Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2018	Mar. 07, 2019	Jun. 29, 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	CUE
Entity Registrant Name	Cue Biopharma, Inc.
Entity Central Index Key	0001645460
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		20,734,232
Entity Public Float			$ 216.4

CONSOLIDATED BALANCE SHEETS - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash	$ 20,800,284	$ 63,533,649
Marketable securities, short term	18,412,500	0
Restricted cash, short term	50,068	50,068
Prepaid expenses and other current assets	1,347,288	1,255,796
Deposits, short-term		225,500
Total current assets	40,610,140	65,065,013
Property and equipment, net	2,781,459	1,690,539
Deposits	1,012,772
Restricted cash, long term	150,000
Other long term assets	808,729	198,282
Total assets	45,363,100	66,953,834
Current liabilities:
Accounts payable	2,035,354	1,659,207
Accrued expenses	1,788,062	1,151,085
Research and development contract liability, current portion	2,011,998	2,500,000
Deferred rent	381,465	36,364
Total current liabilities	6,216,879	5,346,656
Research and development contract liability, net of current portion	5,174,752
Total liabilities	11,391,631	5,346,656
Commitments and Contingencies (Note 14)
Stockholders’ equity:
Preferred stock, $0.001 par value, authorized – 10,000,000 shares; issued and outstanding – none
Common stock, $0.001 par value; authorized – 50,000,000 shares; issued and outstanding – 20,697,453 shares and 19,459,194 shares at December 31, 2018 and 2017, respectively	20,697	19,460
Common stock to be issued		671
Additional paid-in capital	105,762,891	94,407,895
Accumulated other comprehensive loss	(10,958)
Accumulated deficit	(71,801,161)	(32,820,848)
Total stockholders’ equity	33,971,469	61,607,178
Total liabilities and stockholders’ equity	$ 45,363,100	$ 66,953,834

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
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	20,697,453	19,459,194
Common stock, shares outstanding	20,697,453	19,459,194

STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Collaboration revenue	$ 1,142,604
Operating expenses:
General and administrative	11,295,211	$ 4,333,542
Research and development	28,544,051	18,900,328
Total operating expenses	39,839,262	23,233,870
Loss from operations	(38,696,658)	(23,233,870)
Other income (expense):
Interest income	376,008	35
Other income (expense), net	165,337
Total other income (expense)	541,345	35
Loss before provision for income taxes	(38,155,313)	(23,233,835)
Provision for income taxes	(825,000)
Net loss	(38,980,313)	(23,233,835)
Unrealized gains (losses) from available-for-sale securities, net of tax of $0	(10,958)
Comprehensive loss	$ (38,991,271)	$ (23,233,835)
Net loss per common share – basic and diluted	$ (1.94)	$ (2.16)
Weighted average common shares outstanding – basic and diluted	20,134,065	10,732,449

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($)	Total	Initial Public Offering	Common Stock	Common Stock Initial Public Offering	Common Stock To Be Issued	Additional Paid-in Capital	Additional Paid-in Capital Initial Public Offering	AOCI Attributable to Parent	Accumulated Deficit
Balance at Dec. 31, 2016	$ 15,174,640		$ 10,636			$ 24,751,017			$ (9,587,013)
Balance, Shares at Dec. 31, 2016			10,635,684
Common stock issued		$ 66,155,293		$ 8,821			$ 66,146,472
Common stock issued, Shares				8,820,710
Costs incurred in connection with initial public offering		(8,396,661)					(8,396,661)
Stock-based compensation	2,775,363					2,775,363
Common stock to be issued pursuant to license agreements	5,036,789				$ 671	5,036,118
Common stock to be issued pursuant to license agreements, Shares					671,572
Proceeds from sale of placement agent warrants	1,000					1,000
Fair value of warrants issued in connection with initial public offering of common stock		$ 4,086,581					$ 4,086,581
Exercise of stock options	$ 8,008		$ 3			8,005
Exercise of stock options, Shares	2,800		2,800
Net loss	$ (23,233,835)								(23,233,835)
Balance at Dec. 31, 2017	61,607,178		$ 19,460		$ 671	94,407,895			(32,820,848)
Balance, Shares at Dec. 31, 2017			19,459,194		671,572
Common stock issued	4,169,349		$ 1,235		$ (671)	4,168,785
Common stock issued, Shares			1,235,759		(671,572)
Stock-based compensation	7,173,713					7,173,713
Exercise of stock options	$ 12,500		$ 2			12,498
Exercise of stock options, Shares	2,500		2,500
Other comprehensive income (loss)	$ (10,958)							$ (10,958)
Net loss	(38,980,313)								(38,980,313)
Balance at Dec. 31, 2018	$ 33,971,469		$ 20,697			$ 105,762,891		$ (10,958)	$ (71,801,161)
Balance, Shares at Dec. 31, 2018			20,697,453

