Aldeyra Therapeutics (ALDX) 10-K 12 Mar 20 2019 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Mar. 10, 2020	Jun. 28, 2019
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Trading Symbol	ALDX
Entity Registrant Name	ALDEYRA THERAPEUTICS, INC.
Entity Central Index Key	0001341235
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		29,662,125
Entity Public Float			$ 152,791,890
Entity Tax Identification Number	20-1968197
Entity Interactive Data Current	Yes
Document Annual Report	true
Document Transition Report	false
Security Exchange Name	NASDAQ
Documents Incorporated by Reference	Specified portions of the registrant’s proxy statement with respect to the registrant’s 2020 Annual Meeting of Stockholders, which is to be filed pursuant to Regulation 14A within 120 days after the end of the registrant’s fiscal year ended December 31, 2019, are incorporated by reference into Part III of this Annual Report on Form 10-K.
Entity Address, Address Line One	131 Hartwell Avenue
Entity Address, Address Line Two	Suite 320
Entity Address, City or Town	Lexington
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02421
City Area Code	781
Local Phone Number	761-4904
Entity Incorporation, State or Country Code	DE
Title of 12(b) Security	Common Stock, $0.001 par value per share
Entity File Number	001-36332

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 16,425,830	$ 3,357,472
Cash equivalent - Reverse Repurchase Agreements	28,000,000	44,000,000
Marketable securities	28,938,545	46,242,220
Prepaid expenses and other current assets	1,804,450	1,169,594
Total current assets	75,168,825	94,769,286
Deferred offering costs		86,644
Property and equipment, net	148,449	235,225
Right-of-use assets	201,007
Total assets	75,518,281	95,091,155
Current liabilities:
Accounts payable	808,302	3,051,678
Accrued expenses	11,873,122	5,421,498
Current portion of operating lease liabilities	226,328
Total current liabilities	12,907,752	8,473,176
Long-term debt	14,528,212
Total liabilities	27,435,964	8,473,176
Commitments and contingencies (Note 13)
Stockholders' equity:
Preferred stock, $0.001 par value, 15,000,000 shares authorized, none issued and outstanding
Common stock, voting, $0.001 par value; 150,000,000 authorized and 28,656,832 and 26,244,435 shares issued and outstanding, respectively	28,657	26,244
Additional paid-in capital	247,409,793	225,136,127
Accumulated other comprehensive income (loss)	5,866	(9,224)
Accumulated deficit	(199,361,999)	(138,535,168)
Total stockholders’ equity	48,082,317	86,617,979
Total liabilities and stockholders’ equity	$ 75,518,281	$ 95,091,155

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred Stock, par value	$ 0.001	$ 0.001
Preferred Stock, shares authorized	15,000,000	15,000,000
Preferred Stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	28,656,832	26,244,435
Common stock, shares outstanding	28,656,832	26,244,435

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development	$ 44,351,851	$ 29,823,007
Acquired in-process research and development	6,567,754
General and administrative	12,154,702	9,876,144
Loss from operations	(63,074,307)	(39,699,151)
Other income (expense):
Interest income	1,541,349	952,698
Interest expense	(603,846)	(146,792)
Total other income (expense), net	937,503	805,906
Loss before income taxes	(62,136,804)	(38,893,245)
Income tax benefit	1,309,973
Net loss	$ (60,826,831)	$ (38,893,245)
Net loss per share - basic and diluted	$ (2.24)	$ (1.79)
Weighted average common shares outstanding - basic and diluted	27,111,840	21,685,642

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (60,826,831)	$ (38,893,245)
Other comprehensive income/(loss):
Unrealized gain/(loss) on marketable securities	15,090	8,607
Total other comprehensive income/(loss)	15,090	8,607
Comprehensive loss	$ (60,811,741)	$ (38,884,638)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($)	Total	Helio Vision, Inc [Member]	Common Voting Stock [Member]	Common Voting Stock [Member]Helio Vision, Inc [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Helio Vision, Inc [Member]	Accumulated Other Comprehensive Income (Loss), Net of Tax [Member]	Accumulated Deficit [Member]
Beginning Balance at Dec. 31, 2017	$ 39,601,019		$ 19,138		$ 139,241,635		$ (17,831)	$ (99,641,923)
Beginning Balance, Shares at Dec. 31, 2017			19,137,639
Stock-based compensation	4,144,853				4,144,853
Issuance of common stock, net of issuance costs	81,671,172		$ 7,046		81,664,126
Issuance of common stock, net of issuance costs, Shares			7,046,306
Issuance of common stock, ESPP	85,573		$ 14		85,559
Issuance of common stock, ESPP, Shares			14,382
Issuance of common stock, vested restricted stock awards			$ 41		(41)
Issuance of common stock, vested restricted stock awards, shares			40,975
Issuance of common stock, warrants exercised			$ 5		(5)
Issuance of common stock, warrants exercised, Shares			5,133
Other comprehensive income	8,607						8,607
Net loss	(38,893,245)							(38,893,245)
Ending Balance at Dec. 31, 2018	86,617,979		$ 26,244		225,136,127		(9,224)	(138,535,168)
Ending Balance, Shares at Dec. 31, 2018			26,244,435
Stock-based compensation	8,082,751				8,082,751
Issuance of common stock, acquisition of Helio Vision, Inc.		$ 4,944,409		$ 733		$ 4,943,676
Issuance of common stock, acquisition of Helio Vision, inc., Shares				733,972
Issuance of common stock, net of issuance costs	7,891,678		$ 1,348		7,890,330
Issuance of common stock, net of issuance costs, Shares			1,347,156
Issuance of common stock, exercise of stock options	$ 1,162,392		$ 232		1,162,160
Issuance of common stock, exercise of stock options, Shares	232,004		232,004
Issuance of common stock, ESPP	$ 194,849		$ 35		194,814
Issuance of common stock, ESPP, Shares			34,253
Issuance of common stock, vested restricted stock awards			$ 65		(65)
Issuance of common stock, vested restricted stock awards, shares			65,012
Other comprehensive income	15,090						15,090
Net loss	(60,826,831)							(60,826,831)
Ending Balance at Dec. 31, 2019	$ 48,082,317		$ 28,657		$ 247,409,793		$ 5,866	$ (199,361,999)
Ending Balance, Shares at Dec. 31, 2019			28,656,832

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (60,826,831)	$ (38,893,245)
Adjustments to reconcile net loss to net cash used in operating activities:
Acquired in-process research and development	6,567,754
Deferred taxes	(1,309,973)
Stock-based compensation	8,082,751	4,144,853
Amortization of debt discount – non-cash interest expense	248,567	59,322
Net amortization of premium on debt securities available for sale	(583,701)	(237,541)
Depreciation	96,305	71,003
Change in assets and liabilities:
Prepaid expenses and other current assets	(454,429)	(150,627)
Accounts payable	(2,846,142)	2,049,582
Accrued expenses	6,041,473	3,099,522
Net cash used in operating activities	(44,984,226)	(29,857,131)
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions of property and equipment	(9,529)	(262,966)
Purchases of marketable securities	(57,768,084)	(59,731,610)
Sales of marketable securities	75,645,000	36,659,000
Net cash provided by (used in) investing activities	18,476,851	(23,335,576)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	7,891,678	81,837,102
Proceeds from exercise of stock options	1,162,392
Proceeds from employee stock purchase plan	194,849	85,573
Extinguishment of long-term debt		(1,395,833)
Proceeds from long-term debt	14,450,000
Debt issuance costs paid in cash	(123,186)
Net cash provided by financing activities	23,575,733	80,526,842
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(2,931,642)	27,334,135
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	47,357,472	20,023,337
CASH AND CASH EQUIVALENTS, END OF PERIOD	44,425,830	47,357,472
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Interest	238,491	$ 88,963
Helio Vision, Inc [Member]
Adjustments to reconcile net loss to net cash used in operating activities:
Acquired in-process research and development	6,600,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Cash acquired in Helio asset acquisition	609,464
SUPPLEMENTAL DISCLOSURES OF NONCASH ACTIVITIES:
Assets acquired	75,632
Liabilities acquired	637,994
Fair value of securities issued	$ 4,944,409

Nature of Business

Nature of Business	12 Months Ended
	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Business	1. Aldeyra Therapeutics, Inc. (“Aldeyra”, “Company”, “we”, “us” and “our”) was incorporated in the state of Delaware on August 13, 2004 as Neuron Systems, Inc. On December 20, 2012, the Company changed its name to Aldexa Therapeutics, Inc. and, on March 17, 2014, the Company changed its name to Aldeyra Therapeutics, Inc. Aldeyra, together with its wholly-owned subsidiaries, is developing next-generation medicines to i mprove the lives of patients with immune-mediated diseases The Company’s principal activities to date include raising capital and research and development activities.

