Arvinas (ARVN) 10-K 26 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Mar. 21, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	ARVN
Entity Registrant Name	ARVINAS, INC.
Entity Central Index Key	0001655759
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity voluntary Filers	No
Entity Public Float			$ 0
Entity Common Stock, Shares Outstanding		32,328,796

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 3,190,056	$ 30,912,391
Marketable securities	184,637,640	8,258,982
Account receivable	2,775,831	25,000,000
Other receivables	2,255,966	1,040,452
Prepaid expenses and other current assets	2,818,286	316,903
Total current assets	195,677,779	65,528,728
Property, equipment and leasehold improvements, net	3,583,036	1,298,881
Other assets:
Deposits	20,760	20,760
Total assets	199,281,575	66,848,369
Current liabilities:
Accounts payable	2,758,184	596,527
Accrued expenses	4,001,276	3,545,936
Deferred revenue	16,065,957	13,553,136
Current portion of long-term debt	154,461	159,265
Total current liabilities	22,979,878	17,854,864
Deferred revenue	37,484,714	48,545,625
Long term debt, net of current portion	2,000,000	151,122
Other non-current liability	150,000
Preferred unit warrant liability		50,888
Total liabilities	62,614,592	66,602,499
Commitments and contingencies (Note 12)
Stockholders'/Members' equity:
Common stock, $0.001 par value, 31,235,458 shares issued and outstanding as of December 31, 2018	31,236
Accumulated deficit	(302,264,619)	(62,417,397)
Additional paid-in capital	439,118,089
Accumulated other comprehensive loss	(217,723)	(9,751)
Total stockholders'/members’ equity	136,666,983	(61,234,562)
Total liabilities and stockholders'/members’ equity	199,281,575	66,848,369
Series A Redeemable Convertible Preferred Units
Current liabilities:
Redeemable convertible preferred units/stock		19,768,025
Series B Redeemable Convertible Preferred Units
Current liabilities:
Redeemable convertible preferred units/stock		41,712,407
Common Units
Stockholders'/Members' equity:
Common and Incentive units		6,167
Incentive Units
Stockholders'/Members' equity:
Common and Incentive units		$ 1,186,419

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common units, par value		$ 0
Common units, issued		1,897,544
Common units, outstanding		1,897,544
Incentive units, par value			$ 0
Incentive units, issued			3,669,963
Common Stock Par Or Stated Value Per Share	$ 0.001
Common Stock Shares Issued	31,235,458
Common Stock Shares Outstanding	31,235,458
Series A Redeemable Convertible Preferred Units
Redeemable convertible preferred units/stock, par value		$ 0
Redeemable convertible preferred units/stock, issued		22,463,665
Redeemable convertible preferred units/stock, outstanding		22,463,665	22,463,665
Series B Redeemable Convertible Preferred Units
Redeemable convertible preferred units/stock, par value		$ 0
Redeemable convertible preferred units/stock, issued		24,977,489
Redeemable convertible preferred units/stock, outstanding		24,977,489	24,977,489

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenue	$ 3,440,165	$ 3,375,264	$ 3,399,895	$ 4,108,596	$ 2,572,293	$ 1,668,861	$ 1,668,861	$ 1,668,861	$ 14,323,920	$ 7,578,876
Operating expenses:
Research and development	14,562,299	13,149,879	10,337,835	7,143,817	6,690,189	7,222,897	7,823,617	7,056,199	45,193,830	28,792,902
General and administrative	5,821,445	4,284,231	1,579,605	1,246,887	1,189,122	857,310	569,983	929,826	12,932,168	3,546,241
Total operating expenses	20,383,744	17,434,110	11,917,440	8,390,704	7,879,311	8,080,207	8,393,600	7,986,025	58,125,998	32,339,143
Loss from operations	(16,943,579)	(14,058,846)	(8,517,545)	(4,282,108)	(5,307,018)	(6,411,346)	(6,724,739)	(6,317,164)	(43,802,078)	(24,760,267)
Other income (expenses)
Other income, net	(315,764)	160,100	130,945	127,449	553,129	607	159	264	102,730	554,159
Change in fair value of preferred unit warrant			2,516	(196,295)	1,533	1,546	1,457	1,335	(193,779)	5,871
Interest income	1,196,113	523,338	539,413	211,237	35,781	24,140	57,904	83,562	2,470,101	201,388
Interest expense	(24,636)	(12,264)	(9,871)	(10,669)	(11,451)	(12,219)	(12,973)	(13,713)	(57,440)	(50,357)
Total other income	855,713	671,174	663,003	131,722	578,992	14,074	46,547	71,448	2,321,612	711,061
Net loss	(16,087,866)	(13,387,672)	(7,854,542)	(4,150,386)	(4,728,026)	(6,397,272)	(6,678,192)	(6,245,716)	(41,480,466)	(24,049,206)
Change in redemption value of redeemable preferred units		(112,050,609)	(14,834,049)	(71,482,098)	(4,570,431)				(198,366,756)	(4,570,431)
Net loss attributable to common shares/units	$ (16,087,866)	$ (125,438,281)	$ (22,688,591)	$ (75,632,484)	$ (9,298,457)	$ (6,397,272)	$ (6,678,192)	$ (6,245,716)	$ (239,847,222)	$ (28,619,637)
Net loss per common share/unit, basic and diluted	$ (0.52)	$ (62.38)	$ (11.96)	$ (39.86)	$ (4.90)	$ (3.37)	$ (3.52)	$ (3.29)	$ (25.45)	$ (15.08)
Weighted average common shares/units outstanding, basic and diluted	31,098,634	2,010,807	1,897,544	1,897,544	1,897,544	1,897,544	1,897,544	1,897,544	9,422,799	1,897,544

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (41,480,466)	$ (24,049,206)
Other comprehensive gain (loss):
Unrealized gain (loss) on available-for-sale securities	(207,972)	18,928
Comprehensive loss	$ (41,688,438)	$ (24,030,278)

Consolidated Statements of Rede

Consolidated Statements of Redeemable Convertible Preferred Shares/Units and Changes in Stockholders'/Members' Equity - USD ($)	Total	Accumulated Deficit	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Series A Redeemable Convertible Preferred Units	Series B Redeemable Convertible Preferred Units	Series C Redeemable Convertible Preferred Units	Series A,B and C Convertible Preferred Shares	Common UnitsMember Units	Common Shares	Incentive UnitsMember Units
Balance at Dec. 31, 2016					$ 15,300,002	$ 41,609,999
Balance, Units/Shares at Dec. 31, 2016					22,463,665	24,977,489
Balance at Dec. 31, 2016	$ (32,878,901)	$ (33,797,760)		$ (28,679)					$ 6,167		$ 941,371
Balance, Units/Shares at Dec. 31, 2016									1,897,544		3,066,734
Incentive unit-based compensation	245,048										$ 245,048
Incentive unit-based compensation, Units/Shares											603,229
Net loss	(24,049,206)	(24,049,206)
Change in redemption value of redeemable convertible preferred units	(4,570,431)	(4,570,431)			$ 4,468,023	$ 102,408
Unrealized gain (loss) on available-for-sale securities	18,928			18,928
Balance at Dec. 31, 2017					$ 19,768,025	$ 41,712,407
Balance, Units/Shares at Dec. 31, 2017					22,463,665	24,977,489
Balance at Dec. 31, 2017	(61,234,562)	(62,417,397)		(9,751)					$ 6,167		$ 1,186,419
Balance, Units/Shares at Dec. 31, 2017									1,897,544		3,669,963
Incentive unit-based compensation	11,630,300		$ 9,141,239								$ 2,489,061
Incentive unit-based compensation, Units/Shares											1,680,386
Exercise of Series A redeemable convertible preferred warrant					$ 319,667
Exercise of Series A redeemable convertible preferred warrant, Units					110,116
Issuance of Series C redeemable convertible preferred units							$ 55,000,001
Issuance of Series C redeemable convertible preferred units, Units							16,467,066
Net loss	(41,480,466)	(41,480,466)
Change in redemption value of redeemable convertible preferred units	(198,366,756)	(198,366,756)			$ 91,044,716	$ 81,253,577	$ 26,068,463
Conversion of redeemable convertible preferred units to redeemable convertible preferred shares					$ (111,132,408)	$ (122,965,984)	$ (81,068,464)	$ 315,166,856
Conversion of redeemable convertible preferred units to redeemable convertible preferred shares, Units/Shares					(22,573,781)	(24,977,489)	(16,467,066)	64,018,336
Conversion of common and incentive units to common and restricted stock			3,677,954						$ (6,167)	$ 3,693	$ (3,675,480)
Conversion of common and incentive units to common and restricted stock, Units/Shares									(1,897,544)	3,692,765	(5,350,349)
Issuance of common stock, net of underwriters' discounts and issuance costs of $12,048,129	111,159,583		111,151,883							$ 7,700
Issuance of common stock, net of underwriters' discounts and issuance costs of $12,048,129, Shares										7,700,482
Conversion of redeemable convertible preferred stock to common stock	315,166,856		315,147,158					$ (315,166,856)		$ 19,698
Conversion of redeemable convertible preferred stock to common stock, Shares								(64,018,336)		19,697,928
Restricted stock vesting			(145)							$ 145
Restricted stock vesting, Shares										144,283
Unrealized gain (loss) on available-for-sale securities	(207,972)			(207,972)
Balance at Dec. 31, 2018
Balance, Units/Shares at Dec. 31, 2018
Balance at Dec. 31, 2018	$ 136,666,983	$ (302,264,619)	$ 439,118,089	$ (217,723)						$ 31,236
Balance, Units/Shares at Dec. 31, 2018	31,235,458
Balance, Units/Shares at Dec. 31, 2018										31,235,458

Consolidated Statements of Re_2

Consolidated Statements of Redeemable Convertible Preferred Shares/Units and Changes in Stockholders'/Members' Equity (Parenthetical)	12 Months Ended
	Dec. 31, 2018USD ($)
Statement Of Stockholders Equity [Abstract]
Issuance of common stock, underwriters' discounts and issuance costs	$ 12,048,129

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (41,480,466)	$ (24,049,206)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of debt discount	17,963	17,963
Change in fair value of preferred unit warrant liability	193,779	(5,871)
Depreciation and amortization	706,000	347,395
Net accretion of bond discounts/(premiums)	248,069	344,109
Non-cash share/unit-based compensation	11,630,300	245,048
Changes in operating assets and liabilities:
Other receivables	(1,215,514)	369,729
Account receivable	22,224,169	(25,000,000)
Prepaid expenses and other current assets	(2,501,383)	(2,061)
Accounts payable	2,002,163	(969,479)
Accrued expenses	455,340	1,894,343
Deferred liability	150,000	0
Deferred revenue	(8,548,090)	51,921,124
Net cash provided by (used in) operating activities	(16,117,670)	5,113,094
Cash flows from investing activities:
Purchase of marketable securities	(234,894,225)	(3,200,895)
Maturities of marketable securities	58,059,526	16,008,000
Sales of marketable securities	0	9,077,435
Purchase of property, equipment and leasehold improvements	(2,830,661)	(1,012,428)
Net cash provided by (used in) investing activities	(179,665,360)	20,872,112
Cash flows from financing activities:
Repayments of long term debt	(173,889)	(161,363)
Proceeds from long term debt	2,000,000	0
Proceeds from issuance of common stock	114,583,172	0
Payment of common stock offering costs	(3,423,589)	0
Proceeds from issuance of Series C redeemable convertible preferred units	55,000,001	0
Proceeds from exercise of warrant	75,000	0
Net cash provided by (used in) financing activities	168,060,695	(161,363)
Net increase (decrease) in cash and cash equivalents	(27,722,335)	25,823,843
Cash and cash equivalents, beginning of the period	30,912,391	5,088,548
Cash and cash equivalents, end of the period	3,190,056	30,912,391
Supplemental disclosure of cash flow information:
Purchases of property, equipment and leasehold improvements unpaid at period end	159,494	0
Cash paid for interest	39,476	32,393
Increase (decrease) in redemption value of preferred units	$ 198,366,756	$ 4,570,431

