Axsome Therapeutics (AXSM) 10-K 1 Mar 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 22, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2020
Entity File Number	001-37635
Entity Registrant Name	AXSOME THERAPEUTICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-4241907
Entity Address, Address Line One	22 Cortlandt Street
Entity Address, Address Line Two	16th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10007
City Area Code	212
Local Phone Number	332-3241
Title of 12(b) Security	Common Stock, Par Value $0.0001 Per Share
Trading Symbol	AXSM
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		37,405,268
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Central Index Key	0001579428
Amendment Flag	false
ICFR Auditor Attestation Flag	true
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 2.4
Documents Incorporated by Reference	Portions of the registrant's definitive proxy statement for its 2021 Annual Meeting of Stockholders (the "Proxy Statement"), to be filed within 120 days of the registrant's fiscal year ended December 31, 2020, are incorporated by reference in Part III of this Annual Report on Form 10-K. Except with respect to information specifically incorporated by reference in this Annual Report on Form 10-K, the Proxy Statement is not deemed to be filed as part of this Annual Report on Form 10-K.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 183,876,453	$ 219,966,167
Prepaid and other current assets	148,373	413,095
Total current assets	184,024,826	220,379,262
Equipment, net	52,647	30,623
Right-of-use asset - operating lease	1,739,475
Other assets	317,375	139,875
Total assets	186,134,323	220,549,760
Current liabilities:
Accounts payable	13,504,022	10,943,325
Accrued expenses and other current liabilities	8,713,249	10,949,128
Operating lease liability, current portion	1,220,587
Loan payable, current portion		2,602,292
Total current liabilities	23,437,858	24,494,745
Loan payable, long-term	48,321,848	17,332,626
Operating lease liability, long-term	581,708
Total liabilities	72,341,414	41,827,371
Stockholders’ equity:
Preferred stock, $0.0001 par value per share (10,000,000 shares authorized, none issued and outstanding at December 31, 2020 and December 31, 2019, respectively)
Common stock, $0.0001 par value per share (150,000,000 shares authorized, 37,374,088 and 36,933,217 shares issued and outstanding at December 31, 2020 and December 31, 2019, respectively)	3,737	3,693
Additional paid-in capital	392,585,265	354,614,189
Accumulated deficit	(278,796,093)	(175,895,493)
Total stockholders’ equity	113,792,909	178,722,389
Total liabilities and stockholders’ equity	$ 186,134,323	$ 220,549,760

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
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	37,374,088	36,933,217
Common stock, shares outstanding	37,374,088	36,933,217

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development	$ 70,244,579	$ 53,647,067	$ 23,495,055
General and administrative	28,896,749	13,598,030	9,351,522
Total operating expenses	99,141,328	67,245,097	32,846,577
Loss from operations	(99,141,328)	(67,245,097)	(32,846,577)
Interest and amortization of debt discount expense	(2,565,838)	(1,239,537)	(1,127,305)
Tax credit	53,578	139,448	217,418
Change in fair value of warrant liability			2,791,000
Loss on extinguishment of debt	(1,247,012)
Net loss	$ (102,900,600)	$ (68,345,186)	$ (30,965,464)
Net loss per common share, basic and diluted	$ (2.77)	$ (2.01)	$ (1.15)
Weighted average common shares outstanding, basic and diluted	37,206,928	34,020,257	26,883,656

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($)	Total	License Agreement	Common Stock	Common StockLicense Agreement	Additional Paid-in Capital	Additional Paid-in CapitalLicense Agreement	Accumulated Deficit
Beginning balance at Dec. 31, 2017	$ 16,717,223		$ 2,549		$ 93,299,517		$ (76,584,843)
Balance (in shares) at Dec. 31, 2017			25,492,992
Stock-based compensation	1,754,974				1,754,974
Issuance of common stock upon exercise of options	380,322		$ 29		380,293
Issuance of common stock upon exercise of options (in shares)			278,925
Exercise of warrants	131,703		$ 10		131,693
Exercise of warrants (in shares)			101,310
Issuance of warrants upon debt financing	37,842				37,842
Issuance of common stock upon financing	12,881,321		$ 421		12,880,900
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	937,921		$ 3,009		108,485,219		(107,550,307)
Balance (in shares) at Dec. 31, 2018			30,087,213
Stock-based compensation	6,115,160				6,115,160
Issuance of common stock upon exercise of options	1,143,841		$ 25		1,143,816
Issuance of common stock upon exercise of options (in shares)			252,773
Exercise of warrants	249,836		$ 10		249,826
Exercise of warrants (in shares)			97,541
Issuance of warrants upon debt financing	387,000				387,000
Issuance of common stock upon financing	238,233,817		$ 649		238,233,168
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	$ 178,722,389		$ 3,693		354,614,189		(175,895,493)
Balance (in shares) at Dec. 31, 2019	36,933,217		36,933,217
Stock-based compensation	$ 14,756,206				14,756,206
Issuance of common stock upon exercise of options	$ 1,049,849		$ 13		1,049,836
Issuance of common stock upon exercise of options (in shares)	127,778		127,778
Exercise of warrants	$ 6		$ 6
Exercise of warrants (in shares)			63,831
Issuance of warrants upon debt financing	884,216				884,216
Issuance of common stock upon financing	14,125,506	$ 7,155,337	$ 17	$ 8	14,125,489	$ 7,155,329
Issuance of common stock upon financing (in shares)			167,243	82,019
Net loss	(102,900,600)						(102,900,600)
Ending balance at Dec. 31, 2020	$ 113,792,909		$ 3,737		$ 392,585,265		$ (278,796,093)
Balance (in shares) at Dec. 31, 2020	37,374,088		37,374,088

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net loss	$ (102,900,600)	$ (68,345,186)	$ (30,965,464)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	14,756,206	6,115,160	1,754,974
Non-cash research and development license expense	7,155,337
Amortization of debt discount	786,750	649,993	375,635
Loss on extinguishment of debt	1,247,012
Amortization of operating lease right-of-use asset	53,854
Change in fair value of warrants			(2,791,000)
Change in operating lease liability	8,967
Depreciation	23,864	37,330	48,935
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	264,722	833,265	32,058
Other assets	(177,500)	(27,530)	75,607
Accounts payable	2,560,697	7,256,080	251,789
Accrued expenses and other current liabilities	(2,235,878)	7,105,829	1,163,765
Net cash used in operating activities	(78,456,569)	(46,375,059)	(30,053,701)
Cash flows from investing activities
Purchases of equipment	(45,891)	(16,121)	(32,696)
Net cash used in investing activities	(45,891)	(16,121)	(32,696)
Cash flows from financing activities
Proceeds from issuance of term loan	50,000,000	20,000,000
Payment of debt issuance costs	(1,102,609)		(25,997)
Repayment of principal on term loan	(21,660,000)	(7,238,889)	(3,333,333)
Proceeds from issuance of common stock upon financing, net	14,125,506	238,233,817	12,881,321
Proceeds from issuance of common stock upon exercise of warrants		249,836	131,703
Proceeds from issuance of common stock upon exercise of options	1,049,849	1,143,841	380,322
Net cash provided by financing activities	42,412,746	252,388,605	10,034,016
Net (decrease) increase in cash	(36,089,714)	205,997,425	(20,052,381)
Cash at beginning of period	219,966,167	13,968,742	34,021,123
Cash at end of period	183,876,453	219,966,167	13,968,742
Supplemental disclosures of cash flow information:
Interest paid	2,097,292	1,287,506	771,966
Operating lease right-of-use asset obtained in exchange for operating lease liability	1,793,328
Supplemental disclosures of non-cash financing activity:
Issuance of warrants in connection with debt financing	$ 884,216	$ 387,000	$ 37,842

