Ovid Therapeutics (OVID) 10-Q 8 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 01, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Trading Symbol	OVID
Entity Registrant Name	Ovid Therapeutics Inc.
Entity Central Index Key	1,636,651
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		24,654,114

Condensed Balance Sheets

Condensed Balance Sheets - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 30,513,180	$ 87,125,600
Short-term investments	21,994,374
Prepaid expenses and other current assets	2,746,680	1,462,448
Total current assets	55,254,234	88,588,048
Long-term prepaid expenses	4,543,603	604,646
Security deposit	121,905	88,940
Property and equipment, net	68,154	51,775
Other assets	406,078	124,194
Total assets	60,393,974	89,457,603
Current liabilities:
Accounts payable	4,593,501	2,025,766
Accrued expenses	5,829,404	3,995,334
Total current liabilities	10,422,905	6,021,100
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 shares and no shares authorized at September 30, 2018 and December 31, 2017
Common stock, $0.001 par value; 125,000,000 shares authorized at September 30, 2018 and December 31, 2017, 24,654,114 and 24,606,256 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively	24,654	24,606
Additional paid-in-capital	189,746,436	184,127,565
Accumulated other comprehensive loss	(4,675)
Accumulated deficit	(139,795,346)	(100,715,668)
Total stockholders' equity	49,971,069	83,436,503
Total liabilities and stockholders' equity	$ 60,393,974	$ 89,457,603

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	24,654,114	24,606,256
Common stock, shares outstanding	24,654,114	24,606,256

Condensed Statements of Operati

Condensed Statements of Operations - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating expenses:
Research and development	$ 8,544,547	$ 5,899,482	$ 25,168,446	$ 43,258,833
General and administrative	4,631,228	3,509,630	14,636,941	10,700,667
Total operating expenses	13,175,775	9,409,112	39,805,387	53,959,500
Loss from operations	(13,175,775)	(9,409,112)	(39,805,387)	(53,959,500)
Interest income	213,992	50,506	725,709	113,710
Net loss	(12,961,783)	(9,358,606)	(39,079,678)	(53,845,790)
Net loss attributable to common stockholders	$ (12,961,783)	$ (9,358,606)	$ (39,079,678)	$ (53,845,790)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.53)	$ (0.38)	$ (1.59)	$ (3.06)
Weighted-average common shares outstanding basic and diluted	24,634,380	24,601,936	24,623,225	17,571,772

Condensed Statements of Compreh

Condensed Statements of Comprehensive Loss - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (12,961,783)	$ (9,358,606)	$ (39,079,678)	$ (53,845,790)
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale securities	11,347		(4,675)
Comprehensive loss	$ (12,950,436)	$ (9,358,606)	$ (39,084,353)	$ (53,845,790)

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net loss	$ (39,079,678)	$ (53,845,790)
Adjustments to reconcile net loss to cash used in operating activities:
Noncash research and development expense		25,861,228
Stock-based compensation expense	5,332,781	4,987,088
Depreciation and amortization expense	86,441	58,590
Change in accrued interest and accretion of discount on short-term investments	(23,949)
Change in operating assets and liabilities:
Prepaid expenses and other current assets	(1,284,232)	(588,679)
Deferred transaction costs		229,000
Security deposit	(32,965)	(29,240)
Long-term prepaid expenses	(3,938,957)
Accounts payable	2,513,619	581,191
Accrued expenses	1,834,070	275,256
Due from/ to related parties		7,369
Net cash used in operating activities	(34,592,870)	(22,463,987)
Cash flows from investing activities:
Purchases of short-term investments	(49,975,100)
Proceeds from maturities of short-term investments	28,000,000
Purchase of property and equipment	(39,492)	(31,105)
Software development and other assets	(291,096)	(77,988)
Net cash used in investing activities	(22,305,688)	(109,093)
Cash flows from financing activities:
Proceeds from initial public offering, net of offering expenses		66,676,192
Proceeds from employee stock purchase plan	174,761
Proceeds from exercise of options	111,377
Net cash provided by financing activities	286,138	66,676,192
Net (decrease) increase in cash and cash equivalents	(56,612,420)	44,103,112
Cash and cash equivalents, at beginning of period	87,125,600	51,939,661
Cash and cash equivalents, at end of period	$ 30,513,180	$ 96,042,773

