($)Vote / shares$ / sharesshares	Dec. 04, 2017USD ($)$ / shares
Subsidiary, Sale of Stock [Line Items]
Shares issued | shares	207,400,000						3,164,015	1,783,587		89,390	942,285
Share Price | $ / shares			$ 3					$ 5.325
Proceeds from issuance of common stock, gross			$ 8,900,000					$ 9,500,000
Proceeds from issuance of common stock, net		$ 8,800,000						8,800,000
Common stock sales agreement, authorized amount			$ 2,966,667	$ 80,000,000		$ 50,000,000			$ 30,000,000
Common stock sales agreement, gross sales							$ 25,800,000			$ 7,300,000	$ 20,100,000
Common stock sales agreement, net sales										$ 7,100,000	$ 19,500,000
Common stock sales agreement, commission percentage				3.00%		3.00%	3.00%			3.00%	3.00%
Issuance costs								$ 745,856
Exercise price | $ / shares								$ 5.25
Warrant utilized								$ 9,400,000
Common stock, voting right per share | Vote / shares											1
Underwritten Public Offering
Subsidiary, Sale of Stock [Line Items]
Shares issued | shares				2,300,000
Share Price | $ / shares				$ 87						$ 87	$ 87
Proceeds from issuance of common stock, gross				$ 200,100,000
Proceeds from issuance of common stock, net				$ 187,100,000
Common warrants
Subsidiary, Sale of Stock [Line Items]
Shares issued | shares					6,969
Share Price | $ / shares								$ 5.60				$ 5
Issuance costs								$ 583,768
Fair Value Of Warrants								$ 2,683,000				$ 2,064,000
Placement agent warrants
Subsidiary, Sale of Stock [Line Items]
Shares issued | shares								107,015
Share Price | $ / shares								$ 5.60				$ 5
Issuance costs								$ 81,000
Exercise price | $ / shares								$ 6.6562
Warrant utilized								$ 712,313
Fair Value Of Warrants								$ 108,000				$ 81,000

Stockholders' Equity - Equity I

Stockholders' Equity - Equity Incentive Plans (Details)	Dec. 31, 2019shares
2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant	0
2015 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant	3,388,926

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2019USD ($)$ / sharesshares
Number of shares
Beginning balance outstanding (in shares) | shares	2,282,636
Granted (in shares) | shares	1,484,352
Exercised (in shares) | shares	(252,773)
Forfeited (in shares) | shares	(55,768)
Ending balance outstanding (in shares) | shares	3,458,447
Vested and expected to vest (in shares) | shares	3,449,778
Exercisable (in shares) | shares	1,861,890
Weighted average exercise price
Beginning balance outstanding (in dollars per share) | $ / shares	$ 5.06
Granted (in dollars per share) | $ / shares	17
Exercised (in dollars per share) | $ / shares	4.53
Forfeited (in dollars per share) | $ / shares	7.26
Ending balance outstanding (in dollars per share) | $ / shares	10.19
Vested and expected to vest (in dollars per share) | $ / shares	10.21
Exercisable (in dollars per share) | $ / shares	$ 7.23
Weighted average contractual term
Outstanding (in years)	8 years
Vested and expected to vest (in years)	8 years
Exercisable (in years)	6 years 6 months
Aggregate intrinsic value
Outstanding (in dollars) | $	$ 322,229,820
Vested and expected to vest (in dollars) | $	321,347,251
Exercisable (in dollars) | $	$ 178,992,676

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)	$ 12.49	$ 1.99	$ 3.06
Unrecognized compensation cost related to non-vested stock options expected to be recognized	$ 14.9
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected vesting period for non-vested share-based compensation	3 years 3 months 18 days
Non-vested options outstanding	15,269