Nature of Business and Basis of

Nature of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	Note 1. Nature of Business and Basis of Presentation Axsome Therapeutics, Inc. (“Axsome” or the “Company”) is a 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, 2020, the Company had an accumulated deficit of $278.8 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. 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. The Company may use a combination of public and private equity offerings, debt financings, other third-party funding, strategic alliances, licensing arrangements or marketing and distribution arrangements if market conditions are favorable or in light of other strategic considerations to finance its future cash needs. 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, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 2. Summary of Significant Accounting Policies Impact of COVID-19 In December 2019, a novel (new) coronavirus known as SARS-CoV-2 was first detected in Wuhan, Hubei Province, People’s Republic of China, causing outbreaks of the coronavirus disease, known as COVID-19, that has now spread globally. On January 30, 2020, the World Health Organization (WHO) declared COVID-19 a public health emergency. The Secretary of Health and Human Services declared a public health emergency in the United States on January 31, 2020, under section 319 of the Public Health Service Act (42 U.S.C. 247d), in response to the COVID-19 outbreak. On March 11, 2020, the WHO declared COVID-19 a pandemic. The full impact of the COVID-19 pandemic is unknown and rapidly evolving. While the potential economic impact brought by and over the duration of the COVID-19 pandemic may be difficult to assess or predict, the COVID-19 pandemic has resulted in significant disruption of global financial markets, which could in the future negatively affect the Company’s liquidity. In addition, a recession or market volatility resulting from the COVID-19 pandemic could affect the Company’s business. Given the nature and type of the Company’s short-term investments, the Company does not believe the COVID-19 pandemic has had a material impact on the Company’s current investment liquidity. 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, the Company’s 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. The Company’s cash and cash equivalents includes holdings in checking and overnight sweep accounts. The Company’s cash equivalents, which are money market funds held in a sweep account, are measured at fair value on a recurring basis. As of December 31, 2020, the balance of cash and cash equivalents was $183.9 million, which approximates fair value and was determined based upon Level 1 inputs. The sweep account is valued using quoted market prices with no valuation adjustments applied. Accordingly, these securities are categorized as Level 1. 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, 2020, 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 Company’s financial instruments are cash, accounts payable, accrued liabilities, and current and long-term debt. The carrying values for cash, accounts payable and accrued liabilities reported in the accompanying consolidated financial statements approximate their respective fair values due to their short-term maturities. The carrying value of debt on the Company’s balance sheet (see Note 6 – Loan and Security Agreement), is estimated to approximate its fair value as the interest rate approximates the market rate for loans with similar terms and risk characteristics. Debt Issuance Costs Debt issuance costs consist of costs incurred in obtaining long-term financing. These costs are classified on the consolidated balance sheet as a direct deduction from the carrying amount of the related debt liability. These expenses are deferred and amortized as part of interest expense in the consolidated statement of operations using the effective interest rate method over the term of the debt agreement. 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 are expensed as incurred. Research and development expenses consist primarily of personnel costs for our research and development employees, costs incurred to third-party service providers for the conduct of research, preclinical and clinical studies, laboratory supplies, product license fees, consulting and other related expenses. We estimate research, preclinical and clinical study expenses based on services performed, pursuant to contracts with third-party research and development organizations that conduct and manage research, preclinical and clinical activities on our behalf. We estimate these expenses based on discussions with internal management personnel and external service providers as to the progress or stage of completion of services and the contracted fees to be paid for such services. If the actual timing of the performance of services or the level of effort varies from the original estimates, we will adjust the accrual accordingly. Payments associated with licensing agreements to acquire licenses to develop, use, manufacture and commercialize products that have not reached technological feasibility and do not have alternative future use are expensed as incurred. Payments made to third parties under these arrangements in advance of the performance of the related services by the third parties are recorded as prepaid expenses until the services are rendered. 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 of a change in tax rates on deferred tax assets and liabilities 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’s annual effective tax rate was 0% for the year ending December 31, 2020 and has not recorded an income tax benefit for the twelve months ended December 31, 2020 and 2019 since it determined that a full valuation allowance is required against the Company’s deferred tax assets. 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, 2020, 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’s 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 restricted stock units (“RSUs”), the Company issues them in the form of Company common stock. The fair market value of these awards is based on the market closing price per share on the grant date. Prior to January 1, 2020, the Company only granted stock options. Beginning in 2020, for grants to employees, the Company granted a mix of stock options and RSUs. 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 same financial statement line item as the grantee’s cash compensation. The Company’s policy upon exercise of stock options and RSUs 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 warrants, stock options, and RSUs, 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, 2020, 2019, and 2018. Leases The Company determines if an arrangement is a lease at contract inception. Operating lease assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. When evaluating whether a contract contains a lease, the Company considers whether (1) the contract explicitly or implicitly identifies assets that are contractually defined and (2) the Company obtains substantially all of the economic benefits from the use of that underlying asset and directs how and for what purpose the asset is used during the term of the contract. The Company’s lease agreement contain s lease and non-lease components. Non-lease components primarily include payments for maintenance and utilities. The Company has applied the practical expedient to combine fixed payments for non-lease components with lease payments and account for them together as a single lease component, which increases the amount of lease assets and corresponding liabilities. Payments under the Company’s lease arrangement are primarily fixed, however variable payments, are expensed as incurred and not included in the operating lease asset and liabilit y . Operating lease assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company uses the implicit interest rate when readily determinable and uses the Company’s incremental borrowing rate when the implicit rate is not readily determinable based upon the information available at the commencement date in determining the present value of the lease payments. The Company’s operating leases are reflected in the right-of-use operating asset; operating lease liability, current portion; and operating lease liability, long-term portion in the Company’s consolidated balance sheets. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. Short-term leases, defined as leases that have a lease term of 12 months or less at the commencement date, and do not include an option to extend the term or purchase the underlying asset that that the Company is reasonably certain to exercise, are excluded from this treatment and are recognized on a straight-line basis over the term of the lease. Recent Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, enhances and simplifies various aspects of the income tax accounting guidance, including requirements such as tax basis step-up in goodwill obtained in a transaction that is not a business combination, ownership changes in investments, and interim-period accounting for enacted changes in tax law. 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. In October 2020, the FASB issued ASU 2020-10, Codification Improvements, which clarifies various topics in the Accounting Standards Codification, including the addition of existing disclosure requirements to the relevant disclosure sections. The amendments in ASU 2020-10 do not change GAAP and, therefore, are not expected to result in a significant change in practice. ASU 2020-10 should be applied retrospectively to the beginning of the period that includes the adoption date. ASU 2020-10 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We do not expect the adoption of this new standard to have a material impact on our condensed consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 3. Fair Value Measurements 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 The fair value of the Common Warrants and Placement Agent Warrants at December 31, 2017 were determined to be approximately $2,683,000 and $108,000, respectively, which total to $2,791,000 as calculated using Black-Scholes with the following assumptions: (1) stock price of $5.60; (2) a risk-free rate of 1.76%; and (3) an expected volatility of 62%. 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, 2020 and December 31, 2019.

Net Loss per Common Share

Net Loss per Common Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Net Loss per Common Share	Note 4. Net Loss per Common Share The following table sets forth the computation of basic and diluted net loss per common share: Year ended December 31, 2020 2019 2018 Basic and diluted net loss per common share: Net loss $ (102,900,600 ) $ (68,345,186 ) $ (30,965,464 ) Weighted average common shares outstanding—basic and diluted 37,206,928 34,020,257 26,883,656 Net loss per common share—basic and diluted $ (2.77 ) $ (2.01 ) $ (1.15 ) The following potentially dilutive securities outstanding at December 31, 2020, 2019, and 2018 have been excluded from the computation of diluted weighted average shares outstanding, as they would be anti‑dilutive: December 31, 2020 2019 2018 Stock options 3,733,916 3,458,447 2,291,163 Restricted stock units 136,067 — — Warrants 15,541 69,656 123,037 Total 3,885,524 3,528,103 2,414,200

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2020
Accrued Liabilities And Other Liabilities [Abstract]
Accrued Expenses and Other Current Liabilities	Note 5. Accrued Expenses and Other Current Liabilities At December 31, 2020 and 2019, accrued expenses consisted of the following: December 31, 2020 2019 Accrued research and development $ 4,293,522 $ 8,209,594 Accrued compensation 2,870,261 2,056,356 Accrued general and administrative 1,155,508 554,011 Accrued Interest 393,958 129,167 Total $ 8,713,249 $ 10,949,128