Nature of Operations

Nature of Operations	9 Months Ended
	Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Operations	NOTE 1 – NATURE OF OPERATIONS Ovid Therapeutics Inc. (the “Company”) was incorporated under the laws of the state of Delaware on April 1, 2014 and maintains its principal executive office in New York, New York. The Company commenced operations on April 1, 2014 (date of inception). The Company is a biopharmaceutical company focused exclusively on developing impactful medicines for patients and families living with rare neurological disorders. Since its inception, the Company has devoted substantially all its efforts to business development, research and development, recruiting management and technical staff, and raising capital, and has financed its operations through issuance of convertible preferred stock (“Preferred Stock”), common stock and other equity instruments. The Company has not generated any revenue. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, development of viable treatments, dependence on key personnel, protection of proprietary technology, compliance with government regulations, and ability to secure additional capital to fund operations. On May 10, 2017, the Company completed its initial public offering (“IPO”) of 5,000,000 shares of the Company's common stock at a public offering price of $15.00 per share. The gross proceeds from the IPO were $75.0 million and the net proceeds were $66.7 million, after deducting underwriting discounts and commissions and other offering expenses. At the time of the IPO, the Series A Preferred Stock, the Series B Preferred Stock, and the Series B-1 Preferred Stock were converted into common stock (see Note 7). In June 2018, the Company filed a shelf registration statement on Form S-3 (Registration No. 333-225391) that allows it to sell up to an aggregate of $200 million of our common stock, which includes up to $50.0 million designated in the prospectus supplement for an at-the-market offering program. In connection with the at-the-market offering, the Company entered into a Sales Agreement (“ATM Agreement”) with Cowen and Company, LLC (“Cowen”) under which the Company may offer and sell, from time to time at its sole discretion through Cowen, as its sales agent, shares of the Company’s common stock having an aggregate offering price of up to $50.0 million. The Company will pay Cowen a commission equal to 3.0% of the gross sales proceeds of any common stock sold through Cowen under the ATM Agreement and also have provided Cowen with indemnification and contribution rights. To date, the Company has not sold any common stock under the ATM Agreement. The Company has incurred operating losses since inception and had an accumulated deficit of $139.8 million as of September 30, 2018. The Company expects to continue to incur net losses for at least the next several years and is highly dependent on its ability to find additional sources of funding in the form of debt or equity financing or expanded partnering arrangements to fund its operations. Management believes that the Company’s existing cash, cash equivalents, and short-term investments as of September 30, 2018, will be sufficient to fund its current operating plans through at least the next 12 months from the date of filing of the Company’s Quarterly Report on Form 10-Q. Adequate additional funding may not be available to the Company on acceptable terms or at all. The failure to raise capital as and when needed could have a negative impact on the Company’s financial condition and ability to pursue its business strategy. The Company may be required to delay, reduce the scope of or eliminate research and development programs, or obtain funds through arrangements with collaborators or others that may require the Company to relinquish rights to certain drug candidates that the Company might otherwise seek to develop or commercialize independently.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	NOTE 2 – SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES The Company’s significant accounting policies are described in Note 2, “Summary of Significant Accounting Policies,” in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (“SEC”) on March 29, 2018. There have been no material changes to the significant accounting policies during the period ended September 30, 2018, except for items mentioned below. (A) Unaudited Interim Condensed Financial Statements The interim condensed balance sheet at September 30, 2018, the condensed statements of operations and comprehensive loss for the three and nine months ended September 30, 2018 and 2017, and condensed statements of cash flows for the nine months ended September 30, 2018 and 2017 are unaudited. The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and following the requirements of the SEC for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP are condensed or omitted. These condensed financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments that are necessary for a fair statement of its financial information. The results of operations for the three and nine months ended September 30, 2018 and 2017 are not necessarily indicative of the results to be expected for the year ending December 31, 2018 or for any other future annual or interim period. The balance sheet as of December 31, 2017 included herein was derived from the audited financial statements as of that date. These interim condensed financial statements should be read in conjunction with the Company’s audited financial statements as of and for the year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K. (B) Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Actual results could differ materially from those estimates. (C) Fair Value of Financial Instruments Financial Accounting Standards Board (“FASB”) guidance specifies a hierarchy of valuation techniques based on whether the inputs to those valuation techniques are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect market assumptions. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurement) and the lowest priority to unobservable inputs (Level 3 measurement). The three levels of the fair value hierarchy are as follows: • Level 1—Unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. Level 1 primarily consists of financial instruments whose value is based on quoted market prices such as exchange-traded instruments and listed equities. • Level 2—Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly (e.g., quoted prices of similar assets or liabilities in active markets, or quoted prices for identical or similar assets or liabilities in markets that are not active). Level 2 includes financial instruments that are valued using models or other valuation methodologies. • Level 3—Unobservable inputs for the asset or liability. Financial instruments are considered Level 3 when their fair values are determined using pricing models, discounted cash flows or similar techniques and at least one significant model assumption or input is unobservable. The carrying amounts reported in the balance sheets for cash and cash equivalents approximate their fair value based on the short-term maturity of these instruments. (D) Short-term Investments Short-term investments consist of debt securities with maturities greater than three months from the date of purchase. The Company classifies all of its investments as available-for-sale securities. Accordingly, these investments are recorded at fair value with unrealized gains and losses included in other comprehensive income (loss) as a component of stockholders’ equity until realized. Realized gains and losses, amortization and accretion of premiums and discounts are included within net loss. ( E) Recent Accounting Pronouncements Recent accounting standards which have been adopted In May 2017, the FASB issued Accounting Standards Update (“ASU”) No. 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting. This new standard clarifies when to account for a change to the terms or conditions of share-based payment award as a modification. Under the new guidance, modification accounting is required unless the fair value, the vesting conditions, and the classification of the modified award remain the same as the original award. The adoption of this standard on January 1, 2018, did not have a material impact on the Company’s financial statements. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This new standard clarifies the definition of a business and provides a screen to determine when an integrated set of assets and activities is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. ASU 2017-01 is effective for the Company as of January 1, 2018. The adoption of this standard on January 1, 2018, did not have an impact on the Company’s financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The new standard clarifies certain aspects of the statement of cash flows, including the classification of debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, distributions received from equity method investees and beneficial interests in securitization transactions. In situations in which cash receipts and payments have aspects of more than one class of cash flows and cannot be separated by source or use, the appropriate classification should depend on the activity that is likely to be the predominant source or use of cash flows for the item. The adoption of this standard on January 1, 2018 did not have a material impact on the Company’s statements of cash flows. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. This new standard amends certain aspects of accounting and disclosure requirements for financial instruments, including the requirement that equity investments (other than equity method investees) with readily determinable fair values are to be measured at fair value with any changes in fair value recognized in a company's results of operations. Equity investments that do not have readily determinable fair values may be measured at fair value or at cost minus impairment adjusted for changes in observable prices. The standard also includes certain amendments for the accounting for a financial liability that is measured at fair value in accordance with the fair value option and prescribes that a valuation allowance should be evaluated on deferred tax assets related to available-for-sale debt securities in combination with other deferred tax assets. The ASU makes targeted changes to the presentation requirements for financial instruments under current GAAP. All entities are required to disclose financial assets and financial liabilities separately, grouped by measurement category and form of financial asset. ASU No. 2016-01 is effective for the Company as of January 1, 2018. As the Company does not have equity investments, financial liabilities measured at fair value in accordance with the fair value option or deferred tax assets, the recognition and measurement guidance of this new standard is not applicable to the Company. However, since the Company does have financial asset investments, it has adopted the presentation and disclosure requirements of this standard. New accounting standards which have not yet been adopted On August 29, 2018, the FASB issued ASU No. 2018-15, Intangibles – Goodwill and Other - Internal-Use Software (Subtopic 350-40) - which amends ASC 350-40 to address a customer’s accounting for implementation costs incurred in a cloud computing arrangement (“CCA”) that is a service contract. ASU No. 2018-15 aligns the accounting for costs incurred to implement a CCA that is a service arrangement with the guidance on capitalizing costs associated with developing or obtaining internal-use software. Specifically, the ASU amends ASC 350 to include in its scope implementation costs of a CCA that is a service contract and clarifies that a customer should apply ASC 350-40 to determine which implementation costs should be capitalized in a CCA that is considered a service contract. According to the standard the balance sheet line item for the presentation of capitalized implementation costs should be the same as that for the prepayment of fees related to the hosting arrangement and the manner in which an entity classifies the cash flows related to capitalized implementation costs should be the same as that in which it classifies the cash flows for the fees related to the hosting arrangement. ASU 2018-15 is effective for the Company for fiscal years beginning after December 15, 2019, including interim periods therein. Entities are permitted to apply either a retrospective or prospective transition approach to adopt the guidance. When prospective transition is chosen, entities must apply the transition requirements to any eligible costs incurred after adoption. The Company is in the process of assessing the impact of this standard on its financial statements. On August 28, 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement. This standard changes the fair value measurement disclosure requirements of ASC 820. The new standard eliminated certain disclosures, added new disclosures with regard to unrealized gains or losses included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements, as well as modified certain disclosure. ASU 2018-13 is effective for all entities for fiscal years beginning after December 15, 2019, including interim periods therein. Early adoption is permitted. The ASU requires application of the prospective method of transition for the aforementioned new disclosure requirements and for modified disclosure with regard to measurement uncertainty while all other amendments made by the ASU must be applied retrospectively to all periods presented. The Company is in the process of assessing the impact of this standard on its financial statements. On June 20, 2018, the FASB issued ASU 2018-07, Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. This new standard simplifies the accounting for share-based payments granted to nonemployees for goods and services. The standard supersedes ASC 505-50 and expands the scope of ASC 718 to include all share-based payment arrangements related to the acquisition of goods and services from both nonemployees and employees. As such, among others, the measurement date for nonemployee awards would generally be the grant date same as the measurement date for employee equity awards and for performance-based awards, an entity is required to recognize any cost on the basis of the probable outcome of the performance conditions using the grant-date fair value of the award. ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Due to the immaterial volume of nonemployee equity-based awards as well as the immaterial fair value of such awards the Company does not expect ASU 2018-07 to have a material impact on its financial statements. On March 30, 2017, the FASB issued ASU 2017-08, Receivables – Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization and Purchased Callable Debt Securities. This new standard requires premiums on callable debt securities, that have explicit, non-contingent call features that are callable at fixed prices on preset dates, to be amortized to the earliest call date. The amortization period for callable debt securities purchased at a discount will not be impacted. Under current GAAP, premiums on callable debt securities are generally amortized over the contractual life of the security. The guidance is applicable to the Company beginning on January 1, 2019. The Company will be impacted if it will have on January 1, 2019 callable debt purchased with a premium. However, based on the Company’s current investment strategy where it purchases debt securities with maturity dates of less than a year, it does not expect to have significant premiums for callable debt. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. This new standard requires the measurement and recognition of expected credit losses for financial assets held at amortized cost, including loans and trade and other receivables. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss methodology, which will result in more timely recognition of credit losses. The standard also amends the impairment model for available-for-sale debt securities and requires entities to determine whether all or a portion of the unrealized loss on an available-for-sale debt security is a credit loss. Under the new guidance, an entity will recognize an allowance for credit losses on available-for-sale debt securities as a contra-account to the amortized cost basis rather than as a direct reduction of the amortized cost basis of the investment, as is currently required. ASU 2016-13 is effective for annual reporting periods, and interim periods within those years, beginning after December 15, 2019. The Company does not expect this standard to have a material impact on its financial statements due to the immaterial level of its unrealized losses on available-for-sale securities and its immaterial level of loans and receivables. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). This new standard was issued to increase transparency and comparability among entities by recognizing for all leases lease assets and lease liabilities on the balance sheet and disclosing key information about lease arrangements. This new standard is effective for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company does not expect ASU 2016-02 to have a material impact on its financial statements.

Preclinical and Clinical Agreem

Preclinical and Clinical Agreements	9 Months Ended
	Sep. 30, 2018
Research And Development [Abstract]
Preclinical and Clinical Agreements	NOTE 3 – PRECLINICAL AND CLINICAL AGREEMENTS During the ordinary course of business, the Company contracts with clinical research organizations. In connection with these contracts, the Company provides upfront payments for services to be provided over a period greater than 12 months that are applied against final expenses. As of September 30, 2018, the Company reflected $4.5 million within long-term prepaid expenses on the balance sheet related to these contracts. On August 26, 2016, the Company contracted with a clinical research organization for the study entitled “Safety and Efficacy of Gaboxadol in Angelman Syndrome: A Phase 2 Study of OV101 in adolescents and adults.” In connection with the execution of this contract, the Company provided an upfront retainer of $355,435. At September 30, 2018, this retainer is reflected within current assets on the balance sheet. During the nine months ended September 30, 2018 and 2017, the Company has expensed approximately $2,305,127 and $3,169,550 related to this contract, respectively . The expense related to this contract is reflected within research and development on the statement of operations.

