Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2019	Nov. 01, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	CUE
Entity Registrant Name	Cue Biopharma, Inc.
Entity Central Index Key	0001645460
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Interactive Data Current	Yes
Document Transition Report	false
Title of 12(b) Security	Common Stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		22,994,143
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-38327
Entity Tax Identification Number	47-3324577
Entity Address, Address Line One	21 Erie St. Cambridge
Entity Address State Or Province	MA
Entity Address, Postal Zip Code	02139
City Area Code	617
Local Phone Number	949-2680

Consolidated Balance Sheets (Unaudited) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 31,379,000	$ 20,800,000
Marketable securities, short term	0	18,413,000
Accounts receivable	610,000
Restricted cash, short-term		50,000
Prepaid expenses and other current assets	1,001,000	1,347,000
Total current assets	32,990,000	40,610,000
Property and equipment, net	2,031,000	2,781,000
Operating lease right-of-use	6,656,000
Deposits	2,589,000	1,013,000
Restricted cash, long term	150,000	150,000
Other long term assets	793,000	809,000
Total assets	45,209,000	45,363,000
Current liabilities:
Accounts payable	1,178,000	2,035,000
Accrued expenses	1,555,000	1,788,000
Research and development contract liability, current portion	3,225,000	2,012,000
Deferred rent		381,000
Operating lease liability, current portion	4,434,000
Total current liabilities	10,392,000	6,216,000
Research and development contract liability, net of current portion	5,185,000	5,175,000
Operating lease liability, net of current portion	2,610,000
Total liabilities	18,187,000	11,391,000
Stockholders’ equity:
Preferred Stock, $0.001 par value; 10,000,000 shares authorized and 0 shares issued and outstanding at September 30, 2019 and December 31, 2018
Common stock, $0.001 par value; 50,000,000 shares authorized; 22,969,966 and 20,697,453 shares issued and outstanding, at September 30, 2019 and December 31, 2018, respectively	23,000	21,000
Additional paid in capital	126,582,000	105,763,000
Accumulated other comprehensive loss		(11,000)
Accumulated deficit	(99,583,000)	(71,801,000)
Total stockholders’ equity	27,022,000	33,972,000
Total liabilities and stockholders’ equity	$ 45,209,000	$ 45,363,000

Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	22,969,966	20,697,453
Common stock, shares outstanding	22,969,966	20,697,453

Consolidated Statements of Operations and Other Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Collaboration revenue	$ 984	$ 449	$ 2,409	$ 812
Operating expenses:
General and administrative	2,776	2,895	9,640	6,821
Research and development	5,302	10,313	20,523	21,721
Total operating expenses	8,078	13,208	30,163	28,542
Loss from operations	(7,094)	(12,759)	(27,754)	(27,730)
Other income:
Interest income	99	102	309	272
Other income, net	5	98	77	99
Total other income	104	200	386	371
Loss before income taxes	(6,990)	(12,559)	(27,368)	(27,359)
Income tax expense			(413)
Net loss	(6,990)	(12,559)	(27,782)	(27,359)
Unrealized gains (losses) from available-for-sale securities, net of tax of $0		(20)	11	(20)
Comprehensive loss	$ (6,990)	$ (12,579)	$ (27,771)	$ (27,379)
Net loss per common share – basic and diluted	$ (0.31)	$ (0.62)	$ (1.30)	$ (1.36)
Weighted average common shares outstanding – basic and diluted	22,450,071	20,132,277	21,334,195	20,111,519

Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Common Stock To Be Issued	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance at Dec. 31, 2017	$ 61,607	$ 19	$ 1	$ 94,408		$ (32,821)
Balance, Shares at Dec. 31, 2017		19,459,194	671,572
Stock-based compensation	5,163			5,163
Common stock to be issued pursuant to license agreements		$ 1	$ (1)
Common stock to be issued pursuant to license agreements (in shares)		671,572	(671,572)
Exercise of stock options	13			13
Exercise of stock options, Shares		2,500
Net loss	(27,359)				$ (20)	(27,359)
Net loss	(27,379)
Balance at Sep. 30, 2018	39,404	$ 20		99,584	(20)	(60,180)
Balance, Shares at Sep. 30, 2018		20,133,266
Balance at Jul. 01, 2018	49,232	$ 20		96,841		(47,629)
Balance, Shares at Jul. 01, 2018		20,130,766
Stock-based compensation	2,743			2,743
Other comprehensive income (loss)	(20)				(20)
Exercise of stock options, Shares		2,500
Net loss	(12,551)					(12,551)
Balance at Sep. 30, 2018	39,404	$ 20		99,584	(20)	(60,180)
Balance, Shares at Sep. 30, 2018		20,133,266
Balance at Dec. 31, 2018	33,972	$ 21		105,763	(11)	(71,801)
Balance, Shares at Dec. 31, 2018		20,697,453
Issuance of common stock frompublic offerings, net of underwriter commissions and fees	15,652	$ 2		15,650
Issuance of common stock from public offerings, net of underwriter commissions and fees, Shares		2,084,615
Stock-based compensation	4,525			4,525
Other comprehensive income (loss)	11				$ 11
Exercise of stock options	$ 644			644
Exercise of stock options, Shares	187,898	187,898
Net loss	$ (27,782)					(27,782)
Net loss	(27,771)
Balance at Sep. 30, 2019	27,022	$ 23		126,582		(99,583)
Balance, Shares at Sep. 30, 2019		22,969,966
Balance at Jul. 01, 2019	20,280	$ 21		112,852		(92,593)
Balance, Shares at Jul. 01, 2019		21,313,570
Issuance of common stock frompublic offerings, net of underwriter commissions and fees	11,937	$ 2		11,935
Issuance of common stock from public offerings, net of underwriter commissions and fees, Shares		1,560,541
Stock-based compensation	1,440			1,440
Exercise of stock options	355			355
Exercise of stock options, Shares		95,855
Net loss	(6,990)					(6,990)
Balance at Sep. 30, 2019	$ 27,022	$ 23		$ 126,582		$ (99,583)
Balance, Shares at Sep. 30, 2019		22,969,966

Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities
Net loss	$ (27,782,000)	$ (27,359,000)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation	605,000	556,000
Stock-based compensation	4,525,000	5,163,000
Deferred rent		188,000
Operating lease right of use amortization	3,036,000
Non-cash investment expense	(68,000)	(52,000)
Loss on disposal of fixed asset	54,000
Changes in operating assets and liabilities:
Account receivable	(610,000)
Prepaid expenses and other current assets	346,000	(101,000)
Other Assets	8,000
Operating lease liability	(3,029,000)
Deposits	(1,576,000)	(551,000)
Accounts payable	(857,000)	(662,000)
Accrued expenses	(233,000)	1,117,000
Research and development contract liability	1,222,000	(812,000)
Net cash used in operating activities	(24,359,000)	(22,513,000)
Cash flows from investing activities
Purchases of property and equipment	(36,000)	(1,734,000)
Purchases of marketable securities		(23,307,000)
Cash received from sale of fixed asset	127,000
Maturity and redemption of short term investments	18,501,000
Net cash provided by (used in) investing activities	18,592,000	(25,041,000)
Cash flows from financing activities
Proceeds from the public offering of common stock, net of underwriter's commission and fees	15,652,000
Proceeds from exercise of stock options		12,000
Proceeds from the exercise of common stock	644,000
Net cash provided by financing activities	16,296,000	12,000
Net increase/(decrease) in cash, cash equivalents, and restricted cash	10,529,000	(47,542,000)
Cash, cash equivalents, and restricted cash at beginning of period	21,000,000	63,584,000
Cash, cash equivalents, and restricted cash at end of period	31,529,000	$ 16,042,000
Supplemental disclosures of cash flow information:
Cash paid for income taxes	$ (413,000)

Organization and Nature of Business

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Nature of Business

1.	Organization and Nature of Business

Cue Biopharma, Inc. (the “Company”) was incorporated in the State of Delaware on December 31, 2014 under the name Imagen Biopharma, Inc., and completed its organization, formation, and initial capitalization activities effective as of January 1, 2015. In October 2016, the Company changed its name to Cue Biopharma, Inc. The Company’s corporate office and research facilities are located in Cambridge, Massachusetts.