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (38,980,313)	$ (23,233,835)
Adjustments to reconcile net loss to net cash used in operating activities:
Common stock to be issued pursuant to license agreements		5,036,789
Depreciation	760,011	419,568
Deferred rent	345,101	(109,091)
Stock-based compensation	7,173,713	2,775,363
Loss on disposal of property plant and equipment	3,315	10,677
Non-cash investment income	76,544
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(701,939)	(1,116,680)
Deposits	(787,272)	(58,432)
Accounts payable	376,147	921,888
Accrued expenses	636,975	712,307
Research and development contract liability	4,686,750	2,500,000
Net cash used in operating activities	(26,410,968)	(12,141,446)
Cash flows from investing activities:
Increase in certificate of deposit		(35)
Acquisition of trademark		(175,000)
Purchases of property and equipment	(1,854,246)	(1,029,942)
Redemption of short term investments	21,000,000
Purchase of short term investments	(39,500,000)
Net cash used in investing activities	(20,354,246)	(1,204,977)
Cash flows from financing activities:
Proceeds from private placements of common stock	4,169,349
Proceeds from sale of placement agent and underwriters warrants		1,000
Proceeds from the initial public offering of common stock		66,155,293
Proceeds from the exercise of stock options	12,500	8,008
Cash payments made for costs incurred in connection with sale of common stock		(4,159,981)
Net cash provided by financing activities	4,181,849	62,004,320
Net (decrease)/ increase	(42,583,365)	48,657,897
Cash, cash equivalents, and restricted cash at beginning of period	63,583,717	14,925,820
Cash, cash equivalents, and restricted cash at end of period	21,000,352	63,583,717
Supplemental disclosures of cash flow information:
Income taxes	$ (825,000)
Non-cash investing and financing activities:
Fair value of warrants issued in connection with issuance of common stock		4,086,581
Public offering costs included in accounts payable or accrued expenses		150,099
Purchases of property and equipment in accounts payable or accrued expenses		$ 67,477

Organization and Basis of Presentation

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Basis of Presentation

1.	Organization and Basis of Presentation

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 a pre-clinical biopharmaceutical company that is developing a novel and proprietary class of biologic drugs for the selective modulation of the human immune system to treat a broad range of cancers, chronic infectious diseases, and autoimmune disorders.

The Company is in the development stage and has incurred recurring losses and negative cash flows from operations. As of December 31, 2018, the Company had cash, cash equivalents and marketable securities of approximately $39,213,000. Management believes that current cash, cash equivalents and marketable securities on hand at December 31, 2018 are sufficient to fund operations for at least 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

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2.	Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements for the years ended December 31, 2018 and 2017, 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.

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 for the year ended December 31, 2018, the year Cue Biopharma Securities Corporation, Inc. was established.

Reclassification

Certain amounts previously reported in current liabilities for the prior period have been reclassified to the current period presentation to segregate accounts payable and accrued liabilities to conform with current period presentation. Also, certain amounts previously reported in research and development contract advances have been reclassified to the current period presentation to combine research and development contract advances and prepaid expenses. There was no impact to reported net loss. The reclassifications did not have a material impact on previously reported financial statements.

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 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 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 are recognized and determined on a specific identification basis and are included in other comprehensive income (loss). Realized gains are recognized and 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 currently invests 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 certificate of deposit as of December 31, 2018 and 2017. As of December 31, 2018, the Company also had $150,000 in restricted cash with a commercial bank to collateralize a credit card.

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 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 in and 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.

As the Company can renew the underlying rights to the CUE BIOLOGICS Mark indefinitely at nominal cost, this acquired intangible asset has been classified as a component of other long term assets, having a useful life of 15 years at December 31, 2018. 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 operations as incurred. For the years ended December 31, 2018 and 2017, patent expenses were $1,222,000 and $592,000, respectively. Patent expenses are included in general and administrative expenses in the Company’s statement 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 Einstein, including related royalties, maintenance fees, milestone payments and product development costs. Licensing fees and costs are charged to operations as incurred.

Long-Lived Assets

The Company reviews long-lived assets, consisting of property and equipment and a trademark, 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. During the years ended December 31, 2018 and 2017, the company disposed of equipment totaling approximately$58,000 and $16,000, resulting in a loss of $3,315 and $10,677, respectively.