Nature of Business

Nature of Business	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Business	1. Nature of Business Arvinas, Inc. has five wholly owned subsidiaries, Arvinas Operations, Inc., Arvinas Androgen Receptor, Inc., Arvinas Estrogen Receptor, Inc., Arvinas BRD4, Inc., and Arvinas Winchester, Inc. (collectively, the Company). Arvinas Operations, Inc. was formed in 2013, Arvinas Androgen Receptor, Inc. was formed in 2015, Arvinas Estrogen Receptor, Inc. and Arvinas BRD4, Inc. were formed in 2016, and Arvinas Winchester, Inc. was formed in 2018. In September 2018, the Company converted from a Delaware limited liability company to a Delaware corporation. All periods prior to the date of conversion represent the results of the limited liability corporation. The Company is a biopharmaceutical company dedicated to improving the lives of patients suffering from debilitating and life-threatening diseases throughout the discovery, development and commercialization of therapies to degrade disease-causing proteins. Arvinas, Inc. was incorporated in Delaware on July 3, 2013. Effective January 1, 2015, Arvinas Holding Company, LLC (Arvinas LLC) was formed by the shareholders of Arvinas, Inc. and Arvinas, Inc. became a wholly owned subsidiary of Arvinas LLC. In connection with this reorganization, the rights and preferences of the Preferred Stock of Arvinas, Inc. were exchanged for preferred stock units with similar rights and preferences of Arvinas LLC. As part of the reorganization, the employees, consultants and board members of Arvinas, Inc. exchanged their stock options in Arvinas, Inc. stock in exchange for incentive units in Arvinas LLC. Additionally, common stock holders of Arvinas, Inc. exchanged their common stock for common units in Arvinas LLC. All exchanges were made on a 1-for-1 basis. This reorganization was accounted for as a common control transaction as the common stockholders of Arvinas, Inc. formed Arvinas, LLC and transferred all the assets from Arvinas, Inc. to Arvinas LLC. The Company’s Board of Managers approved a one-for-3.25 reverse stock split of its issued and outstanding shares of common units and a proportional adjustment to the existing conversion ratios for the Company’s Series A, Series B, and Series C preferred units effective as of September 14, 2018. Accordingly, all share/unit and per share/unit amounts for all periods presented in the accompanying financial statements and notes thereto have been retroactively adjusted, where applicable, to reflect this reverse unit split and adjustment of the preferred unit conversion ratios. Immediately prior to the effectiveness of the registration statement pertaining to the Company’s initial public offering on September 26, 2018, the Company converted from a Delaware limited liability company to a Delaware corporation. Pursuant to the plan of conversion, each outstanding Series A, Series B, and Series C preferred units converted into an equal number of shares of Series A, Series B, and Series C preferred stock, each outstanding common unit converted into a share of common stock and each outstanding incentive unit converted into a number of shares of common stock and restricted stock based on a conversion price determined by the board of directors. The Company issued 1,795,221 shares of common stock and 1,268,923 shares of restricted stock. On October 1, 2018, the Company completed an initial public offering (IPO) in which the Company issued and sold 7,500,000 shares On October 1, 2018, all of the outstanding shares of convertible preferred stock automatically converted into 19,697,928 shares of common stock at the applicable conversion ratio then in effect. Subsequent to the closing of the IPO, there were no shares of preferred stock outstanding.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Principles of Consolidation The consolidated financial statements of the Company include the accounts of Arvinas Inc. and its wholly owned subsidiaries. All intercompany transactions have been eliminated in consolidation. Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with accounting principles generally accepted in the United States requires management to make certain estimates and assumptions that affect the reported amounts and disclosures in the financial statements. While management believes that estimates and assumptions used in the preparation of the consolidated financial statements are appropriate, actual results could differ from those estimates. The most significant estimates are those used in determination of the Company’s revenue recognition, fair value of its common and preferred units, preferred unit warrant liability and incentive equity compensation. Financial Instruments The Company’s principal financial instruments comprise cash, marketable securities, account receivable, accounts payable, accrued liabilities and long-term debt. The carrying value of all financial instruments approximates fair value. Cash and Cash Equivalents The Company classifies as cash and cash equivalents amounts on deposit in banks and cash invested temporarily in various instruments, primarily money market accounts, with original maturities of three months or less at time of purchase. The carrying amounts reported in the consolidated balance sheets represent the fair values of cash and cash equivalents. Concentration of Credit Risk The Company maintains its cash in financial institution accounts that, at times during the year, may exceed federally insured limits. The cash balances in the financial institutions are insured by the Federal Deposit Insurance Corporation (FDIC) up to $250,000. Cash may also be maintained at commercial institutions that are not insured by the FDIC. For the year ended December 31, 2018, two collaborators each represented over 45% of total revenue. One collaborator accounted for the entire account receivable balance at December 31, 2018 and 2017. For the year ended December 31, 2017, two collaborators represented 60% and 40% of total revenue. Marketable Securities The Company classifies its marketable securities as available-for-sale securities, which are carried at their fair value based on the quoted market prices of the securities with unrealized gains and losses reported as accumulated other comprehensive loss, a separate component of members’ equity. Realized gains and losses on available-for-sale securities are included in net earnings in the period earned or incurred. Property, Equipment, and Leasehold Improvements Property and equipment are recorded at cost. Depreciation is calculated using the straight-line method over the estimated useful lives, which range from three years for office equipment to five years for laboratory equipment. Maintenance and repairs which do not extend the lives of the assets are charged directly to expense as incurred. Upon retirement or disposal, cost and related accumulated depreciation are removed from the related accounts, and any resulting gain or loss is recognized as a component of income or loss for the period. Leasehold improvements are recorded at cost and amortized using the straight-line method over the shorter of the lease term or the useful life of the asset. Impairment of Long-Lived Assets When indications of potential impairments are present, the Company evaluates the carrying value of long-lived assets. The Company adjusts the carrying value of the long-lived assets if the sum of undiscounted expected future cash flows is less than carrying value. No such impairments were recorded during 2018 or 2017. Deferred Financing Costs Deferred financing costs are being amortized over the term of the related debt. Segment Information The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. All of the Company’s tangible assets are held in the United States. To date, all of the Company’s revenue has been generated in the United States. Revenue Recognition and Deferred Revenue Revenues from Contracts As discussed under New Accounting Pronouncements, the Company adopted Accounting Standards Codification (ASC) 606, Revenue from Contracts with Customers The Company’s revenue is generated through research collaboration and license agreements with pharmaceutical partners. The terms of these agreements contain multiple goods and services which may include (i) licenses, (ii) research and development activities, and (iii) participation in joint research and development steering committees. The terms of these agreements may include non-refundable upfront license or option fees, payments for research and development activities, payments upon the achievement of certain milestones, and royalty payments based on product sales derived from the collaboration. Under ASC 606, the Company evaluates whether the license agreement, research and development services, and participation in research and development steering committees, represent separate or combined performance obligations. The Company has determined that these services within its existing contracts represent a combined single performance obligation. The research collaboration and license agreements typically include contingent milestone payments related to specified preclinical and clinical development milestones and regulatory milestones. These milestone payments represent variable consideration to be included within the transaction price using the most likely amount method. The Company determined that the most likely amount to be recognized was zero, against which no constraint was applied. The Company will continue to assess the probability of significant reversals for any amounts that become likely to be realized prior to recognizing the variable consideration associated with these payments within the transaction price. Revenue is recognized ratably over the Company’s expected performance period under each respective arrangement. The Company makes its best estimate of the period over which the Company expects to fulfill the Company’s performance obligations, which includes access to technology through the license agreement and research activities. Given the uncertainties of these collaboration arrangements, significant judgment is required to determine the duration of the performance period. For the years ended December 31, 2018 and 2017, the transaction price allocated to the combined performance obligation identified under the agreements is recognized as revenue on a straight-line basis over the estimated performance period under each respective arrangement. Straight-line basis was considered the best measure of progress in which control of the combined obligation transfers to the customers, due to the contract containing license rights to technology, research and development services, and joint committee participation, which in totality are expected to occur ratably over the performance period. The Company’s contracts may also call for certain sales-based milestone and royalty payments upon successful commercialization of a target. The Company recognizes revenues from sales-based milestone and royalty payments at the later of a) the occurrence of the subsequent sale; or b) the performance obligation to which some or all of the sales-based milestone or royalty payments has been allocated has been satisfied (or partially satisfied). The Company anticipates recognizing these milestones and royalty payments if and when subsequent sales are generated by the customer from the use of the technology. To date, no revenue from these sales-based milestone and royalty payments has been recognized for any periods. Amounts received prior to satisfying the above revenue recognition criteria are recorded as a contract liability in the Company’s accompanying consolidated balance sheets. Preferred Unit Warrants Preferred unit warrants issued in conjunction with debt financings were initially recorded at fair value, using a Black-Scholes option pricing model, with a corresponding discount recorded against the face value of the note and a liability. The discount was then accreted against the face value of the note over its remaining term as additional interest expense. The Company classified warrants to purchase shares of its Series A Redeemable Convertible Preferred Units (Series A Preferred Units) as a liability on its balance sheets as these warrants were free-standing financial instruments that were exercisable for contingently redeemable shares. The preferred unit warrants were recorded in long-term liabilities at fair value, estimated using the Black-Scholes option pricing model, and marked to market at each balance sheet date. The change in carrying value was reported as the change in fair value of warrant liability in the accompanying consolidated statements of operations. Income Taxes Arvinas LLC was taxed under the provisions of Subchapter K—Partners and Partnerships of the Internal Revenue Code. Under those provisions, Arvinas LLC did not pay federal or state corporate income taxes on its taxable income. Instead, each member would include net operating income or loss for Arvinas LLC on its individual return. Arvinas LLC was converted to a C corporation in 2018. Arvinas, Inc. and its wholly owned subsidiaries use the asset and liability method of accounting for income taxes, as set forth in ASC 740, Accounting for Income Taxes Management has evaluated the effect of ASC 740 guidance related to uncertain income tax positions and concluded that the Company has no significant uncertain income tax positions at December 31, 2018 and 2017. Equity-based Compensation Prior to its IPO, the Company periodically granted incentive units to employees and non-employees, which generally vested over a four-year period. The incentive units represented a separate substantive class of equity with defined rights within the LLC Operating Agreement. The incentive units represented profits interests in the Company, which was an interest in the increase in the value of the entity over the Participation Threshold, as defined in the LLC Operating Agreement and as determined at the time of grant. The holder, therefore, had the right to participate in distributions of profits only in excess of the Participation Threshold. The Participation Threshold was based on the valuation of the common unit on or around the grant date. The Company accounted for incentive units granted in accordance with ASC 718, Compensation-Stock Compensation The Company used a Black-Scholes option pricing model to determine fair value of its incentive units. The Black-Scholes option pricing model includes various assumptions, including the expected life of incentive units using the simplified method, the expected volatility and the expected risk-free interest rate. These assumptions reflected the Company’s best estimates, but they involve inherent uncertainties based on market conditions generally outside the control of the Company. As a result, if other assumptions had been used, unit-based compensation cost could have been materially impacted. The Company measures employee and board of director equity-based compensation for stock option and restricted stock grants based on the grant date fair value of the equity awards. Equity-based compensation expense is recognized over the requisite service period of the awards. For equity awards that have a performance condition, the Company recognizes compensation expense based on its assessment of the probability that the performance condition will be achieved. The Company measures equity awards granted to consultants based on the fair value of the award on the date the award is granted. Compensation expense is recognized over the period during which services are rendered by such consultants until completed. At the end of each financial reporting period prior to completion of the service, the fair value of these awards is remeasured using the then-current fair value of that equity award. The Company classifies equity-based compensation expense in its consolidated statement of operations in the same manner in which the award recipient’s salary and related costs are classified or in which the award recipient’s service payments are classified. Research and Development Research and development costs are expensed as incurred. The Company records grants from governmental and non-profit agencies as a reduction in research and development expense. Grants are recognized when there is reasonable assurance that the Company will comply with the conditions attached to the grant arrangement and the grant will be received. Grant payments received related to research and development costs incurred prior to the approval of the qualifying program are recognized immediately upon approval of the program by the grantor. Fair Value Measurements ASC Topic 820, Fair Value Measurements and Disclosures Financial Instruments Level 1—Inputs are based upon observable or quoted prices for identical instruments traded in active markets. Level 2—Inputs are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company’s Level 2 investments consist primarily of corporate notes and bonds and U.S. government and agency securities. Level 3—Inputs are generally unobservable and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability. The fair values are therefore determined using model-based techniques that include option pricing models, discounted cash flow models, and similar techniques. In determining fair value, the Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible as well as considers counterparty credit risk in its assessment of fair value. The Company’s marketable securities consist of corporate bonds and a government bond which are adjusted to fair value each balance sheet date, based on quoted prices, which are considered Level 2 inputs (see Note 5). The fair value of the preferred unit warrant liability was measured on a recurring basis and was considered a Level 3 instrument in the fair value hierarchy. See Note 8 for the valuation method used and significant assumptions used in the valuation. The following tables summarize the fair values and levels within the fair value hierarchy in which the fair value measurements fall for assets and liabilities measured on a recurring basis as of: December 31, 2018 Description Level 1 Level 2 Level 3 Total Assets: Corporate bonds $ — $ 181,668,600 $ — $ 181,668,600 Government securities — 2,969,040 — 2,969,040 December 31, 2017 Description Level 1 Level 2 Level 3 Total Assets: Corporate bonds $ — $ 8,258,982 $ — $ 8,258,982 Liabilities: Preferred unit warrant $ — $ — $ 50,888 $ 50,888 The following table presents the changes in Level 3 instruments measured on a recurring basis for the years ended December 31, 2018 and 2017: Preferred Unit Warrant Balance at December 31, 2016 $ 56,759 Change in fair value (5,871 ) Balance at December 31, 2017 50,888 Change in fair value 193,779 Exercise of warrant (244,667 ) Balance at December 31, 2018 $ — Fluctuation in the fair value of the Company’s Series A Preferred Units was the primary driver for the change in the Preferred Unit Warrant liability valuation during each year prior to its exercise. As the fair value of the Series A Preferred Units increase, the value to the holder of the instrument generally increases. Additionally, unit price volatility is one of the significant unobservable inputs used in the fair value measurement of the Company’s Preferred Unit Warrant liability. A decrease in expected volatility would generally result in a lower fair value measurement. The carrying value of accounts payable and accrued expenses approximate their fair value due to the short‑term nature of these assets and liabilities. Redeemable Preferred Units The Company classified redeemable preferred units as temporary equity in the accompanying consolidated balance sheets due to certain redemption events that were outside the Company’s control, including the passage of time. The Company recorded the redeemable preferred units at its redemption value as of the balance sheet date. Net Loss per Common Share/Unit Basic net loss per common share/unit is computed by dividing net loss, after adjusting for redeemable preferred unit dividends, by the weighted-average number of common shares/units outstanding during the period. The change in current redemption value of the redeemable preferred units was treated as a deemed dividend for all periods presented. Diluted net loss per share/unit was computed using the weighted-average number of common shares/units outstanding during the period and, if dilutive, the weighted average number of potential shares of common shares/units. The effect of the conversion of redeemable preferred units into common units was excluded from the computation of diluted net loss per common unit for all periods as their effect was antidilutive. Additionally, common share/unit equivalents are excluded from the computation of diluted net loss per common unit for all periods as their effect is antidilutive. New Accounting Pronouncements Recently Adopted Accounting Pronouncements In March 2016, the Financial Accounting Standards Board (FASB) issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases In June 2018, the FASB issued ASU No. 2018-07 , Improvements in Nonemployee Share-Based Payment Accounting Other accounting standards that have been issued by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2018
License Agreements [Abstract]
License Agreements	3. License Agreements In July 2013, the Company entered into an exclusive license agreement, including the right to grant sublicenses, with Yale University to develop protein degradation technologies. In connection with the execution of this license agreement, the Company made a non-refundable upfront payment of $149,511. In addition to the upfront payment, the Company paid Yale University a License Maintenance Royalty of varying amounts through the fourth anniversary of the license agreement. After 2017 and until the first sale to a third party of any licensed product, the minimum annual payment will be $75,000. During 2018 and 2017, the Company paid $75,000 and $50,000, respectively, under the license agreement. The Company is also required to pay Yale University success-based milestones for the development of the protein degradation technologies as well as low single-digit running royalties on aggregate worldwide net sales of certain licensed products, which may be subject to reductions, and subject to a minimum royalty payment that ranges from $200,000 to $500,000. If the Company sublicenses the protein degradation technologies to a third party, the Company is required to pay Yale University a mid-single digit to mid-double digit percentage of Sublicense Income (as defined in the agreement). During 2015, the Company paid $750,000 to Yale University as a result of the Company entering into its first Research Collaboration and License Agreement representing the maximum amount to be paid for consideration received prior to the filing of an IND for a licensed product. The Company is also required to reimburse Yale University for patent costs incurred. During 2018 and 2017, the Company reimbursed Yale University $216,093 and $109,287, respectively, for patent costs.