The Company is in the development stage and has incurred recurring losses and negative cash flows from operations. As of September 30, 2019, the Company had cash and cash equivalents of approximately $31,379,000. Management believes that current cash and cash equivalents on hand at September 30, 2019, along with the funds available to the Company through its at-the-market equity offering sales agreement with Stifel Nicolaus & Company, Inc., should be sufficient to fund operations for the next twelve months from the date of issuance of these financial statements; however, the future viability of the Company is dependent on its ability to raise additional capital to finance its operations and to fund increased research and development costs in order to seek approval for commercialization of its product candidates. The Company’s failure to raise capital as and when needed would have a negative impact on its financial condition and its ability to pursue its business strategies as this capital is necessary for the Company to perform the research and development activities required to develop the Company’s product candidates in order to generate future revenue streams.

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2019

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	Summary of Significant Accounting Policies

Basis of Presentation

The accompanying unaudited consolidated financial statements as of September 30, 2019, and for the three and nine months ended September 30, 2019, and 2018, have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”) and Generally Accepted Accounting Principles in the United States (“U.S. GAAP”) for financial information, which prescribes elimination of all significant intercompany accounts and transactions in the accounts of the Company and its wholly owned subsidiary Cue Biopharma Securities Corporation, Inc. which was formed in December 2018 and incorporated in the Commonwealth of Massachusetts. In the opinion of management, these financial statements reflect all adjustments which are necessary for a fair statement of the Company’s financial position and results of its operations, as of and for the periods presented. These financial statements should be read in conjunction with the financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K filed with the SEC on March 14, 2019, as amended on Form 10-K/A filed with the SEC on April 30, 2019 and on Form 10K/A filed with the SEC on July 9, 2019.

Interim results for the three and nine months ended September 30, 2019 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2019, or any future periods.

Public Offerings

In June 2019, the Company entered into an at-the-market equity offering sales agreement with Stifel Nicolaus & Company, Inc. (“Stifel”) to sell shares of the Company’s common stock for aggregate gross proceeds of up to $30 million, from time to time, through an “at-the-market” equity offering program under which Stifel acts as sales agent. The sales agreement will terminate upon the earliest of (a) the sale of $30 million of shares of the Company’s common stock or (b) the termination of the sales agreement by the Company or Stifel. As of September 30, 2019, the Company had sold 2,084,615 shares of common stock under the sales agreement for proceeds of approximately $15.7 million, net of commissions paid, but excluding estimated transaction expenses.

Consolidation

The accompanying consolidated financial statements include the Company and its wholly owned subsidiary, Cue Biopharma Securities Corporation, Inc. The Company has eliminated all intercompany transactions.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Significant estimates include estimates related to collaboration revenue, the accounting for potential liabilities and accrued expenses, the assumptions utilized in valuing stock-based compensation issued for services, the realization of deferred tax assets, and the useful life with respect to long-lived assets and intangibles. Actual results could differ from those estimates.

Cash Concentrations

The Company maintains its cash balances with a financial institution in Federally insured accounts and may periodically have cash balances in excess of insurance limits. The Company maintains its accounts with a financial institution with a high credit rating. The Company has not experienced any losses to date and believes that it is not exposed to any significant credit risk on cash.

Cash and Cash Equivalents

The Company considers all highly liquid investments with a maturity of three months or less at the date of purchase to be cash equivalents. The Company currently invests available cash in money market funds.

Marketable Securities

Marketable securities consist of investments with original maturities greater than ninety days and less than one year from the balance sheet date. The Company classifies all of its investments as available-for-sale securities. Accordingly, these investments are recorded at fair value, which is based on quoted market prices. Unrealized gains and losses are recognized and determined on a specific identification basis and are included in other comprehensive loss. Realized gains and losses are determined on a specific identification basis and are included in other income (loss) on the income statement. Amortization and accretion of discounts and premiums is recorded in interest income. The Company may invest available cash in United States Treasury obligations.

Restricted Cash

The Company purchased a $50,000 certificate of deposit to collateralize a credit card account with a commercial bank that was classified as short-term restricted cash as of December 31, 2018. As of September 30, 2019, the account was closed, resulting in a $0 balance in short-term restricted cash. The Company also had $150,000 in restricted cash with a commercial bank to collateralize a credit card as of September 30, 2019 and December 31, 2018.

Property and Equipment

Property and equipment is recorded at cost. Major improvements are capitalized, while maintenance and repairs are charged to expense as incurred. Gains and losses from disposition of property and equipment are included in income and expense when realized. Amortization of leasehold improvements is provided using the straight-line method over the shorter of the lease term or the useful life of the underlying assets. Depreciation of property and equipment is provided using the straight-line method over the following estimated useful lives:

Laboratory equipment		5 years
Computer and office equipment		3 years
Furniture and fixtures		3-8 years

The Company recognizes depreciation and amortization expense in general and administrative expenses and in research and development expenses in the Company’s statements of operations, depending on how each category of property and equipment is utilized in the Company’s business activities.

Trademark

Trademark consists of the Company’s right, title and interest to the CUE BIOLOGICS Mark, and any derivative mark incorporating CUE, throughout the world, together with all associated goodwill and common law rights appurtenant thereto, including, but not limited to, any right, title and interest in any corporate name, company name, business, name, trade name, dba, domain name, or other source identifier incorporating CUE.

The Company has classified the trademark as a component of other long-term assets, having a useful life of 15 years at September 30, 2019. The Company evaluates the status of this intangible asset for amortization and impairment at each quarter end and year end reporting date.

Revenue Recognition

The Company adopted Accounting Standards Codification, Topic 606, Revenue from Contracts with Customers (“ASC 606”), during 2018. The Company generates revenue solely through collaboration arrangements with strategic partners for the development and commercialization of product candidates. The core principle of ASC 606 is that an entity should recognize revenue to depict the transfer of promised goods and/or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and/or services. To determine the appropriate amount of revenue to be recognized for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following steps: (i) Identify the contract(s) with the customer, (ii) Identify the performance obligations in the contract, (iii) Determine the transaction price, (iv) Allocate the transaction price to the performance obligations in the contract and (v) Recognize revenue when (or as) each performance obligation is satisfied.

The Company recognizes collaboration revenue under certain of the Company’s license or collaboration agreements that are within the scope of ASC 606. The Company’s contracts with customers typically include promises related to licenses to intellectual property and research and development services. If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgement to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. Accordingly, the transaction price is generally comprised of a fixed fee due at contract inception and variable consideration in the form of milestone payments due upon the achievement of specified events and tiered royalties earned when customers recognize net sales of licensed products. The Company measures the transaction price based on the amount of consideration to which it expects to be entitled in exchange for transferring the promised goods and/or services to the customer. The Company utilizes the “most likely amount” method to estimate the amount of variable consideration, to predict the amount of consideration to which it will be entitled for its one open contract. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. At the inception of each arrangement that includes development and regulatory milestone payments, the Company evaluates whether the associated event is considered probable of achievement and estimates the amount to be included in the transaction price using the most likely amount method. Currently, the Company has one contract with an option to acquire additional goods and/or services in the form of additional research and development services for additional product candidates.

Research and Development Expenses

Research and development expenses consist primarily of compensation costs, fees paid to consultants, outside service providers and organizations (including research institutes at universities), facility costs, and development and clinical trial costs with respect to the Company’s product candidates.

Research and development expenses incurred under contracts are expensed ratably over the life of the underlying contracts, unless the achievement of milestones, the completion of contracted work, or other information indicates that a different pattern of performance is more appropriate. Other research and development expenses are charged to operations as incurred.

Nonrefundable advance payments are recognized as an expense as the related services are performed. The Company evaluates whether it expects the services to be rendered at each quarter end and year end reporting date. If the Company does not expect the services to be rendered, the advance payment is charged to expense. Nonrefundable advance payments for research and development services are included in prepaid and other current assets on the balance sheet. To the extent that a nonrefundable advance payment is for contracted services to be performed within 12 months from the reporting date, such advance is included in current assets; otherwise, such advance is included in non-current assets.

The Company evaluates the status of its research and development agreements and contracts, and the carrying amount of the related assets and liabilities, at each quarter end and year end reporting date, and adjusts the carrying amounts and their classification on the balance sheet as appropriate.