Loan and Security Agreement

Loan and Security Agreement	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Loan and Security Agreement	Note 6. Loan and Security Agreement Hercules Capital, Inc. 2020 Term Loan In September 2020, the Company entered into a Loan and Security Agreement (the “Loan Agreement”) with Hercules Capital, Inc., in its capacity as administrative agent and collateral agent and as a lender (in such capacity, the “Agent” or “Hercules”) and the other financial institutions that from time to time become parties to the Loan Agreement as lenders (collectively, the “Lenders”). The Loan Agreement provides for term loans in an aggregate principal amount of up to $225.0 million under multiple tranches (the “2020 Term Loan”). The tranches consist of (i) a first tranche consisting of term loans in an aggregate principal amount of $60.0 million, of which $50.0 million was funded to the Company on the Closing Date (the “First Advance”), and of which the remaining $10.0 million is available at the Company’s option at any time through September 15, 2021; (ii) subject to the approval of the Company’s AXS-05 product candidate for the treatment of major depressive disorder (the “First Milestone”), a second tranche consisting of additional term loans in an aggregate principal amount of up to $35.0 million, available at the Company’s option beginning on the date that the First Milestone is achieved through the earlier of (A) 181 days following such date and (B) June 30, 2022; (iii) subject to the approval of the Company’s AXS-07 product candidate for the treatment of migraine (the “Second Milestone”), a third tranche consisting of additional term loans in an aggregate principal amount of up to $20.0 million, available at the Company’s option beginning on the date that the Second Milestone is achieved through the earlier of (A) 181 days following such date and (B) June 30, 2022; (iv) subject to the achievement of either the First Milestone or the Second Milestone and so long as the Company is in compliance with a required ratio of Lender indebtedness to net product revenue, a fourth tranche consisting of additional term loans in an aggregate principal amount of up to $60.0 million, available at the Company’s option beginning on January 1, 2022 and continuing through March 31, 2023; and (v) subject to approval by the Lenders’ in their discretion, a fifth tranche of additional term loans in an aggregate principal amount of up to $50.0 million, available through December 31, 2023. The Company intends to use the proceeds of the Term Loan Advances for working capital and general corporate purposes. In addition, approximately $21.7 million of the proceeds from the First Advance was used to satisfy in full and retire the Company’s indebtedness under the 2019 Term Loan, as amended. The outstanding principal balance of the term loans bears interest at an annual rate equal to the greater of either (i) the prime rate as reported in The Wall Street Journal plus 5.90% or (ii) 9.15%, subject to an ability by the Company, during certain periods (each, a “PIK Deferral Period”), to request a reduction of the then-effective cash-pay interest rate by up to 1.00% per annum (the “Cash Interest Reduction Amount”). Accrued interest is payable monthly following the funding of each term loan. During each PIK Deferral Period, the term loans will bear cash-pay interest, at the reduced amount, and will accrue paid-in-kind interest at a rate equal to the Cash Interest Reduction Amount multiplied by 1.15, which amount will be capitalized and added to the outstanding principal balance of the term loans on each monthly interest payment date during the PIK Deferral Period. The Company is required to repay the term loans in equal installments of principal and interest commencing on May 1, 2023 through October 1, 2025 (the “Maturity Date”). However, if either the First Milestone or the Second Milestone are achieved prior to May 1, 2023, and no default exists, the amortization commencement date will be automatically extended to November 1, 2023; if both the First Milestone and the Second Milestone are achieved prior to November 1, 2023, and no default exists, the amortization commencement date will be further automatically extended to May 1, 2024 and if any term loans are funded under the fourth tranche noted above prior to May 1, 2024, and no default exists, the amortization commencement date will be further automatically extended to November 1, 2024. On the Maturity Date, all unpaid term loans will be due and payable. As collateral for the obligations, the Company has granted to Hercules a senior security interest in all of Company’s right, title, and interest in, to and under all of Company’s property, inclusive of intellectual property, which includes one of the Company’s existing license agreements (the “License Agreement”) with Antecip Bioventures II LLC (“Antecip”), an entity owned by Axsome’s Chief Executive Officer and Chairman of the Board, Herriot Tabuteau, M.D., subject to limited exceptions. Antecip consented to the collateral assignment of the License Agreement, among other things, under a direct agreement (the “Direct Agreement”) with the Company and Hercules. The Loan Agreement contains customary representations, warranties and covenants, including covenants by the Company limiting additional indebtedness, liens (including a negative pledge on intellectual property and other assets), guaranties, mergers and consolidations, substantial asset sales, investments and loans, certain corporate changes, transactions with affiliates and fundamental changes. At the initial closing, there were no applicable financial covenants contained in the Loan Agreement. Only after additional amounts are drawn down by the Company in the future, if the Company decides to do so, under the terms set forth in the Loan Agreement, there will be certain limited financial covenants that will apply, including: • Effective upon the date the outstanding principal amount of the advances under the Loan Agreement equals or exceeds $55.0 million, which has not yet occurred, the Company at all times thereafter must maintain cash in an account or accounts in which Hercules has a first priority security interest, in an aggregate amount greater than or equal to $15.0 million, plus the amount of the Company’s accounts payable under U.S. GAAP not paid after the 180th day following the invoice for such account payable (such amount, the “Qualified Cash A/P Amount”). • Effective upon the later of (i) the last calendar month of the calendar quarter that is twelve months following the earlier of (x) the date that the First Milestone is achieved and (y) the date that the Second Milestone is achieved, or (ii) the date on which the outstanding principal amount of the term loan advances under the Loan Agreement is equal to or greater than $65.0 million, the Company is required to (A) ensure that at all times its market capitalization exceeds $2.0 billion, and that it maintains cash in an account which Hercules has a first priority security interest in an amount not less than 65% of the sum of the outstanding principal amount of the term loan advances plus the Qualified Cash A/P Amount, (B) ensure that at all times that it maintains cash in an account which Hercules has a first priority security interest in an amount not less than 100% of the sum of the outstanding principal amount of the term loan advances plus the Qualified Cash A/P Amount, or (C) achieve at least 60% of the net product revenue solely from the sale of AXS-05 and AXS-07 (which may include royalty, profit sharing, or sales-based milestone revenue recognized in accordance with GAAP, but will not include any upfront or non-sales-based milestone payments under business development or licensing transactions), measured on a trailing six-month basis as of the date of the Company’s most recent quarterly financial statement, determined on a quarterly basis. • Restrictions on the Company’s ability to incur additional indebtedness, pay dividends, encumber its intellectual property, or engage in certain fundamental business transactions, such as mergers or acquisitions of other businesses, with certain exceptions. The Company’s obligations under the Loan Agreement are subject to acceleration upon the occurrence of specified events of default, including payment default, insolvency and a material adverse change in the Borrower’s business, operations or financial or other condition. In addition, the Company is required to pay a final payment fee equal to the greater of (A) $2,910,000 and (B) 4.85% of the aggregate amount of all term loan advances minus the aggregate amount of repayments made. The final payment fee is being accreted and amortized into interest expense using the effective interest rate method over the term of the loan. The Company may, at its option prepay the term loans in full or in part, subject to a prepayment penalty equal to (i) 2.0% of the principal amount prepaid if the prepayment occurs prior to the first anniversary of the Closing Date, (ii) 1.5% of the principal amount prepaid if the prepayment occurs on or after the first anniversary and prior to the second anniversary of the Closing Date, and (iii) 1.0% of the principal amount prepaid if the prepayment occurs on or after the second anniversary and prior to the third anniversary of the Closing Date. The Company evaluated whether the Hercules Term Loan entered into in September 2020 represented a debt modification or extinguishment of the SVB Loan in accordance with ASC 470-50, Debt – Modifications and Extinguishments. As a result of the repayment and retirement of the SVB Loan, the SVB Loan was accounted for by the Company under the extinguishment accounting model. The Company recorded a loss on extinguishment of debt of approximately $1.2 million on the Company’s statement of operations for the twelve months ended December 31, 2020, representing a prepayment premium, the unamortized discount of the SVB Loan and the write-off of deferred financing costs. Silicon Valley Bank In November 2016, the Company entered into an initial term loan agreement with Silicon Valley Bank (“SVB”) for a total of $20.0 million (“2016 Original Term Loan”). The three-tranche term loan consisted of an initial $10.0 million tranche funded upon closing, and the remaining tranches were not drawn upon as 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. Therefore, the Company amended the 2016 Original Term Loan to provide an additional $4.0 million growth capital loan (“2016 Amended Term Loan”). The Company’s obligations under the 2016 Amended Term Loan, along with the ability to draw down on the additional $4.0 million tranche, were considered to be performed and completed in connection with the establishment of the 2019 Term Loan (as defined below). In March 2019, the Company entered into a $24.0 million growth capital term facility (the “2019 Term Loan”) with SVB and WestRiver Innovation Lending Fund VIII, L.P. (“WestRiver”). The 2019 Term Loan consisted of an initial $20.0 million tranche, which was funded upon closing, and a second tranche of $4.0 million, which was available to be drawn subject to completion of a clinical milestone prior to August 15, 2019. A portion of the first tranche was used to satisfy the Company’s existing obligations under and fully extinguish the 2016 Amended Term Loan, which at the commencement of the 2019 Term Loan consisted of $5.6 million in outstanding principal balance and $0.85 million as a final payment fee. The 2019 Term Loan was subsequently amended in July 2019 (the “First Amendment to the 2019 Term Loan”) to extend the interest-only monthly payment period for 18 months from the date of the 2019 Term Loan and the Company’s ability to draw down on the second tranche of $4.0 million was extended until December 31, 2019. The second tranche of $4.0 million was not drawn down by the Company. The 2019 Term Loan accrued interest at a fixed rate of 7.5%. Interest on the 2019 Term Loan and the First Amendment to the 2019 Term Loan was payable monthly beginning April 1, 2019 and principal was due starting on October 1, 2020. In addition, the Company was required to make a final payment of $1.26 million on February 1, 2023, the maturity date of the 2019 Term Loan. However, the Company subsequently entered into the 2020 Term Loan (as defined below), the proceeds of which were used in part to fully satisfy and extinguish the 2019 Term Loan, as amended. In connection with the 2019 Term Loan, the Company issued SVB and WestRiver a warrant to purchase shares of common stock. These warrants were fully exercised and no longer outstanding as of September 30, 2020 (see Note 6 – Stockholders’ Equity under “Warrants” section for further discussion). In September 2020, the Company terminated and repaid all amounts outstanding under the 2019 Term Loan and recorded a loss on extinguishment of the loan (see further discussion below). The book value of debt approximates its fair value given its short term maturity and variable interest rate. Interest expense was $2,362,083, $1,362,500, and $751,670 and amortization of the final payment was $469,676, $436,567, and $266,668 for the years ended December 31, 2020, 2019, and 2018, respectively. Long-term debt and unamortized debt discount balances are as follows: December 31, December 31, 2020 2019 Outstanding principal amount $ 50,000,000 $ 20,000,000 Add: accreted liability of final payment fee 151,912 404,364 Less: unamortized debt discount, long term (1,830,064 ) (405,071 ) Less: current portion of long-term debt — (2,666,667 ) Loan payable, long-term $ 48,321,848 $ 17,332,626 Current portion of outstanding principal amount — 2,666,667 Less: current portion of unamortized debt discount — (64,375 ) Loan payable, current portion $ — $ 2,602,292 Further information on warrants issued related to the debt financings and amendments are disclosed in Note 9 - Warrants. Amortization of the debt discount in relation to warrants issued in Note 9 - Warrants was $317,074, $213,426, and $108,968 for the year ended December 31, 2020, 2019, and 2018, respectively. Scheduled Principal Payments on Outstanding Debt, as of December 31, 2020, are as follows: 2021 $ — 2022 — 2023 12,193,153 2024 19,761,468 2025 18,045,379 Total principal payments outstanding $ 50,000,000

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 7. Commitments and Contingencies Operating Leases Starting in 2019, leases are accounted for under ASC Topic 842. The Company made an accounting policy election not to apply the recognition requirements to short-term leases. The Company recognizes the lease payments for short-term leases in the consolidated statements of operations and comprehensive loss on a straight-line basis over the lease term, and variable lease payments in the period in which the obligation for those payments is incurred. Therefore, the Company is not recognizing a lease liability or right-of-use asset for any lease that, at the commencement date, has a lease term of 12 months or less and does not include an option to extend the term or purchase the underlying asset that that the Company is reasonably certain to exercise. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company has entered into a lease agreement for the Company’s principal executive offices located in New York, New York. The lease does not include any restrictions or covenants that had to be accounted for under the lease guidance. In June 2020, the company entered into a lease for office space at 22 Cortlandt St, New York, NY consisting of the 16 th In December 2020, the company modified the lease agreement for office space at 22 Cortlandt St, New York, NY, consisting of the 16 th Rent expense incurred during the years ended December 31, 2020, 2019 and 2018 was $870,275, $485,548, and $315,301. The following table summarizes the presentation of operating leases in the Company’s consolidated balance sheet: Balance sheet location As of December 31, 2020 Assets Right-of-use operating asset Right-of-use asset - operating lease $ 1,739,475 Liabilities Current operating lease liabilities Operating lease liability, current portion 1,220,587 Long-term operating lease liabilities Operating lease liability, long-term 581,708 Total operating lease liabilities $ 1,802,295 For the year ended December 31, 2020, the Company noted the following lease expense: Statement of Operations Location Year Ended December 31, 2020 Operating lease expense General and administrative $ 47,821 Total operating lease expense $ 47,821 Future minimum lease payments of our operating leases as of December 31, 2020 were as follows: Years Ending December 31, 2021 $ 1,250,000 2022 630,000 2023 — 2024 — 2025 — Thereafter — Total lease payments 1,880,000 Less imputed interest (77,705 ) Present value of operating lease liabilities $ 1,802,295 As of December 31, 2020, the remaining lease term for our operating lease was 1.6 years with a discount rate of 6.0%. The interest rate implicit in lease contracts is typically not readily determinable and as such, the Company uses its incremental borrowing rate based on the information available at the lease commencement date, which represents an internally developed rate that would be incurred to borrow, on a collateralized basis, over a similar term, an amount equal to the lease payments in a similar economic environment.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Stockholders' Equity	Note 8. 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. Due to expiration of the 2016 Shelf Registration Statement, at the Company’s option, the shares that were unsold of approximately $29.9 million 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. For the year ended December 31, 2020, the Company received approximately $14.6 million in gross proceeds through the sale of 167,243 shares, of which net proceeds were approximately $14.1 million. For the year ended December 31, 2019, 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. 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 $221.9 million pursuant to such shelf registration statement. Under SEC rules, the 2019 Shelf Registration Statement allows for the potential future offer and sale by the Company, from time to time, in one or more public offerings, of an indeterminate amount of the Company’s common stock, preferred stock, debt securities, and units at indeterminate prices. 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 . 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, 2020, there were 4,149,112 shares available for future grant under the 2015 Plan. Modification and Cancellation of Stock Awards In June 2020, in connection with the decision not to stand for re-election by a member of the Company’s Board of Director’s, the vesting of stock options covering 21,666 shares of common stock was accelerated. As a result of this modification, the Company recorded incremental stock-based compensation expense of approximately $1.3 million for the year ended December 31, 2020. In November 2020, certain employee Stock Options and Restricted Stock Units were cancelled. Stock options to purchase an aggregate of 38,267 shares of common stock were cancelled, and the Company recognized non-cash stock-based compensation expense of $2.1 million related to this cancellation for the year ended December 31, 2020. Restricted Stock Units for an aggregate of 11,735 shares of common stock were cancelled, and the Company recognized non-cash stock-based compensation expense of $0.5 million related to this cancellation for the year ended December 31, 2020. Stock Options The following table summarizes stock option activity as of Weighted Weighted average Aggregate Number average contractual intrinsic of shares exercise price term value Outstanding at December 31, 2019 3,458,447 10.19 Granted 649,142 54.50 Exercised (127,778 ) 8.22 Forfeited (207,628 ) 35.85 Cancelled (38,267 ) 58.98 Outstanding at December 31, 2020 3,733,916 16.03 7.2 243,556,917 Vested and expected to vest at December 31, 2020 3,727,747 16.36 7.2 243,062,340 Exercisable at December 31, 2020 2,479,110 10.66 6.0 175,575,360 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, 2020, 2019, and 2018 is as follows: Black-Scholes option valuation assumptions 2020 2019 2018 Risk-free interest rates 0.3 - 1.7% 1.4 - 2.7% 2.0 - 3.1% Dividend yield — — — Volatility 67 - 99% 87 - 91 % 74 - 87% Weighted average expected term 3.51 - 6.14 years 5.00 - 6.13 years 3.66 - 6.13 years The weighted average grant date fair value of options granted was $36.77, $12.49, and $1.99 per option for the years ended December 31, 2020, 2019 and 2018, respectively. As of December 31, 2020, there was $20.9 million of total unrecognized compensation cost related to non‑vested stock options which is expected to be recognized over a weighted average period of 2.8 years. These amounts do not include 10,716 options outstanding as of December 31, 2020, 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. The intrinsic value of stock options exercised during the years ended December 31, 2020, 2019 and 2018 was $9.4 million, $4.5 million and $0.5 million, respectively. Restricted Stock Units In 2020, the Company began granting RSUs covering an equal number of its shares of common stock to employees. The fair value of RSUs is determined on the date of the grant based on the market price of its shares of common stock as of that date. The fair value of the RSUs is recognized as an expense ratably over the vesting period of four years. As of December 31, 2020, total compensation cost not yet recognized related to unvested RSUs was $4.1 million, which is expected to be recognized over a weighted-average period of 3.3 years. The following table sets forth the RSU activity for the year ended December 31, 2020: Weighted average Number grant date of shares fair value Outstanding at December 31, 2019 — $ — Granted 161,268 37.42 Released — — Forfeited (13,466 ) 86.88 Cancelled (11,735 ) 45.14 Outstanding at December 31, 2020 136,067 $ 35.76 Stock‑based compensation expense recognized for the years ended December 31, 2020, 2019, and 2018 was as follows: 2020 2019 2018 Research and development $ 3,953,939 $ 1,584,165 $ 391,946 General and administrative 10,802,267 4,530,995 1,363,028 Total $ 14,756,206 $ 6,115,160 $ 1,754,974