Research Collaboration and Lice

Research Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2018
Research Collaboration And License Agreements [Abstract]
Research Collaboration and License Agreements	4. Research Collaboration and License Agreements In December 2017, the Company entered into a Research Collaboration and License Agreement with Pfizer, Inc. Under the terms of the agreement, the Company received an upfront non-refundable payment and certain additional payments totaling $28.0 million in 2018 in exchange for use of the Company’s technology license and to fund Pfizer-related research as defined within the agreement. These payments are being recognized as revenue over the total estimated period of performance. The Company is also eligible to receive up to an additional $37.5 million in non-refundable option payments if Pfizer exercises its options for all targets under the agreement. Pfizer exercised an option for $2.5 million in December 2018 and the amount is included in accounts receivable at December 31, 2018. The Company is also entitled to receive up to $225 million in development milestone payments and up to $550 million in sales-based milestone payments for all designated targets under the agreement, as well as tiered royalties based on sales. In September 2015, the Company entered into an Option and License Agreement with Genentech, Inc. and F. Hoffman-La Roche Ltd (the Genentech Agreement). During 2015, the Company received an upfront non-refundable payment of $11.0 million in exchange for use of the Company’s technology license and to fund Genentech-related research as defined within the Genentech Agreement. In November 2017, the Company entered into an Amended and Restated Option, License, and Collaboration Agreement with Genentech, Inc. and F. Hoffman-La Roche Ltd (the Genentech Modification), amending the Genentech Agreement. Under the Genentech Modification, the Company received additional upfront non-refundable payments of $34.5 million to fund Genentech-related research and Genentech has the right to designate up to ten targets. Upfront non-refundable payments are recognized as revenue over the total estimated period of performance. The Company is eligible to receive up to $44.0 million per target in development milestone payments, $52.5 million in regulatory milestone payments and $60.0 million in commercial milestone payments based on sales as well as tiered royalties based on sales. In connection with the Genentech Modification, the Company recognized an increase in revenue previously recognized of $0.4 million due to the offsetting impacts effect of an increase in total transaction price and an increase in expected period of performance. In April 2015, the Company entered into a Research Collaboration and License Agreement with Merck Sharp & Dohme Corp. (the Merck Agreement). During 2015, the Company received an upfront non-refundable payment of $7.0 million, which was recognized as revenue over the total estimated period of performance, in exchange for use of the Company’s technology license. The agreement also provided for research program funding to support Merck-related research. The agreement expired in April 2018. Information about contract liabilities, included as deferred revenue in the accompanying Consolidated Balance Sheets, is as follows: 2018 2017 Contract liabilities $ 53,550,671 $ 62,098,761 Revenues recognized in the period from: Amounts included in deferred revenue in previous periods 13,553,136 6,600,000 Changes in deferred revenue from 2017 to 2018 were due to billings of $5.8 million under new and modified contracts and $14.3 million of revenue recognized on the research collaboration and license agreements. The aggregate amount of the transaction price allocated to performance obligations that are unsatisfied as of December 31, 2018 was $53.6 million, which is expected to be recognized as follows (in millions): 2019 $ 16.1 2020 13.6 2021 13.5 2022 8.6 2023 1.8 $ 53.6

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Marketable Securities	5. Marketable Securities The following is a summary of the Company’s available-for-sale securities as of December 31, 2018 and 2017. December 31, 2018 Description Effective Maturity Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Corporate bonds 2019 $ 154,859,427 $ — $ (165,630 ) $ 154,693,797 Government bonds 2019 2,966,262 2,778 — 2,969,040 Corporate bonds 2020 27,029,673 (54,870 ) 26,974,803 Total $ 184,855,362 $ 2,778 $ (220,500 ) $ 184,637,640 December 31, 2017 Description Effective Maturity Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Corporate bonds 2018 $ 8,268,732 $ — $ (9,751 ) $ 8,258,982

Property, Equipment and Leaseho

Property, Equipment and Leasehold Improvements	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Property, Equipment and Leasehold Improvements	6. Property, Equipment and Leasehold Improvements Property, equipment and leasehold improvements consist of the following at December 31: 2018 2017 Laboratory equipment $ 3,757,265 $ 1,952,685 Office equipment 577,418 305,522 Leasehold improvements 981,884 72,294 5,316,567 2,330,501 Less: accumulated depreciation (1,733,531 ) (1,031,620 ) Property, equipment and leasehold improvements, net $ 3,583,036 $ 1,298,881 Depreciation expense totaled $706,000 and $347,395 for the years ended December 31, 2018 and 2017, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2018
Payables And Accruals [Abstract]
Accrued Expenses	7. Accrued Expenses Accrued expenses consisted of the following at December 31: 2018 2017 Employee expenses $ 2,795,205 $ 1,047,022 Research and development expenses 357,148 1,982,525 Professional fees and other 848,923 516,389 $ 4,001,276 $ 3,545,936

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Long-Term Debt	8. Long-Term Debt In August 2013, the Company entered into a Loan Agreement (Loan) and a Stock Subscription Warrant, with Connecticut Innovations, Incorporated (CII). Under the Loan, the Company can draw up to $750,000 for the purpose of purchasing laboratory equipment, information technology equipment and leasehold improvements. Leasehold improvements are limited to $100,000. Interest on the Loan is compounded on a monthly basis at a rate of 7.50% per annum and is required to be paid on a monthly basis beginning on the date of the first draw of funds for 10 months, then with principal payments beginning on June 1, 2015 and payable monthly until the maturity date of July 31, 2019. The Company has the ability to prepay the amount due at any time prior to the maturity date without premium or penalty. The Loan is secured by substantially all of the Company’s assets. As of December 31, 2018, and 2017, the amount outstanding under the Loan was $169,610 and $343,500, respectively. In connection with the issuance of the Loan, and as additional consideration, the Company granted CII a warrant to purchase 110,116 shares of the Company’s Series A Preferred Stock at a purchase price of $0.6811 per share, with a term of 7 years from the date of issuance (CII Series A Preferred Stock Warrant). Effective January 1, 2015, the CII Series A Unit Preferred Stock Warrant was exchanged for a warrant to purchase 110,116 units of the Company’s Series A redeemable convertible preferred units (CII Series A Preferred Unit Warrant).The fair value of the CII Series A Preferred Unit Warrant of $61,796 was determined using the Black Scholes option pricing model and was recorded as a debt discount and is being amortized as non-cash interest expense over the term of the Loan. At December 31, 2018 and 2017, the total unamortized debt discount on the Loan totaled $7,210 and $19,569, respectively. Interest expense recorded related to the amortization of the debt discount in 2018 and 2017 was $12,359 in each year. The Company evaluated the CII Series A Preferred Unit Warrant issued under authoritative guidance and determined that the CII Series A Preferred Unit Warrant does not meet the conditions to be classified as equity and has classified the CII Series A Preferred Unit Warrant as a liability at fair value on the accompanying balance sheets. The warrant was exercised in July 2018. The fair value of the CII Series A Preferred Unit Warrant was determined using the Black-Scholes option pricing model with the following assumptions: December 31, 2017 Expected volatility 100 % Expected term (years) 2.67 Risk free interest rate 1.91 % Expected dividend yield 0 % Fair value of underlying Series A Preferred Units $ 0.98 In connection with an Assistance Agreement with the State of Connecticut (Assistance Agreement) entered into in 2014, under which all the borrowings by the Company were forgiven in accordance with the Assistance Agreement, the Company is required to be located in the State of Connecticut through January 2024,with a default penalty of repayment of the full original funding amount of $2.5 million plus liquidated damages of 7.5%. In June 2018, the Company entered into an Assistance Agreement with the State of Connecticut (2018 Assistance Agreement) to provide funding for the expansion and renovation of laboratory and office space (Project). Under the terms of the 2018 Assistance Agreement, the Company could borrow from the State of Connecticut a maximum of $2.0 million, provided that the funding does not exceed more than 50% of the total Project costs. In September 2018, the Company borrowed $2.0 million under the 2018 Assistance Agreement, bearing interest at 3.25% per annum and interest payments will be required for the first 60 months from the funding date. Thereafter, the loan begins to fully amortize through month 120, maturing in June 2028. According to the terms of the 2018 Assistance Agreement, up to $1.0 million of the funding can be forgiven if the Company meets certain employment conditions, as defined in the agreement. The Company may also be required to prepay a portion of the loan if the employment conditions are not met. The 2018 Assistance Agreement requires that the Company be located in the State of Connecticut through June 2028 with a default penalty of repayment of the full original funding amount of $2.0 million plus liquidated damages of 7.5% of the total amount of funding received. Anticipated future minimum payments on long-term debt, excluding the discount on debt of $7,210, for the years ending December 31 are: 2019 $ 169,610 2023 92,480 Beyond 5 years 1,907,520 Total $ 2,169,610 During the years ended December 31, 2018 and 2017, interest expense was $57,440 and $50,357, respectively.

Members_ Equity

Members’ Equity	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Members' Equity	9. Members’ Equity Common Units In January 2015, all issued and outstanding common stock in Arvinas, Inc. was exchanged on a 1-for-1 basis for common units of Arvinas LLC. Each common unit entitled the holder to one vote on all matters submitted to a vote of the Company’s members. As noted in Note 1, in September 2018, all issued and outstanding common units were converted into common stock. Preferred Units During 2013 and 2014, Arvinas, Inc. sold 22,463,665 shares of Series A Redeemable Convertible Preferred Stock (Series A Preferred Stock) for $15.3 million at a price of $0.6811 per share. The Series A Preferred Stock was subsequently exchanged for Series A Preferred Units in Arvinas LLC upon the reorganization. During 2015, the Company sold 24,977,489 Series B Redeemable Convertible Preferred Units (Series B Preferred Units) in exchange for $41.6 million at a price of $1.6659 per share. In March 2018, the Company entered into a Series C Preferred Unit Purchase Agreement (the Series C Agreement) to raise additional equity. Under the terms of the Series C Agreement, the Company sold 16,467,066 units of Series C Redeemable Convertible Preferred Units (Series C Preferred Units) for $55.0 million at a price of $3.34 per unit. The Series A, Series B, and Series C Preferred Units (collectively, the Preferred Units) had the following rights, preferences and privileges: Conversion Rights At the option of the holder, each Preferred Unit was convertible into common units at any time after the date of issuance. The initial conversion price was equal to the original Series A Preferred Unit issue price of $0.6811 per unit, Series B Preferred Unit issue price of $1.6659, and Series C Preferred Unit issue price of $3.34 and was subject to adjustment as disclosed in the amended and restated operating agreement. Each Preferred Unit would automatically convert into common units at an applicable conversion rate upon the earlier of (i) the sale of the Company’s common units in a public offering which is not less than $3.34 per unit and which results in gross cash proceeds of at least $70 million, or (ii) the date specified by written consent or agreement of 66.67% of the outstanding Preferred Units. The Company has concluded that the embedded feature would not be accounted for separately as the economic characteristics and risks of the embedded conversion feature are clearly and closely related to the economic characteristics and risks of the host contract, the Preferred Units, given that both represent equity interests in the Company. Voting Rights The holders of Preferred Units were entitled to the same voting rights as the holders of common units, with a number of votes equal to the number of common units into which such Preferred Units could be converted. The holders of a majority of the then outstanding Preferred Units would have had the right to vote upon any matter submitted to the shareholders for a vote. Certain matters, prior to being able to be undertaken by the Company, required the approval of 66.67% of the holders of the Preferred Units, voting as a separate class. Dividends The holders of Preferred Units were entitled to receive non-cumulating dividends if declared by the board of managers, at a rate of 8% of the original per unit price per annum, payable upon a liquidation event or upon redemption, in preference and priority to any payment of dividends on common units. No dividends were declared as of December 31, 2018 and 2017. Redemption Rights The Preferred Units were redeemable at the option of the holders of at least 66.67% of the Preferred Units, voting together as a single class after October 1, 2019. The redemption price equaled an amount per Preferred Unit of any series equal to the greater of (A) the Preference Amount, as defined in the agreement, of such series of Preferred Unit and (B) the fair market value of such series of Preferred Unit as determined in good faith by the board. As the units were redeemable, the Company recorded at redemption value each reporting period. The Company must, therefore, measure the fair value of the preferred units each reporting period to determine the greater of the two potential redemption values as defined above. Fair value was determined each period based on unobservable inputs and management’s judgment due to the absence of quoted market prices, inherent lack of liquidity and the long-term nature of such financial instruments. The valuation was based on market approach utilizing the subject company transaction method. Liquidation In the event of a liquidation, dissolution or winding-up of the Company, the holders of the Preferred Units were entitled to receive, in preference to the holders of the common units and the incentive units, an amount equal to the original issue price, plus accrued but unpaid dividends. If funds were insufficient to pay the amount due, all proceeds shall have been distributed ratably to the respective amounts which would otherwise be payable in respect of the units held by them upon such distribution if all amounts payable with respect to such preferred units were paid in full. After payment of all preferential amounts to the holders of Preferred Units, all remaining funds shall be distributed pro rata to the holders of common units and Preferred Units as if the units of Preferred Units had been converted to common units prior to the distribution. Anti-Dilution Provisions In the event that the Company made adjustments for stock dividends, splits, combinations or other similar events or issues additional securities at a purchase price less than current Preferred Units conversion prices, the Preferred Units’ conversion price would have been adjusted in accordance with weighted average formulas, as defined in the agreements.