Cash Equivalents and Short-Term

Cash Equivalents and Short-Term Investments	9 Months Ended
	Sep. 30, 2018
Investments Debt And Equity Securities [Abstract]
Cash Equivalents and Short-Term Investments	NOTE 4 – CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS All short-term investments are classified as available-for-sale. The following tables summarize the fair value of cash, cash equivalents, and short-term investments, as well as gross unrealized holding gains and losses as of September 30, 2018 and December 31, 2017: September 30, 2018 Amortized Gross unrealized Gross unrealized Fair cost holding gains holding losses value Cash $ 265,582 $ - $ - $ 265,582 Money market funds (a) 30,247,598 - - 30,247,598 Total cash and cash equivalents $ 30,513,180 $ - $ - $ 30,513,180 U.S. treasury notes (a) $ 21,999,049 $ - $ (4,675 ) $ 21,994,374 Total short-term investments $ 21,999,049 $ - $ (4,675 ) $ 21,994,374 (a) As of September 30, 2018, the Company's Level 1 assets consisted of money market funds and U.S. treasury notes totaling $52.2 million. The Company had no level 2 or level 3 assets or liabilities as of September 30, 2018. December 31, 2017 Amortized Gross unrealized Gross unrealized Fair cost holding gains holding losses value Cash $ 526,648 $ - $ - $ 526,648 Money market funds (a) 86,598,952 - - 86,598,952 Total cash and cash equivalents $ 87,125,600 $ - $ - $ 87,125,600 U.S. treasury notes $ - $ - $ - $ - Corporate bonds - - - - Total short-term investments $ - $ - $ - $ - (a) As of December 31, 2017, the Company's Level 1 assets consisted of money market funds totaling $86.6 million. The Company had no level 2 or level 3 assets or liabilities as of December 31, 2017. As of September 30, 2018 and December 31, 2017, the aggregate fair value of securities that were in an unrealized loss position for less than 12 months was $22.0 million and zero, respectively. The Company did not hold any securities in an unrealized loss position for more than 12 months as of September 30, 2018. There were no realized gains or losses on available-for-sale securities during the three and nine months ended September 30, 2018.

Property and Equipment and Inta

Property and Equipment and Intangible Assets	9 Months Ended
	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Property and Equipment and Intangible Assets	NOTE 5 – PROPERTY AND EQUIPMENT AND INTANGIBLE ASSETS Property and equipment is summarized as follows: September 30, December 31, 2018 2017 Furniture and equipment $ 144,620 $ 102,690 Less accumulated depreciation (76,466 ) (50,915 ) Total property and equipment, net $ 68,154 $ 51,775 Depreciation expense was $25,551 and $19,155 for the nine months ended September 30, 2018 and 2017, respectively. Depreciation expense was $6,746 and $7,171 for the three months ended September 30, 2018 and 2017, respectively. Intangible assets, net of accumulated amortization, were $406,078 and $124,194 as of September 30, 2018 and December 31, 2017, respectively, and are included in other assets. Amortization expense was $60,890 and $39,436 for the nine months ended September 30, 2018 and 2017, respectively. Amortization expense was $24,615 and $13,864 for the three months ended September 30, 2018 and 2017, respectively.

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2018
Payables And Accruals [Abstract]
Accrued Expenses	NOTE 6 – ACCRUED EXPENSES Accrued expenses consist of the following: September 30, December 31, 2018 2017 Clinical trials accrual $ 2,665,166 $ 753,018 Collaboration agreement accrual - 754,841 Payroll and bonus accrual 2,254,757 1,919,120 Professional fees accrual 740,134 321,852 Other 169,347 246,503 Total $ 5,829,404 $ 3,995,334

Stockholders' Equity and Prefer

Stockholders' Equity and Preferred Stock	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Stockholders' Equity and Preferred Stock	NOTE 7 – STOCKHOLDERS’ EQUITY AND PREFERRED STOCK The Company’s capital structure consists of common stock and preferred stock. Upon inception, the Company was initially authorized to issue 1,000 shares of common stock at $0.001 par value per share. The Company’s certificate of incorporation was amended on January 6, 2017 to increase the authorized shares of common stock available for issuance to 62,000,000 at $0.001 par value per share, and shares of preferred stock to 20,991,252. On May 10, 2017, the Company filed an amended and restated certificate of incorporation with the Secretary of the State of Delaware, which was approved by the Company’s Board of Directors and stockholders on April 12, 2017 and April 24, 2017, respectively, and which went effective immediately after the closing of the Company’s IPO on May 10, 2017. Pursuant to the amended and restated certificate of incorporation, the Company is authorized to issue 125,000,000 shares 2,382,069 shares of Series A Preferred Stock, 5,599,282 shares of Series B Preferred Stock and 1,781,996 shares