Patent Expenses

The Company is the exclusive worldwide licensee of, and has patent applications pending for, numerous domestic and foreign patents. Due to the significant uncertainty associated with the successful development of one or more commercially viable product candidates based on the Company’s research efforts and any related patent applications, all patent costs, including patent-related legal fees, filing fees and other costs are charged to expense as incurred. For the three and nine months ended September 30, 2019, patent expenses were $476,000 and $1,323,000, respectively, and $225,000 and $493,000 for the three and nine months ended September 30, 2018. Patent expenses are included in general and administrative expenses in the Company’s statements of operations.

Licensing Fees and Costs

Licensing fees and costs consist primarily of costs relating to the acquisition of the Company’s license agreement with the Albert Einstein College of Medicine (“Einstein”), including related royalties, maintenance fees, milestone payments and product development costs. Licensing fees and costs are charged to expense as incurred.

Long-Lived Assets

The Company reviews long-lived assets, consisting of property and equipment, for impairment at each fiscal year end or when events or changes in circumstances indicate the carrying value of these assets may exceed their current fair values. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, an impairment charge is recognized for the amount by which the carrying amount of the asset exceeds the fair value of the assets. Assets to be disposed of are separately presented in the balance sheet and reported at the lower of the carrying amount or fair value less costs to sell and are no longer depreciated. The Company has not historically recorded any impairment to its long-lived assets. In the future, if events or market conditions affect the estimated fair value to the extent that a long-lived asset is impaired, the Company will adjust the carrying value of these long-lived assets in the period in which the impairment occurs.

Leases

In February 2016, the FASB issued ASU 2016-02, Leases (ASC 842), which supersedes the existing guidance for lease accounting, Leases (Topic 840). ASU 2016-02 requires a lessee to record a right-of-use asset and a corresponding lease liability, for most lease arrangements on the balance sheet. Under the standard, disclosure of key information about leasing arrangements to assist users of the financial statements to assess the amount, timing and uncertainty of cash flows arising from leases are required. The new standard is effective for fiscal years beginning after December 15, 2018.

The standard permits two transition methods, (1) to apply the new lease requirements at the beginning of the earliest period presented, or (2) to apply the new lease requirements at the effective date. The Company adopted ASC 842 as of January 1, 2019 using the effective date method, in which we did not restate prior periods. Upon adoption, the Company elected the package of practical expedients permitted under the transition guidance within ASC 842, which among other things, allowed it to carry forward the historical lease classification.

Stock-Based Compensation

The Company periodically issues stock options to officers, directors, employees, Scientific and Clinical Advisory Board members, non-employees and consultants for services rendered. Such issuances vest and expire according to terms established at the issuance date.

Stock-based payments to officers, directors, members of the Company’s Scientific and Clinical Advisory Board, non-employees and outside consultants and employees, including grants of employee stock options, are recognized in the financial statements based on their grant date fair values. Stock option grants, which are generally time-vested, are measured at the grant date fair value and charged to operations on a straight-line basis over the service period, which generally approximates the vesting term. The Company also grants performance-based awards to periodically to officers of the Company. The Company recognizes compensation costs related to performance awards over the requisite service period if and when the Company concludes that it is probable that the performance condition will be achieved.

The fair value of stock options is determined utilizing the Black-Scholes option-pricing model, which is affected by several variables, including the risk-free interest rate, the expected dividend yield, the life of the equity award, the exercise price of the stock option as compared to the fair value of the common stock on the grant date, and the estimated volatility of the common stock over the term of the equity award.

The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant. Until the Company has established a trading market for its common stock, estimated volatility is based on the average historical volatilities of comparable public companies in a similar industry. The expected dividend yield is based on the current yield at the grant date; the Company has never declared or paid dividends and has no plans to do so for the foreseeable future. As permitted by Staff Accounting Bulletin No. 107, due to the Company’s lack of trading history and option activity, management utilizes the simplified method to estimate the expected term of options at the date of grant. The exercise price is determined based on the fair value of the Company’s common stock at the date of grant. The Company accounts for forfeitures as they occur.

The Company recognizes the fair value of stock-based compensation in general and administrative expenses and in research and development expenses in the Company’s statements of operations, depending on the type of services provided by the recipient of the equity award.

Comprehensive Income (Loss)

Components of comprehensive income or loss, including net income or loss, are reported in the financial statements in the period in which they are recognized. Other comprehensive income or loss is defined as the change in equity during a period from transactions and other and other events and circumstances from non-owner sources. Net income (loss) and other comprehensive income (loss) are reported net of any related tax effect to arrive at comprehensive income (loss). Comprehensive loss includes net loss as well as changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. The Company’s only element of other comprehensive loss in all periods presented was unrealized gain or loss on available-for-sale securities.

Earnings (Loss) Per Share

The Company’s computation of earnings (loss) per share (“EPS”) for the respective periods includes basic and diluted EPS. Basic EPS is measured as the income (loss) attributable to common stockholders divided by the weighted average number of common shares outstanding for the period. Diluted EPS is similar to basic EPS but presents the dilutive effect on a per share basis of potential common shares that would result from the exercise of outstanding stock options and warrants as if they had been exercised at the beginning of the periods presented, or issuance date, if later. Potential common shares that have an anti-dilutive effect (i.e., those that increase income per share or decrease loss per share) are excluded from the calculation of diluted EPS. Basic and diluted loss per common share is the same for all periods presented because all outstanding stock options and warrants are anti-dilutive.

At September 30, 2019, the Company excluded the outstanding securities summarized below, which entitle the holders thereof to acquire shares of common stock, from its calculation of earnings per share, as their effect would have been anti-dilutive.

	September 30,
	2019		2018
Common stock warrants		1,252,441		1,252,441
Common stock options		4,629,085		4,427,821
Total		5,881,526		5,680,262

Fair Value of Financial Instruments

The authoritative guidance with respect to fair value established a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three levels and requires that assets and liabilities carried at fair value be classified and disclosed in one of three categories, as presented below.

Level 1. Observable inputs such as quoted prices in active markets for an identical asset or liability that the Company has the ability to access as of the measurement date. Financial assets and liabilities utilizing Level 1 inputs include active-exchange traded securities and exchange-based derivatives.

Level 2. Inputs, other than quoted prices included within Level 1, which are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. Financial assets and liabilities utilizing Level 2 inputs include fixed income securities, non-exchange-based derivatives, mutual funds, and fair-value hedges.

Level 3. Unobservable inputs in which there is little or no market data for the asset or liability which requires the reporting entity to develop its own assumptions. Financial assets and liabilities utilizing Level 3 inputs include infrequently traded non-exchange-based derivatives and commingled investment funds and are measured using present value pricing models.

The Company determines the level in the fair value hierarchy within which each fair value measurement falls in its entirety, based on the lowest level input that is significant to the fair value measurement in its entirety. In determining the appropriate levels, the Company performs an analysis of the assets and liabilities at each reporting period end.

The Company had approximately $19,425,000 in cash equivalents and $0 in short-term marketable securities that were measured and recorded at fair value on the Company’s balance sheet as of September 30, 2019. The Company had approximately $10,548,000 in cash equivalents and $18,412,000 in short-term marketable securities that were measured and recorded at fair value on the Company’s balance sheet as of December 31, 2018.

The carrying value of financial instruments (consisting of cash, a certificate of deposit, accounts payable, accrued compensation and accrued expenses) is considered to be representative of their respective fair values due to the short-term nature of those instruments.

Recent Accounting Pronouncements

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, or ASU 2018-03. The guidance in this ASU modify the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement. Under the new guidance, transfers between asset classes and the valuation related to level 3 assets is modified. The new standard is effective for annual reporting periods beginning after December 15, 2019, including interim reporting periods within each annual reporting period. The Company is currently evaluating the impact of the adoption of this ASU on the financial statements.

Management does not believe that any other recently issued, but not yet effective, authoritative guidance, if currently adopted, would have a material impact on the Company’s financial statement presentation or disclosures.

Fair Value

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value

3.	Fair Value

The Company accounts for its financial assets and liabilities using fair value measurements. The authoritative accounting guidance defines fair value, establishes a framework for measuring fair value under generally accepted accounting principles and enhances disclosures about fair value measurements. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date.