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	2. Basis of Presentation – The accompanying consolidated financial statements were prepared in conformity with accounting principles generally accepted in the United States of America (“US GAAP”). Risks and Uncertainties –The ongoing research and development activities will be subject to extensive regulation by numerous governmental authorities in the United States. Prior to marketing in the United States, any drug developed by the Company must undergo rigorous preclinical and clinical testing and an extensive regulatory approval process implemented by the United States Food and Drug Administration (“FDA”) under the Food, Drug and Cosmetic Act. The Company has limited experience in conducting and managing the preclinical and clinical testing necessary to obtain regulatory approval. There can be no assurance that the Company will not encounter problems in the clinical trials that will cause the Company or the FDA to delay or suspend clinical trials. The Company’s success will depend in part on its ability to obtain patents and product license rights, maintain trade secrets, and operate without infringing on the property rights of others, both in the United States and other countries. There can be no assurance that patents issued to or licensed by the Company will not be challenged, invalidated, circumvented, or that the rights granted thereunder will provide proprietary protection or competitive advantages to the Company. Based on its current operating plan, the Company believes that its cash, cash equivalents, and marketable securities as of December 31, 2019, together with the proceeds of the sales of common stock under the Jefferies Sales Agreement through the date of this filing will be adequate to fund our currently anticipated operating expenses through the end of 2021, including the currently planned Part 2 of the Phase 3 clinical trial in dry eye disease (the RENEW trial, pending FDA feedback), the initial part of the adaptive Phase 3 clinical trial in proliferative vitreoretinopathy (the GUARD trial), and the Phase 3 trial in allergic conjunctivitis (the INVIGORATE trial). The Company will need to secure additional funding in the future, from one or more equity or debt financings, collaborations, or other sources, in order to carry out all of the Company’s planned research and development activities; commercialize its product candidates; or conduct any substantial, additional development requirements requested by the FDA. Additional funding may not be available to the Company on acceptable terms, or at all. If the Company is unable to secure additional capital, it will be required to significantly decrease the amount of planned expenditures, and may be required to cease operations. Curtailment of operations would cause significant delays in the Company’s efforts to develop and introduce its products to market, which is critical to the realization of its business plan and the future operations of the Company. Use of Estimates – The preparation of consolidated financial statements in conformity with US GAAP requires management to make estimates and assumptions, including fair value estimates for investments that affect the reported amounts of assets, liabilities, and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. The Company evaluates its estimates and assumptions on an ongoing basis. The most significant estimates in the Company’s financial statements include, but are not limited to, estimates related to clinical trial accruals, estimates related to prepaid and accrued research and development costs, acquired in-process research and development (“IPR&D”) expense, and accounting for income taxes and the related valuation allowance. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may materially differ from these estimates and assumptions. Segment Information – Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one segment, which is the identification and development of next-generation medicines to improve the lives of patients with immune-mediated diseases. Cash and Cash Equivalents – The Company classifies all highly liquid investments with original maturities of three months or less as cash equivalents and all highly liquid investments with original maturities of greater than three months but less than 12 months as current marketable securities. The Company has a policy of making investments only with commercial institutions that have at least an investment grade credit rating. The Company invests its cash primarily in reverse repurchase agreements (“RRAs”), government securities and obligations, and money market funds. RRAs are collateralized by deposits in the form of ‘Government Securities and Obligations’ for an amount not less than 102% of their value. The Company does not record an asset or liability related to the collateral as the Company is not permitted to sell or repledge the associated collateral. The Company has a policy that the collateral has at least an A (or equivalent) credit rating. The Company utilizes a third-party custodian to manage the exchange of funds as well as requirement that collateral received is maintained at 102% of the value of the RRAs on a daily basis. Marketable Securities – Marketable securities consist of government securities and obligations with original maturities of more than 90 days. Investments are classified as available-for-sale and are recorded on the balance sheet at fair value with unrealized gains or losses reported as a separate component of other comprehensive income/(loss). Management determines the appropriate classification of its investments at the time of purchase and re-evaluates such determination at each balance sheet date. Fair Value of Financial Instruments – Financial instruments including cash equivalents and accounts payable are carried in the financial statements at amounts that approximate their fair value based on the short maturities of those instruments. Marketable securities are carried at fair value and are more fully described in Note 6. The carrying amount of the Company’s credit facility with Hercules Capital, Inc. approximates fair value since the effective interest rate approximates market rates currently available to the Company. Concentration of Credit Risk – Financial instruments that potentially subject the Company to significant concentrations of credit risk principally consist of cash, cash equivalents and marketable securities. The Company places its cash and cash equivalents and marketable securities with financial institutions which management believes have high credit ratings. As part of its cash and investment management processes, the Company performs periodic evaluations of the credit standing of the financial institutions with whom it maintains deposits. Intellectual Property – The legal and professional costs incurred by the Company to acquire its patent rights are expensed as incurred and included in general and administrative expenses. At December 31, 2019 and 2018, the Company has determined that these expenses have not met the criteria to be capitalized since the future benefits to be derived from the patents is uncertain. Intellectual property related expenses for the years ended December 31, 2019 and 2018 were $1.4 million and $1.3 million, respectively. Income Taxes – The Company follows the provisions of Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 740, Income Taxes (“ASC 740”) , in reporting deferred income taxes. ASC 740 requires a company to recognize deferred tax liabilities and assets for expected future income tax consequences of events that have been recognized in the Company’s financial statements. Under this method, deferred tax assets and liabilities are determined based on temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates in the years in which the temporary differences are expected to reverse. Valuation allowances are provided if based on the weight of available evidence, it is more likely than not that some or all the deferred tax assets will not be realized. The Company accounts for uncertain tax positions pursuant to ASC 740 which prescribes a recognition threshold and measurement process for financial statement recognition of uncertain tax positions taken or expected to be taken in a tax return. If the tax position meets this threshold, the benefit to be recognized is measured as the tax benefit having the highest likelihood of being realized upon ultimate settlement with the taxing authority. The Company recognizes interest accrued related to unrecognized tax benefits and penalties in the provision for income taxes. Management is not aware of any uncertain tax positions. Research and Development Costs – Research and development (“R&D”) costs are charged to expense as incurred and relate to salaries, employee benefits, stock-based compensation related to employees, consulting services, other operating costs and expenses associated with preclinical and clinical trial activities. Payments made by the Company in advance for research and development services not yet provided and/or for materials not yet received are recorded as prepaid expenses. Accrued liabilities are recorded related to those expenses for which vendors have not yet billed us with respect to services provided and/or materials that we have received. Preclinical and clinical trial expenses relate to third-party services, subject-related fees at the sites where the Company’s clinical trials are being conducted, laboratory costs, analysis costs, toxicology studies and investigator fees. Costs associated with these expenses are generally payable on the passage of time or when certain milestones are achieved. Expense is recorded during the period incurred or in the period in which a milestone is achieved. In order to ensure that the Company has adequately provided for preclinical and clinical expenses during the proper period, the Company maintains an accrual to cover these expenses. These accruals are assessed on a quarterly basis and are based on such assumptions as expected total cost, the number of subjects and clinical trial sites and length of the study. Actual results may differ from these estimates and could have a material impact on the Company’s reported results. The Company’s historical accrual estimates have not been materially different from actual costs. In-process research and development – Assets purchased in an asset acquisition transaction are expensed as in-process research and development unless the assets acquired are deemed to have an alternative future use, provided that the acquired asset did not also include processes or activities that would constitute a “business” as defined under GAAP, the drug has not achieved regulatory approval for marketing and, absent obtaining such approval, has no established alternative future use. Acquired IPR&D payments are immediately expensed in the period in which they are incurred and include upfront payments, as well as transaction fees and subsequent pre-commercial milestone payments. Research and development costs incurred after the acquisition are expensed as incurred. Stock-Based Compensation – Stock-based payments are accounted for in accordance with the provisions of ASC 718, Compensation – Stock Compensation . For options, the fair value of stock-based payments is estimated, on the date of grant, using the Black-Scholes option pricing model. For restricted stock, fair value is based on the fair value of the stock on the date of grant. The resulting fair value for restricted stock and options expected to vest is recognized on a straight-line basis over the requisite service period, which is generally the vesting period of the applicable restricted stock or option. The Company records the effect of forfeitures and cancellations when they occur. Comprehensive Loss – Comprehensive loss is defined as the change in equity during a period from transactions and other events and/or circumstances from non-owner sources. For December 31, 2019, comprehensive loss is equal to the Company’s net loss of $60.8 million and an unrealized gain on marketable securities of $15,000. For December 31, 2018, comprehensive loss is equal to our net loss of $38.9 million and an unrealized gain on marketable securities of $9,000. Net Loss Per Share – The Company computes net loss per share in accordance with the two-class method. Under the two-class method, net loss is allocated between common stock and other participating securities based on their participation rights. The Company has determined that the nonvested shares issued to the Helio founders represents a participating security and as such the nonvested shares are excluded from basic earnings per share. Net losses are not allocated to the nonvested shareholders for computing net loss per share under the two-class method because nonvested shareholders do not have contractual obligations to share in the losses of the Company. Basic earnings per share is calculated by dividing net loss allocable to common stockholders by the weighted average number of common stock outstanding. Diluted net loss per share is computed using the more dilutive of (a) the two-class method, or (b) treasury stock method, as applicable, to the potentially dilutive instruments. The weighted-average number of common shares Recent Accounting Pronouncements In February 2016, the FASB issued Accounting Standards Update (ASU) No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), which supersedes the lease guidance under FASB ASC Topic 840, Leases (“ASC 840”), resulting in the creation of FASB ASC Topic 842, Leases (“ASC 842”). ASU 2016-02 requires lessees to recognize on the balance sheet a right-of-use asset, representing its right to use the underlying asset for the lease term, and a lease liability for all leases with terms greater than 12 months. The guidance also requires qualitative and quantitative disclosures designed to assess the amount, timing, and uncertainty of cash flows arising from leases. The standard requires the use of a modified retrospective transition approach, which includes a number of optional practical expedients that entities may elect to apply. The Company adopted the new standard on January 1, 2019. The Company elected to utilize the available practical expedients. Upon adoption, the Company recorded a ROU asset and a lease liability that were immaterial. There was no impact to opening retained earnings as a result of the adoption of the new guidance. The impact of applying ASC 842 on the results for reporting periods and balance sheet beginning after January 1, 2019 is presented under ASC 842, while prior amounts are not adjusted and continue to be reported in accordance with the Company’s historic accounting under ASC 840, Leases. Refer to Note 14 for further information. In June 2016, the FASB issued (“ASU”) No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 requires that credit losses be reported as an allowance using an expected losses model, representing the entity’s current estimate of credit losses expected to be incurred. The accounting guidance currently in effect is based on an incurred loss model. For available-for-sale debt securities with unrealized losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. The amendments under ASU 2016-13 are effective for interim and annual fiscal periods beginning after December 15, 2022. We do not expect the adoption of ASU 2016-13 to have a material impact on our consolidated financial statements.

Helio vision acquisition

Helio vision acquisition	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Helio vision acquisition	3. HELIO VISION ACQUISITION On January 28, 2019 (the “Closing Date”), the Company acquired Helio Vision, Inc. (“Helio”). As a result of the acquisition, the Company initially issued an aggregate of 1,160,444 shares of common stock to the former securityholders and an advisor of Helio. The founders of Helio were issued 568,627 shares and non-founders were issued 591,817 shares. The Helio founders’ shares are subject to vesting based on continued service to the Company over three years from the Closing Date of which 25% are vested as of December 31, 2019. The Company recognizes the expense associated with the founders’ restricted shares as compensation expense on a straight-line basis as the shares vest over the three-year period. For the year ended December 31, 2019, the Company recorded $2.2 million of research and development compensation expense for the founders’ restricted shares. The Company, subject to the conditions of the acquisition agreement, is contingently obligated to make additional payments to the former securityholders of Helio as follows: (a) $2.5 million of common stock on the date that is 24 months following the Closing Date (assuming certain technical milestones are met); (b) $10.0 million of common stock following approval by the FDA of a new drug approval application for the prevention and/or treatment of proliferative vitreoretinopathy or a substantially similar label prior to the 10th anniversary of the Closing Date; and (c) $2.5 million of common stock following FDA approval of a new drug application for an indication (other than proliferative vitreoretinopathy) prior to the 12th anniversary of the Closing Date (the shares of common stock issuable pursuant to the preceding clauses (a) – (c) are referred to herein as the Milestone Shares), provided that in no event shall the Company be obligated to issue more than an aggregate of 5,248,885 shares of common stock. Additionally, in the event of certain change of control or divestitures by the Company, certain former convertible noteholders of Helio will be entitled to a tax gross-up payment in an amount not to exceed $1.0 million. The Company determined that liability accounting is not required for the Milestone Shares under FASB ASC Topic 480, Distinguishing Liabilities from Equity (“ASC 480”). The Company also determined that the Milestone Shares meet the scope exception as a derivative under FASB ASC Topic 815, Derivatives and Hedging (“ASC 815”), from inception of the Milestone Shares through December 31, 2019. Accordingly, the Milestone Shares are evaluated under FASB ASC Topic 450, Contingencies (“ASC 450”) and the Company will record a liability related to the Milestone Shares if the milestones are achieved, and the obligation to make additional payment(s) becomes probable. At that time, the Company will record the cost of the Milestone Shares issued to the founders as compensation expense and to the Helio non-founders as in-process research and development expense if there is no alternative future use. No milestones related to the Milestone Shares are probable of being achieved as of December 31, 2019. The Company assessed the acquisition of Helio under the FASB ASC Topic 805, Business Combinations

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Net Loss Per Share	4 . For the years ended December 31, 2019 and 2018, diluted weighted-average common shares outstanding is equal to basic weighted-average common shares due to the Company’s net loss position. The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted-average shares outstanding, because such securities had an antidilutive impact: Years ended December 31, 2019 2018 Options to purchase common stock 4,193,814 3,383,047 Warrants to purchase common stock — 40,300 Restricted stock units 430,425 212,297 Unvested restricted shares (1) 426,472 — Total of common stock equivalents 5,050,711 3,635,644 (1) Represents 426,472 shares of common stock that are issued and outstanding but that were subject to a right of repurchase by the Company at December 31, 2019 and are not included in stockholders’ equity pursuant to US GAAP.