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	NOTE 8 – STOCK-BASED COMPENSATION On August 29, 2014, the Company’s Board of Directors adopted and approved the 2014 Equity Incentive Plan (the “2014 Plan”), which authorized the Company to grant shares of common stock in the form of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock and restricted stock units. The types of stock-based awards, including share purchase rights amount, terms, and exercisability provisions of grants are determined by the Company’s Board of Directors. The Company's Board of Directors adopted, and the Company's stockholders approved the 2017 equity incentive plan (“2017 Plan”), which became effective on May 4, 2017. The initial reserve of shares of common stock under the 2017 Plan was 3,052,059 shares. The 2017 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock unit awards, stock appreciation rights, performance-based stock awards, and other forms of stock-based awards. Additionally, the 2017 Plan provides for the grant of performance cash awards. The Company's employees, officers, directors and consultants and advisors are eligible to receive awards under the 2017 Plan. Upon the adoption of the 2017 Plan, no further awards will be granted under the 2014 Plan. P st The Company's Board of Directors adopted, and the Company's stockholders approved the 2017 employee stock purchase plan (the “2017 ESPP”), which became effective immediately prior to the execution of the underwriting agreement related to the IPO on May 4, 2017. The initial reserve of shares of common stock that may be issued under the 2017 ESPP was 279,069 shares. On September 20, 2017, the Company’s Compensation Committee approved an offering period under the 2017 ESPP, which began on October 20, 2017. The ESPP allows employees to purchase common stock of the Company at a 15% discount to the market price on designated purchase dates. During the three and nine months ended September 30, 2018, 22,142 Unless specified otherwise in an individual option agreement, stock options granted under the 2014 Plan and 2017 Plan generally have a ten-year term and a four-year graded vesting period. The vesting requirement is conditioned upon the grantee’s continued service with the Company during the vesting period. Once vested, all awards are exercisable from the date of grant until they expire. The option grants are non-transferable. Vested options generally remain exercisable for 90 days subsequent to the termination of the option holder’s service with the Company. In the event of option holder’s death or disability while employed by or providing service to the Company, the exercisable period extends to 12 months. Performance-based option awards generally have similar terms, with vesting contingent upon the achievement of specified performance condition and expire in accordance to the specific terms of the agreement. At September 30, 2018, there were zero performance-based options outstanding and unvested. The fair value of options granted during the nine months ended September 30, 2018 and 2017 was estimated using the Black-Scholes option valuation model. The inputs for the Black-Scholes option valuation model require management’s significant assumptions and are detailed in the table below. Prior to the IPO, the common stock price was determined by the Board of Directors. In the absence of market data for the Company’s common stock, the Board of Directors considered various factors in estimating the fair value of the common stock at the time of each option grant which included but was not limited to the common stock valuation performed by a third party independent valuation firm, the Company’s performance and future economic outlook, the potential financing available to the Company, and the valuation of common stock of similar companies in the industry. The risk-free interest rates were based on the rate for U.S. Treasury securities at the date of grant with maturity dates approximately equal to the expected life at the grant date. The expected life was based on the simplified method in accordance with the SEC Staff Accounting Bulletin No. Topic 14D. The expected volatility was estimated based on historical volatility information of peer companies that are publicly available. All assumptions used to calculate the grant date fair value of nonemployee options are generally consistent with the assumptions used for options granted to employees. In the event the Company terminates any of its consulting agreements, the unvested options underlying the agreements would also be cancelled. Unvested nonemployee options are marked-to-market at each reporting period until vested. The Company granted zero and 27,906 stock options to nonemployee consultants for services rendered during the nine months ended September 30, 2018 and 2017, respectively. There were 12,356, and 44,333 unvested nonemployee options outstanding as of September 30, 2018, and 2017, respectively. Total expense recognized related to the nonemployee stock options for the three months ended September 30, 2018 and 2017 was $40,730, and $52,348, respectively. Total expense recognized related to the nonemployee stock options for the nine months ended September 30, 2018 and 2017 was $133,460 and $358,554, respectively. Total unrecognized compensation expenses related to the nonemployee stock options was $34,049 as of September 30, 2018. During the nine months ended September 30, 2018 and 2017, the Company recognized zero and $162,700 in expenses for nonemployee performance-based option awards, respectively. The Company granted 1,352,578 and 1,475,087 stock options to employees during the nine months ended September 30, 2018 and 2017 respectively. There were 2,493,308 and 2,686,393 unvested employee options outstanding as of September 30, 2018, and 2017, respectively. Total expense recognized related to the employee stock options for the three months ended September 30, 2018 and 2017 was $1,622,836 and $1,323,198, respectively. Total expense recognized related to the employee stock options for the nine months ended September 30, 2018 and 2017 was $5,122,652 and $4,628,534 respectively. Total unrecognized compensation expense related to employee stock options was $13,161,142 as of September 30, 2018. During the nine months ended September 30, 2018 and 2017, the Company recognized zero and $830,997 in expenses for employee performance-based option awards. The Company’s stock-based compensation expense was recognized in operating expense as follows: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Research and development $ 790,770 $ 771,018 $ 2,296,259 $ 2,030,447 General and administrative 902,836 604,528 3,036,522 2,956,641 Total $ 1,693,606 $ 1,375,546 $ 5,332,781 $ 4,987,088 For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Stock options $ 1,663,566 $ 1,375,546 $ 5,256,112 $ 4,987,088 Employee Stock Purchase Plan 30,040 - 76,669 - Total $ 1,693,606 $ 1,375,546 $ 5,332,781 $ 4,987,088 The fair value of employee options granted during the three and nine months ended September 30, 2018 and 2017 was estimated by utilizing the following assumptions: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Weighted Average Weighted Average Weighted Average Weighted Average Volatility 89.04 % 79.35 % 84.56 % 80.39 % Expected term in years 5.78 6.08 6.00 6.08 Dividend rate 0.00 % 0.00 % 0.00 % 0.00 % Risk-free interest rate 2.78 % 1.86 % 2.60 % 2.06 % Fair value of option on grant date $ 4.84 $ 5.63 $ 6.06 $ 6.26 The fair value of nonemployee options granted and remeasured during the three and nine months ended September 30, 2018 and 2017 was estimated by utilizing the following assumptions: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Weighted Average Weighted Average Weighted Average Weighted Average Volatility 85.80 % 79.45 % 85.80 % 80.52 % Expected term in years 3.48 3.77 3.48 4.36 Dividend rate 0.00 % 0.00 % 0.00 % 0.00 % Risk-free interest rate 2.77 % 1.71 % 2.77 % 1.85 % Fair value of option on measurement date $ 2.92 $ 6.58 $ 2.92 $ 6.32 The following table summarizes the number of options outstanding and the weighted average exercise price: Weighted Weighted Average Average Remaining Aggregate Number of Exercise Contractual Intrinsic Shares Price Life in Years Value Options Outstanding December 31, 2017 4,298,802 $ 8.07 8.32 $ 8,174,686 Granted 1,352,578 8.41 9.47 Exercised (15,744 ) 7.07 $ 31,125 Forfeited or expired (437,721 ) 8.26 Options Outstanding September 30, 2018 5,197,915 $ 8.14 7.23 $ 380,225 Vested and exercisable at September 30, 2018 2,692,251 $ 7.88 5.89 $ 380,225 At September 30, 2018 there was approximately $13,195,191 of unamortized share–based compensation expense, which is expected to be recognized over a remaining average vesting period of 2.28 years.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 9 – INCOME TAXES The Company did not record a federal or state income tax provision for the periods presented as it has incurred net losses since inception. In addition, the net deferred tax assets generated from the net operating losses have been fully reserved as the Company believes it is not more likely than not that the benefit will be realized. During the nine months ended September 30, 2018 and 2017, the Company recorded a $ and $200,251 refundable credit towards future New York City tax expense as a reduction to operating expenses, respectively. The credit is for qualified emerging technology companies focused on biotechnology located in New York City.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE 10 – License Agreements On March 26, 2015, the Company entered into an exclusive agreement with H. Lundbeck A/S (“Lundbeck”) for a worldwide perpetual licensing right related to the research, development and commercialization of OV101. Pursuant to the Lundbeck license agreement, the Company agreed to make milestone payments totaling up to $181.0 million upon the achievement of certain development, regulatory and sales milestones. The first payment of $10.0 million is due upon the successful completion of the first Phase 3 trial for a product in which OV101 is an active ingredient. In addition, the agreement calls for the Company to pay royalties for an initial term based on a low double-digit percentage of sales and provides for the reduction of royalties in certain limited circumstances. On December 15, 2016, the Company entered into a license agreement with Northwestern University, (“Northwestern”), pursuant to which Northwestern granted the Company an exclusive, worldwide license to patent rights in certain inventions, (“Northwestern Patent Rights”), which relate to a specific compound and related methods of use for such compound, along with certain Know-How related to the practice of the inventions claimed in the Northwestern Patents. Under the Northwestern agreement, the Company was granted exclusive rights to research, develop, manufacture and commercialize products utilizing the Northwestern Patent Rights for all uses. The Company has agreed that it will not use the Northwestern Patent Rights to develop any products for the treatment of cancer, but Northwestern may not grant rights in the technology to others for use in cancer. The Company also has an option, exercisable during the term of the agreement to an exclusive license under certain intellectual property rights covering novel compounds with the same or similar mechanism of action as the primary compound that is the subject of the license agreement. Northwestern has retained the right, on behalf of itself and other non-profit institutions, to use the Northwestern Patent Rights and practice the inventions claimed therein for educational and research purposes and to publish information about the inventions covered by the Northwestern Patent Rights. Upon entry into the Northwestern agreement, the Company paid an upfront non-creditable one-time license issuance fee of $75,000, and is required to pay an annual license maintenance fee of $20,000, which will be creditable against any royalties payable to Northwestern following first commercial sale of licensed products under the agreement. The Company is responsible for all ongoing costs of filing, prosecuting and maintaining the Northwestern Patents, but also has the right to control such activities using its own patent counsel. In consideration for the rights granted to the Company under the Northwestern agreement, the Company is required to pay to Northwestern up to an aggregate of $5.3 million upon the achievement of certain development and regulatory milestones for the first product covered by the Northwestern Patents, and, upon commercialization of any such products, will be required to pay to Northwestern a tiered royalty on net sales of such products by the Company, its affiliates or sublicensees, at percentages in the low to mid single-digits, subject to standard reductions and offsets. The Company’s royalty obligations continue on a product-by-product and country-by-country basis until the later of the expiration of the last-to-expire valid claim in a licensed patent covering the applicable product in such country and 10 years following the first commercial sale of such product in such country. If the Company sublicenses a Northwestern Patent Right, it will be obligated to pay to Northwestern a specified percentage of sublicense revenue received by the Company, ranging from the high single digits to the low-teens. The Northwestern agreement requires that the Company use commercially reasonable efforts to develop and commercialize at least one product that is covered by the Northwestern Patent Rights. Unless earlier terminated, the Northwestern agreement will remain in force until the expiration of the Company’s payment obligations thereunder. The Company has the right to terminate the agreement for any reason upon prior written notice or for an uncured material breach by Northwestern. Northwestern may terminate the agreement for the Company’s uncured material breach or insolvency. As of September 30, 2018, the Company does not believe that the payment of any of the aforementioned potential milestones is probable. Contingencies In the ordinary course of business, the Company is from time to time involved in lawsuits, claims, investigations, proceedings, and threats of litigation relating to intellectual property, commercial arrangements, employment and other matters. The Company accrues for loss contingencies when available information indicates that it is probable that a liability has been incurred and the amount of such loss can be reasonably estimated. In the cases where the Company believes that a reasonably possible loss exists, the Company discloses the facts and circumstances of the litigation, including an estimable range, if possible. Legal costs incurred in connection with loss contingencies are expensed as incurred. The Company does not believe that it is probable that a liability has been incurred or that the amount of any potential liability can be reasonably estimated for any of its legal proceedings described in Part II, Item 1, Legal Proceedings, of this Quarterly Report on Form 10-Q, which includes matters pertaining to the Northwestern agreement. As a result, the Company did not record a loss contingency related to any of these legal proceedings. Particularly with respect to the litigation related to the Northwestern license agreement, the Company is presently unable to predict the outcome of such claim or to reasonably estimate the possible loss, or range of potential losses, if any, related to such claim. Severance Benefits Under the terms of their respective employment agreements, each of our named executive officers is eligible to receive severance payments and benefits upon a termination without “cause” or due to “permanent disability,” or upon “resignation for good reason,” contingent upon the named executive officer’s delivery to us of a satisfactory release of claims, and subject to the named executive officer’s compliance with non-competition and non-solicitation restrictive covenants for two years following the termination date.