Warrants

Warrants	12 Months Ended
	Dec. 31, 2020
Warrants And Rights Note Disclosure [Abstract]
Warrants	Note 9. Warrants As of December 31, 2020, the Company had outstanding warrants to purchase 15,541 shares of common stock. The following table summarizes warrant activity as of December 31, 2020, 2019, and 2018: Warrants Weighted average exercise price 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 Issued 15,541 80.43 Exercised (69,656 ) 7.21 Outstanding at December 31, 2020 15,541 $ 80.43 Outstanding Warrants In connection with the entry into the Loan Agreement, the Company issued to Hercules a warrant to purchase a number of shares of the Company’s common stock, par value $0.0001 per share equal to 2.5% of the aggregate amount of the Term Loan Advances that are funded, as such amounts are funded. With the first advance of the 2020 Term Loan, Hercules Capital Inc. received warrants to purchase an aggregate 15,541 shares of the Company’s common stock at an exercise price of $80.43 per share, which was the volume weighted average price of the Company’s common stock over the ten-day Fully Exercised Warrants 2019 and 2020 Exercise of March 2019 and July 2019 Warrants In connection with the Company’s 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 were exercisable until March 4, 2026. The warrants were classified as a component of stockholders' equity of which 58,332 warrants were immediately exercisable and the remaining 11,668 warrants could be earned based on usage of the second tranche of the 2019 Term Loan. The additional warrants were initially immediately exercisable if and when the Term B Loan Advance was funded (however, the March 2019 Warrants were amended in connection with the First Amendment to the 2019 Term Loan, as discussed below). The relative fair value of the warrants of approximately $0.4 million at the time of issuance, which was determined using the Black-Scholes option-pricing model, was recorded as additional paid-in capital and reduced the carrying value of the debt. The discount on the debt was amortized to interest expense over the term of the debt utilizing the effective interest rate method. In July 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 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. In August 2020, WestRiver 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 26,270 shares of its common stock in connection with the warrant exercise and did not receive any cash proceeds. As of December 31, 2020, none of the warrants issued in connection with the First Amendment to the 2019 Term Loan were outstanding . 2019 and 2020 Exercise of 2018 Warrants 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. In August 2020, WestRiver exercised in full the 7,875 warrants it received in connection with the 2016 Amended Term Loan via a cashless exercise. The Company issued SVB 7,579 shares of its common stock in connection with the warrant exercise, and did not receive any cash proceeds. As of December 31, 2020, none 2018 Expiration of 2017 Warrants 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. 2019 and 2020 Exercise of 2016 Warrants 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. In addition, in May 2020, Life Science exercised in full the 32,614 warrants it received in connection with the 2016 Original Term Loan via a cashless exercise. The Company issued Life Science 29,982 shares of its common stock in connection with the warrant exercise and did not receive any cash proceeds. 2019 Exercise of 2014 warrants 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 2017 and 2018 Exercise of 2013 Warrants 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 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 2020 warrants 2019 warrants 2018 warrants 2017 warrants 2016 warrants 2014 warrants 2013 warrants Risk-free interest rate 0.5 % 2.8 % 3.0 % 1.7 % 1.8 % 1.6 % 1.4 % Dividend yield — — — — — — — Volatility 88 % 97 % 85 % 61 % 73 % 70 % 64 % Weighted average contractual term 7 years 7 years 7 years 1 year 7 years 5 years 5 years

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2020
Research And Development [Abstract]
License Agreements	Note 10. License Agreements In January 2020, the Company entered into an exclusive license agreement with Pfizer Inc. (“Pfizer”) 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 stated value of $8.0 million, based on the average closing price of the Company’s common stock for the ten prior trading days of $97.538, in consideration for the license and rights and also received an upfront cash payment of $3.0 million. The Company determined that the fair value of each share of common stock granted to Pfizer on the closing date of January 9, 2020 was $87.24, based on the closing price of the Company’s stock on that date. As a result, the fair value of the stock issued was $7.2 million and therefore, the total research and development expense recognized was $10.2 million related to the Pfizer license agreement during the twelve months ended December 31, 2020. Pfizer can 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. During the twelve months ended December 31, 2020, no milestone payments or royalties were paid to Pfizer by the Company. 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‑05 and two product candidate that are not currently in 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‑05. Under the terms of the agreements, the Company is required to pay to Antecip a royalty equal to 3.0% for AXS‑05, 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 connection with the 2020 Term Loan, the Company entered into a Direct Agreement with Antecip pursuant to which Antecip consented to the collateral assignment of the License Agreement to Hercules, among other things.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Note 11. Income Taxes As of December 31, 2020, the Company has U.S. federal net operating loss (“NOL”) carryforwards of approximately $249 million. NOLs amounting to $60 million generated before the 2018 tax year will start expiring beginning 2032, and the NOL of approximately $189 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, 2020 December 31, 2019 Deferred tax assets: Net federal operating loss carryforward $ 52,329,877 $ 32,299,085 Net foreign operating loss carryforward 86,829 59,557 Net state operating loss carryforward 32,410,604 20,000,317 Non-cash compensation 7,329,228 3,485,519 Research and development credits 13,028,222 10,366,683 Interest Expense 1,765,452 985,431 Charitable Contribution 5,408 5,408 Fixed Assets 7,883 11,401 Lease Liability 612,973 — Accrued expenses 968,709 1,200,754 Deferred tax asset, excluding valuation allowance 108,545,185 68,414,155 Deferred tax liabilities: Deferred finance costs — (121,875 ) Lease Asset (591,607 ) — Deferred tax liability, excluding valuation allowance (591,607 ) (121,875 ) Less valuation allowance (107,953,578 ) (68,292,280 ) 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 $39.7 million, $27.0 million, and $12.5 million, in 2020, 2019, and 2018, 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, 2020, 2019, and 2018. 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, 2020 December 31, 2019 December 31, 2018 U.S. federal statutory income tax rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 13.7 13.5 13.1 Stock based compensation - Excess tax benefit 1.8 1.2 1.1 Other permanent differences (0.6 ) (0.1 ) (1.3 ) Tax credit 2.5 4.2 6.3 Change in valuation allowance (38.4 ) (39.8 ) (40.2 ) 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, 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. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) was enacted and signed into law, and GAAP requires recognition of the tax effects of new legislation during the reporting period that includes the enactment date. The CARES Act, among other things, includes changes to the tax provisions that benefits business entities and makes certain technical corrections to the 2017 Tax Cuts and Jobs Act, including, permitting net operating losses (“NOLs”), carryovers and carrybacks to offset 100% of taxable income for taxable years beginning before 2021. In addition, the CARES Act allows NOLs incurred in 2018, 2019, and 2020 to be carried back to each of the five preceding taxable years to generate a refund of previously paid income taxes. The CARES Act provides other reliefs and stimulus measures. We have evaluated the impact of the CARES Act, however, at present we do not expect that any provision of the CARES Act would result in a material cash benefit to us or have a material impact on our financial statements or internal controls over financial reporting.

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
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 10 – License Agreements for further information regarding the license agreements.