Cash, Cash Equivalents and Mark

Cash, Cash Equivalents and Marketable Securities	12 Months Ended
	Dec. 31, 2019
Cash And Cash Equivalents [Abstract]
Cash, Cash Equivalents and Marketable Securities	5 . At December 31, 2019, cash, cash equivalents and marketable securities were comprised of: Carrying Amount Unrecognized Gain Unrecognized Loss Estimated Fair Value Cash and Cash Equivalents Current Marketable Securities Cash $ 15,363,462 $ — $ — $ 15,363,462 $ 15,363,462 $ — Money market funds 1,062,368 — — 1,062,368 1,062,368 — Reverse repurchase agreements 28,000,000 — — 28,000,000 28,000,000 — Total Cash and cash equivalents 44,425,830 — — 44,425,830 44,425,830 — U.S. government agency securities 28,932,679 5,866 — 28,938,545 — 28,938,545 Available for Sale (1) 28,932,679 5,866 — 28,938,545 — 28,938,545 Total Cash, cash equivalents and current marketable securities $ 44,425,830 $ 28,938,545 (1) Available for sale securities are reported at fair value with unrealized gains and losses reported net of taxes, if material, in other comprehensive income. The contractual maturities of all available for sale securities are less than one year at December 31, 2019. At December 31, 2018, cash, cash equivalents and marketable securities were comprised of: Carrying Amount Unrecognized Gain Unrecognized Loss Estimated Fair Value Cash and Cash Equivalents Current Marketable Securities Cash $ 2,127,175 $ — $ — $ 2,127,175 $ 2,127,175 $ — Money market funds 1,230,297 — — 1,230,297 1,230,297 — Reverse repurchase agreements 44,000,000 — — 44,000,000 44,000,000 — Total Cash and cash equivalents 47,357,472 — — 47,357,472 47,357,472 — U.S. government agency securities 46,251,444 — (9,224 ) 46,242,220 — 46,242,220 Available for Sale (1) 46,251,444 — (9,224 ) 46,242,220 — 46,242,220 Total Cash, cash equivalents and current marketable securities $ 47,357,472 $ 46,242,220 (1) Available for sale securities are reported at fair value with unrealized gains and losses reported net of taxes, if material, in other comprehensive income.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	6 . 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 on the measurement date. Valuation techniques used to measure fair value are performed in a manner to maximize the use of observable inputs and minimize the use of unobservable inputs. ASC 820, Fair Value Measurements Level 1 – Quoted prices in active markets that are accessible at the market date for identical unrestricted assets or liabilities. Level 2 – Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs for which all significant inputs are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. There were no liabilities measured at fair value at December 31, 2019 or 2018, respectively. The following table presents information about the Company’s assets measured at fair value at December 31, 2019 and December 31, 2018: December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Money market funds (a) $ 1,062,368 $ — $ — $ 1,062,368 Reverse repurchase agreements (b) — 28,000,000 — 28,000,000 U.S. government agency securities (b) — 28,938,545 — 28,938,545 Total assets at fair value $ 1,062,368 $ 56,938,545 $ — $ 58,000,913 December 31, 2018 Level 1 Level 2 Level 3 Total Assets: Money market funds (a) $ 1,230,297 $ — $ — $ 1,230,297 Reverse repurchase agreements (b) — 44,000,000 — 44,000,000 U.S. government agency securities (b) — 46,242,220 — 46,242,220 Total assets at fair value $ 1,230,297 $ 90,242,220 $ — $ 91,472,517 (a) Money market funds included in cash and cash equivalents in the consolidated balance sheets, are valued at quoted market prices in active markets. (b) Reverse repurchase agreements and U.S. government agency securities are recorded at fair market values, which are determined based on the most recent observable inputs for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active or are directly or indirectly observable.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued Expenses	7 . Accrued expenses at December 31, 2019 and 2018 were: December 31, December 31, 2019 2018 Accrued compensation $ 1,489,475 $ 1,172,880 Accrued research and development 9,493,093 3,882,313 Accrued general and administrative 890,554 366,305 Accrued expenses $ 11,873,122 $ 5,421,498

Credit Facility

Credit Facility	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Credit Facility	8. The Company’s long-term debt obligation consists of amounts the Company is obligated to repay under its credit facility with Hercules Capital, Inc. (“Hercules”). In March 2019, the Company entered into a Loan and Security Agreement with Hercules and the several banks and other financial institutions or entities, from time-to-time parties thereto (collectively, referred to as “Lender”), providing for a term loan of up to $60.0 million that is secured by a lien covering all of the Company’s assets, other than the Company’s intellectual property (the “Loan and Security Agreement” or the “Hercules Credit Facility”). The Loan and Security Agreement provides for an initial term loan advance of up to $5.0 million at the Company’s option, commencing on March 25, 2019 through and including April 15, 2019, which expired unutilized; three additional term loan advances of up to $15.0 million each, at the Company’s option, available to the Company upon the occurrence of certain funding conditions prior to September 30, 2019, March 31, 2020, and March 31, 2021, respectively, the first of which tranche was drawn down in full by the Company in September 2019; and a final additional term loan advance of up to $10.0 million prior to December 31, 2021, at the Company’s option, subject to approval by the Lender’s investment committee. As of December 31, 2019, $15.0 million was outstanding under the Hercules Credit Facility. As of December 31, 2019, the Company was in material compliance with all covenants of the Hercules Credit Facility. The term loan bears interest at an annual rate equal to the greater of (i) 9.10% and (ii) the prime rate (as reported in the Wall Street Journal or any successor publication thereto) plus 3.10%. The Loan and Security Agreement provides for interest-only payments until May 1, 2021, with an option to extend the interest-only period to May 1, 2022 based upon the achievement of certain milestones. Repayment of the aggregate outstanding principal balance of the term loan, in monthly installments, starts upon expiration of the interest-only period and continues through October 1, 2023 (the “Maturity Date”). Associated with this debt facility, the Company incurred a commitment charge of $25,000, transaction costs of $273,186, a fee of $375,000 upon closing, and is required to pay a fee (“End of Term Charge”) of 6.95% multiplied by the aggregate amount of advances under the Loan and Security Agreement at maturity. The fees, transaction costs and end of term charge are amortized to interest expense through the Maturity Date using the effective interest method. The effective interest rate was 12.9% at December 31, 2019. At the Company’s option, the Company may elect to prepay all, but not less than all, of the outstanding term loan by paying the entire principal balance and all accrued and unpaid interest thereon plus all fees and other amounts due under the Loan and Security Agreement, including a prepayment charge equal to the following percentage of the principal amount being prepaid: 3% if the term loan is prepaid prior to March 25, 2021 and 1.5% if the term loan is prepaid any time thereafter, but prior to March 25, 2022. Future principal payments, including the End of Term Charge, are as follows for the years ending December 31: 2020 $ — 2021 3,659,776 2022 5,931,718 2023 6,451,006 Total $ 16,042,500 The Loan and Security Agreement also contains certain events of default, representations, warranties and non-financial covenants of the Company. In addition, the Company granted the Lender the right to purchase up to an aggregate of $2.0 million of the Company’s equity securities, or instruments exercisable for or convertible into equity securities, sold to investors in financings upon the same terms and conditions afforded to such other investors.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Stockholders' Equity	9 . Common Stock Each share of common stock is entitled to one vote 772,323 Underwritten Public Offerings In October 2018, the Company sold 5,250,000 shares of its common stock in an underwritten public offering at $13.75 per share, for an aggregate gross cash purchase price of $72.2 million or proceeds of $67.6 million after underwriters discount and expenses. Cantor Sales Agreement In June 2017, the Company entered into a Controlled Equity Offering SM Jefferies Sales Agreement In December 2018, the Company entered into an Open Market Sales Agreement SM

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	10 . No current provision for federal and state income taxes has been recorded as the Company has incurred losses since inception for tax purposes. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. In assessing the realizability of net deferred taxes in accordance with ASC 740 the Company considers whether it is more likely than not that some portion or all the deferred tax assets will not be realized. Based on the weight of available evidence, primarily the incurrence of net losses since inception, anticipated net losses in the near future, reversals of existing temporary differences and expiration of various federal and state attributes, the Company does not consider it more likely than not that some or all of the net deferred taxes will be realized. Accordingly, a 100% valuation allowance has been applied against net deferred taxes. As of December 31, 2019, the Company had federal and state income tax net operating loss (“NOL”) carryforwards of approximately $139.5 million and $133.9 million, respectively. Federal NOL carryforwards generated through December 31, 2017 and state NOL carryforwards will expire at various dates through 2037. The federal NOL generated during the year ended December 31, 2018 will carryforward indefinitely. As of December 31, 2019, the Company had federal and state research and development tax credit carryforwards of approximately $4.2 million and $0.8 million, respectively, which will expire at various dates through 2039. On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (“Tax Act”) was enacted into law making significant changes to the Internal Revenue Code. The main provision impacting the Company is the reduction in the U.S. statutory corporate tax rate to 21% for years beginning after December 31, 2017. On the same day, the SEC staff issued Staff Accounting Bulletin No. 118, or SAB 118, which provides guidance for companies that have not completed their accounting for the income tax effects of the Tax Act in the period of enactment, allowing for a measurement period of up to one year after the enactment date to finalize the recording of the related tax impacts. Significant components of the Company’s deferred tax assets and liabilities at December 31, 2019 and 2018 are as follows: Years ended December 31, 2019 2018 Deferred Tax Assets Federal & state NOL carryforward $ 37,752,925 $ 25,311,547 Federal & state R&D credit carryforward 4,840,115 3,781,160 Intangibles – net 120,318 164,508 Accounts payable and accrued expenses 2,898,710 1,958,174 Stock options 4,527,462 3,146,034 Other items 80,812 10,173 Gross deferred tax assets 50,220,342 34,371,596 Valuation allowance (50,165,427 ) (34,371,596 ) Deferred tax assets, net $ 54,915 $ — Deferred Tax Liabilities Lease liability (54,915 ) — TOTAL $ — $ — The change in valuation allowance of $15.8 million from December 31, 2018 to December 31, 2019 was primarily the result of an increase in net operating losses and tax credits during the current year. The components of the incomes tax benefit for the years ended December 31, 2019 and 2018, are as follows: Years ended December 31, 2019 2018 Deferred Taxes Federal $ (1,205,175 ) $ — State (104,798 ) — Total income tax benefit $ (1,309,973 ) $ — Under Section 382 of the Internal Revenue Code of 1986, as amended, a corporation that undergoes an “ownership change” is subject to limitations on its ability to utilize its pre-change NOLs and certain other tax assets to offset future taxable income. In general, an ownership change occurs if the aggregate stock ownership of certain stockholders increases by more than 50 percentage points over such stockholders’ lowest percentage ownership during the testing period (generally three years). Transactions involving the Company’s common stock within the testing period, even those outside the Company’s control such as purchases or sales by investors, could result in an ownership change. A limitation on the Company’s ability to utilize some or all its NOLs or credits could have a material adverse effect on the Company’s results of operations and cash flows. Prior to December 31, 2018, we underwent three ownership changes and it is possible that additional ownership changes have occurred since. However, management believes that we have sufficient “Built-In-Gain” to offset any Section 382 limitation generated by such ownership changes. Any future ownership changes, including those resulting from our recent or future financing activities, may cause our existing tax attributes to have additional limitations. Subject to annual limitations, net operating losses generated in years 2018 and beyond will have an indefinite carryforward period and will not expire. Future changes in federal and state tax laws pertaining to net operating loss carryforwards may also cause limitations or restrictions from us claiming such net operating losses. If the net operating loss carryforwards become unavailable to us or are fully utilized, our future taxable income will not be shielded from federal and state income taxation absent certain U.S. federal and state tax credits, and the funds otherwise available for general corporate purposes would be reduced. All tax years are open for examination by the taxing authorities for both federal and state purposes. A reconciliation of the federal statutory tax rate of 21% to the Company’s effective income tax rates are as follows: Years ended December 31, 2019 2018 Statutory tax rate 21.00 % 21.00 % State taxes, net of federal benefits 5.62 % 6.83 % Federal research and development credits 1.44 % 3.81 % Change in valuation allowance (25.44 ) % (31.51 ) % Stock-based compensation (0.81 ) % (0.20 ) % Other 0.30 % 0.07 % Effective tax rate 2.11 % — %