Stockholders' Equity - Stock _2

Stockholders' Equity - Stock Option Valuation Assumptions (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Black-Scholes option valuation assumptions
Volatility, minimum	87.00%	74.00%	73.00%
Volatility, maximum	91.00%	87.00%	77.00%
Stock Options
Black-Scholes option valuation assumptions
Risk-free interest rate, minimum	1.40%	2.00%	1.60%
Risk-free interest rate, maximum	2.70%	3.10%	2.20%
Stock Options | Minimum
Black-Scholes option valuation assumptions
Expected term	P5Y	P3Y7M28D	P3Y6M
Stock Options | Maximum
Black-Scholes option valuation assumptions
Expected term	P6Y1M17D	P6Y1M17D	P6Y1M13D

Stockholders' Equity - Stock-ba

Stockholders' Equity - Stock-based Compensation Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense (income)	$ 6,115,160	$ 1,754,974	$ 2,072,210
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense (income)	1,584,165	391,946	613,629
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense (income)	$ 4,530,995	$ 1,363,028	$ 1,458,581

Stockholders' Equity - Performa

Stockholders' Equity - Performance-Based Awards Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense (income)	$ 6,115,160	$ 1,754,974	$ 2,072,210
Performance-based
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based awards issued	4,500	19,000	20,650
Weighted average exercise price	$ 16.71	$ 2.18	$ 5.70
Stock-based compensation expense (income)	$ 88,835	$ 1,587	$ 59,424

Warrants - Warrant Activity (De

Warrants - Warrant Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Warrants
Warrants outstanding beginning balance	123,037	2,099,199	337,746
Warrants issued	58,334	15,750	1,890,602
Warrants exercised	(111,715)	(101,310)	(129,149)
Warrants expired		(1,890,602)
Warrants outstanding ending balance	69,656	123,037	2,099,199
Weighted average exercise price
Beginning balance (in dollars per share)	$ 6.35	$ 5.21	$ 3.06
Issued (in dollars per share)	8.10	3.06	5.33
Exercised (in dollars per share)	6.73	1.30	1.30
Expired (in dollars per share)		5.33
Ending balance (in dollars per share)	$ 7.21	$ 6.35	$ 5.21

Warrants - Information (Details

Warrants - Information (Details) - USD ($)	Dec. 05, 2019	Nov. 26, 2018	Dec. 11, 2017	Dec. 04, 2017	Nov. 03, 2014	Oct. 29, 2013	Dec. 31, 2019	Sep. 30, 2019	Aug. 31, 2019	Jan. 31, 2019	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jul. 25, 2019	Mar. 31, 2019	Dec. 31, 2016	Nov. 09, 2016
Class of Warrant or Right [Line Items]
Warrants issued													58,334	15,750	1,890,602
Exercise price of warrants (in dollars per share)							$ 7.21				$ 5.21	$ 7.21	$ 7.21	$ 6.35	$ 5.21			$ 3.06
Warrants exercised													111,715	101,310	129,149
Exercised (in dollars per share)													$ 6.73	$ 1.30	$ 1.30
Shares issued	207,400,000									3,164,015	1,783,587	89,390	942,285
Warrants outstanding							69,656				2,099,199	69,656	69,656	123,037	2,099,199			337,746
Common warrants
Class of Warrant or Right [Line Items]
Warrants issued		15,750	1,783,587	1,783,587
Exercise price of warrants (in dollars per share)		$ 3.06	$ 5.25	$ 5.25
Warrant term		7 years
Warrants exercised									7,875
Shares issued									6,969
Warrants outstanding							7,875					7,875	7,875
Placement agent warrants
Class of Warrant or Right [Line Items]
Warrants issued			107,015	107,015
Exercise price of warrants (in dollars per share)			$ 6.6562	$ 6.6562
Warrant term			1 year
Shares issued											107,015
2013 Warrants
Class of Warrant or Right [Line Items]
Warrant term						5 years	5 years					5 years	5 years
Warrants exercised														101,310	129,149
Exercised (in dollars per share)						$ 1.30
Common stock to be issued if warrants are exercised (in shares)						230,459
Term Loan
Class of Warrant or Right [Line Items]
Exercise price of warrants (in dollars per share)																			$ 7.41
Warrant term																			7 years
Warrants exercised								32,614
Shares issued								24,328
Warrants outstanding							32,164					32,164	32,164
Common stock to be issued if warrants are exercised (in shares)																			65,228
2019 Term Loan
Class of Warrant or Right [Line Items]
Shares issued							24,185
Warrants outstanding							29,167					29,167	29,167
2019 Term Loan | Warrants
Class of Warrant or Right [Line Items]
Exercise price of warrants (in dollars per share)																	$ 8.10
Warrants exercised							29,167
Common stock to be issued if warrants are exercised (in shares)																29,167	70,000
Term Loan 2019, Tranche Two | Warrants
Class of Warrant or Right [Line Items]
Exercise price of warrants (in dollars per share)																$ 25.71
Common stock to be issued if warrants are exercised (in shares)																5,750
September 2014 Notes
Class of Warrant or Right [Line Items]
Exercise price of warrants (in dollars per share)					$ 5.94
Warrant term					5 years
Warrants exercised													42,059
Common stock to be issued if warrants are exercised (in shares)					42,059
Fair value of warrant recorded as a debt discount					$ 79,129
Mandatory conversion, warrant price premium as a percent of the conversion price					10.00%