Quarterly Consolidated Financia

Quarterly Consolidated Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Consolidated Financial Data (Unaudited)	Note 13. Quarterly Consolidated Financial Data (Unaudited) 2020 Mar. 31 June 30 Sept. 30 Dec. 31 Total operating expenses $ 32,491,457 $ 17,778,834 $ 21,126,801 $ 27,744,236 Net loss $ (32,484,146 ) $ (18,326,992 ) $ (22,924,815 ) $ (29,164,647 ) Net loss per common share, basic and diluted (1) $ (0.88 ) $ (0.49 ) $ (0.61 ) $ (0.79 ) 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 ) (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.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Impact of COVID-19	Impact of COVID-19 In December 2019, a novel (new) coronavirus known as SARS-CoV-2 was first detected in Wuhan, Hubei Province, People’s Republic of China, causing outbreaks of the coronavirus disease, known as COVID-19, that has now spread globally. On January 30, 2020, the World Health Organization (WHO) declared COVID-19 a public health emergency. The Secretary of Health and Human Services declared a public health emergency in the United States on January 31, 2020, under section 319 of the Public Health Service Act (42 U.S.C. 247d), in response to the COVID-19 outbreak. On March 11, 2020, the WHO declared COVID-19 a pandemic. The full impact of the COVID-19 pandemic is unknown and rapidly evolving. While the potential economic impact brought by and over the duration of the COVID-19 pandemic may be difficult to assess or predict, the COVID-19 pandemic has resulted in significant disruption of global financial markets, which could in the future negatively affect the Company’s liquidity. In addition, a recession or market volatility resulting from the COVID-19 pandemic could affect the Company’s business. Given the nature and type of the Company’s short-term investments, the Company does not believe the COVID-19 pandemic has had a material impact on the Company’s current investment liquidity.
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, the Company’s 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. The Company’s cash and cash equivalents includes holdings in checking and overnight sweep accounts. The Company’s cash equivalents, which are money market funds held in a sweep account, are measured at fair value on a recurring basis. As of December 31, 2020, the balance of cash and cash equivalents was $183.9 million, which approximates fair value and was determined based upon Level 1 inputs. The sweep account is valued using quoted market prices with no valuation adjustments applied. Accordingly, these securities are categorized as Level 1.
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, 2020, 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 Company’s financial instruments are cash, accounts payable, accrued liabilities, and current and long-term debt. The carrying values for cash, accounts payable and accrued liabilities reported in the accompanying consolidated financial statements approximate their respective fair values due to their short-term maturities. The carrying value of debt on the Company’s balance sheet (see Note 6 – Loan and Security Agreement), is estimated to approximate its fair value as the interest rate approximates the market rate for loans with similar terms and risk characteristics.
Debt Issuance Costs	Debt Issuance Costs Debt issuance costs consist of costs incurred in obtaining long-term financing. These costs are classified on the consolidated balance sheet as a direct deduction from the carrying amount of the related debt liability. These expenses are deferred and amortized as part of interest expense in the consolidated statement of operations using the effective interest rate method over the term of the debt agreement.
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 costs are expensed as incurred. Research and development expenses consist primarily of personnel costs for our research and development employees, costs incurred to third-party service providers for the conduct of research, preclinical and clinical studies, laboratory supplies, product license fees, consulting and other related expenses. We estimate research, preclinical and clinical study expenses based on services performed, pursuant to contracts with third-party research and development organizations that conduct and manage research, preclinical and clinical activities on our behalf. We estimate these expenses based on discussions with internal management personnel and external service providers as to the progress or stage of completion of services and the contracted fees to be paid for such services. If the actual timing of the performance of services or the level of effort varies from the original estimates, we will adjust the accrual accordingly. Payments associated with licensing agreements to acquire licenses to develop, use, manufacture and commercialize products that have not reached technological feasibility and do not have alternative future use are expensed as incurred. Payments made to third parties under these arrangements in advance of the performance of the related services by the third parties are recorded as prepaid expenses until the services are rendered.
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 of a change in tax rates on deferred tax assets and liabilities 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’s annual effective tax rate was 0% for the year ending December 31, 2020 and has not recorded an income tax benefit for the twelve months ended December 31, 2020 and 2019 since it determined that a full valuation allowance is required against the Company’s deferred tax assets. 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, 2020, 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’s 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 restricted stock units (“RSUs”), the Company issues them in the form of Company common stock. The fair market value of these awards is based on the market closing price per share on the grant date. Prior to January 1, 2020, the Company only granted stock options. Beginning in 2020, for grants to employees, the Company granted a mix of stock options and RSUs. 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 same financial statement line item as the grantee’s cash compensation. The Company’s policy upon exercise of stock options and RSUs 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 warrants, stock options, and RSUs, 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, 2020, 2019, and 2018.
Leases	Leases The Company determines if an arrangement is a lease at contract inception. Operating lease assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. When evaluating whether a contract contains a lease, the Company considers whether (1) the contract explicitly or implicitly identifies assets that are contractually defined and (2) the Company obtains substantially all of the economic benefits from the use of that underlying asset and directs how and for what purpose the asset is used during the term of the contract. The Company’s lease agreement contain s lease and non-lease components. Non-lease components primarily include payments for maintenance and utilities. The Company has applied the practical expedient to combine fixed payments for non-lease components with lease payments and account for them together as a single lease component, which increases the amount of lease assets and corresponding liabilities. Payments under the Company’s lease arrangement are primarily fixed, however variable payments, are expensed as incurred and not included in the operating lease asset and liabilit y . Operating lease assets and liabilities are recognized at the commencement date of the lease based upon the present value of lease payments over the lease term. When determining the lease term, the Company includes options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company uses the implicit interest rate when readily determinable and uses the Company’s incremental borrowing rate when the implicit rate is not readily determinable based upon the information available at the commencement date in determining the present value of the lease payments. The Company’s operating leases are reflected in the right-of-use operating asset; operating lease liability, current portion; and operating lease liability, long-term portion in the Company’s consolidated balance sheets. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. Short-term leases, defined as leases that have a lease term of 12 months or less at the commencement date, and do not include an option to extend the term or purchase the underlying asset that that the Company is reasonably certain to exercise, are excluded from this treatment and are recognized on a straight-line basis over the term of the lease.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, enhances and simplifies various aspects of the income tax accounting guidance, including requirements such as tax basis step-up in goodwill obtained in a transaction that is not a business combination, ownership changes in investments, and interim-period accounting for enacted changes in tax law. 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. In October 2020, the FASB issued ASU 2020-10, Codification Improvements, which clarifies various topics in the Accounting Standards Codification, including the addition of existing disclosure requirements to the relevant disclosure sections. The amendments in ASU 2020-10 do not change GAAP and, therefore, are not expected to result in a significant change in practice. ASU 2020-10 should be applied retrospectively to the beginning of the period that includes the adoption date. ASU 2020-10 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. We do not expect the adoption of this new standard to have a material impact on our condensed consolidated financial statements.

Net Loss per Common Share (Tabl

Net Loss per Common Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss per Common Share	The following table sets forth the computation of basic and diluted net loss per common share: Year ended December 31, 2020 2019 2018 Basic and diluted net loss per common share: Net loss $ (102,900,600 ) $ (68,345,186 ) $ (30,965,464 ) Weighted average common shares outstanding—basic and diluted 37,206,928 34,020,257 26,883,656 Net loss per common share—basic and diluted $ (2.77 ) $ (2.01 ) $ (1.15 )
Schedule of Potentially Dilutive Securities	The following potentially dilutive securities outstanding at December 31, 2020, 2019, and 2018 have been excluded from the computation of diluted weighted average shares outstanding, as they would be anti‑dilutive: December 31, 2020 2019 2018 Stock options 3,733,916 3,458,447 2,291,163 Restricted stock units 136,067 — — Warrants 15,541 69,656 123,037 Total 3,885,524 3,528,103 2,414,200

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Accrued Liabilities And Other Liabilities [Abstract]
Schedule of Accrued Expenses	At December 31, 2020 and 2019, accrued expenses consisted of the following: December 31, 2020 2019 Accrued research and development $ 4,293,522 $ 8,209,594 Accrued compensation 2,870,261 2,056,356 Accrued general and administrative 1,155,508 554,011 Accrued Interest 393,958 129,167 Total $ 8,713,249 $ 10,949,128

Loan and Security Agreement (Ta

Loan and Security Agreement (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of Outstanding Debt and Unamortized Debt Discount Balances	Long-term debt and unamortized debt discount balances are as follows: December 31, December 31, 2020 2019 Outstanding principal amount $ 50,000,000 $ 20,000,000 Add: accreted liability of final payment fee 151,912 404,364 Less: unamortized debt discount, long term (1,830,064 ) (405,071 ) Less: current portion of long-term debt — (2,666,667 ) Loan payable, long-term $ 48,321,848 $ 17,332,626 Current portion of outstanding principal amount — 2,666,667 Less: current portion of unamortized debt discount — (64,375 ) Loan payable, current portion $ — $ 2,602,292
Schedule of Principal Payments	Scheduled Principal Payments on Outstanding Debt, as of December 31, 2020, are as follows: 2021 $ — 2022 — 2023 12,193,153 2024 19,761,468 2025 18,045,379 Total principal payments outstanding $ 50,000,000

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Summary of Presentation of Operating Leases	The following table summarizes the presentation of operating leases in the Company’s consolidated balance sheet: Balance sheet location As of December 31, 2020 Assets Right-of-use operating asset Right-of-use asset - operating lease $ 1,739,475 Liabilities Current operating lease liabilities Operating lease liability, current portion 1,220,587 Long-term operating lease liabilities Operating lease liability, long-term 581,708 Total operating lease liabilities $ 1,802,295
Schedule of Lease Expense	For the year ended December 31, 2020, the Company noted the following lease expense: Statement of Operations Location Year Ended December 31, 2020 Operating lease expense General and administrative $ 47,821 Total operating lease expense $ 47,821
Schedule of Future Minimum Lease Payments of Operating Leases	Future minimum lease payments of our operating leases as of December 31, 2020 were as follows: Years Ending December 31, 2021 $ 1,250,000 2022 630,000 2023 — 2024 — 2025 — Thereafter — Total lease payments 1,880,000 Less imputed interest (77,705 ) Present value of operating lease liabilities $ 1,802,295

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Summary of Stock Option Activity	The following table summarizes stock option activity as of Weighted Weighted average Aggregate Number average contractual intrinsic of shares exercise price term value Outstanding at December 31, 2019 3,458,447 10.19 Granted 649,142 54.50 Exercised (127,778 ) 8.22 Forfeited (207,628 ) 35.85 Cancelled (38,267 ) 58.98 Outstanding at December 31, 2020 3,733,916 16.03 7.2 243,556,917 Vested and expected to vest at December 31, 2020 3,727,747 16.36 7.2 243,062,340 Exercisable at December 31, 2020 2,479,110 10.66 6.0 175,575,360
Summary of Black-Scholes Option Valuation Assumptions	The relevant data used to determine the value of the stock option grants for the years ended December 31, 2020, 2019, and 2018 is as follows: Black-Scholes option valuation assumptions 2020 2019 2018 Risk-free interest rates 0.3 - 1.7% 1.4 - 2.7% 2.0 - 3.1% Dividend yield — — — Volatility 67 - 99% 87 - 91 % 74 - 87% Weighted average expected term 3.51 - 6.14 years 5.00 - 6.13 years 3.66 - 6.13 years
Schedule of RSU Activity	The following table sets forth the RSU activity for the year ended December 31, 2020: Weighted average Number grant date of shares fair value Outstanding at December 31, 2019 — $ — Granted 161,268 37.42 Released — — Forfeited (13,466 ) 86.88 Cancelled (11,735 ) 45.14 Outstanding at December 31, 2020 136,067 $ 35.76
Schedule of Stock-Based Compensation Expense Recognized	Stock‑based compensation expense recognized for the years ended December 31, 2020, 2019, and 2018 was as follows: 2020 2019 2018 Research and development $ 3,953,939 $ 1,584,165 $ 391,946 General and administrative 10,802,267 4,530,995 1,363,028 Total $ 14,756,206 $ 6,115,160 $ 1,754,974