Incentive Unit Plans

Incentive Unit Plans	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Incentive Equity Plans	10. Incentive Equity Plans In the Fourth Amendment to the Company’s Incentive Share Plan (the Incentive Plan) adopted in March 2018, the Company was authorized to issue up to an aggregate of 6,199,477 incentive units pursuant to the Incentive Plan. Generally, incentive units were granted at no less than fair value as determined by the board of managers and had vesting periods ranging from one to four years. The Incentive Plan was terminated in September 2018. In September 2018, the Company’s board of directors adopted and the Company’s stockholders approved the 2018 Stock Incentive Plan (the 2018 Plan), which became effective upon the effectiveness of the registration statement on Form S-1 for the Company’s IPO. The number of common shares initially available for issuance under the 2018 Plan is the sum of (1) 4,067,007 shares of common stock; plus (2) the number of shares of common stock (up to 1,277,181) issued in respect of incentive units granted under the Incentive Plan that are subject to vesting immediately prior to the effectiveness of the registration statement that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right; plus (3) an annual increase on the first day of each fiscal year beginning with the fiscal year ending December 31, 2019 and continuing to, and including, the fiscal year ending December 31, 2028, equal to the lowest of 4,989,593 shares of the Company’s common stock, 4% of the number of shares of the Company’s common stock outstanding on the first day of the fiscal year and an amount determined by the Company’s board of directors. During 2018, the Company granted 1,715,368 incentive units to employees and directors under the Incentive Plan. The weighted average fair value of incentive units granted to employees was $4.54 per unit. In September 2018, each outstanding incentive unit was converted into a number of shares of common stock based upon the IPO price. Certain of the shares of common stock issued in respect of incentive units continue to be subject to vesting in accordance with the vesting schedule that was applicable to such incentive units, The Company granted 1,253,263 restricted shares to employees and directors as part of the conversion. The Company also granted 1,744,650 stock options to purchase shares of common stock to employees and directors who were holders of incentive units at the time of the incentive unit conversion and 286,307 in new employee grants. The weighted average fair value of stock options granted to employees and directors in 2018 was $9.88 per share. The options granted generally vest over a requisite service period of four years with a maximum contractual life of ten years from date of grant. During 2018, the Company recognized compensation expense of $10,026,666 relating to the issuance of employee incentive awards, and at December 31, 2018, there was $14,598,081 of compensation expense that is expected to be recognized over a weighted average period of approximately 1.5 years. In September 2018, in connection with the conversion of the incentive units, the Company granted 11,097 restricted shares of common stock and 251,010 stock options to purchase shares of common stock to consultants. Subsequent to the conversion, the Company granted 10,000 options to purchase shares of common stock to a consultant. During 2018, the Company recognized compensation expense of $1,603,633 relating to incentive share awards for consultants and, at December 31, 2018, there was $1,558,421 of compensation expense remaining to be amortized over a weighted average period of less than 1.5 years. The fair value of the incentive units granted during the years ended December 31, 2018 and 2017 was determined using the Black-Scholes option pricing model with the following assumptions: 2018 2017 Expected volatility 66 - 71% 75 – 80% Expected term (years) 5.6-6.1 1.5 – 6.1 Risk free interest rate 2.5-2.9% 1.1 – 2.1% Expected dividend yield 0% 0% Fair value of underlying common units $1.08-8.48 $ 0.72 The fair value of the underlying common units indicated above was utilized as the exercise price within the Black-Scholes option pricing model. The fair value of the stock options granted during the year ended December 31, 2018 was determined using the Black-Scholes option pricing model with the following assumptions: 2018 Expected volatility 68 % Expected term (years) 5.0-10.0 Risk free interest rate 2.6-3.1% Expected dividend yield 0 % Exercise price $ 16.00 Given the Company’s common stock has been trading for a sufficient period of time, the Company utilizes a collection of volatilities of peer companies to estimate the expected volatility of its common stock. The expected term is calculated utilizing the simplified method. The following table provides a summary of the incentive unit activity under the Incentive Plan. These amounts include incentive units granted to employees, directors and consultants. Units Weighted Average Fair Value Outstanding at December 31, 2016 3,066,734 $ 0.46 Granted 1,150,845 $ 0.46 Forfeited (547,616 ) $ 0.49 Outstanding at December 31, 2017 3,669,963 $ 0.46 Granted 1,715,368 $ 4.54 Forfeited (34,982 ) $ 4.85 Cancelled (5,350,349 ) $ 1.86 Outstanding at December 31, 2018 — $ — The following table provides a summary of the restricted stock grant activity under the Incentive Plan in 2018. These amounts include restricted stock granted to employees, directors and consultants. Shares Weighted Average Grant Date Fair Value Per Share Unvested restricted stock at December 31, 2017 — $ — Granted 1,264,360 $ 16.00 Vested (144,283 ) $ 16.00 Forfeited (17,788 ) $ 16.00 Unvested restricted stock at December 31, 2018 1,102,289 $ 16.00 The following table provides a summary of the stock option activity under the 2018 Plan in 2018. These amounts include stock options granted to employees, directors and consultants. Options Weighted Average Fair Value Outstanding at December 31, 2017 — $ — Granted 2,291,967 $ 9.88 Forfeited (18,943 ) $ 9.86 Outstanding at December 31, 2018 2,273,024 $ 9.88 Exercisable at December 31, 2018 420,087 $ 9.53 Included in the stock options granted in the table above are options to purchase 1,995,660 shares of common stock that were granted to employees, directors, and consultants granted at the time of the incentive unit conversion that have the same vesting terms as the profit units that were outstanding in September 2018 before the profit interests were converted into common stock. At the time of issuance of the stock options, 357,658 stock options to purchase shares of common stock became immediately vested, resulting in stock compensation expense of $3,627,507. At December 31, 2018, there were 996,452 restricted shares under the Incentive Plan and 2,054,778 stock options under the 2018 Plan that vested and are expected to vest.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes The Company has had no income tax expense due to operating losses incurred for the years ended December 31, 2018 and 2017. The Company has also not recorded any income tax benefits for the net operating losses incurred in each period due to its uncertainty of realizing a benefit from those items. All of the Company’s losses before income taxes were generated in the United States. A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate for the years ended December 31, 2018 and 2017 is as follows: 2018 2017 Federal statutory rate 21.0 % 34.0 % State taxes — — Federal tax rate change — (30.0 )% Federal research tax credit 2.5 % 2.7 % Stock compensation (3.3 )% (0.3 )% Change in valuation allowance (20.3 )% (6.3 )% Other 0.1 % (0.1 )% 0.0 % 0.0 % Deferred income taxes represent the tax effect of transactions that are reported in different periods for financial and tax reporting purposes. Temporary differences and carryforwards that give rise to a significant portion of the deferred income tax benefits and liabilities are as follows at December 31, 2018 and 2017: 2018 2017 Deferred income tax assets: Loss carryforwards $ 12,236,973 $ 10,978,713 Deferred revenue 6,179,875 736,672 Tax credits 2,681,628 1,658,899 Stock compensation 1,084,096 Other 181,734 65,714 Total deferred income tax assets 22,364,306 13,439,998 Deferred income tax liabilities Other (35,345 ) (24,079 ) Property, equipment and leasehold improvements (540,609 ) (100,072 ) Total deferred income tax liabilities (575,954 ) (124,151 ) Less valuation allowance (21,788,352 ) (13,315,847 ) Net deferred income tax assets $ — $ — The Company has provided a valuation allowance against the full amount of the deferred tax assets since, in the opinion of management, based upon the earnings history of the Company, it is more likely than not that the benefits will not be realized. All or a portion of the remaining valuation allowance may be reduced in future years based on an assessment of earnings sufficient to utilize these potential tax benefits. The valuation allowance increased by $8.5 million in 2018 and $1.5 million in 2017 due to the increase in the net operating loss carryforwards and research and development tax credits, partially decreased by a reduction in deferred revenue. The Company had approximately $58.3 million and $52.3 million of federal net operating loss carryforwards as of December 31, 2018 and 2017, respectively. Federal net operating loss carryforwards as of December 31, 2017 expire at various dates through fiscal year 2037 and federal net operating losses incurred in 2018 and in future years may be carried forward indefinitely, but the deductibility of such carryforwards is limited to 80% of the Company’s taxable income in the year in which carryforwards are used. The Company had approximately $2.7 million and $1.7 million of federal tax credit carryforwards as of December 31, 2018 and 2017, respectively, which expire at various dates through fiscal year 2038. In December 2017, the United States enacted the Tax Cuts and Jobs Act (the “Act”). The Act significantly changed U.S. corporate income tax laws by, among other provisions, reducing the maximum U.S. corporate income tax rate from 35% to 21% starting in 2018. During the year ended December 31, 2017, the Company reduced its deferred income tax asset by approximately $7.2 million as a result of the re-measurement of deferred tax assets and liabilities to the new lower statutory rate of 21%. The rate change did not result in an income tax expense as the effect of the rate change was offset by a corresponding change in the valuation allowance. The Company complies with the provisions of ASC 740 in accounting for its uncertain tax positions. ASC 740 addresses the determination of whether tax benefits claimed or expected to be claimed on a tax return should be recorded in the financial statements. Under ASC 740, the Company may recognize the tax benefit from an uncertain tax position only if it is more likely that not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The Company recognizes interest accrued related to unrecognized tax benefits and penalties in tax expense. The Company had no accruals for interest and penalties at December 31, 2018 and 2017. The Company is required to file income tax returns in the U.S. Federal jurisdiction, and in the States of Connecticut and Massachusetts. The Company is a state franchise taxpayer in Connecticut and Massachusetts due to the Company’s loss position. As a result, there is no state income tax provision included in the financial statements. The 2015 tax year forward remain subject to future examinations by the applicable taxing authorities. For the years ended December 31, 2018 and 2017, the Company recorded a benefit from expected cash refunds to be provided by the State of Connecticut, equal to 65% of research and development credits, of $106,316 and $562,385, respectively, which is included in Other Income in the accompanying consolidated statement of operations and comprehensive loss, due to the Company being a state franchise taxpayer. The benefit results from the exchange of the state research and development tax credit carryforwards for cash refunds. At December 31, 2018 and 2017, the Company has recorded receivables of $1.1 million and $989,219, respectively, relating to research and development credits due to the Company.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. Commitments and Contingencies Lease Commitments On December 31, 2017, the Company signed a new lease for its offices located in New Haven, Connecticut which added additional space through 2022. In addition, the Company has entered into various other equipment leases. Rental payments for the lease arrangements are payable in advance on a monthly basis. Rent expense totaled $606,538 and $402,897 for the years ended December 31, 2018 and 2017, respectively. Future minimum annual lease payments are as follows: 2019 $ 705,606 2020 731,541 2021 731,541 2022 716,906 Total $ 2,885,594

Net Loss Per Common Share_Unit

Net Loss Per Common Share/Unit	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Loss Per Common Share/Unit	13. Net Loss Per Common Share/Unit Basic and diluted loss per common share/unit were calculated as follows: 2018 2017 Net loss $ (41,480,466 ) $ (24,049,206 ) Change in redemption value of preferred units (198,366,756 ) (4,570,431 ) Net loss attributable to common shares/units – basic and diluted $ (239,847,222 ) $ (28,619,637 ) Weighted average number of common shares/units outstanding, basic and diluted 9,422,799 1,897,544 Net loss per common share/unit $ (25.45 ) $ (15.08 ) The Company’s potential dilutive securities have been excluded from the computation of diluted net loss per common share/unit as the effect would be to reduce the net loss per common share/unit. The following common share/unit equivalents have been excluded from the calculations of diluted loss per common share/unit because their inclusion would have been antidilutive. 2018 2017 Redeemable preferred units, as if converted to common units — 14,597,268 Incentive units — 3,669,963 Stock options 2,273,024 — Restricted stock awards 1,102,289 — Preferred unit warrant — 33,881 3,375,313 18,301,112

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Parties	14. Related Parties Dr. Craig Crews, founder of the Company and the Chief Scientific Advisor to the Company, is a common shareholder in the Company and has a consulting agreement with the Company. The Company entered into an amendment to the amended and restated consulting agreement with Professor Crews, which became effective upon the closing of the IPO and continues in effect for three years. Pursuant to the amendment, Professor Crews will be paid $20,833 per month for his services. During the years ended December 31, 2018 and 2017, the Company paid Professor Crews $176,110 and $150,000, respectively, related to his consulting agreement. In connection with the conversion of incentive units, the Company also granted Professor Crews 235,150 options to purchase the Company’s common stock at an exercise price of $16.00 per share, vesting over three years. In July 2013, the Company entered into an exclusive license agreement, including the right to grant sublicenses, with Yale University, a common shareholder in the Company, to develop protein degradation technologies. The Company is required to pay Yale University a minimum annual License Maintenance Royalty of $75,000 until the first commercial sale of product. During the years ended December 31, 2018 and 2017, the Company paid the Office of Cooperative Research at Yale University, a common unit holder in the Company, $288,517 and $152,603, respectively, for the license maintenance royalty fee, reimbursable patent costs and sublicense fee (see Note 3). In July 2016, the Company entered into a Corporate Sponsored Research Agreement (SRA) with Yale University, under the direction of Professor Crews, which was amended in April 2018. The amended SRA extended the agreement until April 2021 and amended the scope of work. The amended SRA requires quarterly payments of $250,000 through the end of the agreement. The total payments made under the SRA for 2018 and 2017 were $851,161 and $404,632, respectively.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Selected Quarterly Financial Data (Unaudited)	15. Selected Quarterly Financial Data (Unaudited) Selected quarterly financial data is as follows: Three months ended March 31, 2017 June 30, 2017 September 30, 2017 December 31, 2017 Revenue $ 1,668,861 $ 1,668,861 $ 1,668,861 $ 2,572,293 Operating expenses: Research and development 7,056,199 7,823,617 7,222,897 6,690,189 General and administrative 929,826 569,983 857,310 1,189,122 Total operating expenses 7,986,025 8,393,600 8,080,207 7,879,311 Loss from operations (6,317,164 ) (6,724,739 ) (6,411,346 ) (5,307,018 ) Other income (expenses) Other income, net 264 159 607 553,129 Change in fair value of preferred unit warrant 1,335 1,457 1,546 1,533 Interest income 83,562 57,904 24,140 35,781 Interest expense (13,713 ) (12,973 ) (12,219 ) (11,451 ) Total other income 71,448 46,547 14,074 578,992 Net loss (6,245,716 ) (6,678,192 ) (6,397,272 ) (4,728,026 ) Change in redemption value of redeemable preferred units — — — (4,570,431 ) Net loss attributable to common units $ (6,245,716 ) $ (6,678,192 ) $ (6,397,272 ) $ (9,298,457 ) Net loss per common unit, basic and diluted $ (3.29 ) $ (3.52 ) $ (3.37 ) $ (4.90 ) Weighted average common units outstanding, basic and diluted 1,897,544 1,897,544 1,897,544 1,897,544 Three months ended March 31, 2018 June 30, 2018 September 30, 2018 December 31, 2018 Revenue $ 4,108,596 $ 3,399,895 $ 3,375,264 $ 3,440,165 Operating expenses: Research and development 7,143,817 10,337,835 13,149,879 14,562,299 General and administrative 1,246,887 1,579,605 4,284,231 5,821,445 Total operating expenses 8,390,704 11,917,440 17,434,110 20,383,744 Loss from operations (4,282,108 ) (8,517,545 ) (14,058,846 ) (16,943,579 ) Other income (expenses) Other income, net 127,449 130,945 160,100 (315,764 ) Change in fair value of preferred unit warrant (196,295 ) 2,516 — — Interest income 211,237 539,413 523,338 1,196,113 Interest expense (10,669 ) (9,871 ) (12,264 ) (24,636 ) Total other income 131,722 663,003 671,174 855,713 Net loss (4,150,386 ) (7,854,542 ) (13,387,672 ) (16,087,866 ) Change in redemption value of redeemable preferred units (71,482,098 ) (14,834,049 ) (112,050,609 ) — Net loss attributable to common shares/units $ (75,632,484 ) $ (22,688,591 ) $ (125,438,281 ) $ (16,087,866 ) Net loss per common share/unit, basic and diluted $ (39.86 ) $ (11.96 ) $ (62.38 ) $ (0.52 ) Weighted average common shares/units outstanding, basic and diluted 1,897,544 1,897,544 2,010,807 31,098,634