Rent Expense and Deferred Rent Liability

Operating lease agreements which contain provisions for future rent increases or periods in which rent payments are reduced or abated are recorded in monthly rent on a straight line basis. The difference between rent expense recorded and the amount paid is credited or charged to a deferred rent liability account. The current portion of deferred rent is included in current liabilities, and the remaining amount is shown in the balance sheets as a non-current liability.

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 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 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 is it 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 fair value of common stock is determined by reference to either recent or anticipated cash transactions involving the sale of the Company’s common stock. The Company accounts for forfeitures as they occur.

The Company recognizes the fair value of all non-employee option awards by estimating the fair value of the awarded options using a Black-Scholes option-pricing model and expected term of the award as of the grant date in accordance with ASU 2018-07. Forfeitures are accounted for as they occur. Stock-based compensation for non-employee awards is recorded in general and administrative expenses or in research and development expenses in the Company’s statement of operations, depending on the type of services provided by the recipient of the equity award. The Company issues new shares of common stock to satisfy stock option exercises.

Income Taxes

The Company accounts for income taxes under an asset and liability approach for financial accounting and reporting for income taxes. Accordingly, the Company recognizes deferred tax assets and liabilities for the expected impact of differences between the financial statements and the tax basis of assets and liabilities.

The Company accounts for uncertainties in income tax law under a comprehensive model for the financial statement recognition, measurement, presentation and disclosure of uncertain tax positions taken or expected to be taken in income tax returns as prescribed by U.S.GAAP. The tax effects of a position are recognized only if it is “more-likely-than-not” to be sustained by the taxing authority as of the reporting date. If the tax position is not considered “more-likely-than-not” to be sustained, then no benefits of the position are recognized.

The Company records a valuation allowance to reduce its deferred tax assets to the amount that is more likely than not to be realized. In the event the Company was to determine that it would be able to realize its deferred tax assets in the future in excess of its recorded amount, an adjustment to the deferred tax assets would be credited to operations in the period such determination was made. Likewise, should the Company determine that it would not be able to realize all or part of its deferred tax assets in the future, an adjustment to the deferred tax assets would be charged to operations in the period such determination was made.

The Company is subject to U.S. Federal and Massachusetts state income taxes. As the Company’s net operating losses have yet to be utilized, all previous tax years remain open to examination by Federal and state taxing authorities in which the Company currently operates. The Company recognized $825,000 of income tax expense related to the foreign taxes withheld from the LG Chem upfront payment received during the year ended December 31, 2018.

The Company recognizes interest accrued relative to unrecognized tax benefits in interest expense and penalties in operating expense. During the years ended December 31, 2018 and 2017, the Company did not recognize any income tax related interest and penalties. The Company did not have any accruals for income tax related interest and penalties at December 31, 2018 and 2017.

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 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 other 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 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 December 31, 2018 and 2017, 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. The common stock to be issued is not included in the calculation of earnings per share.

	December 31,
	2018		2017
Common stock warrants		1,252,441		1,252,441
Common stock options		4,540,321		2,732,221
Total		5,792,762		3,984,662

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 $10,547,628 in cash equivalents and $18,412,500 in short-term marketable securities that were measured and recorded at fair value on the Company’s balance sheet at December 31, 2018. There were no financial instruments that were measured and recorded at fair value on the Company’s balance sheet at December 31, 2017.

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 May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”) to provide updated guidance on revenue recognition. ASU 2014-09 requires a company to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies may need to use more judgment and make more estimates than under today’s guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price, and allocating the transaction price to each separate performance obligation. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which deferred the effective date of ASU 2014-09 by one year. Accordingly, ASU 2014-09 is effective for public business entities for annual reporting periods beginning after December 15, 2017, including interim reporting periods within each annual reporting period. In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross Versus Net), which clarifies the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, which clarifies certain aspects of identifying performance obligations and licensing implementation guidance. In May 2016, the FASB issued ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, which relates to disclosures of remaining performance obligations, as well as other amendments to guidance on collectability, non-cash consideration, and the presentation of sales and other similar taxes collected from customers. Collectively these amendments are referred to as “ASC 606”.

ASC 606 clarifies the principles for recognizing revenue and develops a common revenue standard for U.S. GAAP providing a more robust framework for addressing revenue issues, improves comparability of revenue recognition practices across entities, industries, jurisdictions, and capital markets, provides more useful information to users of financial statements through improved disclosure requirements, and simplifies the preparation of financial statements by reducing the number of requirements to which an entity must refer. This update is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period. The Company adopted this standard during 2018. The Company has recorded approximately $1,142,604 in collaboration revenue for the year ended December 31, 2018 pursuant to this guidance.