The following table presents information about the Company’s assets that are measured at fair value on a recurring basis as of September 30, 2019 and indicate the level of the fair value hierarchy utilized to determine such fair value:

	Fair Value Measurements as of September 30, 2019
	(in thousands)
	Level 1		Level 2		Level 3		Fair Value
Cash equivalents	$	19,425	$	—	$	—	$	19,425
Marketable securities		—		—		—		—
Total	$	19,425	$	—	$	—	$	19,425

	Fair Value Measurements as of December 31, 2018
	(in thousands)
	Level 1		Level 2		Level 3		Fair Value
Cash equivalents	$	10,548	$	—	$	—	$	10,548
Marketable securities		—		18,412		—		18,412
Total	$	10,548	$	18,412	$	—	$	28,960

As of September 30, 2019, the Company reported approximately $19,425,000 of cash equivalents. The Company’s cash equivalents that are invested in money market funds are valued using Level 1 inputs for identical securities. The Company measures the fair value of marketable securities that are invested in United States Treasury securities using Level 2 inputs and primarily relies on quoted prices in active markets for similar marketable securities. During the three and nine months ended September 30, 2019, there were no transfers between Level 2 and Level 3. As of December 31, 2018, the Company reported approximately $28,960,000 of cash equivalents and marketable securities. During the year ended December 31, 2018, there were no transfers between Level 2 and Level 3.

The carrying values of accounts receivable, prepaid expenses, other current assets, accounts payable and accrued expenses approximate their fair value due to the short-term nature of these balances.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Marketable Securities

9 Months Ended

Sep. 30, 2019

Investments Debt And Equity Securities [Abstract]

Marketable Securities

4.	Marketable Securities

As of September 30, 2019 the Company had no investments in marketable securities. As of December 31, 2018, the fair value of available-for-sale marketable securities by type of security was as follows:

	December 31, 2018
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury Securities	$	18,423	$	—	$	(11	)	$	18,412
	$	18,423	$	—	$	(11	)	$	18,412

At September 30, 2019, there were $0 of investments in marketable securities. At December 31, 2018, marketable securities consisted of approximately $18,413,000 of investments that mature within twelve months. `

Property and Equipment

9 Months Ended

Sep. 30, 2019

Property Plant And Equipment [Abstract]

Property and Equipment

5.	Property and Equipment

Property and equipment as of September 30, 2019 and December 31, 2018 consisted of the following:

	September 30, 2019			December 31, 2018
	(in thousands)
Computer equipment	$	192		$	182
Laboratory equipment		3,578			3,872
Furniture and fixtures		93			93
		3,863			4,147
Less: Accumulated depreciation	$	(1,832	)	$	(1,366	)
Total property and equipment, net	$	2,031		$	2,781

Depreciation expense for the nine months ended September 30, 2019 and 2018 was approximately $605,000 and $556,000, respectively. During the nine months ended September 30, 2019, the Company sold lab equipment with an acquisition cost of $319,000 and accumulated depreciation of approximately $138,000 and realized a loss of approximately $54,000. Depreciation expense for the three months ended September 30, 2019 and 2018 was approximately $194,000 and $195,000, respectively.

Stock-Based Compensation

9 Months Ended

Sep. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

6.	Stock-Based Compensation

For stock options requiring an assessment of value during the nine months ended September 30, 2019, the fair value of each stock option award was estimated using the Black-Scholes option-pricing model utilizing the following assumptions:

		September 30, 2019
Risk-free interest rate		1.76 to 2.59%
Expected dividend yield		0%
Expected volatility		82.0-94.0%
Expected life		4.0 to 6.25 years

A summary of stock option activity for the nine months ended September 30, 2019 is as follows:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in Years)
Stock options outstanding at December 31, 2018		4,540,321		$	7.08		5.16
Granted		825,600			6.37
Exercised		(187,898	)	3.43
Cancelled		(548,938	)	9.17
Stock options outstanding at September 30, 2019		4,629,085			6.86		5.36
Stock options exercisable at September 30, 2019		2,172,376		$	5.82		4.58

As of September 30, 2019, total unrecognized stock-based compensation was approximately $11,046,000, which is expected to be recognized as an operating expense in the Company’s statement of operations through June 2023.

The intrinsic value of exercisable but unexercised in-the-money stock options at September 30, 2019, was approximately $7,594,000, based on a fair value of $8.43 per share on September 30, 2019.

Stock-based compensation for the three and nine months ended September 30, 2019 and 2018 was included in the statement of operations as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
(in thousands)	2019		2018		2019		2018
General and administrative	$	520	$	856	$	1,483	$	1,828
Research and development		919		1,875		3,042		3,335
Total	$	1,439	$	2,731	$	4,525	$	5,163

Revenue Recognition

9 Months Ended

Sep. 30, 2019

Revenue From Contract With Customer [Abstract]

Revenue Recognition

8.	Revenue Recognition

The terms of the Company’s arrangements with customers typically include the payment of one or more of the following: (i) Non-refundable, up-front payment, (ii) Development, regulatory and commercial milestone payments, (iii) Future options and (iv) Royalties on net sales of licensed products. Accordingly, the transaction price is generally comprised of a fixed fee due at contract inception and variable consideration in the form of milestone payments due upon the achievement of specified events and tiered royalties earned when customers recognize net sales of licensed products. The Company measures the transaction price based on the amount of consideration to which it expects to be entitled in exchange for transferring the promised goods and/or services to the customer. The Company utilizes the “most likely amount” method to estimate the amount of variable consideration, to predict the amount of consideration to which it will be entitled for its one open contract. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Milestone payments that are not within the control of the Company or the licensee, such as those dependent upon receipt of regulatory approval, are not considered to be probable of achievement until the triggering event occurs. At the end of each reporting period, the Company reevaluates the probability of achievement of each milestone and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenue and net loss in the period of adjustment.

For arrangements that include sales-based royalties, including milestone payments based upon the achievement of a certain level of product sales, the Company recognizes revenue upon the later of: (i) When the related sales occur or (ii) When the performance obligation to which some or all of the payment has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any development, regulatory or commercial milestones or royalty revenue resulting from any of its collaboration arrangements. Consideration that would be received for optional goods and/or services is excluded from the transaction price at contract inception.

The Company allocates the transaction price to each performance obligation identified in the contract on a relative standalone selling price basis, when applicable. However, certain components of variable consideration are allocated specifically to one or more particular performance obligations in a contact to the extent both of the following criteria are met: (i) The terms of the payment relate specifically to the efforts to satisfy the performance obligation or transfer the distinct good or service and (ii) Allocating the variable amount of consideration entirely to the performance obligation or the distinct good or service is consistent with the allocation objective of the standard whereby the amount allocated depicts the amount of consideration to which the entity expects to be entitled in exchange for transferring the promised goods or services. The Company develops assumptions that require judgement to determine the standalone selling price for each performance obligation identified in each contract. The key assumptions utilized in determining the standalone selling price for each performance obligation may include forecasted revenues, development timelines, estimated research and development costs, discount rates, likelihood of exercise and probabilities of technical and regulatory success.

Revenue is recognized based on the amount of the transaction price that is allocated to each respective performance obligation when or as the performance obligation is satisfied by transferring a promised good and/or service to the customer. For performance obligations that are satisfied over time, the Company recognizes revenue by measuring the progress toward complete satisfaction of the performance obligation using a single method of measuring progress which depicts the performance in transferring control of the associated goods and/or services to the customer. The Company uses input methods to measure the progress toward the complete satisfaction of performance obligations satisfied over time. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenue and net loss in the period of adjustment.

As it relates to the Collaboration Agreement with Merck Sharp & Dohme Corp. (“Merck”) the Company recognized the upfront payment associated with its one open contract as a contract liability upon receipt of payment as it requires deferral of revenue recognition to a future period until the Company performs its obligations under the arrangement. Amounts expected to be recognized as revenue within the twelve months following the balance sheet date are classified in current liabilities. Amounts not expected to be recognized as revenue within the twelve months following the balance sheet date are classified as contract liabilities, net of current portion. The Company determined that there was one performance obligation; consisting of the license and research development services. Thus, the transaction price of $2.5 million was allocated to the single performance obligation.