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial statements of the Company include the accounts of Arvinas Inc. and its wholly owned subsidiaries. All intercompany transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with accounting principles generally accepted in the United States requires management to make certain estimates and assumptions that affect the reported amounts and disclosures in the financial statements. While management believes that estimates and assumptions used in the preparation of the consolidated financial statements are appropriate, actual results could differ from those estimates. The most significant estimates are those used in determination of the Company’s revenue recognition, fair value of its common and preferred units, preferred unit warrant liability and incentive equity compensation.
Financial Instruments	Financial Instruments The Company’s principal financial instruments comprise cash, marketable securities, account receivable, accounts payable, accrued liabilities and long-term debt. The carrying value of all financial instruments approximates fair value.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company classifies as cash and cash equivalents amounts on deposit in banks and cash invested temporarily in various instruments, primarily money market accounts, with original maturities of three months or less at time of purchase. The carrying amounts reported in the consolidated balance sheets represent the fair values of cash and cash equivalents.
Concentration of Credit Risk	Concentration of Credit Risk The Company maintains its cash in financial institution accounts that, at times during the year, may exceed federally insured limits. The cash balances in the financial institutions are insured by the Federal Deposit Insurance Corporation (FDIC) up to $250,000. Cash may also be maintained at commercial institutions that are not insured by the FDIC. For the year ended December 31, 2018, two collaborators each represented over 45% of total revenue. One collaborator accounted for the entire account receivable balance at December 31, 2018 and 2017. For the year ended December 31, 2017, two collaborators represented 60% and 40% of total revenue.
Marketable Securities	Marketable Securities The Company classifies its marketable securities as available-for-sale securities, which are carried at their fair value based on the quoted market prices of the securities with unrealized gains and losses reported as accumulated other comprehensive loss, a separate component of members’ equity. Realized gains and losses on available-for-sale securities are included in net earnings in the period earned or incurred.
Property, Equipment, and Leasehold Improvements	Property, Equipment, and Leasehold Improvements Property and equipment are recorded at cost. Depreciation is calculated using the straight-line method over the estimated useful lives, which range from three years for office equipment to five years for laboratory equipment. Maintenance and repairs which do not extend the lives of the assets are charged directly to expense as incurred. Upon retirement or disposal, cost and related accumulated depreciation are removed from the related accounts, and any resulting gain or loss is recognized as a component of income or loss for the period. Leasehold improvements are recorded at cost and amortized using the straight-line method over the shorter of the lease term or the useful life of the asset.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets When indications of potential impairments are present, the Company evaluates the carrying value of long-lived assets. The Company adjusts the carrying value of the long-lived assets if the sum of undiscounted expected future cash flows is less than carrying value. No such impairments were recorded during 2018 or 2017.
Deferred Financing Costs	Deferred Financing Costs Deferred financing costs are being amortized over the term of the related debt.
Segment Information	Segment Information The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. All of the Company’s tangible assets are held in the United States. To date, all of the Company’s revenue has been generated in the United States.
Revenue Recognition and Deferred Revenue	Revenue Recognition and Deferred Revenue Revenues from Contracts As discussed under New Accounting Pronouncements, the Company adopted Accounting Standards Codification (ASC) 606, Revenue from Contracts with Customers The Company’s revenue is generated through research collaboration and license agreements with pharmaceutical partners. The terms of these agreements contain multiple goods and services which may include (i) licenses, (ii) research and development activities, and (iii) participation in joint research and development steering committees. The terms of these agreements may include non-refundable upfront license or option fees, payments for research and development activities, payments upon the achievement of certain milestones, and royalty payments based on product sales derived from the collaboration. Under ASC 606, the Company evaluates whether the license agreement, research and development services, and participation in research and development steering committees, represent separate or combined performance obligations. The Company has determined that these services within its existing contracts represent a combined single performance obligation. The research collaboration and license agreements typically include contingent milestone payments related to specified preclinical and clinical development milestones and regulatory milestones. These milestone payments represent variable consideration to be included within the transaction price using the most likely amount method. The Company determined that the most likely amount to be recognized was zero, against which no constraint was applied. The Company will continue to assess the probability of significant reversals for any amounts that become likely to be realized prior to recognizing the variable consideration associated with these payments within the transaction price. Revenue is recognized ratably over the Company’s expected performance period under each respective arrangement. The Company makes its best estimate of the period over which the Company expects to fulfill the Company’s performance obligations, which includes access to technology through the license agreement and research activities. Given the uncertainties of these collaboration arrangements, significant judgment is required to determine the duration of the performance period. For the years ended December 31, 2018 and 2017, the transaction price allocated to the combined performance obligation identified under the agreements is recognized as revenue on a straight-line basis over the estimated performance period under each respective arrangement. Straight-line basis was considered the best measure of progress in which control of the combined obligation transfers to the customers, due to the contract containing license rights to technology, research and development services, and joint committee participation, which in totality are expected to occur ratably over the performance period. The Company’s contracts may also call for certain sales-based milestone and royalty payments upon successful commercialization of a target. The Company recognizes revenues from sales-based milestone and royalty payments at the later of a) the occurrence of the subsequent sale; or b) the performance obligation to which some or all of the sales-based milestone or royalty payments has been allocated has been satisfied (or partially satisfied). The Company anticipates recognizing these milestones and royalty payments if and when subsequent sales are generated by the customer from the use of the technology. To date, no revenue from these sales-based milestone and royalty payments has been recognized for any periods. Amounts received prior to satisfying the above revenue recognition criteria are recorded as a contract liability in the Company’s accompanying consolidated balance sheets.
Preferred Unit Warrants	Preferred Unit Warrants Preferred unit warrants issued in conjunction with debt financings were initially recorded at fair value, using a Black-Scholes option pricing model, with a corresponding discount recorded against the face value of the note and a liability. The discount was then accreted against the face value of the note over its remaining term as additional interest expense. The Company classified warrants to purchase shares of its Series A Redeemable Convertible Preferred Units (Series A Preferred Units) as a liability on its balance sheets as these warrants were free-standing financial instruments that were exercisable for contingently redeemable shares. The preferred unit warrants were recorded in long-term liabilities at fair value, estimated using the Black-Scholes option pricing model, and marked to market at each balance sheet date. The change in carrying value was reported as the change in fair value of warrant liability in the accompanying consolidated statements of operations.
Income Taxes	Income Taxes Arvinas LLC was taxed under the provisions of Subchapter K—Partners and Partnerships of the Internal Revenue Code. Under those provisions, Arvinas LLC did not pay federal or state corporate income taxes on its taxable income. Instead, each member would include net operating income or loss for Arvinas LLC on its individual return. Arvinas LLC was converted to a C corporation in 2018. Arvinas, Inc. and its wholly owned subsidiaries use the asset and liability method of accounting for income taxes, as set forth in ASC 740, Accounting for Income Taxes Management has evaluated the effect of ASC 740 guidance related to uncertain income tax positions and concluded that the Company has no significant uncertain income tax positions at December 31, 2018 and 2017.
Equity-based Compensation	Equity-based Compensation Prior to its IPO, the Company periodically granted incentive units to employees and non-employees, which generally vested over a four-year period. The incentive units represented a separate substantive class of equity with defined rights within the LLC Operating Agreement. The incentive units represented profits interests in the Company, which was an interest in the increase in the value of the entity over the Participation Threshold, as defined in the LLC Operating Agreement and as determined at the time of grant. The holder, therefore, had the right to participate in distributions of profits only in excess of the Participation Threshold. The Participation Threshold was based on the valuation of the common unit on or around the grant date. The Company accounted for incentive units granted in accordance with ASC 718, Compensation-Stock Compensation The Company used a Black-Scholes option pricing model to determine fair value of its incentive units. The Black-Scholes option pricing model includes various assumptions, including the expected life of incentive units using the simplified method, the expected volatility and the expected risk-free interest rate. These assumptions reflected the Company’s best estimates, but they involve inherent uncertainties based on market conditions generally outside the control of the Company. As a result, if other assumptions had been used, unit-based compensation cost could have been materially impacted. The Company measures employee and board of director equity-based compensation for stock option and restricted stock grants based on the grant date fair value of the equity awards. Equity-based compensation expense is recognized over the requisite service period of the awards. For equity awards that have a performance condition, the Company recognizes compensation expense based on its assessment of the probability that the performance condition will be achieved. The Company measures equity awards granted to consultants based on the fair value of the award on the date the award is granted. Compensation expense is recognized over the period during which services are rendered by such consultants until completed. At the end of each financial reporting period prior to completion of the service, the fair value of these awards is remeasured using the then-current fair value of that equity award. The Company classifies equity-based compensation expense in its consolidated statement of operations in the same manner in which the award recipient’s salary and related costs are classified or in which the award recipient’s service payments are classified.
Research and Development	Research and Development Research and development costs are expensed as incurred. The Company records grants from governmental and non-profit agencies as a reduction in research and development expense. Grants are recognized when there is reasonable assurance that the Company will comply with the conditions attached to the grant arrangement and the grant will be received. Grant payments received related to research and development costs incurred prior to the approval of the qualifying program are recognized immediately upon approval of the program by the grantor.
Fair Value Measurements	Fair Value Measurements ASC Topic 820, Fair Value Measurements and Disclosures Financial Instruments Level 1—Inputs are based upon observable or quoted prices for identical instruments traded in active markets. Level 2—Inputs are based upon quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company’s Level 2 investments consist primarily of corporate notes and bonds and U.S. government and agency securities. Level 3—Inputs are generally unobservable and typically reflect management’s estimates of assumptions that market participants would use in pricing the asset or liability. The fair values are therefore determined using model-based techniques that include option pricing models, discounted cash flow models, and similar techniques. In determining fair value, the Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible as well as considers counterparty credit risk in its assessment of fair value. The Company’s marketable securities consist of corporate bonds and a government bond which are adjusted to fair value each balance sheet date, based on quoted prices, which are considered Level 2 inputs (see Note 5). The fair value of the preferred unit warrant liability was measured on a recurring basis and was considered a Level 3 instrument in the fair value hierarchy. See Note 8 for the valuation method used and significant assumptions used in the valuation. The following tables summarize the fair values and levels within the fair value hierarchy in which the fair value measurements fall for assets and liabilities measured on a recurring basis as of: December 31, 2018 Description Level 1 Level 2 Level 3 Total Assets: Corporate bonds $ — $ 181,668,600 $ — $ 181,668,600 Government securities — 2,969,040 — 2,969,040 December 31, 2017 Description Level 1 Level 2 Level 3 Total Assets: Corporate bonds $ — $ 8,258,982 $ — $ 8,258,982 Liabilities: Preferred unit warrant $ — $ — $ 50,888 $ 50,888 The following table presents the changes in Level 3 instruments measured on a recurring basis for the years ended December 31, 2018 and 2017: Preferred Unit Warrant Balance at December 31, 2016 $ 56,759 Change in fair value (5,871 ) Balance at December 31, 2017 50,888 Change in fair value 193,779 Exercise of warrant (244,667 ) Balance at December 31, 2018 $ — Fluctuation in the fair value of the Company’s Series A Preferred Units was the primary driver for the change in the Preferred Unit Warrant liability valuation during each year prior to its exercise. As the fair value of the Series A Preferred Units increase, the value to the holder of the instrument generally increases. Additionally, unit price volatility is one of the significant unobservable inputs used in the fair value measurement of the Company’s Preferred Unit Warrant liability. A decrease in expected volatility would generally result in a lower fair value measurement.
Redeemable Preferred Units	Redeemable Preferred Units The Company classified redeemable preferred units as temporary equity in the accompanying consolidated balance sheets due to certain redemption events that were outside the Company’s control, including the passage of time. The Company recorded the redeemable preferred units at its redemption value as of the balance sheet date.
Net Loss per Common Share/Unit	Net Loss per Common Share/Unit Basic net loss per common share/unit is computed by dividing net loss, after adjusting for redeemable preferred unit dividends, by the weighted-average number of common shares/units outstanding during the period. The change in current redemption value of the redeemable preferred units was treated as a deemed dividend for all periods presented. Diluted net loss per share/unit was computed using the weighted-average number of common shares/units outstanding during the period and, if dilutive, the weighted average number of potential shares of common shares/units. The effect of the conversion of redeemable preferred units into common units was excluded from the computation of diluted net loss per common unit for all periods as their effect was antidilutive. Additionally, common share/unit equivalents are excluded from the computation of diluted net loss per common unit for all periods as their effect is antidilutive.
New Accounting Pronouncements	New Accounting Pronouncements Recently Adopted Accounting Pronouncements In March 2016, the Financial Accounting Standards Board (FASB) issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases In June 2018, the FASB issued ASU No. 2018-07 , Improvements in Nonemployee Share-Based Payment Accounting Other accounting standards that have been issued by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables summarize the fair values and levels within the fair value hierarchy in which the fair value measurements fall for assets and liabilities measured on a recurring basis as of: December 31, 2018 Description Level 1 Level 2 Level 3 Total Assets: Corporate bonds $ — $ 181,668,600 $ — $ 181,668,600 Government securities — 2,969,040 — 2,969,040 December 31, 2017 Description Level 1 Level 2 Level 3 Total Assets: Corporate bonds $ — $ 8,258,982 $ — $ 8,258,982 Liabilities: Preferred unit warrant $ — $ — $ 50,888 $ 50,888
Summary of Changes In Level 3 Instruments Measured On Recurring Basis	The following table presents the changes in Level 3 instruments measured on a recurring basis for the years ended December 31, 2018 and 2017: Preferred Unit Warrant Balance at December 31, 2016 $ 56,759 Change in fair value (5,871 ) Balance at December 31, 2017 50,888 Change in fair value 193,779 Exercise of warrant (244,667 ) Balance at December 31, 2018 $ —