In February 2016, the FASB issued Accounting Standards Update No. 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 requires a lessee to record a right-of-use asset and a corresponding lease liability, initially measured at the present value of the lease payments, on the balance sheet for all leases with terms longer than 12 months, as well as the disclosure of key information about leasing arrangements. ASU 2016-02 requires recognition in the statement of operations of a single lease cost, calculated so that the cost of the lease is allocated over the lease term, generally on a straight-line basis. ASU 2016-02 requires classification of all cash payments within operating activities in the statement of cash flows. Disclosures are required to provide the amount, timing and uncertainty of cash flows arising from leases. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. We elected to adopt the package of practical expedients, which among other things, allows us to carry forward the historical lease classification and combine lease and non-lease components as a single component. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application is permitted. The Company adopted the provisions of ASU 2016-02 on January 1, 2019. This adoption approach will result in a balance sheet presentation that will not be comparable to the prior period in the first year of adoption. The adoption of this ASU will result in a balance sheet presentation that will not be comparable to the prior period in the first year of adoption. The adoption of this ASU will result in a recognition of a right of use asset of approximately $9,692,000 and lease liability of approximately $9,347,000. There was no cumulative adjustment to retained earnings as a result of this adoption.

In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows: Restricted Cash (“ASU 2016-18”). The amendments in this update require that amounts generally described as restricted cash and restricted cash equivalents be included within cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. ASU 2016-18 was effective January 1, 2018. As a result of adopting ASU 2016-18, the Company includes its restricted cash balance in the cash and cash equivalents reconciliation of operating, investing and financing activities. The following table provides a reconciliation of cash, cash equivalents, and restricted cash within the statement of financial position that sum to the total of the same such amounts shown in the statement of cash flows.

	December 31,
in thousands	2018		2017
Cash and cash equivalents	$	20,800	$	63,533
Restricted cash included in prepaid expenses and other current assets		50		50
Restricted cash included in other non-current assets		150	—
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	$	21,000	$	63,583

In May 2017, the FASB issued Accounting Standards Update No. 2017-09, Compensation-Stock Compensation (Topic 718); Scope of Modification Accounting (“ASU 2017-09”). ASU 2017-09 provides clarity and reduces both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718 to a change to the terms or conditions of a share-based payment award. The amendments in this ASU are effective for public entities for fiscal years and interim periods beginning after December 15, 2017. The ASU is applied prospectively on and after the effective date. This standard did not have a material effect on the Company’s financial statements.

In July 2017, the FASB issued Accounting Standards Update No. 2017-11, Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features; (Part II) Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (“ASU 2017-11”). ASU 2017-11 allows companies to exclude a down round feature when determining whether a financial instrument (or embedded conversion feature) is considered indexed to the entity’s own stock. As a result, financial instruments (or embedded conversion features) with down round features may no longer be required to be accounted for as derivative liabilities. A company will recognize the value of a down round feature only when it is triggered and the strike price has been adjusted downward. For equity-classified freestanding financial instruments, an entity will treat the value of the effect of the down round as a dividend and a reduction of income available to common shareholders in computing basic earnings per share. For convertible instruments with embedded conversion features containing down round provisions, entities will recognize the value of the down round as a beneficial conversion discount to be amortized to earnings. ASU 2017-11 is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The guidance in ASU 2017-11 can be applied using a full or modified retrospective approach. The adoption of ASU 2017-11 is not currently expected to have any impact on the Company’s financial statement presentation or disclosures.

In June 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2018-07 to simplify the accounting for share-based payments to nonemployees by aligning it with the accounting for share-based payments to employees, with certain exceptions. The new guidance expands the scope of Accounting Standards Codification (ASC) 718 to include share-based payments granted to nonemployees in exchange for goods or services used or consumed in an entity’s own operations and supersedes the guidance in ASC 505-50. The ASU aligns much of the measurement and classification guidance for share-based payments to nonemployees with that for share-based payments to employees. The guidance is effective for public business entities (PBEs) in annual periods beginning after 15 December 2018, early adoption is permitted. For all other entities, it is effective in annual periods beginning after 15 December 2019, and interim periods within annual periods beginning after 15 December 2020. Early adoption is permitted.

The Company adopted ASU 2018-07 on October 1, 2018. Management valued all non-employee option awards as of this date by estimating the fair value of the awarded options using a Black-Scholes option-pricing model and expected term and data inputs as of October 1, 2018.