Collaboration Agreement

Collaboration Agreement	9 Months Ended
	Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration Agreement	NOTE 11 – COLLABORATION AGREEMENT Takeda Collaboration On January 6, 2017, the Company entered into a license and collaboration agreement with Takeda, pursuant to which Takeda granted the Company an exclusive license to commercialize the compound TAK-935, which the Company now refers to as OV935, in certain territories, and a co-exclusive worldwide license, together with Takeda, to develop OV935. In consideration of certain license rights granted to the Company pursuant to the Takeda collaboration, the Company issued 1,781,996 shares of its Series B-1 Preferred Stock, pursuant to a Series B-1 preferred stock purchase agreement entered into on January 6, 2017, at an ascribed price per share of $14.513 on January 6, 2017 for an aggregate fair value of $25,861,228, which was recorded as research and development expense at the date of the transaction. The 1,781,996 shares of Series B-1 Preferred Stock held by Takeda was automatically converted into 1,781,996 shares of the Company’s common stock upon the completion of its IPO. Under the Takeda collaboration, the Company is obligated to pay Takeda future payments if and when certain milestones are achieved. Upon the first patient enrollment in the first Phase 3 trial for the first of the initial indications the Company and Takeda are focusing on in the Takeda collaboration, the Company is obligated to issue to Takeda the number of unregistered shares of the Company’s common stock equal to the lesser of (a) 8% of the Company outstanding capital stock on the issuance date or (b) $50.0 million divided by the applicable share price. The remaining potential global commercial and regulatory milestone payments equal approximately $35.0 million and can be satisfied in cash or unregistered shares of the Company’s common stock at its election, unless certain events occur. In the event a payment settled in shares of the Company’s common stock would cause Takeda to own over 19.99% of the Company’s outstanding capital stock or certain other events occur, such payment must be paid in cash. None of these potential milestone payments mentioned above are deemed probable at balance sheet date. During the three and nine months ended September 30, 2018, the Company recognized a credit in research and development expenses of $ 776,129 $ representing costs reimbursed to the Company from Takeda During the three and nine months ended September 30, 2017, the Company recognized $790,962 and $3,567,110 in research and development expenses representing research and development expenses reimbursed to Takeda in respect of this collaboration agreement. The Takeda collaboration will expire upon the cessation of commercialization of the products by both the Company and Takeda. Either party may terminate the Takeda collaboration because of the other party’s uncured material breach or insolvency, for safety reasons, or, after completion of the first proof of mechanism clinical trial, for convenience. Takeda may terminate the Takeda collaboration for the Company’s (or the Company’s sublicensee’s) challenge to the patents licensed under the Takeda collaboration. If the collaboration is terminated by Takeda for material breach by the Company, bankruptcy or patent challenge or by the Company for convenience or safety reasons, the Company’s rights to the products will cease, the Company will transition all activities related to the products to Takeda, and the Company will grant Takeda an exclusive, royalty-bearing license under certain patents and other intellectual property controlled by the Company to commercialize OV935 and products containing OV935 for the treatment of certain rare neurological disorders. If the collaboration is terminated by the Company for Takeda’s material breach or bankruptcy or by Takeda for convenience or safety reasons, Takeda’s rights to the products will cease, Takeda will transition all activities related to the products to the Company, and Takeda will grant the Company an exclusive, royalty-bearing license under certain patents and other intellectual property controlled by Takeda to commercialize OV935 and products containing OV935 for the treatment of certain rare neurological disorders.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Net Loss Per Share	NOTE 12 – NET LOSS PER SHARE Basic and diluted net loss per common share is determined by dividing net loss attributable to common stockholders by the weighted-average common shares outstanding during the period. For all periods presented, the common shares underlying the options have been excluded from the calculation because their effect would be anti-dilutive. Therefore, the weighted-average shares outstanding used to calculate both basic and diluted loss per common share are the same. The following potentially dilutive securities have been excluded from the computations of diluted weighted-average shares outstanding as they would be anti-dilutive: For the Nine Months Ended September 30, 2018 2017 Stock options to purchase common stock 5,197,915 4,290,220

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Unaudited Interim Condensed Financial Statements	(A) Unaudited Interim Condensed Financial Statements The interim condensed balance sheet at September 30, 2018, the condensed statements of operations and comprehensive loss for the three and nine months ended September 30, 2018 and 2017, and condensed statements of cash flows for the nine months ended September 30, 2018 and 2017 are unaudited. The accompanying unaudited condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and following the requirements of the SEC for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP are condensed or omitted. These condensed financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments that are necessary for a fair statement of its financial information. The results of operations for the three and nine months ended September 30, 2018 and 2017 are not necessarily indicative of the results to be expected for the year ending December 31, 2018 or for any other future annual or interim period. The balance sheet as of December 31, 2017 included herein was derived from the audited financial statements as of that date. These interim condensed financial statements should be read in conjunction with the Company’s audited financial statements as of and for the year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K.
Use of Estimates	(B) Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Actual results could differ materially from those estimates.
Fair Value of Financial Instruments	(C) Fair Value of Financial Instruments Financial Accounting Standards Board (“FASB”) guidance specifies a hierarchy of valuation techniques based on whether the inputs to those valuation techniques are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect market assumptions. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurement) and the lowest priority to unobservable inputs (Level 3 measurement). The three levels of the fair value hierarchy are as follows: • Level 1—Unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. Level 1 primarily consists of financial instruments whose value is based on quoted market prices such as exchange-traded instruments and listed equities. • Level 2—Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly (e.g., quoted prices of similar assets or liabilities in active markets, or quoted prices for identical or similar assets or liabilities in markets that are not active). Level 2 includes financial instruments that are valued using models or other valuation methodologies. • Level 3—Unobservable inputs for the asset or liability. Financial instruments are considered Level 3 when their fair values are determined using pricing models, discounted cash flows or similar techniques and at least one significant model assumption or input is unobservable. The carrying amounts reported in the balance sheets for cash and cash equivalents approximate their fair value based on the short-term maturity of these instruments.
Short-term Investments	(D) Short-term Investments Short-term investments consist of debt securities with maturities greater than three months from the date of purchase. The Company classifies all of its investments as available-for-sale securities. Accordingly, these investments are recorded at fair value with unrealized gains and losses included in other comprehensive income (loss) as a component of stockholders’ equity until realized. Realized gains and losses, amortization and accretion of premiums and discounts are included within net loss.
Recent Accounting Pronouncements	( E) Recent Accounting Pronouncements Recent accounting standards which have been adopted In May 2017, the FASB issued Accounting Standards Update (“ASU”) No. 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting. This new standard clarifies when to account for a change to the terms or conditions of share-based payment award as a modification. Under the new guidance, modification accounting is required unless the fair value, the vesting conditions, and the classification of the modified award remain the same as the original award. The adoption of this standard on January 1, 2018, did not have a material impact on the Company’s financial statements. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. This new standard clarifies the definition of a business and provides a screen to determine when an integrated set of assets and activities is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. ASU 2017-01 is effective for the Company as of January 1, 2018. The adoption of this standard on January 1, 2018, did not have an impact on the Company’s financial statements. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The new standard clarifies certain aspects of the statement of cash flows, including the classification of debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, distributions received from equity method investees and beneficial interests in securitization transactions. In situations in which cash receipts and payments have aspects of more than one class of cash flows and cannot be separated by source or use, the appropriate classification should depend on the activity that is likely to be the predominant source or use of cash flows for the item. The adoption of this standard on January 1, 2018 did not have a material impact on the Company’s statements of cash flows. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. This new standard amends certain aspects of accounting and disclosure requirements for financial instruments, including the requirement that equity investments (other than equity method investees) with readily determinable fair values are to be measured at fair value with any changes in fair value recognized in a company's results of operations. Equity investments that do not have readily determinable fair values may be measured at fair value or at cost minus impairment adjusted for changes in observable prices. The standard also includes certain amendments for the accounting for a financial liability that is measured at fair value in accordance with the fair value option and prescribes that a valuation allowance should be evaluated on deferred tax assets related to available-for-sale debt securities in combination with other deferred tax assets. The ASU makes targeted changes to the presentation requirements for financial instruments under current GAAP. All entities are required to disclose financial assets and financial liabilities separately, grouped by measurement category and form of financial asset. ASU No. 2016-01 is effective for the Company as of January 1, 2018. As the Company does not have equity investments, financial liabilities measured at fair value in accordance with the fair value option or deferred tax assets, the recognition and measurement guidance of this new standard is not applicable to the Company. However, since the Company does have financial asset investments, it has adopted the presentation and disclosure requirements of this standard. New accounting standards which have not yet been adopted On August 29, 2018, the FASB issued ASU No. 2018-15, Intangibles – Goodwill and Other - Internal-Use Software (Subtopic 350-40) - which amends ASC 350-40 to address a customer’s accounting for implementation costs incurred in a cloud computing arrangement (“CCA”) that is a service contract. ASU No. 2018-15 aligns the accounting for costs incurred to implement a CCA that is a service arrangement with the guidance on capitalizing costs associated with developing or obtaining internal-use software. Specifically, the ASU amends ASC 350 to include in its scope implementation costs of a CCA that is a service contract and clarifies that a customer should apply ASC 350-40 to determine which implementation costs should be capitalized in a CCA that is considered a service contract. According to the standard the balance sheet line item for the presentation of capitalized implementation costs should be the same as that for the prepayment of fees related to the hosting arrangement and the manner in which an entity classifies the cash flows related to capitalized implementation costs should be the same as that in which it classifies the cash flows for the fees related to the hosting arrangement. ASU 2018-15 is effective for the Company for fiscal years beginning after December 15, 2019, including interim periods therein. Entities are permitted to apply either a retrospective or prospective transition approach to adopt the guidance. When prospective transition is chosen, entities must apply the transition requirements to any eligible costs incurred after adoption. The Company is in the process of assessing the impact of this standard on its financial statements. On August 28, 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement. This standard changes the fair value measurement disclosure requirements of ASC 820. The new standard eliminated certain disclosures, added new disclosures with regard to unrealized gains or losses included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements, as well as modified certain disclosure. ASU 2018-13 is effective for all entities for fiscal years beginning after December 15, 2019, including interim periods therein. Early adoption is permitted. The ASU requires application of the prospective method of transition for the aforementioned new disclosure requirements and for modified disclosure with regard to measurement uncertainty while all other amendments made by the ASU must be applied retrospectively to all periods presented. The Company is in the process of assessing the impact of this standard on its financial statements. On June 20, 2018, the FASB issued ASU 2018-07, Compensation – Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. This new standard simplifies the accounting for share-based payments granted to nonemployees for goods and services. The standard supersedes ASC 505-50 and expands the scope of ASC 718 to include all share-based payment arrangements related to the acquisition of goods and services from both nonemployees and employees. As such, among others, the measurement date for nonemployee awards would generally be the grant date same as the measurement date for employee equity awards and for performance-based awards, an entity is required to recognize any cost on the basis of the probable outcome of the performance conditions using the grant-date fair value of the award. ASU 2018-07 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Due to the immaterial volume of nonemployee equity-based awards as well as the immaterial fair value of such awards the Company does not expect ASU 2018-07 to have a material impact on its financial statements. On March 30, 2017, the FASB issued ASU 2017-08, Receivables – Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization and Purchased Callable Debt Securities. This new standard requires premiums on callable debt securities, that have explicit, non-contingent call features that are callable at fixed prices on preset dates, to be amortized to the earliest call date. The amortization period for callable debt securities purchased at a discount will not be impacted. Under current GAAP, premiums on callable debt securities are generally amortized over the contractual life of the security. The guidance is applicable to the Company beginning on January 1, 2019. The Company will be impacted if it will have on January 1, 2019 callable debt purchased with a premium. However, based on the Company’s current investment strategy where it purchases debt securities with maturity dates of less than a year, it does not expect to have significant premiums for callable debt. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. This new standard requires the measurement and recognition of expected credit losses for financial assets held at amortized cost, including loans and trade and other receivables. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss methodology, which will result in more timely recognition of credit losses. The standard also amends the impairment model for available-for-sale debt securities and requires entities to determine whether all or a portion of the unrealized loss on an available-for-sale debt security is a credit loss. Under the new guidance, an entity will recognize an allowance for credit losses on available-for-sale debt securities as a contra-account to the amortized cost basis rather than as a direct reduction of the amortized cost basis of the investment, as is currently required. ASU 2016-13 is effective for annual reporting periods, and interim periods within those years, beginning after December 15, 2019. The Company does not expect this standard to have a material impact on its financial statements due to the immaterial level of its unrealized losses on available-for-sale securities and its immaterial level of loans and receivables. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). This new standard was issued to increase transparency and comparability among entities by recognizing for all leases lease assets and lease liabilities on the balance sheet and disclosing key information about lease arrangements. This new standard is effective for public companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company does not expect ASU 2016-02 to have a material impact on its financial statements.