The Company does not believe that any variable consideration should be included in the transaction price at September 30, 2019. Such assessment considered the application of the constraint to ensure that estimates of variable consideration would be included in the transaction price only to the extent the Company had a high degree of confidence that revenue would not be reversed in a subsequent reporting period. The Company will re-evaluate the transaction price, including the estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as other changes in circumstances occur. For the three months ended September 30, 2019 and 2018, the Company recorded approximately $174,000 and $449,000, respectively and for the nine months ended September 30, 2019 and 2018, the Company recognized approximately $874,000 and $812,000, respectively, in collaboration revenue related to this agreement. As of September 30, 2019, the Company recorded short and long-term research and development liabilities on its balance sheet dated of approximately $484,000 and $0, respectively.

On November 6, 2018, the Company entered into a Collaboration Agreement with LG Chem Life Sciences (“LG Chem”) related to the development of the Company’s Immuno-STATs focused in the field of oncology. Pursuant to the Collaboration Agreement the Company granted LG Chem an exclusive license to develop, manufacture and commercialize the Company’s lead product, CUE-101, as well as Immuno-STATs that target T-cells against two additional cancer antigens, in certain Asian countries (collectively, the “LG Chem Territory”). LG Chem has the option to elect one additional Immuno-STAT for an oncology target within two years of the agreement for a worldwide development and commercialization license, and Cue Biopharma will retain an option to co-develop and co-commercialize the additional program worldwide. Cue Biopharma retains rights to develop and commercialize all assets included in the agreement in the United States and in global markets outside of Asia. In exchange for the licenses and other rights granted to LG Chem under the Collaboration Agreement, LG Chem made a $5.0 million equity investment in common stock of Cue Biopharma, Inc. and a $5.0 million nonrefundable upfront cash payment. Cue Biopharma is also be eligible to receive up to an additional $400 million in research, development, regulatory and sales milestones. In addition, the Collaboration Agreement also provides that LG Chem will pay the Company tiered single-digit royalties on net sales of commercialized product candidates in the LG Chem Territory.

As it relates to the LG Chem Agreement, the Company recorded the $5.0 million upfront payment as a contract liability upon receipt of payment as it requires deferral of revenue recognition to a future period until the Company performs its obligations under the arrangement. Of the $5.0 million upfront payment, $825,000 was recognized as tax withholding, shown as income tax expense on the statement of operations and comprehensive loss for the year ended December 31, 2018. The Company also recorded approximately $829,000 in premium paid for the stock purchased by LG Chem pursuant to the Stock Purchase Agreement dated November 6, 2018, as a contract liability upon receipt of payment. These amounts require deferral of revenue recognition to a future period until the Company performs its obligations under the arrangement. Amounts expected to be recognized as revenue within the twelve months following the balance sheet date are classified in current liabilities. Amounts not expected to be recognized as revenue within the twelve months following the balance sheet date are classified as contract liabilities, net of current portion. Thus, the transaction price of $5.8 million was recorded in short and long-term research and development liabilities on its balance sheet dated December 31, 2018.

On May 16, 2019, LG Chem paid the Company a $2.5 million milestone payment for the United States Food and Drug Administration (“FDA”) acceptance of the Investigational New Drug (“IND”) for the Company’s lead drug candidate, CUE-101, pursuant to the LG Chem Agreement. The $2.5 million milestone payment was recorded as a contract liability upon receipt of payment as it requires deferral of revenue recognition to a future period until the Company performs its obligations under the arrangement. Of the $2.5 million milestone payment, approximately $413,000 was recognized as tax withholding, shown as income tax expense on the statement of operations and comprehensive loss. The Company recorded short and long-term research and development liabilities on its balance sheet dated of approximately $2,741,000 and $5,185,000, respectively, as of September 30, 2019.

Aside from the $2.5 million milestone payment, the Company does not believe that any variable consideration should be included in the transaction price as of September 30, 2019. Such assessment considered the application of the constraint to ensure that estimates of variable consideration would be included in the transaction price only to the extent the Company had a high degree of confidence that revenue would not be reversed in a subsequent reporting period. The Company will re-evaluate the transaction price, including the estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as other changes in circumstances occur. For the three and nine months ended September 30, 2019, the Company recognized revenue of approximately $810,000 and approximately $1,535,000, respectively, related to this agreement.

The Company considered the capitalization of contract costs under the guidance in ASC 340-40, Other Assets and Deferred Costs: Contracts with Customers. There were no contract costs identified in the Collaboration Agreement with Merck. As it related to the LG Chem agreement, the Company capitalized license expenses of approximately $592,000 as of September 30, 2019, pursuant to the Einstein license agreement which requires the Company to pay a percentage of sublicenses related to the Company’s patent rights for components of its core technology that is licensed from Einstein. This amount is comprised of approximately $438,000 of capitalized license expenses related to the upfront payment received from LG Chem in December 2018 and approximately $313,000 in capitalized license expenses related to the milestone payment received in June 2019, net of accumulated amortization of approximately $159,000. As of September 30, 2019, $215,000 was included in prepaid expenses and other short-term assets and $377,000 is included in other long-term assets. Related to the LG Chem agreement, the Company capitalized license expenses of approximately $438,000 as of December 31, 2018, pursuant to the Einstein license agreement. Of the total approximately, $54,000 is included in prepaid expenses and other short-term assets and approximately $384,000 is included in other long-term assets as of December 31, 2018.

Commitments and Contingencies

9 Months Ended

Sep. 30, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

10.	Commitments and Contingencies

Einstein License and Service Agreement

In 2015, the Company entered into the Einstein License with Einstein for certain patent rights relating to the Company’s core technology platform for the engineering of biologics to control T-cell activity, precision, immune-modulatory drug candidates, and two supporting technologies that enable the discovery of costimulatory signaling molecules (ligands) and T-cell targeting peptides. On July 31, 2017, the Company entered into an amended and restated license agreement which modified certain obligations of the parties under the Einstein License. For the three and nine months ended September 30, 2019 the Company incurred approximately $150,000, and $325,000 respectively, for the three and nine months ended September 30, 2018 the Company incurred approximately $12,500 and $25,000, respectively, in fees and expenses to Einstein in relation to this license.

The Company’s remaining commitments with respect to the Einstein License are based on the attainment of future milestones. The aggregate amount of milestone payments made under the Einstein License may equal up to $1.85 million for each product, process or service that use the patents covered by the Einstein License, including certain technology received from Einstein relating thereto (“Licensed Products”), and up to $1.85 million for each new indication of a Licensed Product. Additionally, the aggregate amount of one-time milestone payments based on cumulative sales of all Licensed Products may equal up to $5.75 million. The Company is also party to a service agreement with Einstein to support the Company’s ongoing research and development activities.

Agreements with Catalent

On March 7, 2017, the Company entered into an agreement with Catalent Pharma Solutions, LLC (“Catalent”) for Catalent to provide services on a sequential milestone basis with respect to the development and manufacture of the Company’s lead drug candidate, CUE-101. The services under the agreement are designed to support the preparation and filing of an Investigational New Drug Application with the United States Food and Drug Administration to allow for the commencement of a Phase 1 clinical trial of CUE-101 in the United States. The Company incurred total direct costs under this agreement aggregating $0.6 million during the nine months ended September 30, 2019. Certain of these agreements contain nonrefundable advance payments for which the Company anticipates receiving the contracted services within 12 months from the date of payment. Management periodically reviews and updates the project’s estimated budget and timeline.

Collaboration Agreement with Merck

On November 14, 2017, the Company entered into the Collaboration Agreement with Merck for a partnership to research and develop certain of the Company’s proprietary biologics that target certain autoimmune disease indications (the “Initial Indications”). We view this Collaboration Agreement as a component of our development strategy since it will allow us to advance our autoimmune programs in partnership with a world class pharmaceutical company, while also continuing our focus on our more advanced cancer programs. The research program outlined in the Collaboration Agreement entails (1) our research, discovery and development of certain Immuno-STAT™ drug candidates up to the point of demonstration of certain biologically relevant effects (“Proof of Mechanism”) and (2) the further development by Merck of the Immuno-STAT™ drug candidates that have demonstrated Proof of Mechanism (the “Proposed Product Candidates”) up to the point of demonstration of all or substantially all of the properties outlined in such Proposed Product Candidates’ profiles as described in the Collaboration Agreement.