Warrants (Tables)

Warrants (Tables)	12 Months Ended
	Dec. 31, 2020
Warrants And Rights Note Disclosure [Abstract]
Schedule of Warrant Activity	As of December 31, 2020, the Company had outstanding warrants to purchase 15,541 shares of common stock. The following table summarizes warrant activity as of December 31, 2020, 2019, and 2018: Warrants Weighted average exercise price 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 Issued 15,541 80.43 Exercised (69,656 ) 7.21 Outstanding at December 31, 2020 15,541 $ 80.43
Summary of Initial Fair Value of Warrants Estimated using Black - Scholes Option Pricing Model	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 2020 warrants 2019 warrants 2018 warrants 2017 warrants 2016 warrants 2014 warrants 2013 warrants Risk-free interest rate 0.5 % 2.8 % 3.0 % 1.7 % 1.8 % 1.6 % 1.4 % Dividend yield — — — — — — — Volatility 88 % 97 % 85 % 61 % 73 % 70 % 64 % Weighted average contractual term 7 years 7 years 7 years 1 year 7 years 5 years 5 years

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Components of Deferred Tax Assets	The components of the Company’s deferred tax assets and deferred tax liabilities are as follows: December 31, 2020 December 31, 2019 Deferred tax assets: Net federal operating loss carryforward $ 52,329,877 $ 32,299,085 Net foreign operating loss carryforward 86,829 59,557 Net state operating loss carryforward 32,410,604 20,000,317 Non-cash compensation 7,329,228 3,485,519 Research and development credits 13,028,222 10,366,683 Interest Expense 1,765,452 985,431 Charitable Contribution 5,408 5,408 Fixed Assets 7,883 11,401 Lease Liability 612,973 — Accrued expenses 968,709 1,200,754 Deferred tax asset, excluding valuation allowance 108,545,185 68,414,155 Deferred tax liabilities: Deferred finance costs — (121,875 ) Lease Asset (591,607 ) — Deferred tax liability, excluding valuation allowance (591,607 ) (121,875 ) Less valuation allowance (107,953,578 ) (68,292,280 ) Net deferred tax assets $ — $ —
Schedule of Income Tax Rate Reconciliation	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, 2020 December 31, 2019 December 31, 2018 U.S. federal statutory income tax rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 13.7 13.5 13.1 Stock based compensation - Excess tax benefit 1.8 1.2 1.1 Other permanent differences (0.6 ) (0.1 ) (1.3 ) Tax credit 2.5 4.2 6.3 Change in valuation allowance (38.4 ) (39.8 ) (40.2 ) Effective tax rate — % — % — %

Quarterly Consolidated Financ_2

Quarterly Consolidated Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Consolidated Financial Data	2020 Mar. 31 June 30 Sept. 30 Dec. 31 Total operating expenses $ 32,491,457 $ 17,778,834 $ 21,126,801 $ 27,744,236 Net loss $ (32,484,146 ) $ (18,326,992 ) $ (22,924,815 ) $ (29,164,647 ) Net loss per common share, basic and diluted (1) $ (0.88 ) $ (0.49 ) $ (0.61 ) $ (0.79 ) 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 )

Nature of Business and Basis _2

Nature of Business and Basis of Presentation - Additional Information (Details)	Dec. 31, 2020USD ($)product$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Nov. 24, 2015$ / sharesshares
Number of late-stage candidates in Company's product candidate portfolio | product	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 | $	$ 278,796,093	$ 175,895,493
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 - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)segmentinstitution
Segment and Geographic Information
Number of operating segments | segment	1
Cash Equivalents
Cash Equivalents | $	$ 183.9
Concentration of Credit Risk
Number of financial institutions that hold the Company's cash | institution	1
Equipment
Estimated useful life	3 years
Income Taxes
Effective tax rate	0.00%

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details)	Dec. 31, 2020USD ($)$ / shares	Dec. 31, 2019USD ($)$ / shares	Dec. 31, 2018USD ($)$ / shares	Dec. 31, 2017USD ($)$ / shares	Dec. 11, 2017$ / sharesshares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Exercise price of warrants (in dollars per share)	$ 80.43	$ 7.21	$ 6.35	$ 5.21
Warrant expiration date					Dec. 11, 2018
Fair value | $				$ 2,791,000
Share Price				$ 5.325
Warrant liability | $			$ 0
Financial liabilities fair value disclosure | $	$ 0	$ 0
Common warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Common stock to be issued if warrants are exercised (in shares) | shares					1,783,587
Exercise price of warrants (in dollars per share)				$ 5.25	$ 5.25
Fair value | $				$ 2,683,000
Share Price				$ 5.60
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				1.76
Common warrants | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants and Rights Outstanding, Measurement Input				62
Placement agent warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Common stock to be issued if warrants are exercised (in shares) | shares					107,015
Exercise price of warrants (in dollars per share)					$ 6.6562
Warrant expiration date					Dec. 11, 2018
Fair value | $				$ 108,000
Share Price				$ 5.60
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				1.76
Placement agent warrants | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants and Rights Outstanding, Measurement Input				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, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic and diluted net loss per common share:
Net loss	$ (29,164,647)	$ (22,924,815)	$ (18,326,992)	$ (32,484,146)	$ (24,806,984)	$ (19,135,612)	$ (13,762,214)	$ (10,640,376)	$ (102,900,600)	$ (68,345,186)	$ (30,965,464)
Weighted average common shares outstanding, basic and diluted									37,206,928	34,020,257	26,883,656
Net loss per common share, basic and diluted	$ (0.79)	$ (0.61)	$ (0.49)	$ (0.88)	$ (0.71)	$ (0.56)	$ (0.41)	$ (0.32)	$ (2.77)	$ (2.01)	$ (1.15)

Net Loss per Common Share - Pot

Net Loss per Common Share - Potentially Dilutive Securities Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	3,885,524	3,528,103	2,414,200
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	3,733,916	3,458,447	2,291,163
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	136,067
Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities	15,541	69,656	123,037

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Accrued Liabilities And Other Liabilities [Abstract]
Accrued research and development	$ 4,293,522	$ 8,209,594
Accrued compensation	2,870,261	2,056,356
Accrued general and administrative	1,155,508	554,011
Accrued Interest	393,958	129,167
Total	$ 8,713,249	$ 10,949,128

Loan and Security Agreement - A

Loan and Security Agreement - Additional Information (Details)	1 Months Ended			12 Months Ended
	Sep. 30, 2020USD ($)	Mar. 31, 2019USD ($)	Nov. 30, 2016USD ($)tranche	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Line Of Credit Facility [Line Items]
Loss on extinguishment of debt				$ (1,247,012)
Repayment of principal on term loan				21,660,000	$ 7,238,889	$ 3,333,333
Interest expense				2,362,083	1,362,500	751,670
Amortization of debt issuance costs				469,676	436,567	266,668
Amortization of debt discount				786,750	649,993	375,635
Warrants
Line Of Credit Facility [Line Items]
Amortization of debt discount				317,074	$ 213,426	$ 108,968
Term Loan 2020
Line Of Credit Facility [Line Items]
First advance used to repay previous debt	$ 21,700,000
Base interest rate	9.15%
Cash pay interest rate	1.00%
Cash pay interest multiplier	1.15
Final payment fee	$ 2,910,000
Percentage of final payment fee	4.85%
Loss on extinguishment of debt				$ 1,200,000
Term Loan 2020 | Prime Rate
Line Of Credit Facility [Line Items]
Interest rate basis	5.90%
Term Loan 2020 | Prepayment Occurs Prior to First Anniversary of Closing Date
Line Of Credit Facility [Line Items]
Maximum loan amount	$ 225,000,000
Percentage of prepayment penalty	2.00%
Term Loan 2020 | Outstanding principle and advances under the loans agreement exceeds 55 million
Line Of Credit Facility [Line Items]
Minimum cash to be maintain as a first priority security interest	$ 15,000,000
Period of unpaid invoices amount maintain as security	180 days
Term Loan 2020 | Outstanding principle and advances under the loans agreement exceeds 55 million | Minimum
Line Of Credit Facility [Line Items]
Outstanding amount	$ 55,000,000
Term Loan 2020 | Outstanding principle and advances under the loans agreement exceeds 65 million
Line Of Credit Facility [Line Items]
Minimum amount of market capital to be maintained	$ 2,000,000,000
Minimum percentage of cash to be maintained as a security following market capitalization condition	65.00%
Minimum percentage of cash to be maintained as a security	100.00%
Term Loan 2020 | Outstanding principle and advances under the loans agreement exceeds 65 million | AXS-05 and AXS-07
Line Of Credit Facility [Line Items]
Minimum product revenue percent	60.00%
Term Loan 2020 | Outstanding principle and advances under the loans agreement exceeds 65 million | Minimum
Line Of Credit Facility [Line Items]
Outstanding amount	$ 65,000,000
Term Loan 2020 | Prepayment Occurs on or After First Anniversary and Prior to Second Anniversary of the Closing Date
Line Of Credit Facility [Line Items]
Percentage of prepayment penalty	1.50%
Term Loan 2020 | Prepayment Occurs on or After Second Anniversary and Prior to Third Anniversary of Closing Date
Line Of Credit Facility [Line Items]
Percentage of prepayment penalty	1.00%
Term loan 2020 tranche one
Line Of Credit Facility [Line Items]
Maximum loan amount	$ 60,000,000
Proceeds from debt	50,000,000
Remaining credit facility to be drawn	10,000,000
Term loan 2020 tranche two
Line Of Credit Facility [Line Items]
Maximum loan amount	$ 35,000,000
Period to achieve first milestone	181 days
Term loan 2020 tranche three
Line Of Credit Facility [Line Items]
Maximum loan amount	$ 20,000,000
Period to achieve second milestone	181 days
Term loan 2020 tranche four
Line Of Credit Facility [Line Items]
Maximum loan amount	$ 60,000,000
Term loan 2020 tranche five
Line Of Credit Facility [Line Items]
Maximum loan amount	$ 50,000,000
Original Term Loan 2016
Line Of Credit Facility [Line Items]
Maximum loan amount			$ 20,000,000
Number of loan tranches | tranche			3
Term Loan 2016, Tranche One
Line Of Credit Facility [Line Items]
Maximum loan amount			$ 10,000,000
Term Loan 2016, Tranche Two and Three
Line Of Credit Facility [Line Items]
Maximum loan amount			10,000,000
Amended Term Loan 2016
Line Of Credit Facility [Line Items]
Remaining credit facility to be drawn			$ 4,000,000
2019 Term Loan
Line Of Credit Facility [Line Items]
Maximum loan amount		$ 24,000,000
Interest rate basis		7.50%
Repayment of principal on term loan		$ 1,260,000
Term Loan 2019, Tranche One
Line Of Credit Facility [Line Items]
Final payment fee		850,000
Loan amount		20,000,000
Repayment of principal on term loan		5,600,000
Term Loan 2019, Tranche Two
Line Of Credit Facility [Line Items]
Remaining credit facility to be drawn		$ 4,000,000