Stock Incentive Plan

Stock Incentive Plan	12 Months Ended
	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Incentive Plan	1 1 . The Company approved the 2010 Employee, Director and Consultant Equity Incentive Plan (“2010 Plan”) in September 2010 to replace the 2004 Plan. The 2010 Plan provided for the granting of stock options and restricted stock awards. The 2010 Plan terminated upon the Company’s initial public offering in May 2014. However, grants made under the 2010 Plan are still governed by that plan. As of December 31, 2019, options to purchase 413,130 shares of common stock at a weighted average exercise price of $1.58 per share remained outstanding under the 2010 Plan. The Company approved the 2013 Equity Incentive Plan in October 2013. The 2013 Equity Incentive Plan became effective immediately on adoption although no awards were to be made under it until the effective date of the registration statement for the Company’s initial public offering. The Company recognizes stock-based compensation expense over the requisite service period. The Company’s share-based awards are accounted for as equity instruments. The amounts included in the consolidated statements of operations relating to stock-based compensation, employee incentive plan and Helio founder shares as are as follows: Years ended December 31, 2019 2018 Research and development expenses $ 2,441,542 $ 1,541,915 General and administrative expenses $ 3,446,887 $ 2,602,938 Helio founders' shares (Note 3) $ 2,194,322 $ — Total stock-based compensation expense $ 8,082,751 $ 4,144,853 Stock Options Terms of stock option agreements, including vesting requirements, are determined by the board of directors or its compensation committee, subject to the provisions of the respective plan they were granted. Options granted by the Company typically vest over a four year period. The options are subject to acceleration of vesting in the event of certain change of control transactions. The options may be granted for a term of up to ten years from the date of grant. The exercise price for options granted under the Amended 2013 Plan must be at a price no less than 100% of the fair market value of a common share on the date of grant. The following table summarizes option activity under the incentive plans for the year ended December 31, 2019: Number of Shares Weighted Average Exercise Price Weighted Average Contractual Term Aggregate Intrinsic Value(a) Outstanding at December 31, 2018 3,383,047 $ 6.17 Granted 1,447,255 7.71 Cancelled/Forfeited (404,484 ) 7.66 Exercised (232,004 ) 5.01 Outstanding at December 31, 2019 4,193,814 $ 6.62 7.34 $ 2,615,717 Exercisable at December 31, 2019 2,514,720 $ 5.91 6.38 $ 2,471,702 (a) The aggregate intrinsic value in this table was calculated on the positive difference, if any, between the closing price per share of the Company’s common stock on December 31, 2019 of $5.81 and the per share exercise price of the underlying options. The Company records stock-based compensation related to stock options granted at fair value. During the years ended December 31, 2019 and 2018, the Company used the Black-Scholes option-pricing model to estimate the fair value of stock option grants and to determine the related compensation expense. The assumptions used in calculating the fair value of stock-based payment awards represent management’s best estimates. The weighted-average fair value of options granted was $5.23 and $5.79 for the years ended December 31, 2019 and 2018, respectively. The assumptions used in determining fair value of the employee stock options for the years ended December 2019 and 2018, are as follows: December 31, 2019 December 31, 2018 Expected dividend yield 0% 0% Anticipated volatility 74.65% - 77.12% 76.52% - 78.38% Stock price $5.16 - $8.76 $6.80 - $11.83 Exercise price $5.16 - $8.76 $6.80 - $11.83 Expected life (years) 5.50 - 6.08 5.50 - 6.25 Risk free interest rate 1.59% - 2.62% 2.32% - 3.10% The dividend yield of zero is based on the fact that the Company has never paid cash dividends and have no present intention to pay cash dividends. Expected volatility is estimated using the historical volatility of the Company. The Company has estimated the expected life of our employee stock options using the “simplified” method, whereby, the expected life equals the average of the vesting term and the original contractual term of the option for service-based awards since the Company doesn’t have sufficient historical or implied data of its own. The risk-free interest rates for periods within the expected life of the option are based on the yields of zero-coupon United States Treasury securities. At December 31, 2019, there is approximately $8.1 million of unrecognized compensation cost relating to stock options outstanding, which the Company expects to recognize over a weighted average period of 2.54 years. Total unrecognized compensation cost will be adjusted for future forfeitures, if necessary. Restricted Stock Units Terms of restricted stock unit (“RSUs”) agreements, including vesting requirements, are determined by the board of directors or its compensation committee, subject to the provisions of the Amended 2013 Plan. RSUs granted by the Company typically vest over a four year period. In the event that the employees’ employment with the Company terminates any unvested shares are forfeited and revert to the Company. Restricted stock units are not included in issued and outstanding common stock until the shares are vested and released. The table below summarizes activity relating to RSUs for the year ended December 31, 2019: Number of Shares Outstanding at December 31, 2018 212,297 Granted 283,140 Vested/released (65,012 ) Outstanding at December 31, 2019 430,425 The weighted-average fair value of RSUs granted was $8.05 and $8.60 per share for the years ended December 31, 2019 and 2018, respectively. As of December 31, 2019, the outstanding restricted stock units had unamortized stock-based compensation of $2.3 million with a weighted-average remaining recognition period of 2.65 years and an aggregate intrinsic value of $2.5 million. Employee Stock Purchase Plan In March 2016, the Company’s board of directors approved the 2016 Employee Stock Purchase Plan (“2016 ESPP”), which became effective in June 2016 following the approval of the Company’s stockholders. The 2016 ESPP authorizes the issuance of up to a total of 414,639 shares of the Company’s common stock to participating employees. The number of shares reserved for issuance under the 2016 ESPP automatically increases on the first business day of each fiscal year, commencing in 2017, by a number equal to the lower of (i) 1% of the shares of common stock outstanding on the last business day of the prior fiscal year; or (ii) the number of shares determined by the Company’s Board of Directors. Unless otherwise determined by the administrator of the 2016 ESPP, two offering periods of six months’ duration will begin each year on January 1 and July 1. Participating employees purchase stock under the 2016 ESPP at a price equal to the lower of 85% of the closing price on the applicable offering commencement date or 85% of the closing price on the applicable offering termination date. The fair value of the purchase rights granted under this plan was estimated on the date of grant using the Black-Scholes option-pricing model using assumptions as shown below: December 31, 2019 December 31, 2018 Expected dividend yield 0% 0% Anticipated volatility 70.55% - 76.02% 77.49% - 80.59% Stock price $6.12 - $8.51 $7.00 - $8.05 Exercise price $6.12 - $8.51 $7.00 - $8.05 Expected life (years) 0.50 0.50 Risk free interest rate 2.10% - 2.56% 1.61% - 2.11% At December 31, 2019, the Company has 596,693 shares available for issuance under the 2016 ESPP. A summary of the weighted-average grant-date fair value, shares issued and total stock-based compensation expense recognized related to the 2016 ESPP for the years ended December 31, 2019 and 2018 are as follows: December 31, 2019 December 31, 2018 Weighted-average grant-date fair value per share $ 2.79 $ 2.21 Total shares issued 34,253 14,382 Total stock-based compensation expense $ 91,790 $ 75,141

Stock Purchase Warrants

Stock Purchase Warrants	12 Months Ended
	Dec. 31, 2019
Text Block [Abstract]
Stock Purchase Warrants	1 2 . In connection with the Initial Public Offering, the Company issued the underwriters of the offering warrants to purchase up to 60,000 shares of common stock. The warrants were exercisable beginning on May 1, 2015 for cash, or on a cashless basis, at a per share price of $10.00. Unexercised warrants to purchase up to 40,300 shares of common stock expired on May 1, 2019 pursuant to their terms and as of December 31, 2019, none of these warrants were outstanding.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	1 3 . COMMITMENTS AND CONTINGENCIES Guarantees and Indemnifications As permitted under Delaware law, the Company indemnifies its officers and directors for certain events or occurrences while the officer or director is, or was, serving at the Company’s request in such capacity. The term of the indemnification is for the officer’s or director’s lifetime. Through December 31, 2019, the Company had not experienced any losses related to these indemnification obligations and no material claims were outstanding. The Company does not expect significant claims related to these indemnification obligations, and consequently, concluded that the fair value of these obligations is negligible, and no related reserves were established. In-License Agreements Madrigal Agreement The Company is developing ADX-1612 pursuant to a License Agreement with Madrigal Pharmaceuticals, Inc. (Madrigal), entered into on December 26, 2016 (the “Madrigal Agreement”). Pursuant to the Madrigal Agreement, the Company obtained an exclusive, worldwide license from Madrigal under certain patents and patent applications, and other licenses to intellectual property, to develop and commercialize Hsp90 inhibitors, including ADX-1612 and ADX-1615 (“Madrigal Agreement Products”). The Company has agreed to use its commercially reasonable efforts to develop Madrigal Agreement Products. In consideration for the rights licensed under the Madrigal Agreement, the Company paid Madrigal an upfront license fee of $250,000 and are obligated to make future regulatory and development and sales-dependent milestone payments to Madrigal of less than $340 million in the aggregate (over 80% of such amount being tied to the Company’s achievement of increasingly greater annual worldwide net sales milestones), as well as royalty payments to Madrigal at a rate which, as a percentage of net sales, is in the high single digits for products containing ADX-1612 and mid-single digits for any other Hsp90 inhibitor product. The Company is also obligated under the Madrigal Agreement to pay Madrigal a percentage of certain sublicense revenue that the Company receives in connection with entering into any sublicensing arrangements with any third parties, at a percentage rate which tiers downward from the mid-twenties to low-single digits based on the development stage of the product at the time of the sublicense. The Madrigal Agreement will remain in effect until all payment obligations under the Madrigal Agreement expire. The Company may terminate the Madrigal Agreement in its entirety or on a Madrigal Agreement Product-by Madrigal Agreement Product basis with timely notice to Madrigal. Either party may terminate the Madrigal Agreement for uncured material breach by the other party or upon certain insolvency or bankruptcy proceedings involving the other party, both with timely notice to the other party. In addition, Madrigal has the right to terminate the Madrigal Agreement if the Company, its affiliates, or sublicensees interfere with, challenge the validity or enforceability of, oppose the extension of, or grant of a supplementary protection certificate with respect to any of the Company’s licensed patents under the Madrigal Agreement. In the event of an early termination of the Madrigal Agreement, all rights licensed and developed by the Company under the Madrigal Agreement may revert back to Madrigal. Each party has agreed to indemnify the other party for certain third party claims arising under the Madrigal Agreement. MEEI Agreement The Company is developing ADX-2191 pursuant to an Exclusive License Agreement with Massachusetts Eye and Ear Infirmary (“MEEI”) originally entered into in July 2016 between MEEI and Helio Vision, Inc. (as amended, the “MEEI Agreement”). The Company assumed the MEEI Agreement in connection with its 2019 acquisition of Helio Vision. Pursuant and subject to the MEEI Agreement, the Company obtained an exclusive, worldwide license from MEEI to develop and commercialize ADX-2191 under certain patents and patent applications, and other licenses to intellectual property (the “MEEI Patent Rights”). The Company has agreed to use our commercially reasonable efforts to develop ADX-2191 and to meet certain specified effort and achievement benchmarks by certain dates. In consideration for the rights licensed under the MEEI Agreement, Helio Vision issued MEEI a number of shares of its preferred stock and Helio Vision agreed to pay non-creditable non-refundable license maintenance fees to MEEI of $15,000 on each of the second and third anniversary of the MEEI Agreement, $25,000 on each of the fourth and fifth anniversary of the MEEI Agreement and $35,000 on the sixth and each subsequent anniversary of the MEEI Agreement during the term of such agreement. In addition, Helio Vision was obligated to make future sales-dependent milestone payments to MEEI of up to the low seven figures in the aggregate, as well as royalty payments to MEEI at a rate which, as a percentage of net sales, is in the low single digits for products that incorporate or use the MEEI Patent Rights in the United States and as a percentage in the low single digits for products that incorporate or use the MEEI Patent Rights outside the United States. The Company is also obligated under the MEEI Agreement to pay MEEI a percentage of certain sublicense revenue that it receives in connection with entering into any sublicensing arrangements with any third parties, at a percentage rate which tiers downward from low-double digits to mid-single digits based on the date of the sublicense. Following the Company’s acquisition of Helio Vision, the Company became obligated to make any future payments owed under the MEEI Agreement. There is no additional equity consideration issuable under the MEEI Agreement. The MEEI Agreement will remain in effect until the expiration date of the last to expire patent licensed under the MEEI Agreement. The Company may terminate the MEEI Agreement with timely written notice to MEEI. MEEI has the right to terminate the MEEI Agreement if it, subject to certain specified cure periods, ceases all business operations with respect to licensed products, fails to pay amounts due under the MEEI Agreement, fail to comply with certain due diligence obligations, defaults in our obligation to maintain insurance, one of our officers is convicted of a felony relating to the manufacture, use, sale or importation of licensed products, we materially breach any provisions of the MEEI Agreement or in the event of its insolvency or bankruptcy. In the event of an early termination of the MEEI Agreement, all rights licensed and developed by the Company under the MEEI Agreement may revert back to MEEI. The Company has agreed to indemnify MEEI for certain claims that may arise under the MEEI Agreement.