Cash Equivalents and Short-Te_2

Cash Equivalents and Short-Term Investments (Tables)	9 Months Ended
	Sep. 30, 2018
Investments Debt And Equity Securities [Abstract]
Summary of Fair Value of Cash Equivalents, Short-Term Investments and Gross Unrealized Holding Gains and Losses	The following tables summarize the fair value of cash, cash equivalents, and short-term investments, as well as gross unrealized holding gains and losses as of September 30, 2018 and December 31, 2017: September 30, 2018 Amortized Gross unrealized Gross unrealized Fair cost holding gains holding losses value Cash $ 265,582 $ - $ - $ 265,582 Money market funds (a) 30,247,598 - - 30,247,598 Total cash and cash equivalents $ 30,513,180 $ - $ - $ 30,513,180 U.S. treasury notes (a) $ 21,999,049 $ - $ (4,675 ) $ 21,994,374 Total short-term investments $ 21,999,049 $ - $ (4,675 ) $ 21,994,374 (a) As of September 30, 2018, the Company's Level 1 assets consisted of money market funds and U.S. treasury notes totaling $52.2 million. The Company had no level 2 or level 3 assets or liabilities as of September 30, 2018. December 31, 2017 Amortized Gross unrealized Gross unrealized Fair cost holding gains holding losses value Cash $ 526,648 $ - $ - $ 526,648 Money market funds (a) 86,598,952 - - 86,598,952 Total cash and cash equivalents $ 87,125,600 $ - $ - $ 87,125,600 U.S. treasury notes $ - $ - $ - $ - Corporate bonds - - - - Total short-term investments $ - $ - $ - $ - (a) As of December 31, 2017, the Company's Level 1 assets consisted of money market funds totaling $86.6 million. The Company had no level 2 or level 3 assets or liabilities as of December 31, 2017.

Property and Equipment and In_2

Property and Equipment and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Property Plant And Equipment [Abstract]
Summary of Property and Equipment	Property and equipment is summarized as follows: September 30, December 31, 2018 2017 Furniture and equipment $ 144,620 $ 102,690 Less accumulated depreciation (76,466 ) (50,915 ) Total property and equipment, net $ 68,154 $ 51,775

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2018
Payables And Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following: September 30, December 31, 2018 2017 Clinical trials accrual $ 2,665,166 $ 753,018 Collaboration agreement accrual - 754,841 Payroll and bonus accrual 2,254,757 1,919,120 Professional fees accrual 740,134 321,852 Other 169,347 246,503 Total $ 5,829,404 $ 3,995,334

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Summary of Recognized Stock-Based Compensation Expense	The Company’s stock-based compensation expense was recognized in operating expense as follows: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Research and development $ 790,770 $ 771,018 $ 2,296,259 $ 2,030,447 General and administrative 902,836 604,528 3,036,522 2,956,641 Total $ 1,693,606 $ 1,375,546 $ 5,332,781 $ 4,987,088
Schedule of Allocation of Stock-based Compensation Expense by Plan	For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Stock options $ 1,663,566 $ 1,375,546 $ 5,256,112 $ 4,987,088 Employee Stock Purchase Plan 30,040 - 76,669 - Total $ 1,693,606 $ 1,375,546 $ 5,332,781 $ 4,987,088
Summary of Options Outstanding and Weighted Average Exercise Price	The following table summarizes the number of options outstanding and the weighted average exercise price: Weighted Weighted Average Average Remaining Aggregate Number of Exercise Contractual Intrinsic Shares Price Life in Years Value Options Outstanding December 31, 2017 4,298,802 $ 8.07 8.32 $ 8,174,686 Granted 1,352,578 8.41 9.47 Exercised (15,744 ) 7.07 $ 31,125 Forfeited or expired (437,721 ) 8.26 Options Outstanding September 30, 2018 5,197,915 $ 8.14 7.23 $ 380,225 Vested and exercisable at September 30, 2018 2,692,251 $ 7.88 5.89 $ 380,225
Employee Stock Option [Member]
Summary of Assumptions Used to Compute Fair Value of Employee Option Granted	The fair value of employee options granted during the three and nine months ended September 30, 2018 and 2017 was estimated by utilizing the following assumptions: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Weighted Average Weighted Average Weighted Average Weighted Average Volatility 89.04 % 79.35 % 84.56 % 80.39 % Expected term in years 5.78 6.08 6.00 6.08 Dividend rate 0.00 % 0.00 % 0.00 % 0.00 % Risk-free interest rate 2.78 % 1.86 % 2.60 % 2.06 % Fair value of option on grant date $ 4.84 $ 5.63 $ 6.06 $ 6.26
Nonemployee Stock Options [Member]
Summary of Assumptions Used to Compute Fair Value of Employee Option Granted	The fair value of nonemployee options granted and remeasured during the three and nine months ended September 30, 2018 and 2017 was estimated by utilizing the following assumptions: For the Three Months Ended September 30, For the Nine Months Ended September 30, 2018 2017 2018 2017 Weighted Average Weighted Average Weighted Average Weighted Average Volatility 85.80 % 79.45 % 85.80 % 80.52 % Expected term in years 3.48 3.77 3.48 4.36 Dividend rate 0.00 % 0.00 % 0.00 % 0.00 % Risk-free interest rate 2.77 % 1.71 % 2.77 % 1.85 % Fair value of option on measurement date $ 2.92 $ 6.58 $ 2.92 $ 6.32