In exchange for the licenses and other rights granted to Merck under the Collaboration Agreement, Merck paid to the Company a $2.5 million nonrefundable up-front payment. Additionally, the Company may be eligible to receive funding in developmental milestone payments, as well as tiered royalties, if all research, development, regulatory and commercial milestones agreed upon by both parties are successfully achieved. Excluding the up-front payment described above, the Company is eligible to earn up to $101 million for the achievement of certain research and development milestones, $120 million for the achievement of certain regulatory milestones and $150 million for the achievement of certain commercial milestones, in addition to tiered royalties on sales, if all pre-specified milestones associated with multiple products across the primary disease indication areas are achieved. The Collaboration Agreement requires the Company to use the first $2.5 million of milestone payments we receive under the agreement to fund contract research. The amount of the royalty payments is a percentage of product sales ranging in the single digits based on the amount of such sales.

Collaboration Agreement with LG Chem Life Sciences

On November 6, 2018, the Company entered into a Collaboration Agreement with LG Chem. related to the development of the Company’s Immuno-STATs focused in the field of oncology. Pursuant to the Collaboration Agreement the Company granted LG Chem an exclusive license to develop, manufacture and commercialize the Company’s lead product, CUE-101, as well as Immuno-STATs that target T-cells against two additional cancer antigens, in certain Asian countries (collectively, the “LG Chem Territory”). LG Chem has the option to elect one additional Immuno-STAT for an oncology target within two years of the agreement for a worldwide development and commercialization license, and Cue Biopharma will retain an option to co-develop and co-commercialize the additional program worldwide. Cue Biopharma retains rights to develop and commercialize all assets included in the agreement in the United States and in global markets outside of Asia. In exchange for the licenses and other rights granted to LG Chem under the Collaboration Agreement, LG Chem made a $5.0 million equity investment in common stock of Cue Biopharma, Inc. and a $5.0 million nonrefundable upfront cash payment. Cue Biopharma is also be eligible to receive up to an additional $400 million in research, development, regulatory and sales milestones. In addition, the Collaboration Agreement also provides that LG Chem will pay the Company tiered single-digit royalties on net sales of commercialized product candidates in the LG Chem Territory.

On May 16, 2019, LG Chem paid the Company a $2.5 million milestone payment for the FDA acceptance of the IND for the Company’s lead drug candidate, CUE-101, pursuant to the LG Chem Agreement. The $2.5 million milestone payment was recorded as a contract liability upon receipt of payment as it requires deferral of revenue recognition to a future period until the Company performs its obligations under the arrangement pursuant to the Company’s revenue recognition policy.

Contingencies

The Company accrues for contingent liabilities to the extent that the liability is probable and estimable. There are no accruals for contingent liabilities in these consolidated financial statements.

The Company may be subject to various legal proceedings from time to time as part of its business. As of September 30, 2019, the Company was not a party to any legal proceedings or threatened legal proceedings, the adverse outcome of which, individually or in the aggregate, would have a material adverse effect on its business, financial condition or results of operations.

Leases

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Leases

11. Leases

The Company adopted ASC 842 as of January 1, 2019 using the effective date method, in which we did not restate prior periods. Upon adoption, the Company elected the package of practical expedients permitted under the transition guidance within ASC 842, which among other things, allowed it to carry forward the historical lease classification. The Company does not allocate consideration in its leases to lease and non-lease components and does not record leases on its balance sheets with terms of 12 months or less.

The Company uses its estimated incremental borrowing rate, which is derived from information available at the lease commencement date, in determining the present value of lease payments. The Company’s incremental borrowing rate represents the rate of interest that it would have to pay to borrow over a similar term an amount equal to the lease payments in a similar economic environment.

The adoption of ASC 842 on January 1, 2019 resulted in the recognition of approximately $ 9,692,000 of right-of-use asset and $9,347,000 of lease liabilities on the Company’s balance sheet. The adoption did not have a material net impact on the Company’s consolidated statements of operations or accumulated deficit. The Company will review the classification of newly entered leases as either an operating or a finance lease and recognize a related right-of-use asset and lease liability on its balance sheet upon commencement.

On January 9, 2018, the Company entered into an operating lease agreement for its corporate headquarters in Cambridge, Massachusetts, with a termination date of April 2021. This lease was amended on June 18, 2019 to provide the Company with a reduction in rental fees in exchange for prepayment of a portion of the fees. The lease contains escalating payments during the lease period. The Company records monthly rent expense on a straight-line basis, equal to the total of the lease payments over the lease term divided by the number of months of the lease term. As of September 30, 2019, and December 30, 2018, a security deposit of approximately $777,000 is included in deposits on the Company’s balance sheet.

On September 20, 2018, the Company entered into an operating lease for additional laboratory space in Cambridge, Massachusetts for the period from October 15, 2018 through April 14, 2021. The lease contains escalating payments during the lease period. The monthly rental rate under the lease agreement is $72,600 for the first 12 months and $78,600 for the remainder of the term. Upon execution of this lease agreement the Company prepaid twelve months rent pursuant to the lease agreement executed on September 20, 2018. As of September 30, 2019, and December 31, 2018, a security deposit of approxima1ely $236,000 is included in deposits on the Company’s balance sheet.

On September 16, 2019, the Company entered into an amended lease agreement that removed one holding room from the additional laboratory space lease entered into on September 20, 2018. The amendment was effective beginning on October 1, 2019 and expires on April 14, 2021. The monthly rental rate under the amended lease agreement decreased from $78,600 to $58,995, for the remainder of the lease term.

Future minimum lease payments under these leases at September 30, 2019 are as follows:

Year	(in thousands)
2019	$	1,057
2020		4,911
2021		1,432
Total lease payment	$	7,400
Less: present value discount		(356	)
Total	$	7,044

Total rent expense of approximately $1,137,000 and $863,000 was included in the statement of operations for the three months ended September 30, 2019 and 2018, respectively, and $3,411,000 and $2,250,000 for the nine months ended September 30, 2019 and 2018, respectively. Other information pertaining to the Company’s operating leases for the nine months ended September 30, 2019 are summarized in the table below.


Other information (in thousands)	Three Months Ended September 30, 2019		Nine Months Ended September 30, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	893	$	2,677
Operating lease cost	$	1,137	$	3,411

Weighted average discount rate	6.0%		6.0%

Weighted average remaining lease term	1.58 years		1.58 years

The Company recorded a right of use asset of approximately $6,656,000 and lease liability of approximately $7,044,000 at September 30, 2019. The change in the right of use asset and lease liability is due to rental expense of approximately $1,137,000 and $3,411,000, recorded during the three and nine months ended September 30, 2019, respectively.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2019

Accounting Policies [Abstract]

Basis of Presentation

Cash and Cash Equivalents

Marketable Securities

Restricted Cash

Property and Equipment

Laboratory equipment		5 years
Computer and office equipment		3 years
Furniture and fixtures		3-8 years

Trademark

Revenue Recognition

Research and Development Expenses

Patent Expenses

Licensing Fees and Costs

Long-Lived Assets

Leases

Stock-Based Compensation

Comprehensive Income (Loss)

Earnings (Loss) Per Share

	September 30,
	2019		2018
Common stock warrants		1,252,441		1,252,441
Common stock options		4,629,085		4,427,821
Total		5,881,526		5,680,262

Fair Value of Financial Instruments

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2019

Accounting Policies [Abstract]

Summary of Estimated Useful Lives of Assets

Depreciation of property and equipment is provided using the straight-line method over the following estimated useful lives:

Laboratory equipment		5 years
Computer and office equipment		3 years
Furniture and fixtures		3-8 years

Schedule of Anti-dilutive Securities Excluded from Computation of Earnings Per Share

	September 30,
	2019		2018
Common stock warrants		1,252,441		1,252,441
Common stock options		4,629,085		4,427,821
Total		5,881,526		5,680,262

Fair Value (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Schedule of Fair Value Assets Measured on Recurring Basis

	Fair Value Measurements as of September 30, 2019
	(in thousands)
	Level 1		Level 2		Level 3		Fair Value
Cash equivalents	$	19,425	$	—	$	—	$	19,425
Marketable securities		—		—		—		—
Total	$	19,425	$	—	$	—	$	19,425