Research Collaboration and Li_2

Research Collaboration and License Agreements (Tables)	12 Months Ended
	Dec. 31, 2018
Research Collaboration And License Agreements [Abstract]
Summary of Contract Liabilities	Information about contract liabilities, included as deferred revenue in the accompanying Consolidated Balance Sheets, is as follows: 2018 2017 Contract liabilities $ 53,550,671 $ 62,098,761 Revenues recognized in the period from: Amounts included in deferred revenue in previous periods 13,553,136 6,600,000
Transaction Price Allocated to Performance Obligations	The aggregate amount of the transaction price allocated to performance obligations that are unsatisfied as of December 31, 2018 was $53.6 million, which is expected to be recognized as follows (in millions): 2019 $ 16.1 2020 13.6 2021 13.5 2022 8.6 2023 1.8 $ 53.6

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Summary of Company's Available for Sale Securities	The following is a summary of the Company’s available-for-sale securities as of December 31, 2018 and 2017. December 31, 2018 Description Effective Maturity Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Corporate bonds 2019 $ 154,859,427 $ — $ (165,630 ) $ 154,693,797 Government bonds 2019 2,966,262 2,778 — 2,969,040 Corporate bonds 2020 27,029,673 (54,870 ) 26,974,803 Total $ 184,855,362 $ 2,778 $ (220,500 ) $ 184,637,640 December 31, 2017 Description Effective Maturity Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Corporate bonds 2018 $ 8,268,732 $ — $ (9,751 ) $ 8,258,982

Property, Equipment and Lease_2

Property, Equipment and Leasehold Improvements (Tables)	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Schedule of Property, Equipment and Leasehold Improvements	Property, equipment and leasehold improvements consist of the following at December 31: 2018 2017 Laboratory equipment $ 3,757,265 $ 1,952,685 Office equipment 577,418 305,522 Leasehold improvements 981,884 72,294 5,316,567 2,330,501 Less: accumulated depreciation (1,733,531 ) (1,031,620 ) Property, equipment and leasehold improvements, net $ 3,583,036 $ 1,298,881

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2018
Payables And Accruals [Abstract]
Components of Accrued Expenses	Accrued expenses consisted of the following at December 31: 2018 2017 Employee expenses $ 2,795,205 $ 1,047,022 Research and development expenses 357,148 1,982,525 Professional fees and other 848,923 516,389 $ 4,001,276 $ 3,545,936

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Schedule of Anticipated Future Minimum Payments on Long-Term Debt Excluding Discount on Debt	Anticipated future minimum payments on long-term debt, excluding the discount on debt of $7,210, for the years ending December 31 are: 2019 $ 169,610 2023 92,480 Beyond 5 years 1,907,520 Total $ 2,169,610
Series A Preferred Unit Warrant
Schedule of Assumptions Used in Determining Fair Value of Warrant	The fair value of the CII Series A Preferred Unit Warrant was determined using the Black-Scholes option pricing model with the following assumptions: December 31, 2017 Expected volatility 100 % Expected term (years) 2.67 Risk free interest rate 1.91 % Expected dividend yield 0 % Fair value of underlying Series A Preferred Units $ 0.98

Incentive Equity Plans (Tables)

Incentive Equity Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Assumptions Used to Determine Fair Value of Incentive Units Granted	The fair value of the incentive units granted during the years ended December 31, 2018 and 2017 was determined using the Black-Scholes option pricing model with the following assumptions: 2018 2017 Expected volatility 66 - 71% 75 – 80% Expected term (years) 5.6-6.1 1.5 – 6.1 Risk free interest rate 2.5-2.9% 1.1 – 2.1% Expected dividend yield 0% 0% Fair value of underlying common units $1.08-8.48 $ 0.72
Schedule of Assumptions Used to Determine Fair Value of Stock Options Granted	The fair value of the stock options granted during the year ended December 31, 2018 was determined using the Black-Scholes option pricing model with the following assumptions: 2018 Expected volatility 68 % Expected term (years) 5.0-10.0 Risk free interest rate 2.6-3.1% Expected dividend yield 0 % Exercise price $ 16.00
Summary of Incentive Unit Activity	The following table provides a summary of the incentive unit activity under the Incentive Plan. These amounts include incentive units granted to employees, directors and consultants. Units Weighted Average Fair Value Outstanding at December 31, 2016 3,066,734 $ 0.46 Granted 1,150,845 $ 0.46 Forfeited (547,616 ) $ 0.49 Outstanding at December 31, 2017 3,669,963 $ 0.46 Granted 1,715,368 $ 4.54 Forfeited (34,982 ) $ 4.85 Cancelled (5,350,349 ) $ 1.86 Outstanding at December 31, 2018 — $ —
Summary of Restricted Stock Grant Activity	The following table provides a summary of the restricted stock grant activity under the Incentive Plan in 2018. These amounts include restricted stock granted to employees, directors and consultants. Shares Weighted Average Grant Date Fair Value Per Share Unvested restricted stock at December 31, 2017 — $ — Granted 1,264,360 $ 16.00 Vested (144,283 ) $ 16.00 Forfeited (17,788 ) $ 16.00 Unvested restricted stock at December 31, 2018 1,102,289 $ 16.00
Summary of Stock Option Activity	The following table provides a summary of the stock option activity under the 2018 Plan in 2018. These amounts include stock options granted to employees, directors and consultants. Options Weighted Average Fair Value Outstanding at December 31, 2017 — $ — Granted 2,291,967 $ 9.88 Forfeited (18,943 ) $ 9.86 Outstanding at December 31, 2018 2,273,024 $ 9.88 Exercisable at December 31, 2018 420,087 $ 9.53

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Reconciliation of the U.S. Federal Statutory Income Tax Rate to Effective Income Tax Rate	A reconciliation of the U.S. federal statutory income tax rate to the Company’s effective income tax rate for the years ended December 31, 2018 and 2017 is as follows: 2018 2017 Federal statutory rate 21.0 % 34.0 % State taxes — — Federal tax rate change — (30.0 )% Federal research tax credit 2.5 % 2.7 % Stock compensation (3.3 )% (0.3 )% Change in valuation allowance (20.3 )% (6.3 )% Other 0.1 % (0.1 )% 0.0 % 0.0 %
Summary of Deferred Income Taxes	Temporary differences and carryforwards that give rise to a significant portion of the deferred income tax benefits and liabilities are as follows at December 31, 2018 and 2017: 2018 2017 Deferred income tax assets: Loss carryforwards $ 12,236,973 $ 10,978,713 Deferred revenue 6,179,875 736,672 Tax credits 2,681,628 1,658,899 Stock compensation 1,084,096 Other 181,734 65,714 Total deferred income tax assets 22,364,306 13,439,998 Deferred income tax liabilities Other (35,345 ) (24,079 ) Property, equipment and leasehold improvements (540,609 ) (100,072 ) Total deferred income tax liabilities (575,954 ) (124,151 ) Less valuation allowance (21,788,352 ) (13,315,847 ) Net deferred income tax assets $ — $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Annual Lease Payments	Future minimum annual lease payments are as follows: 2019 $ 705,606 2020 731,541 2021 731,541 2022 716,906 Total $ 2,885,594

Net Loss Per Common Share_Unit

Net Loss Per Common Share/Unit (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Basic and Diluted Loss per Common Share/Unit	Basic and diluted loss per common share/unit were calculated as follows: 2018 2017 Net loss $ (41,480,466 ) $ (24,049,206 ) Change in redemption value of preferred units (198,366,756 ) (4,570,431 ) Net loss attributable to common shares/units – basic and diluted $ (239,847,222 ) $ (28,619,637 ) Weighted average number of common shares/units outstanding, basic and diluted 9,422,799 1,897,544 Net loss per common share/unit $ (25.45 ) $ (15.08 )
Common Share/Unit Equivalents Excluded from the Calculations of Diluted Loss Per Common Share/Unit	The following common share/unit equivalents have been excluded from the calculations of diluted loss per common share/unit because their inclusion would have been antidilutive. 2018 2017 Redeemable preferred units, as if converted to common units — 14,597,268 Incentive units — 3,669,963 Stock options 2,273,024 — Restricted stock awards 1,102,289 — Preferred unit warrant — 33,881 3,375,313 18,301,112

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Data [Abstract]
Schedule of Selected Quarterly Financial Data (Unaudited)	Selected quarterly financial data is as follows: Three months ended March 31, 2017 June 30, 2017 September 30, 2017 December 31, 2017 Revenue $ 1,668,861 $ 1,668,861 $ 1,668,861 $ 2,572,293 Operating expenses: Research and development 7,056,199 7,823,617 7,222,897 6,690,189 General and administrative 929,826 569,983 857,310 1,189,122 Total operating expenses 7,986,025 8,393,600 8,080,207 7,879,311 Loss from operations (6,317,164 ) (6,724,739 ) (6,411,346 ) (5,307,018 ) Other income (expenses) Other income, net 264 159 607 553,129 Change in fair value of preferred unit warrant 1,335 1,457 1,546 1,533 Interest income 83,562 57,904 24,140 35,781 Interest expense (13,713 ) (12,973 ) (12,219 ) (11,451 ) Total other income 71,448 46,547 14,074 578,992 Net loss (6,245,716 ) (6,678,192 ) (6,397,272 ) (4,728,026 ) Change in redemption value of redeemable preferred units — — — (4,570,431 ) Net loss attributable to common units $ (6,245,716 ) $ (6,678,192 ) $ (6,397,272 ) $ (9,298,457 ) Net loss per common unit, basic and diluted $ (3.29 ) $ (3.52 ) $ (3.37 ) $ (4.90 ) Weighted average common units outstanding, basic and diluted 1,897,544 1,897,544 1,897,544 1,897,544 Three months ended March 31, 2018 June 30, 2018 September 30, 2018 December 31, 2018 Revenue $ 4,108,596 $ 3,399,895 $ 3,375,264 $ 3,440,165 Operating expenses: Research and development 7,143,817 10,337,835 13,149,879 14,562,299 General and administrative 1,246,887 1,579,605 4,284,231 5,821,445 Total operating expenses 8,390,704 11,917,440 17,434,110 20,383,744 Loss from operations (4,282,108 ) (8,517,545 ) (14,058,846 ) (16,943,579 ) Other income (expenses) Other income, net 127,449 130,945 160,100 (315,764 ) Change in fair value of preferred unit warrant (196,295 ) 2,516 — — Interest income 211,237 539,413 523,338 1,196,113 Interest expense (10,669 ) (9,871 ) (12,264 ) (24,636 ) Total other income 131,722 663,003 671,174 855,713 Net loss (4,150,386 ) (7,854,542 ) (13,387,672 ) (16,087,866 ) Change in redemption value of redeemable preferred units (71,482,098 ) (14,834,049 ) (112,050,609 ) — Net loss attributable to common shares/units $ (75,632,484 ) $ (22,688,591 ) $ (125,438,281 ) $ (16,087,866 ) Net loss per common share/unit, basic and diluted $ (39.86 ) $ (11.96 ) $ (62.38 ) $ (0.52 ) Weighted average common shares/units outstanding, basic and diluted 1,897,544 1,897,544 2,010,807 31,098,634

Nature of Business - Additional

Nature of Business - Additional Information (Details)	Oct. 01, 2018USD ($)$ / sharesshares	Oct. 31, 2018$ / sharesshares	Sep. 30, 2018	Dec. 31, 2018USD ($)Subsidiary	Dec. 31, 2017USD ($)
Nature Of Business [Line Items]
Number of wholly owned subsidiaries | Subsidiary				5
Reverse stock split, conversion ratio			3.25
Fees and expenses | $	$ 12,000,000			$ 3,423,589	$ 0
Preferred stock outstanding	0
Restricted Stock
Nature Of Business [Line Items]
Restricted shares issued	1,268,923
Common Shares
Nature Of Business [Line Items]
Reverse stock split, description				The Company’s Board of Managers approved a one-for-3.25 reverse stock split of its issued and outstanding shares of common units
Reverse stock split, conversion ratio	0.3077
Common shares issued	1,795,221
Gross proceeds from sale of shares in Initial public offering before fees and expenses | $	$ 123,200,000
Conversion of redeemable convertible preferred stock to common stock, Shares	19,697,928
Common Shares | Initial Public Offering
Nature Of Business [Line Items]
Issuance of common stock, net of underwriters' discounts and issuance costs of $12,048,129, Shares	7,500,000
Share price, issued and sold | $ / shares	$ 16
Common Shares | Over-Allotment Option
Nature Of Business [Line Items]
Issuance of common stock, net of underwriters' discounts and issuance costs of $12,048,129, Shares		200,482
Share price, issued and sold | $ / shares		$ 16