Loan and Security Agreement - S

Loan and Security Agreement - Schedule of Outstanding Debt and Unamortized Debt Discount Balances (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Outstanding principal amount	$ 50,000,000	$ 20,000,000
Add: accreted liability of final payment fee	151,912	404,364
Less: unamortized debt discount, long term	(1,830,064)	(405,071)
Less: current portion of long-term debt		(2,666,667)
Loan payable, long-term	$ 48,321,848	17,332,626
Current portion of outstanding principal amount		2,666,667
Less: current portion of unamortized debt discount		(64,375)
Loan payable, current portion		$ 2,602,292

Loan and Security Agreement -_2

Loan and Security Agreement - Schedule of Principal Payments (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
2023	$ 12,193,153
2024	19,761,468
2025	18,045,379
Total principal payments outstanding	$ 50,000,000	$ 20,000,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Lease commencement date	Aug. 1, 2020
Lease, expiration date	Jul. 31, 2021
Lessee, operating lease, description		In June 2020, the company entered into a lease for office space at 22 Cortlandt St, New York, NY consisting of the 16th floor which began on August 1, 2020. The term for this lease was to expire on July 31, 2021. At lease inception the lease arrangement was deemed to be a short-term lease due to its term not exceeding one year, and as such was accounted for on a straight-line basis until December 2020.
Lessee, operating lease, existence of option to extend [true false]		true
Lessee, operating lease, option to extend		extend through July 31, 2022
Rent expense		$ 870,275	$ 485,548	$ 315,301
Operating lease, remaining lease term		1 year 7 months 6 days
Operating lease, discount rate		6.00%
Maximum [Member]
Loss Contingencies [Line Items]
Lease term		12 months

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Presentation of Operating Leases (Details)	Dec. 31, 2020USD ($)
Assets
Right-of-use asset - operating lease	$ 1,739,475
Liabilities
Operating lease liability, current portion	1,220,587
Operating lease liability, long-term	581,708
Total operating lease liabilities	$ 1,802,295

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Lease Expense (Details)	12 Months Ended
	Dec. 31, 2020USD ($)
Loss Contingencies [Line Items]
Total operating lease expense	$ 47,821
General and Administrative
Loss Contingencies [Line Items]
Total operating lease expense	$ 47,821

Commitments and Contingencies_4

Commitments and Contingencies - Schedule of Future Minimum Lease Payments of Operating Leases (Details)	Dec. 31, 2020USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2021	$ 1,250,000
2022	630,000
Total lease payments	1,880,000
Less imputed interest	(77,705)
Present value of operating lease liabilities	$ 1,802,295

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details)	Dec. 05, 2019USD ($)	Oct. 01, 2018USD ($)	Sep. 27, 2018USD ($)$ / sharesshares	Nov. 30, 2020shares	Jun. 30, 2020USD ($)shares	Dec. 31, 2019USD ($)$ / sharesshares	May 31, 2019USD ($)	Jan. 31, 2019USD ($)shares	Dec. 31, 2017USD ($)$ / sharesshares	Oct. 31, 2017USD ($)	Dec. 31, 2020USD ($)Vote$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / shares	Dec. 11, 2017$ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued | shares									1,783,587
Proceeds from issuance of common stock, gross									$ 9,500,000
Share Price | $ / shares									$ 5.325
Exercise price of warrants (in dollars per share) | $ / shares						$ 7.21			$ 5.21		$ 80.43	$ 7.21	$ 6.35
Proceeds from issuance of common stock, net									$ 8,800,000
Issuance costs									$ 745,856
Common stock, voting right per share | Vote											1
Stock-based compensation expense											$ 14,756,206	$ 6,115,160	$ 1,754,974
Stock option to purchase shares of common stock cancelled | shares											207,628
Weighted average grant date fair value | $ / shares											$ 36.77	$ 12.49	$ 1.99
Unrecognized compensation cost related to non-vested stock options expected to be recognized											$ 20,900,000
Expected vesting period for non-vested share-based compensation											2 years 9 months 18 days
Non-vested options outstanding | shares											10,716
Intrinsic value of stock options exercised						$ 4,500,000					$ 9,400,000	$ 4,500,000	$ 500,000
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option to purchase shares of common stock cancelled | shares				38,267
Non-cash stock-based compensation expense related to plan cancelled											2,100,000
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation expense related to plan cancelled											$ 500,000
Stock option to purchase shares of common stock cancelled | shares											11,735
Vesting period											4 years
Compensation cost not yet recognized related to unvested RSUs											$ 4,100,000
Weighted average contractual term											3 years 3 months 18 days
Director
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting of stock options | shares					21,666
Stock-based compensation expense					$ 1,300,000
2013 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future grant | shares											0
2015 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future grant | shares											4,149,112
2018 Registered Direct Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued | shares			2,966,667
Proceeds from issuance of common stock, gross			$ 8,900,000
Share Price | $ / shares			$ 3
Proceeds from issuance of common stock, net		$ 8,800,000
Underwritten Public Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued | shares						2,300,000
Proceeds from issuance of common stock, gross						$ 200,100,000
Share Price | $ / shares						$ 87						$ 87
Proceeds from issuance of common stock, net						$ 187,100,000
2019 Shelf Registration
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Proceeds from issuance of common stock, gross	$ 221,900,000
Common warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share Price | $ / shares									$ 5.60
Exercise price of warrants (in dollars per share) | $ / shares									$ 5.25					$ 5.25
Issuance costs									$ 583,768
Common warrants | 2016 Shelf Registration
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price | $ / shares									$ 5.25
Warrant utilized									$ 9,400,000
Placement agent warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued | shares									107,015
Share Price | $ / shares									$ 5.60
Exercise price of warrants (in dollars per share) | $ / shares														$ 6.6562
Issuance costs									$ 81,000
Exercise price | $ / shares									$ 6.6562
Placement agent warrants | 2016 Shelf Registration
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price | $ / shares									$ 6.6562
Warrant utilized									$ 712,313
SVB Leerink
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock sales agreement, gross sales								$ 25,800,000
Shares issued | shares								3,164,015
Common stock sales agreement, commission percentage							3.00%	3.00%
Common stock sales agreement, shares unsold amount							$ 29,900,000
SVB Leerink | December 2019 Sales Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued | shares											167,243	89,390
Common stock sales agreement, commission percentage						3.00%						3.00%
Proceeds from issuance of common stock, gross											$ 14,600,000	$ 7,300,000
Proceeds from issuance of common stock, net											$ 14,100,000	$ 7,100,000
SVB Leerink | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock sales agreement, authorized amount							$ 50,000,000			$ 30,000,000
SVB Leerink | Maximum [Member] | December 2019 Sales Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock sales agreement, authorized amount						$ 80,000,000

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2020USD ($)$ / sharesshares
Number of shares
Number of shares, Outstanding, beginning balance | shares	3,458,447
Number of shares, Granted | shares	649,142
Number of shares, Exercised | shares	(127,778)
Number of shares, Forfeited | shares	(207,628)
Number of shares, Cancelled | shares	(38,267)
Number of shares, Outstanding, ending balance | shares	3,733,916
Number of shares, Vested and expected to vest | shares	3,727,747
Number of shares, Exercisable | shares	2,479,110
Weighted average exercise price
Weighted average exercise price, Outstanding, beginning balance | $ / shares	$ 10.19
Weighted average exercise price, Granted | $ / shares	54.50
Weighted average exercise price, Exercised | $ / shares	8.22
Weighted average exercise price, Forfeited | $ / shares	35.85
Weighted average exercise price, Cancelled | $ / shares	58.98
Weighted average exercise price, Outstanding, ending balance | $ / shares	16.03
Weighted average exercise price, Vested and expected to vest | $ / shares	16.36
Weighted average exercise price, Exercisable | $ / shares	$ 10.66
Weighted average contractual term
Weighted average contractual term, Outstanding	7 years 2 months 12 days
Weighted average contractual term, Vested and expected to vest	7 years 2 months 12 days
Weighted average contractual term, Exercisable	6 years
Aggregate intrinsic value
Aggregate intrinsic value, Outstanding | $	$ 243,556,917
Aggregate intrinsic value, Vested and expected to vest | $	243,062,340
Aggregate intrinsic value, Exercisable | $	$ 175,575,360

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Black-Scholes Option Valuation Assumptions (Details) - Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Black-Scholes option valuation assumptions
Risk-free interest rate, minimum	0.30%	1.40%	2.00%
Risk-free interest rate, maximum	1.70%	2.70%	3.10%
Volatility, minimum	67.00%	87.00%	74.00%
Volatility, maximum	99.00%	91.00%	87.00%
Minimum
Black-Scholes option valuation assumptions
Weighted average expected term	3 years 6 months 3 days	5 years	3 years 7 months 28 days
Maximum [Member]
Black-Scholes option valuation assumptions
Weighted average expected term	6 years 1 month 20 days	6 years 1 month 17 days	6 years 1 month 17 days

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of RSU Activity (Details) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Number of shares
Number of shares, Granted | shares	161,268
Number of shares, Forfeited | shares	(13,466)
Number of shares, Cancelled | shares	(11,735)
Number of shares, Outstanding, ending balance | shares	136,067
Weighted average grant date fair value
Weighted average grant date fair value, Granted | $ / shares	$ 37.42
Weighted average grant date fair value, Forfeited | $ / shares	86.88
Weighted average grant date fair value, Cancelled | $ / shares	45.14
Weighted average grant date fair value, Outstanding, ending balance | $ / shares	$ 35.76