	Fair Value Measurements as of December 31, 2018
	(in thousands)
	Level 1		Level 2		Level 3		Fair Value
Cash equivalents	$	10,548	$	—	$	—	$	10,548
Marketable securities		—		18,412		—		18,412
Total	$	10,548	$	18,412	$	—	$	28,960

Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2019

Investments Debt And Equity Securities [Abstract]

Schedule of Fair Value of Available-for-Sale Marketable Securities

	December 31, 2018
(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury Securities	$	18,423	$	—	$	(11	)	$	18,412
	$	18,423	$	—	$	(11	)	$	18,412

Property and Equipment (Tables)

9 Months Ended

Sep. 30, 2019

Property Plant And Equipment [Abstract]

Summary of Property and Equipment

Property and equipment as of September 30, 2019 and December 31, 2018 consisted of the following:

	September 30, 2019			December 31, 2018
	(in thousands)
Computer equipment	$	192		$	182
Laboratory equipment		3,578			3,872
Furniture and fixtures		93			93
		3,863			4,147
Less: Accumulated depreciation	$	(1,832	)	$	(1,366	)
Total property and equipment, net	$	2,031		$	2,781

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Estimated Fair Value of Each Stock Option Award

		September 30, 2019
Risk-free interest rate		1.76 to 2.59%
Expected dividend yield		0%
Expected volatility		82.0-94.0%
Expected life		4.0 to 6.25 years

Summary of Stock Option Activity

A summary of stock option activity for the nine months ended September 30, 2019 is as follows:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in Years)
Stock options outstanding at December 31, 2018		4,540,321		$	7.08		5.16
Granted		825,600			6.37
Exercised		(187,898	)	3.43
Cancelled		(548,938	)	9.17
Stock options outstanding at September 30, 2019		4,629,085			6.86		5.36
Stock options exercisable at September 30, 2019		2,172,376		$	5.82		4.58

Schedule of Stock-Based Compensation Included in Statement of Operations

Stock-based compensation for the three and nine months ended September 30, 2019 and 2018 was included in the statement of operations as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
(in thousands)	2019		2018		2019		2018
General and administrative	$	520	$	856	$	1,483	$	1,828
Research and development		919		1,875		3,042		3,335
Total	$	1,439	$	2,731	$	4,525	$	5,163

Leases (Tables)

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Schedule of Future Minimum Lease Payments for Operating Lease

Future minimum lease payments under these leases at September 30, 2019 are as follows:

Year	(in thousands)
2019	$	1,057
2020		4,911
2021		1,432
Total lease payment	$	7,400
Less: present value discount		(356	)
Total	$	7,044

Schedule of Other Information of Operating Leases

Other information pertaining to the Company’s operating leases for the nine months ended September 30, 2019 are summarized in the table below.


Other information (in thousands)	Three Months Ended September 30, 2019		Nine Months Ended September 30, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	893	$	2,677
Operating lease cost	$	1,137	$	3,411

Weighted average discount rate	6.0%		6.0%

Weighted average remaining lease term	1.58 years		1.58 years

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019	Dec. 31, 2018
Summary Of Significant Accounting Policies [Line Items]
Restricted cash used to collateralize a credit card	$ 150,000		$ 150,000			$ 150,000
Acquired intangible asset, useful life			15 years
Operating lease, right-of-use asset	6,656,000		$ 6,656,000
Operating lease, liability	7,044,000		7,044,000
Cash equivalents	19,425,000		19,425,000			10,548,000
Short-term marketable securities	0		0			18,412,000
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Operating lease, right-of-use asset					$ 9,692,000
Operating lease, liability					$ 9,347,000
General and Administrative Expense
Summary Of Significant Accounting Policies [Line Items]
Patent expenses	$ 476,000	$ 225,000	$ 1,323,000	$ 493,000
Type of Cost, Good or Service [Extensible List]	us-gaap:LicenseMember	us-gaap:LicenseMember	us-gaap:LicenseMember	us-gaap:LicenseMember
Certificate of Deposit
Summary Of Significant Accounting Policies [Line Items]
Short-term restricted cash	$ 0		$ 0			$ 50,000
Stifel Nicolaus and Company Inc.
Summary Of Significant Accounting Policies [Line Items]
Proceeds from Issuance Initial Public Offering			30,000,000
Sale of company stock under sale agreement			$ 30,000,000
Stifel Nicolaus and Company Inc. \| Sales Agreement
Summary Of Significant Accounting Policies [Line Items]
Stock Issued During Period, Shares, New Issues			2,084,615
Proceeds from sale of common stock	$ 15,700,000		$ 15,700,000

Fair Value - Schedule of Fair Value Assets Measured on Recurring Basis (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 19,425,000	$ 10,548,000
Marketable securities	0	18,412,000
Total	19,425,000	28,960,000
Fair Value Measurements, Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	19,425,000	10,548,000
Marketable securities		18,412,000
Total	19,425,000	28,960,000
Fair Value Measurements, Recurring Basis \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	19,425,000	10,548,000
Total	$ 19,425,000	10,548,000
Fair Value Measurements, Recurring Basis \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities		18,412,000
Total		$ 18,412,000

Marketable Securities - Schedule of Fair Value of Available-for-Sale Marketable Securities (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		$ 18,423,000
Gross Unrealized Losses		(11,000)
Fair Value	$ 0	18,412,000
U.S. Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		18,423,000
Gross Unrealized Losses		(11,000)
Fair Value		$ 18,412,000

Property and Equipment - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 3,863	$ 4,147
Less: Accumulated depreciation	(1,832)	(1,366)
Total property and equipment, net	2,031	2,781
Computer Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	192	182
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	3,578	3,872
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 93	$ 93

Property and Equipment - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Depreciation expense	$ 194,000	$ 195,000	$ 605,000	$ 556,000
Accumulated Depreciation	1,832,000		1,832,000		$ 1,366,000
Laboratory Equipment
Property Plant And Equipment [Line Items]
Disposal of property and equipment, gross	319,000		319,000
Accumulated Depreciation	$ 138,000		138,000
Loss on disposal of property and equipment			$ 54,000

Stock-Based Compensation - Schedule of Estimated Fair Value of Each Stock Option Award (Details)	9 Months Ended
	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	1.76%
Risk-free interest rate, maximum	2.59%
Expected dividend yield	0.00%
Expected volatility, minimum	82.00%
Expected volatility, maximum	94.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life	4 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life	6 years 3 months

Stock-Based Compensation - Summary of Stock Option Activity (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2019 $ / shares shares	Dec. 31, 2018 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward
Number of Shares, Outstanding Beginning Balance \| shares	4,540,321
Number of Shares, Granted \| shares	825,600
Number of Shares, Exercised \| shares	(187,898)
Number of Shares, Cancelled \| shares	(548,938)
Number of Shares, Outstanding Ending Balance \| shares	4,629,085	4,540,321
Number of Shares, Exercisable \| shares	2,172,376
Weighted Average Exercise Price, Outstanding Beginning Balance \| $ / shares	$ 7.08
Weighted Average Exercise Price, Granted \| $ / shares	6.37
Weighted Average Exercise Price, Exercised \| $ / shares	3.43
Weighted Average Exercise Price, Cancelled \| $ / shares	9.17
Weighted Average Exercise Price, Outstanding Ending Balance \| $ / shares	6.86	$ 7.08
Weighed Average Exercise Price, Exercisable \| $ / shares	$ 5.82
Weighted Average Remaining Contractual Life (in Years)	5 years 4 months 9 days	5 years 1 month 28 days
Weighted Average Remaining Contractual Life (in Years), Exercisable	4 years 6 months 29 days

Warrants - Additional Information (Details)	9 Months Ended
Warrants - Additional Information (Details)	Sep. 30, 2019 USD ($) Tranche $ / shares shares	Jun. 15, 2015 $ / shares
Class Of Warrant Or Right [Line Items]
Number of tranches \| Tranche	2
First tranche
Class Of Warrant Or Right [Line Items]
Common stock warrants outstanding \| shares	370,370
Exercise price of common stock warrants		$ 2.70
Common stock warrants life		7 years
Common stock warrants expiration date	Jun. 15, 2022
Warrant
Class Of Warrant Or Right [Line Items]
Intrinsic value of common stock warrants \| $	$ 2,122,000
Fair value of common stock	$ 8.43
Second tranche
Class Of Warrant Or Right [Line Items]
Common stock warrants outstanding \| shares	882,071
Exercise price of common stock warrants	$ 9.38
Common stock warrants life	5 years
Common stock warrants expiration date	Dec. 26, 2022