Per ASU 2018-07, management compared the cumulative amounts that were recorded for the non-employee option awards through the end of the reporting period immediately preceding the date of adoption, September 30, 2018, to the cumulative amounts that should be recognized at the adoption date, October 1, 2018, to calculate the transition adjustment. The cumulative effect of the transition adjustment was de minimus and therefore no adjustment was made to the Company’s financial records.

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

12 Months Ended

Dec. 31, 2018

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 December 31, 2018 and indicate the level of the fair value hierarchy utilized to determine such fair value:

	Fair Value Measurements as of December 31, 2018
	Level 1		Level 2		Level 3		Fair Value
Cash equivalents	$	10,547,628	$	—	$	—	$	10,547,628
Marketable securities		—		18,412,500		—		18,412,500
Total	$	10,547,628	$	18,412,500	$	—	$	28,960,128

As of December 31, 2018, the Company’s cash equivalents that are invested in money market funds 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 year ended December 31, 2018, there were no transfers between Level 2 and Level 3. As of December 31, 2017, the Company did not have assets measured at fair value as the majority of its assets consisted of cash.

- 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

12 Months Ended

Dec. 31, 2018

Investments Debt And Equity Securities [Abstract]

Marketable Securities

4.	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
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury Securities	$	18,423,458	$	—	$	(10,958	)	$	18,412,500
	$	18,423,458	$	—	$	(10,958	)	$	18,412,500

At December 31, 2018, marketable securities consisted of $18,412,500 of investments that mature within twelve months. The Company recognized a loss on investments of $612 for the year ended December 31, 2018. At December 31, 2017, the Company did not have marketable securities as the majority of its assets consisted of cash.

Property and Equipment

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Property and Equipment

5.	Property and Equipment

Property and equipment as of December 31, 2018 and 2017 is summarized as follows:

	December 31,
	2018			2017
Laboratory equipment	$	3,872,233		$	2,205,410
Furniture and fixtures		93,321			9,606
Computer equipment		181,844			82,958
Leasehold improvements		—			53,718
		4,147,398			2,351,692
Less accumulated depreciation and amortization		(1,365,939	)		(661,153	)
Net property and equipment	$	2,781,459		$	1,690,539

Depreciation expense for the years ended December 31, 2018 and 2017 was included in the statement of operations as follows:

	Years Ended December 31,
	2018		2017
General and administrative	$	35,287	$	15,163
Research and development		724,724		404,405
Total	$	760,011	$	419,568

Accrued Expenses

12 Months Ended

Dec. 31, 2018

Accrued Liabilities Current [Abstract]

Accrued Expenses

6.	Accrued Expenses

Accrued expenses as of December 31, 2018 and 2017 is summarized as follows:

	December 31,
	2018		2017
Accrued compensation	$	1,195,749	$	824,349
Contract manufacturing services		160,650		95,657
Professional Services		207,440		111,750
Contract research services		145,035		21,472
Other expenses		79,188		97,857
	$	1,788,062	$	1,151,085

Einstein License and Service Agreement

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Einstein License and Service Agreement

7.Einstein License and Service Agreement

License Agreement

On January 14, 2015, the Company entered into a license agreement, as amended on June 2, 2015 (the “Einstein License”), with Einstein for certain patent rights (the “Patents”) 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.

Under the Einstein License, the Company holds an exclusive worldwide license, with the right to sublicense, import, make, have made, use, provide, offer to sell, and sell all products, processes and services that use the Patents, including certain technology received from Einstein relating thereto (the “Licensed Products”). Under the Einstein License, the Company is required to:

•

Pay royalties based on certain percentage of proceeds, as defined in the Einstein License, from sales of Licensed Products, including sublicense agreements.

•

Pay escalating annual maintenance fees as follows: $25,000 on January 14, 2017; $50,000 on each of January 14, 2018 and 2019; $75,000 on each of January 14, 2020 and 2021; and $100,000 on January 14, 2022 and each year thereafter. Annual maintenance fees are nonrefundable but are creditable against the amount due to Einstein for royalties during the 12 month period following each of the due dates for annual maintenance fees.

•

Make significant payments up to $5,000,000 based upon the achievement of certain milestones, as defined in the Einstein License. Payments made upon achievement of milestones are nonrefundable and are not creditable against any other payment due to Einstein. At December 31, 2018, none of these milestones had been achieved by the Company.

•

Incur a minimum of $250,000 per year of product development costs until the first commercial sale of the first licensed product.

The Company was in compliance with its obligations under the Einstein License at December 31, 2018 and 2017.

The Einstein License expires upon the expiration of the Company’s last obligation to make royalty payments to Einstein which may be due with respect to certain Licensed Products, unless terminated earlier under the provisions thereof. The Einstein License includes certain termination provisions if the Company fails to meet its obligations thereunder.