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule Potentially Dilutive Securities Excluded from Computations of Diluted Weighted Average Shares Outstanding	The following potentially dilutive securities have been excluded from the computations of diluted weighted-average shares outstanding as they would be anti-dilutive: For the Nine Months Ended September 30, 2018 2017 Stock options to purchase common stock 5,197,915 4,290,220

Nature of Operations - Addition

Nature of Operations - Additional Information (Detail) - USD ($)	May 10, 2017	Jun. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Organization Consolidation and Presentation of Financial Statements [Line Items]
Net proceeds from issuance of stock			$ 66,676,192
Operating losses				$ 139,795,346	$ 100,715,668
Maximum [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Aggregate common stock		$ 200,000,000
IPO [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Number of shares issued	5,000,000
Stock issued, price per share	$ 15
Gross proceeds from issuance of stock	$ 75,000,000
Net proceeds from issuance of stock	$ 66,700,000
ATM Agreement [Member] | Cowen and Company, LLC [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Percentage of commission for gross proceeds from sale of common stock.		3.00%
ATM Agreement [Member] | Cowen and Company, LLC [Member] | Maximum [Member]
Organization Consolidation and Presentation of Financial Statements [Line Items]
Common stock aggregate offering price		$ 50,000,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2018
Minimum [Member]
Summary of Significant Accounting Policy [Line Items]
Short term investments, maturity period	3 months

Preclinical and Clinical Agre_2

Preclinical and Clinical Agreements - Additional Information (Detail) - USD ($)	Aug. 26, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Expenses related to clinical research agreements		$ 8,544,547	$ 5,899,482	$ 25,168,446	$ 43,258,833
Clinical Research Contract [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront retainer	$ 355,435
Expenses related to clinical research agreements				2,305,127	$ 3,169,550
Contract value with customer relected within long term prepaid expense		$ 4,500,000		$ 4,500,000
Clinical Research Contract [Member] | Minimum [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contract period of upfront payments for services to be provided				12 months

Cash Equivalents and Short-Te_3

Cash Equivalents and Short-Term Investments - Summary of Fair Value of Cash Equivalents, Short-Term Investments and Gross Unrealized Holding Gains and Losses (Detail) - USD ($)		Sep. 30, 2018		Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Total cash and cash equivalents, Amortized cost		$ 30,513,180		$ 87,125,600
Total cash and cash equivalents, Fair value		30,513,180		87,125,600
Total short-term investments, Amortized cost		21,999,049
Total short-term investments, Gross unrealized holding losses		(4,675)
Total short-term investments, Fair value		21,994,374
U.S. Treasury Notes [Member]
Schedule Of Available For Sale Securities [Line Items]
Total short-term investments, Amortized cost	[1]	21,999,049
Total short-term investments, Gross unrealized holding losses	[1]	(4,675)
Total short-term investments, Fair value	[1]	21,994,374
Cash [Member]
Schedule Of Available For Sale Securities [Line Items]
Total cash and cash equivalents, Amortized cost		265,582		526,648
Total cash and cash equivalents, Fair value		265,582		526,648
Money Market Funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Total cash and cash equivalents, Amortized cost		30,247,598	[1]	86,598,952	[2]
Total cash and cash equivalents, Fair value		$ 30,247,598	[1]	$ 86,598,952	[2]
[1]	As of September 30, 2018, the Company's Level 1 assets consisted of money market funds and U.S. treasury notes totaling $52.2 million. The Company had no level 2 or level 3 assets or liabilities as of September 30, 2018.
[2]	As of December 31, 2017, the Company's Level 1 assets consisted of money market funds totaling $86.6 million. The Company had no level 2 or level 3 assets or liabilities as of December 31, 2017.

Cash Equivalents and Short-Te_4

Cash Equivalents and Short-Term Investments - Summary of Fair Value of Cash Equivalents, Short-Term Investments and Gross Unrealized Holding Gains and Losses (Parenthetical) (Detail) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Fair Value Level 1 [Member] | Money Market Funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair value assets		$ 86,600,000
Fair Value Level 1 [Member] | Money Market Funds US Treasury Notes [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair value assets	$ 52,200,000
Fair Value Level 2 [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair value assets	0	0
Fair value liabilities	0	0
Fair Value Level 3 [Member]
Schedule Of Available For Sale Securities [Line Items]
Fair value assets	0	0
Fair value liabilities	$ 0	$ 0

Cash Equivalents and Short-Te_5

Cash Equivalents and Short-Term Investments - Additional Information (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2018USD ($)Investment	Sep. 30, 2018USD ($)Investment	Dec. 31, 2017USD ($)
Investments Debt And Equity Securities [Abstract]
Aggregate fair value of securities that were in an unrealized loss position for less than 12 months	$ 22,000,000	$ 22,000,000	$ 0
Number of securities in an unrealized loss position for more than 12 months | Investment	0	0
Gains or losses on available-for-sale securities	$ 0	$ 0

Property and Equipment and In_3

Property and Equipment and Intangible Assets - Summary of Property and Equipment (Detail) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Less accumulated depreciation	$ (76,466)	$ (50,915)
Total property and equipment, net	68,154	51,775
Furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Furniture and equipment	$ 144,620	$ 102,690

Property and Equipment and In_4

Property and Equipment and Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Depreciation expense	$ 6,746	$ 7,171	$ 25,551	$ 19,155
Intangible assets, net of accumulated amortization	406,078		406,078		$ 124,194
Amortization expense	$ 24,615	$ 13,864	$ 60,890	$ 39,436

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Clinical trials accrual	$ 2,665,166	$ 753,018
Collaboration agreement accrual		754,841
Payroll and bonus accrual	2,254,757	1,919,120
Professional fees accrual	740,134	321,852
Other	169,347	246,503
Total	$ 5,829,404	$ 3,995,334

Stockholders' Equity and Pref_2

Stockholders' Equity and Preferred Stock - Additional Information (Detail) - $ / shares	May 10, 2017	Sep. 30, 2018	Dec. 31, 2017	Jan. 06, 2017	Apr. 01, 2014
Class of Stock [Line Items]
Common stock, shares authorized		125,000,000	125,000,000		1,000
Common stock, par value per share		$ 0.001	$ 0.001		$ 0.001
Preferred stock, shares authorized		10,000,000	0
IPO [Member]
Class of Stock [Line Items]
Common stock, shares authorized	125,000,000
Preferred stock, shares authorized	10,000,000
Number of shares issued	5,000,000
IPO [Member] | Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding	2,382,069
IPO [Member] | Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding	5,599,282
IPO [Member] | Series B-1 Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding	1,781,996
Amendment [Member]
Class of Stock [Line Items]
Common stock, shares authorized				62,000,000
Common stock, par value per share				$ 0.001
Preferred stock, shares authorized				20,991,252
Common Stock [Member] | IPO [Member]
Class of Stock [Line Items]
Conversion of convertible preferred stock into common stock	9,763,346

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	Jan. 01, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock-Based Compensation [Line Items]
Share based compensation expense		$ 1,693,606	$ 1,375,546	$ 5,332,781	$ 4,987,088
Stock options, granted				1,352,578
Unrecognized compensation expenses		$ 13,195,191		$ 13,195,191
Unrecognized compensation not yet recognized, period for recognition				2 years 3 months 10 days
Performance-based Option Awards [Member]
Stock-Based Compensation [Line Items]
Share based compensation expense				$ 0	830,997
Unvested stock options, outstanding		0		0
Nonemployee Stock Options [Member]
Stock-Based Compensation [Line Items]
Share based compensation expense		$ 40,730	$ 52,348	$ 133,460	$ 358,554
Unvested stock options, outstanding		12,356	44,333	12,356	44,333
Stock options, granted				0	27,906
Unrecognized compensation expenses		$ 34,049		$ 34,049
Non-employee Performance Based Option Awards [Member]
Stock-Based Compensation [Line Items]
Share based compensation expense				0	$ 162,700
Employee Stock Option [Member]
Stock-Based Compensation [Line Items]
Share based compensation expense		$ 1,622,836	$ 1,323,198	$ 5,122,652	$ 4,628,534
Unvested stock options, outstanding		2,493,308	2,686,393	2,493,308	2,686,393
Stock options, granted				1,352,578	1,475,087
Unrecognized compensation expenses		$ 13,161,142		$ 13,161,142
2017 Equity Incentive Plan [Member]
Stock-Based Compensation [Line Items]
Common stock, reserved for future issuance		3,052,059		3,052,059
Increase of equity incentive plan/ employee stock purchase plan limit description				Pursuant to the terms of the 2017 Plan, on each January 1st, the plan limit shall be increased by the lesser of (x) 5% of the number of shares of common stock outstanding as of the immediately preceding December 31 and (y) such lesser number as the Board of Directors may determine in its discretion.
Percentage of number of shares of common stock outstanding				5.00%
Number of additional shares reserved for issuance under the plan	1,230,312
Number of company's common stock reserved for issuance under the plan		3,174,440		3,174,440
Share based compensation, term of plan				10 years
Share based compensation, graded vesting period				4 years
Share based compensation, exercisable				90 days
2014 Equity Incentive Plan [Member]
Stock-Based Compensation [Line Items]
Shares of common stock authorized for issuance under the Plan		0		0
Share based compensation, term of plan				10 years
Share based compensation, graded vesting period				4 years
Share based compensation, exercisable				90 days
2017 ESPP [Member]
Stock-Based Compensation [Line Items]
Common stock, reserved for future issuance		279,069		279,069
Increase of equity incentive plan/ employee stock purchase plan limit description				The number of shares of common stock reserved for issuance under the 2017 ESPP will automatically increase on January 1 of each year, beginning on January 1, 2018 and continuing through and including January 1, 2027, by the lesser of (i) 1% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, (ii) 550,000 shares or (iii) such lesser number of shares determined by our Board.
Percentage of number of shares of common stock outstanding				1.00%
Number of additional shares reserved for issuance under the plan	246,062
Number of company's common stock reserved for issuance under the plan		493,017		493,017
Offering period description				On September 20, 2017, the Company’s Compensation Committee approved an offering period under the 2017 ESPP, which began on October 20, 2017.
Share based compensation, percentage of discount from market price on purchase date				15.00%
Share based compensation, number of shares purchased		22,142		32,114
Share based compensation expense		$ 30,040		$ 76,669
Increase in number of shares each year under the plan				550,000