Revenue Recognition - Additional Information (Details) - USD ($)				1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	May 16, 2019	Nov. 06, 2018	Nov. 14, 2017	Jun. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Transaction price recorded in liabilities					$ 2,500,000		$ 2,500,000
Collaboration revenue					984,000	$ 449,000	2,409,000	$ 812,000
Short-term research and development contract liability					3,225,000		3,225,000		$ 2,012,000
Long-term research and development contract liability					5,185,000		5,185,000		5,175,000
Income tax expense							413,000
Prepaid expenses and other short-term assets					1,001,000		1,001,000		1,347,000
Other long-term assets					793,000		793,000		809,000
Merck \| Collaboration Agreement with Merck
Disaggregation Of Revenue [Line Items]
Collaboration revenue					174,000	$ 449,000	874,000	$ 812,000
Short-term research and development contract liability					484,000		484,000
Long-term research and development contract liability					0		0
Milestone payments received			$ 2,500,000
LG Chem Life Sciences \| Collaboration Agreement with LG Chem Life Sciences
Disaggregation Of Revenue [Line Items]
Collaboration revenue					810,000		1,535,000
Short-term research and development contract liability					2,741,000		2,741,000
Long-term research and development contract liability					5,185,000		5,185,000
Equity investment nonrefundable upfront cash payment		$ 5,000,000
Equity investment for research collaboration agreement		5,000,000
Additional amount receivable research development regulatory and sales milestones		400,000,000
Upfront payment associated with contract liability	$ 2,500,000								5,000,000
Income tax expense		413,000							825,000
Premium paid for stock purchased		829,000
Milestone payments received	$ 2,500,000
LG Chem Life Sciences \| Collaboration Agreement with LG Chem Life Sciences \| Maximum
Disaggregation Of Revenue [Line Items]
Additional amount receivable research development regulatory and sales milestones		$ 400,000,000
Einstein \| Einstein License And Service Agreement
Disaggregation Of Revenue [Line Items]
Transaction price recorded in liabilities									5,800,000
License expenses				$ 313,000			592,000		438,000
Prepaid expenses and other short-term assets					215,000		215,000		54,000
Other long-term assets					$ 377,000		$ 377,000		$ 384,000
Amortization of Intangible Assets				$ 159,000

Commitments and Contingencies - Additional Information (Details)			3 Months Ended		9 Months Ended		12 Months Ended
	May 16, 2019 USD ($)	Nov. 14, 2017 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Nov. 06, 2018 USD ($)	Dec. 31, 2015 SupportingTechnology
Albert Einstein College Of Medicine \| Einstein License And Service Agreement
Commitments And Contingencies [Line Items]
Milestone payments for each product, process or service					$ 1,850,000
Milestone payments for each new indication of licensed product					1,850,000
Aggregate amount of additional milestone payments					5,750,000
Catalent \| Agreements with Catalent \| Services on Development and Manufacture of Lead Drug Candidate
Commitments And Contingencies [Line Items]
Total direct costs under agreement					$ 600,000
Anticipated contracted services to be received, period from date of payment					12 months
Merck \| Collaboration Agreement with Merck
Commitments And Contingencies [Line Items]
Up front non refundable payment		$ 2,500,000
Achievement of certain research and development milestones		120,000,000
Achievement of certain commercial milestones		150,000,000
Milestone payments received		2,500,000
Merck \| Collaboration Agreement with Merck \| Maximum
Commitments And Contingencies [Line Items]
Eligible to earn achievement of certain research and development milestones		$ 101,000,000
LG Chem Life Sciences \| Collaboration Agreement with LG Chem Life Sciences
Commitments And Contingencies [Line Items]
Milestone payments received	$ 2,500,000
Equity investment nonrefundable upfront cash payment								$ 5,000,000
Equity investment for research collaboration agreement								5,000,000
Additional amount receivable research development regulatory and sales milestones								400,000,000
Upfront payment associated with contract liability	$ 2,500,000						$ 5,000,000
LG Chem Life Sciences \| Collaboration Agreement with LG Chem Life Sciences \| Maximum
Commitments And Contingencies [Line Items]
Additional amount receivable research development regulatory and sales milestones								$ 400,000,000
Einstein License
Commitments And Contingencies [Line Items]
Number of supporting technologies \| SupportingTechnology									2
Patent expenses			$ 150,000	$ 12,500	$ 325,000	$ 25,000
Type of Cost, Good or Service [Extensible List]			us-gaap:LicenseMember	us-gaap:LicenseMember	us-gaap:LicenseMember	us-gaap:LicenseMember

Leases - Additional Information (Details) - USD ($)				3 Months Ended		9 Months Ended
Leases - Additional Information (Details) - USD ($)	Sep. 16, 2019	Sep. 20, 2018	Jan. 09, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019	Dec. 31, 2018	Dec. 30, 2018
Lessee Lease Description [Line Items]
Operating lease, right-of-use asset				$ 6,656,000		$ 6,656,000
Operating lease, liability				7,044,000		7,044,000
Rent expense				1,137,000	$ 863,000	3,411,000	$ 2,250,000
Operating Lease Agreement
Lessee Lease Description [Line Items]
Lease termination date			2021-04
Security deposit				777,000		777,000				$ 777,000
Operating Lease Agreement For Additional Laboratory Space
Lessee Lease Description [Line Items]
Security deposit				$ 236,000		$ 236,000			$ 236,000
Lease agreement effective date		Oct. 15, 2018
Lease expiration date		Apr. 14, 2021
Lessee operating lease monthly rental payments for first twelve months		$ 72,600
Lessee operating lease monthly rental payments for remaining term		$ 78,600
Amended Lease Agreement
Lessee Lease Description [Line Items]
Lease agreement effective date	Oct. 01, 2019
Lease expiration date	Apr. 14, 2021
Lessee operating lease monthly rental payments for remaining term	$ 58,995
Lessee operating lease monthly rental payments	$ 78,600
ASC 842
Lessee Lease Description [Line Items]
Operating lease, right-of-use asset								$ 9,692,000
Operating lease, liability								$ 9,347,000

Leases - Schedule of Future Minimum Lease Payments on Operating Leases (Details)	Sep. 30, 2019 USD ($)
Leases [Abstract]
2019	$ 1,057,000
2020	4,911,000
2021	1,432,000
Total lease payment	7,400,000
Less: present value discount	(356,000)
Total	$ 7,044,000

Leases - Schedule of Other Information of Operating Leases (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 893	$ 2,677
Operating lease cost	$ 1,137	$ 3,411
Weighted average discount rate	6.00%	6.00%
Weighted average remaining lease term	1 year 6 months 29 days	1 year 6 months 29 days

Stock-Based Compensation - Additional Information (Details)	Sep. 30, 2019 USD ($) $ / shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Unrecognized stock-based compensation	$ 11,046,000
Intrinsic value of exercisable stock options	$ 7,594,000
Intrinsic value of exercisable fair value per share \| $ / shares	$ 8.43

Summary of Significant Accounting Policies - Schedule of Anti-dilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	5,881,526	5,680,262
Common Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	1,252,441	1,252,441
Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	4,629,085	4,427,821

Fair Value Measurements - Additional Information (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair value assets transfers between Level 2 and Level 3	$ 0	$ 0
Cash equivalents and marketable securities	$ 19,425,000	$ 28,960,000

Marketable Securities - Additional Information (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Marketable securities	$ 0	$ 18,413,000

Revenue Recognition - Additional Information (Details1) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-07-01	Sep. 30, 2019
Current Liabilities \| Maximum
Disaggregation Of Revenue [Line Items]
Revenue expected to be recognized	12 months
Current Liabilities \| Maximum \| Einstein \| Einstein License And Service Agreement
Disaggregation Of Revenue [Line Items]
Revenue expected to be recognized	12 months
Contract Liabilities \| Minimum
Disaggregation Of Revenue [Line Items]
Revenue expected to be recognized	12 months
Contract Liabilities \| Minimum \| Einstein \| Einstein License And Service Agreement
Disaggregation Of Revenue [Line Items]
Revenue expected to be recognized	12 months