The Einstein License required the Company to issue to Einstein a specified number of shares of common stock of the Company on a fully diluted, as converted basis, depending on the achievement of (1) a funding threshold and (2) a liquidity event, each as defined in the Einstein License. The funding threshold was achieved through the completion of the June 15, 2015 private placement as described in Note 11. The Company’s initial public offering in December 27, 2017 met the definition of a liquidity event as defined by the agreement and therefore the Company was required to issue 671,572 shares of the Company’s common stock.

The Company accounted for the issuance of these shares as a charge to research and development expenses in the statement of operations at their aggregate fair value of $5,036,789 on the date of issuance, in accordance with ASC 730, Research and Development, as the Patents acquired from Einstein are for use in the Company’s research and development activities exclusively with respect to its core technology platform and have no alternative future use by the Company, and therefore no separate economic value. The shares issuable in connection with Einstein License were recorded as common stock to be issued at December 31, 2017, and were issued on January 9, 2018.

The Company accounts for the costs incurred in connection with the Einstein License in accordance with ASC 730, Research and Development. For the years ended December 31, 2018 and 2017, costs incurred with respect to the Einstein License aggregated $487,929 and $5,084,708, respectively. For the years ended December 31 2018 and 2017, $50,000 and $5,084,708 were included in research and development expenses in the statements of operations. For the year ended December 31, 2018, the Company capitalized $437,929 in costs incurred with respect to the Einstein License pursuant to ASC 606 and ASC 340.

Stock-Based Compensation

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

8.Stock-Based Compensation

Effective March 23, 2016, the Company adopted the 2016 Omnibus Incentive Plan (the “Omnibus Plan”) and the 2016 Non-Employee Equity Incentive Plan (the “Non-Employee Plan”), which are intended to allow the Company to compensate and retain the services of key employees, non-employees, Scientific and Clinical Advisory Board members, and outside advisors and consultants. The plans are under the administration of the Company’s Board of Directors. Under the plans, the Company, at its discretion, may grant stock option awards to certain employees and non-employees through March 23, 2026. The Omnibus Plan and the Non-Employee Plan provide for the grant of a total of 2,000,000 shares and 500,000 shares of common stock, respectively.

On August 13, 2017, the Company’s Board of Directors approved an amendment and restatement of the Company’s 2016 Omnibus Incentive Plan to increase the number of shares authorized for issuance under such plan by 800,000 shares, from 2,000,000 shares to 2,800,000 shares, subject to stockholder approval of such amendment within 12 months following board approval thereof. The Company’s stockholders approved the plan in December 2017. The 2016 Omnibus Incentive Plan, as amended and restated, provides that on the first day of each fiscal year of the Company during the period beginning in fiscal year 2018 and ending on the second day of fiscal year 2027, the number of shares of common stock authorized to be issued under such plan shall be increased by an amount equal to the lesser of (i) the number of shares necessary such that the aggregate number of shares available to be issued under the plan equals 20% of the number of fully diluted outstanding shares on such date (assuming the conversion of all outstanding shares of preferred stock and other outstanding convertible securities and exercise of all outstanding options and warrants to purchase shares) and (ii) an amount to be determined by the Company’s Board of Directors.

Pursuant to the plans, during the year ended December 31, 2018, the Company granted stock options to purchase 1,835,600 shares of the Company’s common stock. At December 31, 2018, stock options for 4,070,721 shares of common stock had been granted and 618,050 shares of common stock were reserved for future grants under the Omnibus Plan, and stock options for 469,600 shares of common stock had been granted and 30,400 shares of common stock were reserved for future grants under the Non-Employee Plan. In the aggregate, at December 31, 2018, stock options for a total of 4,540,321 shares of common stock had been granted and 648,450 shares of common stock were reserved for future grants. Such grants are accounted for as share-based compensation in accordance with ASC 718, Compensation - Stock Compensation, and ASC 505-50, Equity-Based Payments to Non-Employees.

For stock options requiring an assessment of value during the years ended December 31, 2018 and 2017, the fair value of each stock option award was estimated using the Black-Scholes option-pricing model utilizing the following assumptions:

	December 31,
	2018			2017
Risk-free interest rate	2.43 to 2.95%			1.71 to 2.22%
Expected dividend yield		0	%		0	%
Expected volatility	82.0-83.6%			80.9-83.0%
Expected life	4.0 to 7.0 years			3.2 to 7 years

The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected term of the stock option award; as permitted by Staff Accounting Bulletin 107, due to insufficient history of stock option activity, management has utilized the simplified approach to estimate the expected term of the stock options, which represents the period of time that stock options granted are expected to be outstanding; the expected volatility is based upon historical volatilities of comparable companies in a similar industry; and the expected dividend yield based upon the Company’s current dividend rate and future expectations.