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	1 4 . LEASES The Company currently leases an office used to conduct business. The exercise of lease renewal options is at our discretion and the renewal to extend the lease terms are not included in the Company’s Right-Of-Use assets and lease liabilities as they are not reasonably certain of exercise. The Company regularly evaluates the renewal options and when they are reasonably certain of exercise, the Company includes the renewal period in its lease term. As the Company’s lease does not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the present value of the lease payments. As of December 31, 2019, the Company maintained an unamortized Right-Of-Use asset with a corresponding operating lease liability of approximately $0.2 million based on the present value of the minimum rental payments as a result of adoption of ASC Topic 842, Leases 2020 total lease payments $ 237,671 Less: effect of discounting (11,343 ) Present value of lease liabilities $ 226,328 Current operating lease liabilities $ 226,328 Non-current operating lease liabilities — Total $ 226,328 The Company’s gross future minimum payments under all non-cancelable operating leases as of December 31, 2019 are: Total 2020 2021 2022 2023 Operating lease obligations $ 237,671 $ 237,671 $ — $ — $ —

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	1 5 . None.

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation – The accompanying consolidated financial statements were prepared in conformity with accounting principles generally accepted in the United States of America (“US GAAP”).
Risks and Uncertainties	Risks and Uncertainties –The ongoing research and development activities will be subject to extensive regulation by numerous governmental authorities in the United States. Prior to marketing in the United States, any drug developed by the Company must undergo rigorous preclinical and clinical testing and an extensive regulatory approval process implemented by the United States Food and Drug Administration (“FDA”) under the Food, Drug and Cosmetic Act. The Company has limited experience in conducting and managing the preclinical and clinical testing necessary to obtain regulatory approval. There can be no assurance that the Company will not encounter problems in the clinical trials that will cause the Company or the FDA to delay or suspend clinical trials. The Company’s success will depend in part on its ability to obtain patents and product license rights, maintain trade secrets, and operate without infringing on the property rights of others, both in the United States and other countries. There can be no assurance that patents issued to or licensed by the Company will not be challenged, invalidated, circumvented, or that the rights granted thereunder will provide proprietary protection or competitive advantages to the Company. Based on its current operating plan, the Company believes that its cash, cash equivalents, and marketable securities as of December 31, 2019, together with the proceeds of the sales of common stock under the Jefferies Sales Agreement through the date of this filing will be adequate to fund our currently anticipated operating expenses through the end of 2021, including the currently planned Part 2 of the Phase 3 clinical trial in dry eye disease (the RENEW trial, pending FDA feedback), the initial part of the adaptive Phase 3 clinical trial in proliferative vitreoretinopathy (the GUARD trial), and the Phase 3 trial in allergic conjunctivitis (the INVIGORATE trial). The Company will need to secure additional funding in the future, from one or more equity or debt financings, collaborations, or other sources, in order to carry out all of the Company’s planned research and development activities; commercialize its product candidates; or conduct any substantial, additional development requirements requested by the FDA. Additional funding may not be available to the Company on acceptable terms, or at all. If the Company is unable to secure additional capital, it will be required to significantly decrease the amount of planned expenditures, and may be required to cease operations. Curtailment of operations would cause significant delays in the Company’s efforts to develop and introduce its products to market, which is critical to the realization of its business plan and the future operations of the Company.
Use of Estimates	Use of Estimates – The preparation of consolidated financial statements in conformity with US GAAP requires management to make estimates and assumptions, including fair value estimates for investments that affect the reported amounts of assets, liabilities, and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. The Company evaluates its estimates and assumptions on an ongoing basis. The most significant estimates in the Company’s financial statements include, but are not limited to, estimates related to clinical trial accruals, estimates related to prepaid and accrued research and development costs, acquired in-process research and development (“IPR&D”) expense, and accounting for income taxes and the related valuation allowance. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may materially differ from these estimates and assumptions.
Segment Information	Segment Information – Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one segment, which is the identification and development of next-generation medicines to improve the lives of patients with immune-mediated diseases.
Cash and Cash Equivalents	Cash and Cash Equivalents – The Company classifies all highly liquid investments with original maturities of three months or less as cash equivalents and all highly liquid investments with original maturities of greater than three months but less than 12 months as current marketable securities. The Company has a policy of making investments only with commercial institutions that have at least an investment grade credit rating. The Company invests its cash primarily in reverse repurchase agreements (“RRAs”), government securities and obligations, and money market funds. RRAs are collateralized by deposits in the form of ‘Government Securities and Obligations’ for an amount not less than 102% of their value. The Company does not record an asset or liability related to the collateral as the Company is not permitted to sell or repledge the associated collateral. The Company has a policy that the collateral has at least an A (or equivalent) credit rating. The Company utilizes a third-party custodian to manage the exchange of funds as well as requirement that collateral received is maintained at 102% of the value of the RRAs on a daily basis.
Marketable Securities	Marketable Securities – Marketable securities consist of government securities and obligations with original maturities of more than 90 days. Investments are classified as available-for-sale and are recorded on the balance sheet at fair value with unrealized gains or losses reported as a separate component of other comprehensive income/(loss). Management determines the appropriate classification of its investments at the time of purchase and re-evaluates such determination at each balance sheet date.
Fair Value of Financial Instruments	Fair Value of Financial Instruments – Financial instruments including cash equivalents and accounts payable are carried in the financial statements at amounts that approximate their fair value based on the short maturities of those instruments. Marketable securities are carried at fair value and are more fully described in Note 6. The carrying amount of the Company’s credit facility with Hercules Capital, Inc. approximates fair value since the effective interest rate approximates market rates currently available to the Company.
Concentration of Credit Risk	Concentration of Credit Risk – Financial instruments that potentially subject the Company to significant concentrations of credit risk principally consist of cash, cash equivalents and marketable securities. The Company places its cash and cash equivalents and marketable securities with financial institutions which management believes have high credit ratings. As part of its cash and investment management processes, the Company performs periodic evaluations of the credit standing of the financial institutions with whom it maintains deposits.
Intellectual Property	Intellectual Property – The legal and professional costs incurred by the Company to acquire its patent rights are expensed as incurred and included in general and administrative expenses. At December 31, 2019 and 2018, the Company has determined that these expenses have not met the criteria to be capitalized since the future benefits to be derived from the patents is uncertain. Intellectual property related expenses for the years ended December 31, 2019 and 2018 were $1.4 million and $1.3 million, respectively.
Income Taxes	Income Taxes – The Company follows the provisions of Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 740, Income Taxes (“ASC 740”) , in reporting deferred income taxes. ASC 740 requires a company to recognize deferred tax liabilities and assets for expected future income tax consequences of events that have been recognized in the Company’s financial statements. Under this method, deferred tax assets and liabilities are determined based on temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates in the years in which the temporary differences are expected to reverse. Valuation allowances are provided if based on the weight of available evidence, it is more likely than not that some or all the deferred tax assets will not be realized. The Company accounts for uncertain tax positions pursuant to ASC 740 which prescribes a recognition threshold and measurement process for financial statement recognition of uncertain tax positions taken or expected to be taken in a tax return. If the tax position meets this threshold, the benefit to be recognized is measured as the tax benefit having the highest likelihood of being realized upon ultimate settlement with the taxing authority. The Company recognizes interest accrued related to unrecognized tax benefits and penalties in the provision for income taxes. Management is not aware of any uncertain tax positions.
Research and Development Costs	Research and Development Costs – Research and development (“R&D”) costs are charged to expense as incurred and relate to salaries, employee benefits, stock-based compensation related to employees, consulting services, other operating costs and expenses associated with preclinical and clinical trial activities. Payments made by the Company in advance for research and development services not yet provided and/or for materials not yet received are recorded as prepaid expenses. Accrued liabilities are recorded related to those expenses for which vendors have not yet billed us with respect to services provided and/or materials that we have received. Preclinical and clinical trial expenses relate to third-party services, subject-related fees at the sites where the Company’s clinical trials are being conducted, laboratory costs, analysis costs, toxicology studies and investigator fees. Costs associated with these expenses are generally payable on the passage of time or when certain milestones are achieved. Expense is recorded during the period incurred or in the period in which a milestone is achieved. In order to ensure that the Company has adequately provided for preclinical and clinical expenses during the proper period, the Company maintains an accrual to cover these expenses. These accruals are assessed on a quarterly basis and are based on such assumptions as expected total cost, the number of subjects and clinical trial sites and length of the study. Actual results may differ from these estimates and could have a material impact on the Company’s reported results. The Company’s historical accrual estimates have not been materially different from actual costs.
In Process Research and Development	In-process research and development – Assets purchased in an asset acquisition transaction are expensed as in-process research and development unless the assets acquired are deemed to have an alternative future use, provided that the acquired asset did not also include processes or activities that would constitute a “business” as defined under GAAP, the drug has not achieved regulatory approval for marketing and, absent obtaining such approval, has no established alternative future use. Acquired IPR&D payments are immediately expensed in the period in which they are incurred and include upfront payments, as well as transaction fees and subsequent pre-commercial milestone payments. Research and development costs incurred after the acquisition are expensed as incurred.
Stock-Based Compensation	Stock-Based Compensation – Stock-based payments are accounted for in accordance with the provisions of ASC 718, Compensation – Stock Compensation . For options, the fair value of stock-based payments is estimated, on the date of grant, using the Black-Scholes option pricing model. For restricted stock, fair value is based on the fair value of the stock on the date of grant. The resulting fair value for restricted stock and options expected to vest is recognized on a straight-line basis over the requisite service period, which is generally the vesting period of the applicable restricted stock or option. The Company records the effect of forfeitures and cancellations when they occur.
Comprehensive Loss	Comprehensive Loss – Comprehensive loss is defined as the change in equity during a period from transactions and other events and/or circumstances from non-owner sources. For December 31, 2019, comprehensive loss is equal to the Company’s net loss of $60.8 million and an unrealized gain on marketable securities of $15,000. For December 31, 2018, comprehensive loss is equal to our net loss of $38.9 million and an unrealized gain on marketable securities of $9,000.
Net Loss Per Share	Net Loss Per Share – The Company computes net loss per share in accordance with the two-class method. Under the two-class method, net loss is allocated between common stock and other participating securities based on their participation rights. The Company has determined that the nonvested shares issued to the Helio founders represents a participating security and as such the nonvested shares are excluded from basic earnings per share. Net losses are not allocated to the nonvested shareholders for computing net loss per share under the two-class method because nonvested shareholders do not have contractual obligations to share in the losses of the Company. Basic earnings per share is calculated by dividing net loss allocable to common stockholders by the weighted average number of common stock outstanding. Diluted net loss per share is computed using the more dilutive of (a) the two-class method, or (b) treasury stock method, as applicable, to the potentially dilutive instruments. The weighted-average number of common shares
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the FASB issued Accounting Standards Update (ASU) No. 2016-02, Leases (Topic 842) (“ASU 2016-02”), which supersedes the lease guidance under FASB ASC Topic 840, Leases (“ASC 840”), resulting in the creation of FASB ASC Topic 842, Leases (“ASC 842”). ASU 2016-02 requires lessees to recognize on the balance sheet a right-of-use asset, representing its right to use the underlying asset for the lease term, and a lease liability for all leases with terms greater than 12 months. The guidance also requires qualitative and quantitative disclosures designed to assess the amount, timing, and uncertainty of cash flows arising from leases. The standard requires the use of a modified retrospective transition approach, which includes a number of optional practical expedients that entities may elect to apply. The Company adopted the new standard on January 1, 2019. The Company elected to utilize the available practical expedients. Upon adoption, the Company recorded a ROU asset and a lease liability that were immaterial. There was no impact to opening retained earnings as a result of the adoption of the new guidance. The impact of applying ASC 842 on the results for reporting periods and balance sheet beginning after January 1, 2019 is presented under ASC 842, while prior amounts are not adjusted and continue to be reported in accordance with the Company’s historic accounting under ASC 840, Leases. Refer to Note 14 for further information. In June 2016, the FASB issued (“ASU”) No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”). ASU 2016-13 requires that credit losses be reported as an allowance using an expected losses model, representing the entity’s current estimate of credit losses expected to be incurred. The accounting guidance currently in effect is based on an incurred loss model. For available-for-sale debt securities with unrealized losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. The amendments under ASU 2016-13 are effective for interim and annual fiscal periods beginning after December 15, 2022. We do not expect the adoption of ASU 2016-13 to have a material impact on our consolidated financial statements.