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Recognized Stock-Based Compensation Expense (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock-Based Compensation [Line Items]
Stock-based compensation expense, Total	$ 1,693,606	$ 1,375,546	$ 5,332,781	$ 4,987,088
Research and Development [Member]
Stock-Based Compensation [Line Items]
Stock-based compensation expense, Total	790,770	771,018	2,296,259	2,030,447
General and Administrative Expenses [Member]
Stock-Based Compensation [Line Items]
Stock-based compensation expense, Total	$ 902,836	$ 604,528	$ 3,036,522	$ 2,956,641

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Allocation of Stock-Based Compensation Expense by Plan (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Stock-Based Compensation [Line Items]
Share based compensation expense	$ 1,693,606	$ 1,375,546	$ 5,332,781	$ 4,987,088
Stock Options [Member]
Stock-Based Compensation [Line Items]
Share based compensation expense	1,663,566	$ 1,375,546	5,256,112	$ 4,987,088
Employee Stock Purchase Plan [Member]
Stock-Based Compensation [Line Items]
Share based compensation expense	$ 30,040		$ 76,669

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Assumptions Used to Compute Fair Value of Employee Option Granted (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Employee Stock Option [Member]
Stock-Based Compensation [Line Items]
Weighted Average, Volatility	89.04%	79.35%	84.56%	80.39%
Weighted Average, Expected term in years	5 years 9 months 10 days	6 years 29 days	6 years	6 years 29 days
Weighted Average, Dividend rate	0.00%	0.00%	0.00%	0.00%
Weighted Average, Risk-free interest rate	2.78%	1.86%	2.60%	2.06%
Weighted Average, Fair value of option on grant date	$ 4.84	$ 5.63	$ 6.06	$ 6.26
Nonemployee Stock Options [Member]
Stock-Based Compensation [Line Items]
Weighted Average, Volatility	85.80%	79.45%	85.80%	80.52%
Weighted Average, Expected term in years	3 years 5 months 23 days	3 years 9 months 7 days	3 years 5 months 23 days	4 years 4 months 9 days
Weighted Average, Dividend rate	0.00%	0.00%	0.00%	0.00%
Weighted Average, Risk-free interest rate	2.77%	1.71%	2.77%	1.85%
Weighted Average, Fair value of option on grant date	$ 2.92	$ 6.58	$ 2.92	$ 6.32

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Options Outstanding and Weighted Average Exercise Price (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Options Outstanding, Beginning balance	4,298,802
Number of Shares, Granted	1,352,578
Number of Shares, Exercised	(15,744)
Number of Shares, Forfeited or expired	(437,721)
Number of Shares, Options Outstanding, Ending balance	5,197,915	4,298,802
Number of Shares, Vested and exercisable	2,692,251
Weighted Average Exercise Price, Options Outstanding	$ 8.07
Weighted Average Exercise Price, Granted	8.41
Weighted Average Exercise Price, Exercised	7.07
Weighted Average Exercise Price, Forfeited or expired	8.26
Weighted Average Exercise Price, Options Outstanding	8.14	$ 8.07
Weighted Average Exercise Price, Vested and exercisable	$ 7.88
Weighted Average Remaining Contractual Life, Options Outstanding	7 years 2 months 23 days	8 years 3 months 25 days
Weighted Average Remaining Contractual Life, Granted	9 years 5 months 19 days
Weighted Average Remaining Contractual Life, Vested and exercisable	5 years 10 months 20 days
Aggregate Intrinsic Value, Options Outstanding	$ 380,225	$ 8,174,686
Aggregate Intrinsic Value, Exercised	31,125
Aggregate Intrinsic Value, Vested and exercisable	$ 380,225

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Income Taxes Disclosure [Line Items]
Federal or state income tax provision	$ 0
New York State Division of Taxation and Finance Member [Member]
Income Taxes Disclosure [Line Items]
Refundable tax credit towards future tax expense	$ 186,218	$ 200,251

Commitment and Contingencies -

Commitment and Contingencies - Additional Information (Detail) - License Agreement [Member]	Dec. 15, 2016USD ($)Product	Mar. 26, 2015USD ($)Trial	Sep. 30, 2018
Lundbeck [Member]
Loss Contingencies [Line Items]
License agreement entered date		Mar. 26, 2015
First payment due upon completion of first phase		$ 10,000,000
Number of trial | Trial		3
Lundbeck [Member] | Maximum [Member]
Loss Contingencies [Line Items]
License agreement milestone payments		$ 181,000,000
Northwestern University [Member]
Loss Contingencies [Line Items]
License agreement entered date	Dec. 15, 2016
Upfront non-creditable one-time license issuance fee payment	$ 75,000
Annual license maintenance fee payable	$ 20,000
License agreement, description of rights and obligation			In consideration for the rights granted to the Company under the Northwestern agreement, the Company is required to pay to Northwestern up to an aggregate of $5.3 million upon the achievement of certain development and regulatory milestones for the first product covered by the Northwestern Patents, and, upon commercialization of any such products, will be required to pay to Northwestern a tiered royalty on net sales of such products by the Company, its affiliates or sublicensees, at percentages in the low to mid single-digits, subject to standard reductions and offsets. The Company’s royalty obligations continue on a product-by-product and country-by-country basis until the later of the expiration of the last-to-expire valid claim in a licensed patent covering the applicable product in such country and 10 years following the first commercial sale of such product in such country. If the Company sublicenses a Northwestern Patent Right, it will be obligated to pay to Northwestern a specified percentage of sublicense revenue received by the Company, ranging from the high single digits to the low-teens.
Minimum number of product covered under license agreement | Product	1
Northwestern University [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Consideration payable for rights grant	$ 5,300,000

Collaboration Agreement - Addit

Collaboration Agreement - Additional Information (Detail) - USD ($)	May 10, 2017	Jan. 06, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Preferred stock, price per share			$ 0.001		$ 0.001		$ 0.001
Research and development			$ 8,544,547	$ 5,899,482	$ 25,168,446	$ 43,258,833
IPO [Member] | Common Stock [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Conversion of convertible preferred stock into common stock	9,763,346
Takeda Pharmaceutical Company Limited [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of outstanding capital stock on the issuance date		8.00%
Value fixed on collaboration for share obligation terms		$ 50,000,000
Global commercial and regulatory milestone payments		$ 35,000,000
Threshold percentage of outstanding capital stock to make cash payment		19.99%
Takeda Pharmaceutical Company Limited [Member] | Collaborative Arrangement, Co-promotion [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development				$ 790,962		$ 3,567,110
Research and development expense reimbursement received			$ 776,129		$ 680,721
Takeda Pharmaceutical Company Limited [Member] | Series B-1 Preferred Stock [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Preferred stock, shares issued		1,781,996
Preferred stock, price per share		$ 14.513
Fair value of Series B-1 Preferred Stock		$ 25,861,228
Takeda Pharmaceutical Company Limited [Member] | IPO [Member] | Common Stock [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Conversion of convertible preferred stock into common stock					1,781,996

Net Loss Per Share - Schedule P

Net Loss Per Share - Schedule Potentially Dilutive Securities Excluded from Computations of Diluted Weighted Average Shares Outstanding (Detail) - shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Stock options to purchase common stock [Member]
Dilutive Securities Included and Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive Securities Excluded from computations of Diluted Weighted Average shares outstanding	5,197,915	4,290,220