A summary of stock option activity for the years ended December 31, 2018 is as follows:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in Years)
Stock options outstanding at December 31, 2016		1,663,221		$	2.86		6.22
Granted		1,089,000			5.89
Exercised		(2,800	)		2.86
Cancelled		(17,200	)		2.86
Stock options outstanding at December 31, 2017		2,732,221		$	4.07		5.76
Granted		1,835,600			11.33
Exercised		(2,500	)		5.00
Cancelled		(25,000	)		7.79
Stock options outstanding at December 31, 2018		4,540,321		$	7.08		5.16
Stock options exercisable at December 31, 2018		1,422,014		$	4.81		4.68

The Company recognized $7,173,713, and $2,775,363 in stock-based compensation during the years ended December 31, 2018 and 2017, respectively. As of December 31, 2018, total unrecognized stock-based compensation was approximately $15,816,662, which is expected to be recognized as an operating expense in the Company’s statement of operations through June 2022.

The intrinsic value of exercisable but unexercised in-the-money stock options at December 31, 2018 was approximately $1,682,014 based on a fair value of $4.70 per share on December 31, 2018.

The intrinsic value of exercisable but unexercised in-the-money stock options at December 31, 2017 was approximately $2,522,000, based on a fair value of $7.50 per share at December 31, 2017.

Stock-based compensation for the years ended December 31, 2018 and 2017 was included in the statement of operations as follows:

	December 31,
	2018		2017
General and administrative	$	3,221,512	$	1,022,962
Research and development		3,952,201		1,752,401
Total	$	7,173,713	$	2,775,363

Revenue Recognition

12 Months Ended

Dec. 31, 2018

Revenue From Contract With Customer [Abstract]

Revenue Recognition

10.	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 Merck Agreement , 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.

Revenue is recognized over time by allocating a portion of the Company’s direct costs incurred to provide research and development services related to the performance obligation. Furthermore, the Company has not capitalized any contract costs under the guidance in ASC 340-40, Other Assets and Deferred Costs: Contracts with Customers.

The Company does not believe that any variable consideration should be included in the transaction price at December 31, 2018. 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 year ended December 31, 2018, the Company recognized $1,142,605 in collaboration revenue related to this agreement and recorded short and long-term research and development liabilities on its balance sheet dated December 31, 2018 of $1,198,122 and $159,272, respectively.

On November 6, 2018, the Company entered into the LG Chem 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 will make 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 recognized the $5.0 million 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. 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. 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 of $813,876 and $5,015,479 respectively.

The Company does not believe that any variable consideration should be included in the transaction price as of December 31, 2018. 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 year ended December 31, 2018, the Company did not recognized revenue 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 Merck Agreement. As it 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 discussed in Note 7. Of the total, $54,200 is included in prepaid expenses and other short-term assets and $383,729 is included in other long-term assets.

Stockholders' Equity

12 Months Ended

Dec. 31, 2018

Stockholders Equity [Abstract]

Stockholders' Equity

11.	Stockholders’ Equity

Preferred Stock

The Company has authorized a total of 10,000,000 shares of preferred stock, par value $0.001 per share, none of which were outstanding at December 31, 2018 and 2017. The Company’s Board of Directors has the authority to issue preferred stock and to determine the rights, preferences, privileges, and restrictions, including voting rights.

Common Stock

The Company has authorized a total of 50,000,000 shares of common stock, par value $0.001 per share, of which 20,697,453 shares and 19,459,194 shares were issued and outstanding at December 31, 2018 and 2017, respectively.

June 15, 2015 Private Placement of Common Stock. On June 15, 2015, the Company sold 3,703,704 shares of common stock in a private placement to accredited investors at $2.70 per share, resulting in gross cash proceeds of $10,000,000. Direct costs of the private placement consisted of a 10% placement agent fee to the placement agent, MDB Capital Group, LLC (“MDB”) of $1,000,000, and related legal fees and reimbursable expenses of $137,588. In conjunction with this private placement, the Company issued warrants to the placement agent to purchase 370,370 shares of common stock, exercisable at issuance for a period of seven years at $2.70 per share, for a cash consideration of $1,000. The placement agent warrants had a fair value of $773,941, calculated pursuant to the Black-Scholes option-pricing model. Issuance costs of the private placement, including the fair value of placement agent warrants of $773,941, aggregated $1,911,529 and were charged directly to additional paid-in capital.