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Computation of Diluted Weighted-Average Shares Outstanding	The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted-average shares outstanding, because such securities had an antidilutive impact: Years ended December 31, 2019 2018 Options to purchase common stock 4,193,814 3,383,047 Warrants to purchase common stock — 40,300 Restricted stock units 430,425 212,297 Unvested restricted shares (1) 426,472 — Total of common stock equivalents 5,050,711 3,635,644 (1) Represents 426,472 shares of common stock that are issued and outstanding but that were subject to a right of repurchase by the Company at December 31, 2019 and are not included in stockholders’ equity pursuant to US GAAP.

Cash, Cash Equivalents and Ma_2

Cash, Cash Equivalents and Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2019
Cash And Cash Equivalents [Abstract]
Schedule of Cash, Cash Equivalents and Marketable Securities	At December 31, 2019, cash, cash equivalents and marketable securities were comprised of: Carrying Amount Unrecognized Gain Unrecognized Loss Estimated Fair Value Cash and Cash Equivalents Current Marketable Securities Cash $ 15,363,462 $ — $ — $ 15,363,462 $ 15,363,462 $ — Money market funds 1,062,368 — — 1,062,368 1,062,368 — Reverse repurchase agreements 28,000,000 — — 28,000,000 28,000,000 — Total Cash and cash equivalents 44,425,830 — — 44,425,830 44,425,830 — U.S. government agency securities 28,932,679 5,866 — 28,938,545 — 28,938,545 Available for Sale (1) 28,932,679 5,866 — 28,938,545 — 28,938,545 Total Cash, cash equivalents and current marketable securities $ 44,425,830 $ 28,938,545 (1) Available for sale securities are reported at fair value with unrealized gains and losses reported net of taxes, if material, in other comprehensive income. At December 31, 2018, cash, cash equivalents and marketable securities were comprised of: Carrying Amount Unrecognized Gain Unrecognized Loss Estimated Fair Value Cash and Cash Equivalents Current Marketable Securities Cash $ 2,127,175 $ — $ — $ 2,127,175 $ 2,127,175 $ — Money market funds 1,230,297 — — 1,230,297 1,230,297 — Reverse repurchase agreements 44,000,000 — — 44,000,000 44,000,000 — Total Cash and cash equivalents 47,357,472 — — 47,357,472 47,357,472 — U.S. government agency securities 46,251,444 — (9,224 ) 46,242,220 — 46,242,220 Available for Sale (1) 46,251,444 — (9,224 ) 46,242,220 — 46,242,220 Total Cash, cash equivalents and current marketable securities $ 47,357,472 $ 46,242,220

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents information about the Company’s assets measured at fair value at December 31, 2019 and December 31, 2018: December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Money market funds (a) $ 1,062,368 $ — $ — $ 1,062,368 Reverse repurchase agreements (b) — 28,000,000 — 28,000,000 U.S. government agency securities (b) — 28,938,545 — 28,938,545 Total assets at fair value $ 1,062,368 $ 56,938,545 $ — $ 58,000,913 December 31, 2018 Level 1 Level 2 Level 3 Total Assets: Money market funds (a) $ 1,230,297 $ — $ — $ 1,230,297 Reverse repurchase agreements (b) — 44,000,000 — 44,000,000 U.S. government agency securities (b) — 46,242,220 — 46,242,220 Total assets at fair value $ 1,230,297 $ 90,242,220 $ — $ 91,472,517 (a) Money market funds included in cash and cash equivalents in the consolidated balance sheets, are valued at quoted market prices in active markets. (b) Reverse repurchase agreements and U.S. government agency securities are recorded at fair market values, which are determined based on the most recent observable inputs for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active or are directly or indirectly observable.

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2019
Payables And Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses at December 31, 2019 and 2018 were: December 31, December 31, 2019 2018 Accrued compensation $ 1,489,475 $ 1,172,880 Accrued research and development 9,493,093 3,882,313 Accrued general and administrative 890,554 366,305 Accrued expenses $ 11,873,122 $ 5,421,498

Credit Facility (Tables)

Credit Facility (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Principal Payments Including End of Term Charges	Future principal payments, including the End of Term Charge, are as follows for the years ending December 31: 2020 $ — 2021 3,659,776 2022 5,931,718 2023 6,451,006 Total $ 16,042,500

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Components of Deferred Tax Assets and Liabilities	Significant components of the Company’s deferred tax assets and liabilities at December 31, 2019 and 2018 are as follows: Years ended December 31, 2019 2018 Deferred Tax Assets Federal & state NOL carryforward $ 37,752,925 $ 25,311,547 Federal & state R&D credit carryforward 4,840,115 3,781,160 Intangibles – net 120,318 164,508 Accounts payable and accrued expenses 2,898,710 1,958,174 Stock options 4,527,462 3,146,034 Other items 80,812 10,173 Gross deferred tax assets 50,220,342 34,371,596 Valuation allowance (50,165,427 ) (34,371,596 ) Deferred tax assets, net $ 54,915 $ — Deferred Tax Liabilities Lease liability (54,915 ) — TOTAL $ — $ —
Components of Income Tax Benefit	The components of the incomes tax benefit for the years ended December 31, 2019 and 2018, are as follows: Years ended December 31, 2019 2018 Deferred Taxes Federal $ (1,205,175 ) $ — State (104,798 ) — Total income tax benefit $ (1,309,973 ) $ —
Summary of Statutory Tax Rates and Effective Tax Rates	A reconciliation of the federal statutory tax rate of 21% to the Company’s effective income tax rates are as follows: Years ended December 31, 2019 2018 Statutory tax rate 21.00 % 21.00 % State taxes, net of federal benefits 5.62 % 6.83 % Federal research and development credits 1.44 % 3.81 % Change in valuation allowance (25.44 ) % (31.51 ) % Stock-based compensation (0.81 ) % (0.20 ) % Other 0.30 % 0.07 % Effective tax rate 2.11 % — %

Stock Incentive Plan (Tables)

Stock Incentive Plan (Tables)	12 Months Ended
	Dec. 31, 2019
Schedule of Stock-Based Compensation Expense	The amounts included in the consolidated statements of operations relating to stock-based compensation, employee incentive plan and Helio founder shares as are as follows: Years ended December 31, 2019 2018 Research and development expenses $ 2,441,542 $ 1,541,915 General and administrative expenses $ 3,446,887 $ 2,602,938 Helio founders' shares (Note 3) $ 2,194,322 $ — Total stock-based compensation expense $ 8,082,751 $ 4,144,853
Summary of Activity Relating to Stock Options	The following table summarizes option activity under the incentive plans for the year ended December 31, 2019: Number of Shares Weighted Average Exercise Price Weighted Average Contractual Term Aggregate Intrinsic Value(a) Outstanding at December 31, 2018 3,383,047 $ 6.17 Granted 1,447,255 7.71 Cancelled/Forfeited (404,484 ) 7.66 Exercised (232,004 ) 5.01 Outstanding at December 31, 2019 4,193,814 $ 6.62 7.34 $ 2,615,717 Exercisable at December 31, 2019 2,514,720 $ 5.91 6.38 $ 2,471,702 (a) The aggregate intrinsic value in this table was calculated on the positive difference, if any, between the closing price per share of the Company’s common stock on December 31, 2019 of $5.81 and the per share exercise price of the underlying options.
Summary of Activity Relating to Restricted Stock Units	The table below summarizes activity relating to RSUs for the year ended December 31, 2019: Number of Shares Outstanding at December 31, 2018 212,297 Granted 283,140 Vested/released (65,012 ) Outstanding at December 31, 2019 430,425
Schedule of Fair Value of Employee Stock Purchase Plan Assumptions	The fair value of the purchase rights granted under this plan was estimated on the date of grant using the Black-Scholes option-pricing model using assumptions as shown below: December 31, 2019 December 31, 2018 Expected dividend yield 0% 0% Anticipated volatility 70.55% - 76.02% 77.49% - 80.59% Stock price $6.12 - $8.51 $7.00 - $8.05 Exercise price $6.12 - $8.51 $7.00 - $8.05 Expected life (years) 0.50 0.50 Risk free interest rate 2.10% - 2.56% 1.61% - 2.11%
Summary of Employee Stock Purchase Plan Activity	A summary of the weighted-average grant-date fair value, shares issued and total stock-based compensation expense recognized related to the 2016 ESPP for the years ended December 31, 2019 and 2018 are as follows: December 31, 2019 December 31, 2018 Weighted-average grant-date fair value per share $ 2.79 $ 2.21 Total shares issued 34,253 14,382 Total stock-based compensation expense $ 91,790 $ 75,141
Employee Stock Options [Member]
Schedule of Fair Value of Stock Option Assumptions	The assumptions used in determining fair value of the employee stock options for the years ended December 2019 and 2018, are as follows: December 31, 2019 December 31, 2018 Expected dividend yield 0% 0% Anticipated volatility 74.65% - 77.12% 76.52% - 78.38% Stock price $5.16 - $8.76 $6.80 - $11.83 Exercise price $5.16 - $8.76 $6.80 - $11.83 Expected life (years) 5.50 - 6.08 5.50 - 6.25 Risk free interest rate 1.59% - 2.62% 2.32% - 3.10%

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Schedule of Maturities and Balance Sheet Presentation of Lease Liabilities	Maturities and balance sheet presentation of our lease liabilities for all operating leases as of December 31, 2019 is as follows: 2020 total lease payments $ 237,671 Less: effect of discounting (11,343 ) Present value of lease liabilities $ 226,328 Current operating lease liabilities $ 226,328 Non-current operating lease liabilities — Total $ 226,328 The Company’s gross future minimum payments under all non-cancelable operating leases as of December 31, 2019 are: Total 2020 2021 2022 2023 Operating lease obligations $ 237,671 $ 237,671 $ — $ — $ —

Basis of Presentation and Sig_3

Basis of Presentation and Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)Segment	Dec. 31, 2018USD ($)
Basis of Presentation and Significant Accounting Policies [Line Items]
Number of segment | Segment	1
Investment maturity period	Three months or less
Marketable securities maturity period	90 days
Unrealized gain on marketable securities	$ 15,090	$ 8,607
Net loss	(60,826,831)	(38,893,245)
Impact to opening retained earnings	0
Intellectual Property [Member]
Basis of Presentation and Significant Accounting Policies [Line Items]
Legal expense	$ 1,400,000	$ 1,300,000
Minimum [Member]
Basis of Presentation and Significant Accounting Policies [Line Items]
Percentage of Collateral Deposits under Reverse Repurchase Agreement	102.00%