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Summary Of Significant Accounting Policies [Line Items]
Impairment of long lived assets	$ 0	$ 0
Non-cash interest expense	$ 5,605	$ 5,605
Incentive units vesting period	4 years
ASU 2016-02 | Subsequent Event
Summary Of Significant Accounting Policies [Line Items]
Right-of-use assets			$ 2,400,000
Lease liabilities			$ 2,400,000
Office Equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life	3 years
Laboratory Equipment
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life	5 years
Minimum | Accounts Receivable | Customer Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage		60.00%
Minimum | Sales Revenue, Net | Customer Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage		40.00%
Maximum
Summary Of Significant Accounting Policies [Line Items]
Federal deposit insurance corporation premium expense	$ 250,000
Maximum | Accounts Receivable | Customer Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	45.00%
Maximum | Sales Revenue, Net | Customer Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	45.00%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Assets:
Fair value measurements of assets	$ 184,637,640
Fair Value, Measurements, Recurring | Preferred Unit Warrant
Liabilities:
Fair value measurements of liabilities		$ 50,888
Fair Value, Measurements, Recurring | Level 3 | Preferred Unit Warrant
Liabilities:
Fair value measurements of liabilities		50,888
Fair Value, Measurements, Recurring | Corporate Bonds
Assets:
Fair value measurements of assets	181,668,600	8,258,982
Fair Value, Measurements, Recurring | Corporate Bonds | Level 2
Assets:
Fair value measurements of assets	181,668,600	$ 8,258,982
Fair Value, Measurements, Recurring | Government Securities
Assets:
Fair value measurements of assets	2,969,040
Fair Value, Measurements, Recurring | Government Securities | Level 2
Assets:
Fair value measurements of assets	$ 2,969,040

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Summary of Changes In Level 3 Instruments Measured On Recurring Basis (Details) - Fair Value, Measurements, Recurring - Level 3 - Preferred Unit Warrant - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 50,888	$ 56,759
Change in fair value	193,779	(5,871)
Exercise of warrant	$ (244,667)
Balance at end of period		$ 50,888

License Agreements - Additional

License Agreements - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jul. 31, 2013	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2015
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment for license agreement		$ 75,000	$ 50,000
Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual payment for license		75,000
Yale University
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable upfront payment	$ 149,511
Reimbursed patent costs		216,093	$ 109,287
Yale University | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Royalty payment		200,000
Yale University | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment for license agreement				$ 750,000
Royalty payment		$ 500,000

Research Collaboration and Li_3

Research Collaboration and License Agreements - Additional Information (Details)	1 Months Ended	4 Months Ended	9 Months Ended	12 Months Ended
	Nov. 30, 2017USD ($)Target	Dec. 31, 2015USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Research Collaboration And License Agreements [Line Items]
Changes in deferred revenue due to billings				$ (8,548,090)	$ 51,921,124
Revenue recognized on research collaboration and license agreements				14,300,000
Unsatisfied performance obligations expected to be recognized as revenue				53,600,000
Pfizer, Inc.
Research Collaboration And License Agreements [Line Items]
Upfront non-refundable payment and certain additional payments received				28,000,000
Changes in deferred revenue due to billings				5,800,000
Pfizer, Inc. | Option Payments | Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised				37,500,000
Pfizer, Inc. | Development Milestone Payments | Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised				225,000,000
Pfizer, Inc. | Sales-based Milestone Payments | Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised				$ 550,000,000
Genentech, Inc. and F. Hoffman-La Roche Ltd.
Research Collaboration And License Agreements [Line Items]
Upfront non-refundable payment and certain additional payments received	$ 34,500,000	$ 11,000,000
Number of designated targets | Target	10
Increase in revenue previously recognized due to offsetting impacts in total transaction price and expected period of performance	$ 400,000
Genentech, Inc. and F. Hoffman-La Roche Ltd. | Development Milestone Payments | Maximum
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised	44,000,000
Genentech, Inc. and F. Hoffman-La Roche Ltd. | Regulatory Milestone Payments
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised	52,500,000
Genentech, Inc. and F. Hoffman-La Roche Ltd. | Commercial Milestone Payments
Research Collaboration And License Agreements [Line Items]
Contract revenue receivable if milestones achieved or options for all targets exercised	$ 60,000,000
Merck Sharp & Dohme Corp.
Research Collaboration And License Agreements [Line Items]
Upfront non-refundable payment and certain additional payments received			$ 7,000,000
Agreement expiration period			2018-04

Research Collaboration and Li_4

Research Collaboration and License Agreements - Summary of Contract Liabilities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue From Contract With Customer [Abstract]
Contract liabilities	$ 53,550,671	$ 62,098,761
Amounts included in deferred revenue in previous periods	$ 13,553,136	$ 6,600,000

Research Collaboration and Li_5

Research Collaboration and License Agreements - Transaction Price Allocated to Performance Obligations (Details) $ in Millions	Dec. 31, 2018USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 53.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 16.1
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 13.6
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 13.5
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 8.6
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 1.8
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 53.6
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year

Research Collaboration and Li_6

Research Collaboration and License Agreements - Transaction Price Allocated to Performance Obligations (Details1) $ in Millions	Dec. 31, 2018USD ($)
Revenue From Contract With Customer [Abstract]
Revenue, remaining performance obligation	$ 53.6

Marketable Securities - Summary

Marketable Securities - Summary of Company's Available for Sale Securities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 184,855,362
Gross Unrealized Gains	2,778
Gross Unrealized Losses	(220,500)
Fair value measurements of assets	$ 184,637,640
Corporate Bonds | 2019
Schedule Of Available For Sale Securities [Line Items]
Effective Maturity	2019
Amortized Cost	$ 154,859,427
Gross Unrealized Losses	(165,630)
Fair value measurements of assets	$ 154,693,797
Corporate Bonds | 2020
Schedule Of Available For Sale Securities [Line Items]
Effective Maturity	2020
Amortized Cost	$ 27,029,673
Gross Unrealized Losses	(54,870)
Fair value measurements of assets	$ 26,974,803
Corporate Bonds | 2018
Schedule Of Available For Sale Securities [Line Items]
Effective Maturity		2018
Amortized Cost		$ 8,268,732
Gross Unrealized Losses		(9,751)
Fair value measurements of assets		$ 8,258,982
Government Bonds | 2019
Schedule Of Available For Sale Securities [Line Items]
Effective Maturity	2019
Amortized Cost	$ 2,966,262
Gross Unrealized Gains	2,778
Fair value measurements of assets	$ 2,969,040

Property, Equipment and Lease_3

Property, Equipment and Leasehold Improvements - Schedule of Property, Equipment and Leasehold Improvements (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Property, equipment and leasehold improvements, gross	$ 5,316,567	$ 2,330,501
Less: accumulated depreciation	(1,733,531)	(1,031,620)
Property, equipment and leasehold improvements, net	3,583,036	1,298,881
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property, equipment and leasehold improvements, gross	3,757,265	1,952,685
Office Equipment
Property Plant And Equipment [Line Items]
Property, equipment and leasehold improvements, gross	577,418	305,522
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, equipment and leasehold improvements, gross	$ 981,884	$ 72,294

Property, Equipment and Lease_4

Property, Equipment and Leasehold Improvements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Depreciation expense	$ 706,000	$ 347,395

Accrued Expenses - Components o

Accrued Expenses - Components of Accrued Expenses (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Employee expenses	$ 2,795,205	$ 1,047,022
Research and development expenses	357,148	1,982,525
Professional fees and other	848,923	516,389
Accrued expenses	$ 4,001,276	$ 3,545,936

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) - USD ($)

1 Months Ended

3 Months Ended

12 Months Ended

Sep. 30, 2018

Jun. 30, 2018

Aug. 31, 2013

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2014

Jan. 01, 2015

Debt Instrument [Line Items]

Debt instrument, outstanding amount

$ 2,169,610

Fair value of warrant

$ (2,516)

$ 196,295

$ (1,533)

$ (1,546)

$ (1,457)

$ (1,335)

193,779

$ (5,871)

Total unamortized debt discount on Loan

19,569

7,210

19,569

Amortization of debt discount

12,359

12,359

Discount on long-term debt

7,210

Interest expense, Debt

$ 57,440

50,357

2014 Assistance Agreement | State of Connecticut

Debt Instrument [Line Items]

Debt instrument maturity month and year

2024-01

Debt instrument face amount

$ 2,500,000

Percentage of liquidated damages

7.50%

2018 Assistance Agreement | State of Connecticut

Debt Instrument [Line Items]

Debt instrument, interest rate per annum

3.25%

Debt instrument maturity month and year

2028-06

Debt instrument face amount

$ 2,000,000

Percentage of liquidated damages

7.50%

Percentage of maximum funding on total project costs

50.00%

Debt instrument interest payments term

60 months

Debt Instrument Amortization Period After Interest Payments Period

120 months

2018 Assistance Agreement | State of Connecticut | Maximum

Debt Instrument [Line Items]

Debt instrument face amount

$ 2,000,000

$ 2,000,000

Forgiveness of funding on achieving certain employment conditions

$ 1,000,000

Series A Preferred Unit Warrant

Debt Instrument [Line Items]

Warrant to purchase of stock

110,116

Warrant purchase price per share

$ 0.6811

Term of warrant from the date of issuance

7 years

Fair value of warrant

$ 61,796

Series A Redeemable Convertible Preferred Units

Debt Instrument [Line Items]

Warrant to purchase of stock

110,116

Loan Agreement | Connecticut Innovations, Incorporated. | Secured Debt

Debt Instrument [Line Items]

Debt instrument, maximum borrowing capacity

$ 750,000

Debt instrument, frequency of periodic payment

monthly

Debt instrument, interest rate per annum

7.50%

Debt instrument, interest only payment period upon first draw of funds

10 months

Debt instrument, date of first required payment

Jun. 1, 2015

Debt instrument, maturity date

Jul. 31, 2019

Debt instrument, outstanding amount

$ 343,500

$ 169,610

$ 343,500

Loan Agreement | Connecticut Innovations, Incorporated. | Secured Debt | Leasehold Improvements

Debt Instrument [Line Items]

Debt instrument, maximum borrowing capacity

$ 100,000

Long-Term Debt - Schedule of As

Long-Term Debt - Schedule of Assumptions Used in Determining Fair Value of Warrant (Details) - Series A Preferred Unit Warrant	12 Months Ended
	Dec. 31, 2017$ / shares
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Expected term (years)	2 years 8 months 1 day
Fair value of underlying Series A Preferred Units	$ 0.98
Expected Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value assumption	1
Risk Free Interest Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value assumption	0.0191
Expected Dividend Yield
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value assumption	0

Long-Term Debt - Schedule of An

Long-Term Debt - Schedule of Anticipated Future Minimum Payments on Long-Term Debt Excluding Discount on Debt (Details)	Dec. 31, 2018USD ($)
Long Term Debt By Maturity [Abstract]
2019	$ 169,610
2023	92,480
Beyond 5 years	1,907,520
Total	$ 2,169,610

Members' Equity - Additional In

Members' Equity - Additional Information (Details)	1 Months Ended			12 Months Ended			24 Months Ended
	Sep. 30, 2018	Mar. 31, 2018USD ($)$ / sharesshares	Jan. 31, 2015	Dec. 31, 2018USD ($)$ / shares	Dec. 31, 2017USD ($)	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Dec. 31, 2016USD ($)
Preferred stock issued, value				$ 111,159,583
Reverse stock split, conversion ratio	3.25
Proceeds from issuance of common stock				114,583,172	$ 0
Dividends declared					$ 0			$ 0
Initial Public Offering | Minimum
Proceeds from issuance of common stock				$ 70,000,000
Series A Redeemable Convertible Preferred Stock
Preferred stock issued, shares | shares							22,463,665
Preferred stock issued, value							$ 15,300,000
Stock issued, price per share/unit | $ / shares							$ 0.6811
Series B Redeemable Convertible Preferred Units
Preferred stock issued, shares | shares						24,977,489
Preferred stock issued, value						$ 41,600,000
Stock issued, price per share/unit | $ / shares				$ 1.6659		$ 1.6659
Series C Redeemable Convertible Preferred Units
Preferred stock issued, shares | shares		16,467,066
Preferred stock issued, value		$ 55,000,000
Stock issued, price per share/unit | $ / shares		$ 3.34		3.34
Series A Redeemable Convertible Preferred Units
Stock issued, price per share/unit | $ / shares				0.6811
Common Units
Common stock, conversion basis			1-for-1 basis
Convertible common stock conversion ratio			1.00%
Common stock, voting rights			one
Common Units | Initial Public Offering | Minimum
Stock issued, price per share/unit | $ / shares				$ 3.34
Preferred Units
Percentage of preferred units outstanding required for conversion				66.67%
Preferred units, voting rights				The holders of Preferred Units were entitled to the same voting rights as the holders of common units, with a number of votes equal to the number of common units into which such Preferred Units could be converted. The holders of a majority of the then outstanding Preferred Units would have had the right to vote upon any matter submitted to the shareholders for a vote. Certain matters, prior to being able to be undertaken by the Company, required the approval of 66.67% of the holders of the Preferred Units, voting as a separate class.
Preferred units, dividend payment terms				The holders of Preferred Units were entitled to receive non-cumulating dividends if declared by the board of managers, at a rate of 8% of the original per unit price per annum, payable upon a liquidation event or upon redemption, in preference and priority to any payment of dividends on common units. No dividends were declared as of December 31, 2018 and 2017.
Percentage of non cumulative dividends per annum				8.00%
Preferred units, redemption rights				The Preferred Units were redeemable at the option of the holders of at least 66.67% of the Preferred Units, voting together as a single class after October 1, 2019. The redemption price equaled an amount per Preferred Unit of any series equal to the greater of (A) the Preference Amount, as defined in the agreement, of such series of Preferred Unit and (B) the fair market value of such series of Preferred Unit as determined in good faith by the board. As the units were redeemable, the Company recorded at redemption value each reporting period. The Company must, therefore, measure the fair value of the preferred units each reporting period to determine the greater of the two potential redemption values as defined above. Fair value was determined each period based on unobservable inputs and management’s judgment due to the absence of quoted market prices, inherent lack of liquidity and the long-term nature of such financial instruments. The valuation was based on market approach utilizing the subject company transaction method.