Warrants - Fair Value Warrants

Warrants - Fair Value Warrants Assumptions (Details)	Nov. 26, 2018$ / sharesshares	Dec. 11, 2017$ / sharesshares	Dec. 04, 2017USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Sep. 27, 2018$ / shares	Dec. 31, 2016$ / shares	Oct. 29, 2013
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Change in fair value of warrant liabilities					$ 2,791,000	$ (646,000)
Warrants issued | shares				58,334	15,750	1,890,602
Exercise price of warrants (in dollars per share) | $ / shares				$ 7.21	$ 6.35	$ 5.21		$ 3.06
Share Price | $ / shares						$ 5.325	$ 3
2019 Warrants
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Weighted average contractual term				7 years
2019 Warrants | Risk Free Interest Rate
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.028
2019 Warrants | Volatility
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.97
2018 Warrants
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Weighted average contractual term				7 years
2018 Warrants | Risk Free Interest Rate
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.030
2018 Warrants | Volatility
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.85
2017 Warrants
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Weighted average contractual term				1 year
2017 Warrants | Risk Free Interest Rate
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.017
2017 Warrants | Volatility
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.61
2016 Warrants
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Weighted average contractual term				7 years
2016 Warrants | Risk Free Interest Rate
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.018
2016 Warrants | Volatility
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.73
2014 Warrants
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Weighted average contractual term				5 years
2014 Warrants | Risk Free Interest Rate
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.016
2014 Warrants | Volatility
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.70
2013 Warrants
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Weighted average contractual term				5 years					5 years
2013 Warrants | Risk Free Interest Rate
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.014
2013 Warrants | Volatility
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input				0.64
Common warrants
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrants issued | shares	15,750	1,783,587	1,783,587
Exercise price of warrants (in dollars per share) | $ / shares	$ 3.06	$ 5.25	$ 5.25
Fair Value Of Warrants			$ 2,064,000			$ 2,683,000
Share Price | $ / shares			$ 5			$ 5.60
Weighted average contractual term	7 years
Common warrants | Risk Free Interest Rate
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input			1.66			1.76
Common warrants | Volatility
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input			61			62
Placement agent warrants
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrants issued | shares		107,015	107,015
Exercise price of warrants (in dollars per share) | $ / shares		$ 6.6562	$ 6.6562
Fair Value Of Warrants			$ 81,000			$ 108,000
Share Price | $ / shares			$ 5			$ 5.60
Weighted average contractual term		1 year
Placement agent warrants | Risk Free Interest Rate
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input			1.66			1.76
Placement agent warrants | Volatility
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Warrant measurement input			61			62

License Agreements (Details)

License Agreements (Details) - Antecip - License Agreements - item	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2012
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of exclusive license agreements	3	3
License agreement royalty, maximum reduction percent as a result of required third party payments		50.00%
License agreement term, from first commercial sale		10 years
AXS-02
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License agreement royalty as a percent of net sales		4.50%
AXS-05
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License agreement royalty as a percent of net sales		3.00%
AXS-04
Research and Development Arrangement, Contract to Perform for Others [Line Items]
License agreement royalty as a percent of net sales		1.50%