Helio vision acquisition - Addi

Helio vision acquisition - Additional Information (Detail) - USD ($)	Jan. 28, 2019	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Share-based compensation award, vesting period			4 years
Stock-based compensation expense		$ 8,082,751	$ 4,144,853
Income tax benefit		1,309,973
Acquired in-process research and development		6,567,754
Research and Development Expenses [Member]
Business Acquisition [Line Items]
Stock-based compensation expense		2,441,542	$ 1,541,915
Helio Vision, Inc [Member]
Business Acquisition [Line Items]
Business combination, stock issued	1,160,444
Income tax benefit		1,300,000
Acquired in-process research and development		6,600,000
Helio Vision, Inc [Member] | Founders [Member]
Business Acquisition [Line Items]
Business combination, stock issued	568,627
Helio Vision, Inc [Member] | Founders [Member] | Service Based Awards [Member]
Business Acquisition [Line Items]
Share-based compensation award, vesting period	3 years
Vesting Percentage Of Shares Of Common Stock Issued Former Security Holders And Advisor	25.00%
Helio Vision, Inc [Member] | Founders [Member] | Restricted Stock [Member]
Business Acquisition [Line Items]
Share-based compensation award, vesting period	3 years
Helio Vision, Inc [Member] | Founders [Member] | Restricted Stock [Member] | Research and Development Expenses [Member]
Business Acquisition [Line Items]
Stock-based compensation expense		$ 2,200,000
Helio Vision, Inc [Member] | Non Founders [Member]
Business Acquisition [Line Items]
Business combination, stock issued	591,817
Helio Vision, Inc [Member] | Common Stock, 24 Months Following the Closing Date [Member]
Business Acquisition [Line Items]
Business combination, contingent consideration liability	$ 2,500,000
Helio Vision, Inc [Member] | Common Stock after FDA Approval prior to 10th Anniversary [Member]
Business Acquisition [Line Items]
Business combination, contingent consideration liability	10,000,000
Helio Vision, Inc [Member] | Common Stock After F D A Approval Prior To Twelfth Anniversary
Business Acquisition [Line Items]
Business combination, contingent consideration liability	$ 2,500,000
Helio Vision, Inc [Member] | Common Stock After F D A Approval Prior To Twelfth Anniversary | Maximum [Member]
Business Acquisition [Line Items]
Business combination, contingent consideration stock to be issued	5,248,885
Helio Vision, Inc [Member] | Tax Gross-up Payment in Event of Change of Control or Divesture [Member]
Business Acquisition [Line Items]
Business combination, contingent consideration liability	$ 1,000,000

Net Loss Per Share - Computatio

Net Loss Per Share - Computation of Diluted Weighted-Average Shares Outstanding (Detail) - shares		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of common stock equivalents		5,050,711	3,635,644
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of common stock equivalents		4,193,814	3,383,047
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of common stock equivalents			40,300
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of common stock equivalents		430,425	212,297
Unvested Restricted Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of common stock equivalents	[1]	426,472
[1]	Represents 426,472 shares of common stock that are issued and outstanding but that were subject to a right of repurchase by the Company at December 31, 2019 and are not included in stockholders’ equity pursuant to US GAAP.

Net Loss Per Share - Computat_2

Net Loss Per Share - Computation of Diluted Weighted-Average Shares Outstanding (Parenthetical) (Detail)	Dec. 31, 2019shares
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of common stock shares outstanding, subject to repurchase	426,472

Cash, Cash Equivalents and Ma_3

Cash, Cash Equivalents and Marketable Securities - Schedule of Cash, Cash Equivalents and Marketable Securities (Detail) - USD ($)		Dec. 31, 2019	Dec. 31, 2018
Cash Cash Equivalents And Marketable Securities [Line Items]
Cash		$ 15,363,462	$ 2,127,175
Money market funds		1,062,368	1,230,297
Reverse repurchase agreements		28,000,000	44,000,000
Total Cash and cash equivalents		44,425,830	47,357,472
U.S. government agency securities		28,932,679	46,251,444
Available for Sale	[1]	28,932,679	46,251,444
Cash and Cash Equivalents		44,425,830	47,357,472
Current Marketable Securities		28,938,545	46,242,220
Available for Sale [Member]
Cash Cash Equivalents And Marketable Securities [Line Items]
Unrecognized Gain	[1]	5,866	0
Unrecognized Loss	[1]		(9,224)
Estimated Fair Value	[1]	28,938,545	46,242,220
Current Marketable Securities	[1]	28,938,545	46,242,220
Cash [Member]
Cash Cash Equivalents And Marketable Securities [Line Items]
Unrecognized Gain		0	0
Estimated Fair Value		15,363,462	2,127,175
Cash and Cash Equivalents		15,363,462	2,127,175
Money Market Funds [Member]
Cash Cash Equivalents And Marketable Securities [Line Items]
Unrecognized Gain		0	0
Estimated Fair Value		1,062,368	1,230,297
Cash and Cash Equivalents		1,062,368	1,230,297
Reverse Repurchase Agreements [Member]
Cash Cash Equivalents And Marketable Securities [Line Items]
Unrecognized Gain		0	0
Estimated Fair Value		28,000,000	44,000,000
Cash and Cash Equivalents		28,000,000	44,000,000
Total Cash and cash equivalents [Member]
Cash Cash Equivalents And Marketable Securities [Line Items]
Unrecognized Gain		0	0
Estimated Fair Value		44,425,830	47,357,472
Cash and Cash Equivalents		44,425,830	47,357,472
U.S. Government Agencies Securities [Member]
Cash Cash Equivalents And Marketable Securities [Line Items]
Unrecognized Gain		5,866	0
Unrecognized Loss			(9,224)
Estimated Fair Value		28,938,545	46,242,220
Current Marketable Securities		$ 28,938,545	$ 46,242,220
[1]	Available for sale securities are reported at fair value with unrealized gains and losses reported net of taxes, if material, in other comprehensive income.

Cash, Cash Equivalents and Ma_4

Cash, Cash Equivalents and Marketable Securities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019
Maximum [Member]
Cash Cash Equivalents And Marketable Securities [Line Items]
Contractual maturities of available for sale securities	1 year

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Liabilities measured at fair value on a recurring basis	$ 0	$ 0

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)		Dec. 31, 2019	Dec. 31, 2018
Assets:
Total assets at fair value		$ 58,000,913	$ 91,472,517
Level 1 [Member]
Assets:
Total assets at fair value		1,062,368	1,230,297
Level 2 [Member]
Assets:
Total assets at fair value		56,938,545	90,242,220
Money Market Funds [Member]
Assets:
Total assets at fair value	[1]	1,062,368	1,230,297
Money Market Funds [Member] | Level 1 [Member]
Assets:
Total assets at fair value	[1]	1,062,368	1,230,297
U.S. Government Agencies Securities [Member]
Assets:
Total assets at fair value	[2]	28,938,545	46,242,220
U.S. Government Agencies Securities [Member] | Level 2 [Member]
Assets:
Total assets at fair value	[2]	28,938,545	46,242,220
Reverse Repurchase Agreements [Member]
Assets:
Total assets at fair value	[2]	28,000,000	44,000,000
Reverse Repurchase Agreements [Member] | Level 2 [Member]
Assets:
Total assets at fair value	[2]	$ 28,000,000	$ 44,000,000
[1]	Money market funds included in cash and cash equivalents in the consolidated balance sheets, are valued at quoted market prices in active markets.
[2]	Reverse repurchase agreements and U.S. government agency securities are recorded at fair market values, which are determined based on the most recent observable inputs for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active or are directly or indirectly observable.

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Accrued compensation	$ 1,489,475	$ 1,172,880
Accrued research and development	9,493,093	3,882,313
Accrued general and administrative	890,554	366,305
Accrued expenses	$ 11,873,122	$ 5,421,498

Credit Facility - Additional In

Credit Facility - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Mar. 31, 2019
Line Of Credit Facility [Line Items]
Proceeds from Long-term lines of credit	$ 16,042,500
Hercules Credit Facility [Member]
Line Of Credit Facility [Line Items]
Credit facility amount		$ 60,000,000
Credit facility amount outstanding	$ 15,000,000
Debt instrument annual interest rate	9.10%
Interest payment period	May 1, 2021
Interest payment extension period	May 1, 2022
Term loan maturity date	Oct. 1, 2023
Commitment charge	$ 25,000
Transaction costs	273,186
Credit facility fee	$ 375,000
Credit facility commitment fee percentage	6.95%
Credit facility, interest rate	12.90%
Term loan prepayment term	3% if the term loan is prepaid prior to March 25, 2021 and 1.5% if the term loan is prepaid any time thereafter, but prior to March 25, 2022.
Hercules Credit Facility [Member] | Maximum [Member]
Line Of Credit Facility [Line Items]
Credit facility prepayment fee percentage	3.00%
Loan agreement right to purchase aggregate amount of equity securities	$ 2,000,000
Hercules Credit Facility [Member] | Minimum [Member]
Line Of Credit Facility [Line Items]
Credit facility prepayment fee percentage	1.50%
Hercules Credit Facility [Member] | Prime Rate [Member]
Line Of Credit Facility [Line Items]
Debt instrument variable annual interest rate	3.10%
Hercules Credit Facility [Member] | Term Loan Advance One [Member]
Line Of Credit Facility [Line Items]
Credit facility amount		5,000,000
Hercules Credit Facility [Member] | Term Loan Advance Two [Member]
Line Of Credit Facility [Line Items]
Proceeds from Long-term lines of credit		15,000,000
Hercules Credit Facility [Member] | Term Loan Advance Three [Member]
Line Of Credit Facility [Line Items]
Proceeds from Long-term lines of credit		15,000,000
Hercules Credit Facility [Member] | Term Loan Advance Four [Member]
Line Of Credit Facility [Line Items]
Proceeds from Long-term lines of credit		15,000,000
Hercules Credit Facility [Member] | Term Loan Advance Five [Member]
Line Of Credit Facility [Line Items]
Proceeds from Long-term lines of credit		$ 10,000,000

Credit Facility - Schedule of P

Credit Facility - Schedule of Principal Payments Incuding End of Term Charges (Detail)	Dec. 31, 2019USD ($)
Line Of Credit Facility [Abstract]
2021	$ 3,659,776
2022	5,931,718
2023	6,451,006
Long-term Debt	$ 16,042,500

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended			2 Months Ended	12 Months Ended
	Dec. 31, 2018	Oct. 31, 2018	Jun. 30, 2017	Mar. 12, 2020	Dec. 31, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Common stock, voting rights					Each share of common stock is entitled to one vote
Issuance of common stock, net of issuance costs					$ 7,891,678	$ 81,671,172
Proceeds from issuance of common stock					$ 7,891,678	$ 81,837,102
Underwritten Public Offering [Member]
Class Of Stock [Line Items]
Proceeds from issuance of common stock		$ 67,600,000
Cantor Sales Agreement [Member] | Cantor Fitzgerald And Co [Member]
Class Of Stock [Line Items]
Issuance of common stock, net of issuance costs, Shares						1,796,306
Proceeds from issuance of common stock						$ 14,200,000
Cantor Sales Agreement [Member] | Cantor Fitzgerald And Co [Member] | Maximum [Member]
Class Of Stock [Line Items]
Expected aggregate gross proceeds from issuance of stock			$ 20,000,000
Jefferies Sales Agreement [Member] | Jefferies LLC [Member]
Class Of Stock [Line Items]
Issuance of common stock, net of issuance costs, Shares					1,300,000
Proceeds from issuance of common stock					$ 8,000,000
Volume-weighted average price					$ 9.73
Jefferies Sales Agreement [Member] | Jefferies LLC [Member] | Subsequent Event [Member]
Class Of Stock [Line Items]
Issuance of common stock, net of issuance costs, Shares				562,669
Proceeds from issuance of common stock				$ 3,200,000
Volume-weighted average price				$ 5.79
Jefferies Sales Agreement [Member] | Jefferies LLC [Member] | Maximum [Member]
Class Of Stock [Line Items]
Expected aggregate gross proceeds from issuance of stock	$ 50,000,000
Common Voting Stock [Member]
Class Of Stock [Line Items]
Issuance of common stock, net of issuance costs, Shares					1,347,156	7,046,306
Issuance of common stock, net of issuance costs					$ 1,348	$ 7,046
Common Voting Stock [Member] | Underwritten Public Offering [Member]
Class Of Stock [Line Items]
Issuance of common stock, net of issuance costs, Shares		5,250,000
Shares issued, price per share		$ 13.75
Issuance of common stock, net of issuance costs		$ 72,200,000
Employee Stock Options [Member]
Class Of Stock [Line Items]
Common stock reserved for issuance of shares					4,193,814
Two Thousand And Thirteen Incentive Plan [Member]
Class Of Stock [Line Items]
Common stock reserved for issuance of shares					772,323
2016 Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Common stock reserved for issuance of shares					596,693