Incentive Equity Plans - Additi

Incentive Equity Plans - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended	12 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, vesting period				4 years
Share-based award, stock options granted	1,995,660
Weighted average fair value of stock options granted				$ 9.88
Stock options vested	357,658
Consultants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Compensation expense				$ 1,603,633
Compensation expense not yet recognized			$ 1,558,421	$ 1,558,421
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, requisite service period				4 years
Share-based award, maximum contractual term				10 years
Compensation expense	$ 3,627,507
Maximum | Consultants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Compensation expense not yet recognized, period of recognition				1 year 6 months
Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incentive units authorized for issuance		6,199,477
Share-based award, expiration date		Sep. 30, 2018
Weighted average fair value of incentive units granted				$ 4.54
Share-based award, stock options granted	1,744,650
Restricted shares vested and expected to vest			996,452	996,452
Incentive Plan | Employee
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Compensation expense				$ 10,026,666
Compensation expense not yet recognized			$ 14,598,081	$ 14,598,081
Compensation expense not yet recognized, period of recognition				1 year 6 months
Incentive Plan | Consultants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, stock options granted	251,010
Incentive Plan | Incentive Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, non-option equity instruments granted				1,715,368
Incentive Plan | Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, non-option equity instruments granted	1,253,263
Incentive Plan | Restricted Stock | Consultants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, non-option equity instruments granted	11,097
Incentive Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, vesting period		1 year
Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, vesting period		4 years
Available for issuance of common stock	1,277,181
2018 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Available for issuance of common stock	4,067,007
Annual increase in reserved shares as percentage of outstanding common stock	4.00%
Share-based award, stock options granted			286,307	2,291,967
Weighted average fair value of stock options granted				$ 9.88
Stock options vested			420,087	420,087
Stock options vested and expected to vest			2,054,778	2,054,778
2018 Plan | Consultants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based award, stock options granted			10,000
2018 Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual increase in reserved shares of common stock	4,989,593

Incentive Equity Plans - Schedu

Incentive Equity Plans - Schedule of Assumptions Used to Determine Fair Value of Incentive Units Granted (Details) - Incentive Units - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, Minimum	66.00%	75.00%
Expected volatility, Maximum	71.00%	80.00%
Risk free interest rate, Minimum	2.50%	1.10%
Risk free interest rate, Maximum	2.90%	2.10%
Expected dividend yield	0.00%	0.00%
Fair value of underlying common units		$ 0.72
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 7 months 6 days	1 year 6 months
Fair value of underlying common units	$ 1.08
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 years 1 month 6 days	6 years 1 month 6 days
Fair value of underlying common units	$ 8.48

Incentive Equity Plans - Sche_2

Incentive Equity Plans - Schedule of Assumptions Used to Determine Fair Value of Stock Options Granted (Details) - Stock Options	12 Months Ended
	Dec. 31, 2018$ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	68.00%
Risk free interest rate, Minimum	2.60%
Risk free interest rate, Maximum	3.10%
Expected dividend yield	0.00%
Fair value of underlying common units	$ 16
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	10 years

Incentive Equity Plans - Summar

Incentive Equity Plans - Summary of Incentive Unit Activity (Details) - Incentive Plan - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average fair value of incentive units granted	$ 4.54
Incentive Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incentive Units, Granted	1,715,368
Incentive Units | Employees, Directors and Consultants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incentive Units, Outstanding, Beginning Balance	3,669,963	3,066,734
Incentive Units, Granted	1,715,368	1,150,845
Incentive Units, Forfeited	(34,982)	(547,616)
Incentive Units, Cancelled	(5,350,349)
Incentive Units, Outstanding, Ending Balance	0	3,669,963
Weighted Average Fair Value, Outstanding, Beginning Balance	$ 0.46	$ 0.46
Weighted average fair value of incentive units granted	4.54	0.46
Weighted Average Fair Value, Forfeited	4.85	0.49
Weighted Average Fair Value, Cancelled	1.86
Weighted Average Fair Value, Outstanding, Ending Balance	$ 0	$ 0.46

Incentive Equity Plans - Summ_2

Incentive Equity Plans - Summary of Restricted Stock Grant Activity (Details) - Incentive Plan - $ / shares	1 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted Average Grant Date Fair Value Per Share, Granted		$ 4.54
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted Shares, Granted	1,253,263
Restricted Stock | Employees, Directors and Consultants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested Restricted Stock, Shares, Beginning Balance		0
Restricted Shares, Granted		1,264,360
Restricted Shares, Vested		(144,283)
Restricted Shares, Forfeited		(17,788)
Unvested Restricted Stock, Shares, Ending Balance		1,102,289
Weighted Average Fair Value, Outstanding, Beginning Balance		$ 0
Weighted Average Grant Date Fair Value Per Share, Granted		16
Weighted Average Grant Date Fair Value Per Share, Vested		16
Weighted Average Grant Date Fair Value Per Share, Forfeited		16
Weighted Average Fair Value, Outstanding, Ending Balance		$ 16

Incentive Equity Plans - Summ_3

Incentive Equity Plans - Summary of Stock Option Activity (Details) - $ / shares	1 Months Ended	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options, Granted	1,995,660
Options, Exercisable, Ending Balance	357,658
Weighted Average Fair Value, Granted			$ 9.88
2018 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options, Outstanding, Beginning Balance			0
Options, Granted		286,307	2,291,967
Options, Forfeited			(18,943)
Options, Outstanding, Ending Balance		2,273,024	2,273,024
Options, Exercisable, Ending Balance		420,087	420,087
Weighted Average Fair Value, Outstanding, Beginning Balance			$ 0
Weighted Average Fair Value, Granted			9.88
Weighted Average Fair Value, Forfeited			9.86
Weighted Average Fair Value, Outstanding, Ending Balance		$ 9.88	9.88
Weighted Average Fair Value, Exercisable, Ending Balance		$ 9.53	$ 9.53

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Income tax expense (benefit)	$ 0	$ 0
U.S. corporate tax rate	21.00%	34.00%
Reduction to the deferred tax assets		$ 7,200,000
Unrecognized tax benefits, income tax penalties and interest accrued	$ 0	$ 0
Effective income tax rate reconciliation, tax credit, research and development, percent	2.50%	2.70%
Effective income tax rate reconciliation, tax credit, research and development, amount	$ 106,316	$ 562,385
Maximum
Income Tax Disclosure [Line Items]
U.S. corporate tax rate		35.00%
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 58,300,000	$ 52,300,000
Net operating loss carryforwards, expiration year	2037	2037
Operating losses carry forward, maximum deductibility percentage	80.00%
Tax credit carryforwards	$ 2,700,000	$ 1,700,000
Tax credit carryforwards, expiration year	2038	2038
Income tax examination year			2015
State
Income Tax Disclosure [Line Items]
Income tax expense (benefit)	$ 0
Research and Development Tax Credits
Income Tax Disclosure [Line Items]
Increase in valuation allowance	$ 8,500,000	$ 1,500,000
Effective income tax rate reconciliation, tax credit, research and development, percent	65.00%	65.00%
Income taxes receivable	$ 1,100,000	$ 989,219

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of the U.S. Federal Statutory Income Tax Rate to Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Federal statutory rate	21.00%	34.00%
Federal tax rate change		(30.00%)
Federal research tax credit	2.50%	2.70%
Stock compensation	(3.30%)	(0.30%)
Change in valuation allowance	(20.30%)	(6.30%)
Other	0.10%	(0.10%)
Reconciliation of effective income tax rate	0.00%	0.00%

Income Taxes - Summary of Defer

Income Taxes - Summary of Deferred Income Taxes (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Deferred income tax assets:
Loss carryforwards	$ 12,236,973	$ 10,978,713
Deferred revenue	6,179,875	736,672
Tax credits	2,681,628	1,658,899
Stock compensation	1,084,096
Other	181,734	65,714
Total deferred income tax assets	22,364,306	13,439,998
Deferred income tax liabilities
Other	(35,345)	(24,079)
Property, equipment and leasehold improvements	(540,609)	(100,072)
Total deferred income tax liabilities	(575,954)	(124,151)
Less valuation allowance	(21,788,352)	(13,315,847)
Net deferred income tax assets	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Frequency of rental payments	monthly
Rent expense	$ 606,538	$ 402,897

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Annual Lease Payments (Details)	Dec. 31, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 705,606
2020	731,541
2021	731,541
2022	716,906
Total	$ 2,885,594

Net Loss Per Common Share_Uni_2

Net Loss Per Common Share/Unit - Basic and Diluted Loss per Common Share/Unit (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net loss	$ (16,087,866)	$ (13,387,672)	$ (7,854,542)	$ (4,150,386)	$ (4,728,026)	$ (6,397,272)	$ (6,678,192)	$ (6,245,716)	$ (41,480,466)	$ (24,049,206)
Change in redemption value of redeemable preferred units		$ (112,050,609)	$ (14,834,049)	$ (71,482,098)	$ (4,570,431)				(198,366,756)	(4,570,431)
Net loss attributable to common shares/units – basic and diluted									$ (239,847,222)	$ (28,619,637)
Weighted average number of common shares/units outstanding, basic and diluted	31,098,634	2,010,807	1,897,544	1,897,544	1,897,544	1,897,544	1,897,544	1,897,544	9,422,799	1,897,544
Net loss per common share/unit	$ (0.52)	$ (62.38)	$ (11.96)	$ (39.86)	$ (4.90)	$ (3.37)	$ (3.52)	$ (3.29)	$ (25.45)	$ (15.08)

Net Loss Per Common Share_Uni_3

Net Loss Per Common Share/Unit - Common Share/Unit Equivalents Excluded from the Calculations of Diluted Loss Per Common Share/Unit (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common share/unit equivalents excluded from the calculations of diluted loss per common share/unit	3,375,313	18,301,112
Redeemable Preferred Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common share/unit equivalents excluded from the calculations of diluted loss per common share/unit		14,597,268
Incentive Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common share/unit equivalents excluded from the calculations of diluted loss per common share/unit		3,669,963
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common share/unit equivalents excluded from the calculations of diluted loss per common share/unit	2,273,024
Preferred Unit Warrant
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common share/unit equivalents excluded from the calculations of diluted loss per common share/unit		33,881
Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common share/unit equivalents excluded from the calculations of diluted loss per common share/unit	1,102,289

Related Parties - Additional In

Related Parties - Additional Information (Details) - USD ($)	1 Months Ended		12 Months Ended
	Sep. 30, 2018	Jul. 31, 2013	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Share-based award, stock options granted	1,995,660
Incentive units vesting period			4 years
Yale University | Minimum
Related Party Transaction [Line Items]
Payment for annual license maintenance royalty until the first commercial sale of product		$ 75,000
Yale University | Office of Cooperative Research
Related Party Transaction [Line Items]
Payments for license maintenance royalty fee, reimbursable patent costs and sublicense fee			$ 288,517	$ 152,603
Consulting Agreement | Dr. Craig Crews
Related Party Transaction [Line Items]
Payment for consulting service			176,110	150,000
Monthly consulting services fee			$ 20,833
Consulting agreement term			3 years
Share-based award, stock options granted			235,150
Exercise price of stock options			$ 16
Incentive units vesting period			3 years
Corporate Sponsored Research Agreement (SRA) | Yale University
Related Party Transaction [Line Items]
Total research payments			$ 851,161	$ 404,632
Related party agreement, description			In July 2016, the Company entered into a Corporate Sponsored Research Agreement (SRA) with Yale University, under the direction of Professor Crews, which was amended in April 2018. The amended SRA extended the agreement until April 2021 and amended the scope of work. The amended SRA requires quarterly payments of $250,000 through the end of the agreement. The total payments made under the SRA for 2018 and 2017 were $851,161 and $404,632, respectively.
Agreement expiration period			2018-04
Amended Corporate Sponsored Research Agreement | Yale University
Related Party Transaction [Line Items]
Quarterly research payments			$ 250,000

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Selected Quarterly Financial Information [Abstract]
Revenue	$ 3,440,165	$ 3,375,264	$ 3,399,895	$ 4,108,596	$ 2,572,293	$ 1,668,861	$ 1,668,861	$ 1,668,861	$ 14,323,920	$ 7,578,876
Operating expenses:
Research and development	14,562,299	13,149,879	10,337,835	7,143,817	6,690,189	7,222,897	7,823,617	7,056,199	45,193,830	28,792,902
General and administrative	5,821,445	4,284,231	1,579,605	1,246,887	1,189,122	857,310	569,983	929,826	12,932,168	3,546,241
Total operating expenses	20,383,744	17,434,110	11,917,440	8,390,704	7,879,311	8,080,207	8,393,600	7,986,025	58,125,998	32,339,143
Loss from operations	(16,943,579)	(14,058,846)	(8,517,545)	(4,282,108)	(5,307,018)	(6,411,346)	(6,724,739)	(6,317,164)	(43,802,078)	(24,760,267)
Other income (expenses)
Other income, net	(315,764)	160,100	130,945	127,449	553,129	607	159	264	102,730	554,159
Change in fair value of preferred unit warrant			2,516	(196,295)	1,533	1,546	1,457	1,335	(193,779)	5,871
Interest income	1,196,113	523,338	539,413	211,237	35,781	24,140	57,904	83,562	2,470,101	201,388
Interest expense	(24,636)	(12,264)	(9,871)	(10,669)	(11,451)	(12,219)	(12,973)	(13,713)	(57,440)	(50,357)
Total other income	855,713	671,174	663,003	131,722	578,992	14,074	46,547	71,448	2,321,612	711,061
Net loss	(16,087,866)	(13,387,672)	(7,854,542)	(4,150,386)	(4,728,026)	(6,397,272)	(6,678,192)	(6,245,716)	(41,480,466)	(24,049,206)
Change in redemption value of redeemable preferred units		(112,050,609)	(14,834,049)	(71,482,098)	(4,570,431)				(198,366,756)	(4,570,431)
Net loss attributable to common shares/units	$ (16,087,866)	$ (125,438,281)	$ (22,688,591)	$ (75,632,484)	$ (9,298,457)	$ (6,397,272)	$ (6,678,192)	$ (6,245,716)	$ (239,847,222)	$ (28,619,637)
Net loss per common share/unit, basic and diluted	$ (0.52)	$ (62.38)	$ (11.96)	$ (39.86)	$ (4.90)	$ (3.37)	$ (3.52)	$ (3.29)	$ (25.45)	$ (15.08)
Weighted average common shares/units outstanding, basic and diluted	31,098,634	2,010,807	1,897,544	1,897,544	1,897,544	1,897,544	1,897,544	1,897,544	9,422,799	1,897,544
Total other income	$ 855,713	$ 671,174	$ 663,003	$ 131,722	$ 578,992	$ 14,074	$ 46,547	$ 71,448	$ 2,321,612	$ 711,061