Stockholders' Equity - Schedu_2

Stockholders' Equity - Schedule of Stock-Based Compensation Expense Recognized (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 14,756,206	$ 6,115,160	$ 1,754,974
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	3,953,939	1,584,165	391,946
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 10,802,267	$ 4,530,995	$ 1,363,028

Warrants - Additional Informati

Warrants - Additional Information (Details) - USD ($)	Nov. 03, 2014	Aug. 31, 2020	May 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Aug. 31, 2019	Mar. 31, 2019	Dec. 31, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jul. 25, 2019	Nov. 26, 2018	Dec. 11, 2017	Nov. 09, 2016	Oct. 29, 2013
Class Of Warrant Or Right [Line Items]
Warrants outstanding				69,656				2,099,199	15,541	69,656	123,037	2,099,199
Common stock, par value				$ 0.0001					$ 0.0001	$ 0.0001
Exercise price of warrants (in dollars per share)				$ 7.21				$ 5.21	$ 80.43	$ 7.21	$ 6.35	$ 5.21
Fair value								$ 2,791,000				$ 2,791,000
Warrants exercised									69,656	111,715	101,310
Shares issued								1,783,587
Warrant expiration date															Dec. 11, 2018
September 2014 Notes
Class Of Warrant Or Right [Line Items]
Common stock to be issued if warrants are exercised (in shares)	42,059
Exercise price of warrants (in dollars per share)	$ 5.94
Warrants exercised										42,059
Warrant term	5 years
Warrant expiration date	Nov. 2, 2019
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%
Common warrants
Class Of Warrant Or Right [Line Items]
Common stock to be issued if warrants are exercised (in shares)															1,783,587
Exercise price of warrants (in dollars per share)								$ 5.25				$ 5.25			$ 5.25
Fair value								$ 2,683,000				$ 2,683,000
Placement agent warrants
Class Of Warrant Or Right [Line Items]
Common stock to be issued if warrants are exercised (in shares)															107,015
Exercise price of warrants (in dollars per share)															$ 6.6562
Fair value								$ 108,000				$ 108,000
Shares issued								107,015
Warrant term															1 year
Warrant expiration date															Dec. 11, 2018
2013 Warrants
Class Of Warrant Or Right [Line Items]
Common stock to be issued if warrants are exercised (in shares)																	230,459
Exercise price of warrants (in dollars per share)																	$ 1.30
Warrants exercised											101,310	129,149
Warrant term									5 years								5 years
Amended Term Loan 2016
Class Of Warrant Or Right [Line Items]
Shares issued		7,579
Warrants | Term loan 2020 tranche one
Class Of Warrant Or Right [Line Items]
Common stock, par value									$ 0.0001
Percentage of aggregate amount of loan									2.50%
Common stock to be issued if warrants are exercised (in shares)									15,541
Exercise price of warrants (in dollars per share)									$ 80.43
Trading days									10 days
Term of warrants (in years)									7 years
Fair value									$ 900,000
Warrants | 2019 Term Loan
Class Of Warrant Or Right [Line Items]
Warrants outstanding									0
Common stock to be issued if warrants are exercised (in shares)							70,000						29,167
Exercise price of warrants (in dollars per share)							$ 8.10
Fair value							$ 400,000
Warrants exercisable date							Mar. 4, 2026
Warrants exercisable							58,332
Warrants exercised		29,167		29,167
Shares issued		26,270		24,185
Warrants | Term Loan 2019, Tranche Two
Class Of Warrant Or Right [Line Items]
Common stock to be issued if warrants are exercised (in shares)													5,750
Exercise price of warrants (in dollars per share)													$ 25.71
Warrants exercisable							11,668
Warrants | Amended Term Loan 2016
Class Of Warrant Or Right [Line Items]
Warrants outstanding									0
Common stock to be issued if warrants are exercised (in shares)														15,750
Exercise price of warrants (in dollars per share)														$ 3.06
Warrants exercised		7,875				7,875
Shares issued						6,969
Warrant term														7 years
Warrants | Original Term Loan 2016
Class Of Warrant Or Right [Line Items]
Warrants outstanding									0
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			29,982		24,328

Warrants - Schedule of Warrant

Warrants - Schedule of Warrant Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Warrants And Rights Note Disclosure [Abstract]
Warrants outstanding beginning balance	69,656	123,037	2,099,199
Issued	15,541	58,334	15,750
Exercised	(69,656)	(111,715)	(101,310)
Expired			(1,890,602)
Warrants outstanding ending balance	15,541	69,656	123,037
Weighted average exercise price, Beginning balance	$ 7.21	$ 6.35	$ 5.21
Issued	80.43	8.10	3.06
Exercised	7.21	6.73	1.30
Expired			5.33
Weighted average exercise price, Ending balance	$ 80.43	$ 7.21	$ 6.35

Warrants - Summary of Initial F

Warrants - Summary of Initial Fair Value of Warrants Estimated using Black - Scholes Option Pricing Model (Details)	Dec. 31, 2020	Oct. 29, 2013
2020 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrant term	7 years
2019 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrant term	7 years
2018 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrant term	7 years
2017 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrant term	1 year
2016 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrant term	7 years
2014 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrant term	5 years
2013 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrant term	5 years	5 years
Risk Free Interest Rate | 2020 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.005
Risk Free Interest Rate | 2019 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.028
Risk Free Interest Rate | 2018 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.030
Risk Free Interest Rate | 2017 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.017
Risk Free Interest Rate | 2016 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.018
Risk Free Interest Rate | 2014 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.016
Risk Free Interest Rate | 2013 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.014
Volatility | 2020 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.88
Volatility | 2019 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.97
Volatility | 2018 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.85
Volatility | 2017 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.61
Volatility | 2016 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.73
Volatility | 2014 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.70
Volatility | 2013 Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.64

License Agreements - Additional

License Agreements - Additional Information (Details)	1 Months Ended	12 Months Ended
	Jan. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2020USD ($)itemshares	Dec. 31, 2019USD ($)shares	Dec. 31, 2018USD ($)	Dec. 31, 2012item	Jan. 09, 2020USD ($)$ / shares	Dec. 31, 2017$ / shares
Research And Development Arrangement Contract To Perform For Others [Line Items]
Number of common shares | shares		37,374,088	36,933,217
Value of common stock		$ 3,737	$ 3,693
Share price | $ / shares							$ 5.325
Research and development expense recognized		$ 70,244,579	$ 53,647,067	$ 23,495,055
License Agreement | Antecip
Research And Development Arrangement Contract To Perform For Others [Line Items]
Number of exclusive license agreements | item		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
License Agreement | Antecip | AXS-05
Research And Development Arrangement Contract To Perform For Others [Line Items]
License agreement royalty as a percent of net sales					3.00%
Pfizer Inc | License Agreement
Research And Development Arrangement Contract To Perform For Others [Line Items]
Number of common shares | shares	82,019
Value of common stock	$ 8,000,000
Prior trading days	10 days
Share price | $ / shares	$ 97.538
Upfront cash payment	$ 3,000,000
Fair value share price | $ / shares						$ 87.24
Fair value of common stock						$ 7,200,000
Research and development expense recognized		$ 10,200,000
Future milestone payments		323,000,000
Milestone payments or royalties		$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 249,000,000
Increase in valuation allowance	39,700,000	$ 27,000,000	$ 12,500,000
Income tax expense (benefit)	$ 0	$ 0	$ 0
Net operating loss carryovers and carry backs offset percentage	100.00%
Net operating loss carryback period	5 years
Tax Year 2017
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 60,000,000
NOL carryforwards expiration year	2032
Tax Year 2018
Operating Loss Carryforwards [Line Items]
NOL carryforwards	$ 189,000,000

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Deferred Tax Assets (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net federal operating loss carryforward	$ 52,329,877	$ 32,299,085
Net foreign operating loss carryforward	86,829	59,557
Net state operating loss carryforward	32,410,604	20,000,317
Non-cash compensation	7,329,228	3,485,519
Research and development credits	13,028,222	10,366,683
Interest Expense	1,765,452	985,431
Charitable Contribution	5,408	5,408
Fixed Assets	7,883	11,401
Lease Liability	612,973
Accrued expenses	968,709	1,200,754
Deferred tax asset, excluding valuation allowance	108,545,185	68,414,155
Deferred tax liabilities:
Deferred finance costs		(121,875)
Lease Asset	(591,607)
Deferred tax liability, excluding valuation allowance	(591,607)	(121,875)
Less valuation allowance	$ (107,953,578)	$ (68,292,280)

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
U.S. federal statutory income tax rate	21.00%	21.00%	21.00%
State taxes, net of federal benefit	13.70%	13.50%	13.10%
Stock based compensation - Excess tax benefit	1.80%	1.20%	1.10%
Other permanent differences	(0.60%)	(0.10%)	(1.30%)
Tax credit	2.50%	4.20%	6.30%
Change in valuation allowance	(38.40%)	(39.80%)	(40.20%)
Effective tax rate	0.00%

Related-Party Transactions - Ad

Related-Party Transactions - Additional Information (Details)	1 Months Ended		12 Months Ended
	Dec. 31, 2017shares	Jan. 31, 2012shares	Dec. 31, 2020item	Dec. 31, 2012item
Related Party Transaction [Line Items]
Shares issued	1,783,587
Antecip
Related Party Transaction [Line Items]
Shares issued		7,344,500
Antecip | License Agreement
Related Party Transaction [Line Items]
Number of exclusive license agreements | item			3	3
Minimum | Dr. Tabuteau
Related Party Transaction [Line Items]
Beneficial ownership percentage			5.00%

Quarterly Consolidated Financ_3

Quarterly Consolidated Financial Data (Unaudited) - Summary of Quarterly Consolidated Financial Data (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total operating expenses	$ 27,744,236	$ 21,126,801	$ 17,778,834	$ 32,491,457	$ 24,428,170	$ 18,947,235	$ 13,448,219	$ 10,421,473	$ 99,141,328	$ 67,245,097	$ 32,846,577
Net loss	$ (29,164,647)	$ (22,924,815)	$ (18,326,992)	$ (32,484,146)	$ (24,806,984)	$ (19,135,612)	$ (13,762,214)	$ (10,640,376)	$ (102,900,600)	$ (68,345,186)	$ (30,965,464)
Net loss per common share, basic and diluted	$ (0.79)	$ (0.61)	$ (0.49)	$ (0.88)	$ (0.71)	$ (0.56)	$ (0.41)	$ (0.32)	$ (2.77)	$ (2.01)	$ (1.15)