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Current provision for income tax benefit	$ (1,309,973)
Deferred tax assets valuation allowance	100.00%
Net operating loss carryforwards expire period	2037
Increasing in research activities expire period	2039
Statutory tax rate	21.00%	21.00%
Change in valuation allowance	$ 15,800,000
State and Federal [Member]
Income Tax Contingency [Line Items]
Current provision for income tax benefit	0
Federal [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	139,500,000
Increasing in research activities	4,200,000
State [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	133,900,000
Increasing in research activities	$ 800,000

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets
Federal & state NOL carryforward	$ 37,752,925	$ 25,311,547
Federal & state R&D credit carryforward	4,840,115	3,781,160
Intangibles – net	120,318	164,508
Accounts payable and accrued expenses	2,898,710	1,958,174
Stock options	4,527,462	3,146,034
Other items	80,812	10,173
Gross deferred tax assets	50,220,342	34,371,596
Valuation allowance	(50,165,427)	$ (34,371,596)
Deferred tax assets, net	54,915
Deferred Tax Liabilities
Lease liability	$ (54,915)

Income Taxes - Components of In

Income Taxes - Components of Income Tax Benefit (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)
Deferred Taxes
Federal	$ (1,205,175)
State	(104,798)
Total income tax benefit	$ (1,309,973)

Income Taxes - Summary of Statu

Income Taxes - Summary of Statutory Tax Rates and Effective Tax Rates (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Statutory tax rate	21.00%	21.00%
State taxes, net of federal benefits	5.62%	6.83%
Federal research and development credits	1.44%	3.81%
Change in valuation allowance	(25.44%)	(31.51%)
Stock-based compensation	(0.81%)	(0.20%)
Other	0.30%	0.07%
Effective tax rate	2.11%

Stock Incentive Plan - Addition

Stock Incentive Plan - Additional Information (Detail) - USD ($)	Jan. 01, 2020	Jan. 02, 2016	Mar. 31, 2016	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase of shares of common stock				4,193,814	3,383,047
Exercise price per share of common stock				$ 6.62	$ 6.17
Share-based compensation award, vesting period					4 years
Fair value of a common stock percentage				100.00%
Unamortized stock-based compensation				$ 8,100,000
Weighted average recognition period				2 years 6 months 14 days
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted in term years					10 years
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock underlying restricted stock units outstanding				430,425
Share-based compensation award, vesting period				4 years
Weighted average grant date fair value of shares				$ 5.23	$ 5.79
Unamortized stock-based compensation				$ 2,300,000
Weighted average grant date fair value				$ 8.05	$ 8.60
Weighted average remaining recognition period				2 years 7 months 24 days
Aggregate intrinsic value of options outstanding				$ 2,500,000
Employee Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield				0.00%	0.00%
Cash dividend paid				$ 0
2010 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase of shares of common stock				413,130
Exercise price per share of common stock				$ 1.58
2013 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options to purchase of shares of common stock				3,780,684
Exercise price per share of common stock				$ 7.17
Common stock available for issuance	2,517,321			772,323
Common stock issued	1,744,998
Amended 2013 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of increase in common stock outstanding		6.00%
2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance				596,693
Expected dividend yield				0.00%	0.00%
Weighted average grant date fair value				$ 2.79	$ 2.21
Issuance of common stock authorized				414,639
Percentage increase in number of shares of common stock reserved for issuance			1.00%
Share-based compensation arrangement by share-based payment award, closing price on the applicable offering commencement				85.00%
Share-based compensation arrangement by share-based payment award, closing price on the applicable offering termination date				85.00%
Share-based compensation arrangement by share-based payment award, description				In March 2016, the Company’s board of directors approved the 2016 Employee Stock Purchase Plan (“2016 ESPP”), which became effective in June 2016 following the approval of the Company’s stockholders. The 2016 ESPP authorizes the issuance of up to a total of 414,639 shares of the Company’s common stock to participating employees. The number of shares reserved for issuance under the 2016 ESPP automatically increases on the first business day of each fiscal year, commencing in 2017, by a number equal to the lower of (i) 1% of the shares of common stock outstanding on the last business day of the prior fiscal year; or (ii) the number of shares determined by the Company’s Board of Directors. Unless otherwise determined by the administrator of the 2016 ESPP, two offering periods of six months’ duration will begin each year on January 1 and July 1. Participating employees purchase stock under the 2016 ESPP at a price equal to the lower of 85% of the closing price on the applicable offering commencement date or 85% of the closing price on the applicable offering termination date.

Stock Incentive Plan - Schedule

Stock Incentive Plan - Schedule of Stock-Based Compensation Expense (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 8,082,751	$ 4,144,853
Research and Development Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	2,441,542	1,541,915
General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	3,446,887	$ 2,602,938
Helio Founders' Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 2,194,322

Stock Incentive Plan - Summary

Stock Incentive Plan - Summary of Stock Option Activity (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares Outstanding, Beginning Balance | shares	3,383,047
Number of Shares, Granted | shares	1,447,255
Number of Shares,Cancelled/Forfeited | shares	(404,484)
Number of Shares, Exercised | shares	(232,004)
Number of Shares Outstanding, Ending Balance | shares	4,193,814
Number of Shares Exercisable, Ending Balance | shares	2,514,720
Weighted Average Exercise Price, Beginning Balance | $ / shares	$ 6.17
Weighted Average Exercise Price, Granted | $ / shares	7.71
Weighted Average Exercise Price, Cancelled/Forfeited | $ / shares	7.66
Weighted Average Exercise Price, Exercised | $ / shares	5.01
Weighted Average Exercise Price, Ending Balance | $ / shares	6.62
Weighted Average Exercise Price Exercisable, Ending Balance | $ / shares	$ 5.91
Weighted Average Contractual Term, Outstanding	7 years 4 months 2 days
Weighted Average Contractual Term, Exercisable	6 years 4 months 17 days
Aggregate Intrinsic Value, Outstanding | $	$ 2,615,717	[1]
Aggregate Intrinsic Value, Exercisable | $	$ 2,471,702	[1]
[1]	The aggregate intrinsic value in this table was calculated on the positive difference, if any, between the closing price per share of the Company’s common stock on December 31, 2019 of $5.81 and the per share exercise price of the underlying options.

Stock Incentive Plan - Summar_2

Stock Incentive Plan - Summary of Stock Option Activity (Parenthetical) (Detail)	Dec. 31, 2019$ / shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Closing market value of common stock	$ 5.81

Stock Incentive Plan - Schedu_2

Stock Incentive Plan - Schedule of Fair Value of Stock Option Assumptions (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock price	$ 5.81
Employee Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Employee Stock Options [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Anticipated volatility	74.65%	76.52%
Stock price	$ 5.16	$ 6.80
Exercise price	$ 5.16	$ 6.80
Expected life (years)	5 years 6 months	5 years 6 months
Risk free interest rate	1.59%	2.32%
Employee Stock Options [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Anticipated volatility	77.12%	78.38%
Stock price	$ 8.76	$ 11.83
Exercise price	$ 8.76	$ 11.83
Expected life (years)	6 years 29 days	6 years 3 months
Risk free interest rate	2.62%	3.10%

Stock Incentive Plan - Summar_3

Stock Incentive Plan - Summary of Activity Relating to Restricted Stock Units (Detail) - Restricted Stock Units (RSUs)	12 Months Ended
	Dec. 31, 2019shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance	212,297
Granted	283,140
Vested/released	(65,012)
Number of Shares Outstanding, Ending Balance	430,425

Stock Incentive Plan - Schedu_3

Stock Incentive Plan - Schedule of Fair Value of Employee Stock Purchase Plan Assumptions (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock price	$ 5.81
2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Expected life (years)	6 months	6 months
2016 Employee Stock Purchase Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Anticipated volatility	70.55%	77.49%
Stock price	$ 6.12	$ 7
Exercise price	$ 6.12	$ 7
Risk free interest rate	2.10%	1.61%
2016 Employee Stock Purchase Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Anticipated volatility	76.02%	80.59%
Stock price	$ 8.51	$ 8.05
Exercise price	$ 8.51	$ 8.05
Risk free interest rate	2.56%	2.11%

Stock Incentive Plan - Summar_4

Stock Incentive Plan - Summary of Employee Stock Purchase Plan Activity (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 8,082,751	$ 4,144,853
2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value per share	$ 2.79	$ 2.21
Total shares issued	34,253	14,382
Total stock-based compensation expense	$ 91,790	$ 75,141

Stock Purchase Warrants - Addit

Stock Purchase Warrants - Additional Information (Detail) - Warrant [Member]	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Class Of Warrant Or Right [Line Items]
Warrants redeemable into common shares	60,000
Warrants exercisable date	May 1, 2015
Exercise price of warrants | $ / shares	$ 10
Class of warrants issued and expired unexercised	40,300
Warrants expiration date	May 1, 2019
Number outstanding	0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)
Commitments And Contingencies [Line Items]
Outstanding material claims	$ 0
Reserve for indemnification	0
Madrigal Agreement [Member]
Commitments And Contingencies [Line Items]
License fee	$ 250,000
Percentage over future regulatory, development and sales-dependent milestone payments	80.00%
Madrigal Agreement [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Future regulatory, development and sales-dependent milestone payments	$ 340,000,000
MEEI Agreement [Member]
Commitments And Contingencies [Line Items]
Additional equity consideration issuable	0
MEEI Agreement [Member] | Second and Third Anniversary [Member]
Commitments And Contingencies [Line Items]
Non-creditable non-refundable license maintenance fees	15,000
MEEI Agreement [Member] | Fourth and Fifth Anniversary [Member]
Commitments And Contingencies [Line Items]
Non-creditable non-refundable license maintenance fees	25,000
MEEI Agreement [Member] | Sixth and Subsequent Anniversary [Member]
Commitments And Contingencies [Line Items]
Non-creditable non-refundable license maintenance fees	$ 35,000

Leases - Additional Information

Leases - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Present value of lease liabilities	$ 226,328
Operating leases, weighted average remaining lease term (years)	1 year
Operating leases, weighted average discount rate	9.10%
Operating lease expense	$ 210,753

Leases - Schedule of Maturities

Leases - Schedule of Maturities and Balance Sheet Presentation of Lease Liabilities (Detail)	Dec. 31, 2019USD ($)
Leases [Abstract]
2020 total lease payments	$ 237,671
Less: effect of discounting	(11,343)
Present value of lease liabilities	226,328
Current operating lease liabilities	226,328
Non-current operating lease liabilities	0
Present value of lease liabilities	$ 226,328

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Payments Under Non-Cancelable Operating Leases (Detail)	Dec. 31, 2019USD ($)
Leases [Abstract]
2020 total lease payments	$ 237,671
Operating lease obligations, 2020	237,671
Operating lease obligations, 2021	0
Operating lease obligations, 2022	0
Operating lease obligations, 2023	$ 0