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies
Rent expense	$ 485,548	$ 315,301	$ 307,557

Income Taxes - Net Operating Lo

Income Taxes - Net Operating Loss Carryforwards (Details) $ in Millions	Dec. 31, 2019USD ($)
NOL carryforwards	$ 154
Tax Year 2017
NOL carryforwards	60
Tax Year 2018
NOL carryforwards	$ 94

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Asset (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets
Net federal operating loss carryforwards	$ 32,299,085	$ 18,911,435
Net foreign operating loss carryforwards	59,557	40,927
Net state operating loss carryforwards	20,000,317	11,842,460
Non-cash compensation	3,485,519	1,625,560
Research and development credits	10,366,683	7,651,781
Deferred finance costs		38,578
Interest Expense	985,431	400,946
Charitable Contribution	5,408	5,408
Fixed assets	11,401	8,595
Accrued expenses	1,200,754	732,958
Deferred tax asset, excluding valuation allowance	68,414,155	41,258,648
Deferred finance costs	(121,875)
Deferred tax liability, excluding valuation allowance	(121,875)
Less valuation allowance	(68,292,280)	(41,258,648)
Increase in valuation allowance	$ 27,000,000	$ 12,500,000	$ 6,700,000

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax Expense (Benefit) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of income tax expense (benefit)
Income tax expense (benefit)	$ 0	$ 0	$ 0
U.S. federal statutory income tax rate	21.00%	21.00%	34.00%
State taxes, net of federal benefit	13.50%	13.10%	10.00%
Stock based compensation - Excess tax benefit	1.20%	1.10%	(1.00%)
Other permanent differences	(0.10%)	(1.30%)	(1.90%)
Tax credit	4.20%	6.30%	7.70%
US federal taz rate change - tax reform			(25.4)
Change in valuation allowance	(39.80%)	(40.20%)	(23.40%)

Related-Party Transactions - Lo

Related-Party Transactions - Loan Payable (Details)	Dec. 05, 2019shares	Jan. 31, 2019shares	Dec. 31, 2017shares	Jan. 31, 2012shares	Dec. 31, 2019shares	Dec. 31, 2019itemshares	Dec. 31, 2012item
Related Party Transaction [Line Items]
Shares issued	207,400,000	3,164,015	1,783,587		89,390	942,285
Dr. Tabuteau
Related Party Transaction [Line Items]
Ownership of outstanding common shares, percent					5.00%	5.00%
Antecip
Related Party Transaction [Line Items]
Shares issued				7,344,500
License Agreements | Antecip
Related Party Transaction [Line Items]
Number of exclusive license agreements | item						3	3

Quarterly Consolidated Financ_3

Quarterly Consolidated Financial Data (Unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Consolidated Financial Data (Unaudited)
Total operating expenses	$ 24,428,170	$ 18,947,235	$ 13,448,219	$ 10,421,473	$ 9,450,315	$ 8,243,459	$ 7,989,593	$ 7,163,210	$ 67,245,097	$ 32,846,577	$ 27,164,307
Net loss	$ (24,806,984)	$ (19,135,612)	$ (13,762,214)	$ (10,640,376)	$ (9,597,015)	$ (8,281,974)	$ (8,280,916)	$ (4,805,559)	$ (68,345,186)	$ (30,965,464)	$ (28,943,392)
Net loss per common share, basic and diluted	$ (0.71)	$ (0.56)	$ (0.41)	$ (0.32)	$ (0.32)	$ (0.31)	$ (0.32)	$ (0.19)	$ (2.01)	$ (1.15)	$ (1.27)

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)	1 Months Ended
	Jan. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 27, 2018	Dec. 31, 2017
Number of common shares		36,933,217	30,087,213
Value of common stock		$ 3,693	$ 3,009
Share Price				$ 3	$ 5.325
Subsequent Event
Number of common shares	82,019
Subsequent Event | Pfizer Inc
Value of common stock	$ 8,000,000
Prior trading days	10 days
Share Price	$ 97.5380
Upfront cash payment	$ 3,000,000
Future milestone payments	$ 323,000,000