December 22, 2016 Private Placement of Common Stock. On December 22, 2016, the Company sold 3,282,980 shares of common stock in a private placement to accredited investors at $5.00 per share, resulting in gross cash proceeds of $16,414,900. Direct costs of the private placement consisted of a placement agent fee to the placement agent, MDB, of $1,320,745 and related legal fees and reimbursable expenses of $89,119. Issuance costs of the private placement aggregated $1,409,864 and were charged directly to additional paid-in capital.

Down Round Protection. The Company provided investors in the December 22, 2016 private placement of common stock with certain limited protections resulting from one or more issuances of shares of common stock at a per share purchase price below that was paid by the investors in the private placement, terminating on December 31, 2019. If the Company issued additional shares of common stock without consideration, or for consideration per share less than the effective per share price deemed to be in effect immediately prior to such issuance, then concurrently with such issuance, the Company was required to issue to each investor, for no additional consideration additional shares of common stock as specified in the private placement memorandum.

Pursuant to an Irrevocable Waiver and Amendment to Securities Purchase Agreements entered into on December 4, 2017, the Majority Investors in the December 2016 private placement agreed that no shares shall be issuable pursuant to these anti-dilution rights in connection with any issuance of common stock occurring after the Company’s initial public offering.

Related Party Transactions

12 Months Ended

Dec. 31, 2018

Related Party Transactions

12.	Related Party Transactions

During the years ended December 31, 2018, and 2017, MDB provided investment banking services to the Company. For those services, the Company paid MDB cash placement agent fees of $0 and $3,473,155 respectively. In 2017, the Company also issued to MDB underwriter warrants to purchase 833,312 shares of the Company’s common stock for a cash consideration of $1,000, exercisable for five years at $9.38 per share. As of December 31, 2017, MDB beneficially owned approximately 10.2% of the Company’s common stock, has served as the underwriter of the Company’s initial public offering as well as the placement agent in previous private placements of the Company’s common stock, and one employee of which is a director of the Company.

MDB assigned one-half of the warrants that it acquired in conjunction with the June 15, 2015 private placement (see Note 9) to eight employees of MDB, two of which are also current officers or directors of the Company, who received a total of 72,222 of such warrants as part of the normal distribution of warrants received by MDB to its employees.

Beginning in June 2015, the interim Chief Financial Officer of the Company, who is also the Chief Financial Officer of MDB, has been compensated at a rate of $6,000 per month, reflecting an aggregate annual charge to operations for the years ended December 31, 2018 and 2017 of $24,000 and $72,000, respectively, and no longer serves as the interim Chief Financial Officer as December 31, 2018.

Information with respect to payments under the Einstein License and the Service Agreement is described in Note 7.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

13.	Income Taxes

The Company accounts for income taxes under the provision of ASC 740, Income Taxes. The Company reported a $825,000 tax provision for the year ended December 31, 2018 related to foreign withholding taxes paid. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets as of December 31, 2018 and 2017 are as follows:

	2018			2017
Deferred tax assets:
Net operating loss carryforwards	$	15,738,000		$	8,424,000
Research and other credits		1,450,000			867,000
Reserves and accruals		1,953,000			595,000
Other		3,000			—
Intangibles		—			4,000
Total gross deferred tax assets		19,144,000			9,890,000
Less valuation allowance		(19,004,000	)		(9,793,000	)
Total deferred tax assets		140,000			97,000
Deferred tax liability:
Depreciation		(140,000	)		(97,000	)
Net deferred tax assets	$	—		$	—

In assessing the potential realization of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will be realized. The ultimate realization of deferred tax assets is dependent upon the Company attaining future taxable income during the periods in which those temporary differences become deductible. As of December 31, 2018 and 2017, management was unable to determine if it is more likely than not that the Company’s deferred tax assets will be realized and has therefore recorded a 100% valuation allowance against deferred tax assets at such dates.

No Federal tax provision has been provided for the years ended December 31, 2018 and 2017, due to the losses incurred during such periods. A reconciliation of the difference between the income tax rate computed by applying the U.S. Federal statutory rate and the effective tax rate for the years ended December 31, 2018 and 2017 is as follows:

	Years Ended December 31,
	2018			2017
U. S. Federal statutory tax rate		(21	)%		(35	)%
State Taxes		(4	)%		0	%
Change in valuation allowance		24	%		16	%
Tax credits		(2	)%		(2	)%
Stock based compensation		3	%		2	%
Tax reform		0	%		18	%
Foreign withholding taxes		2	%		0	%
Other		0	%		1	%
Effective tax rate		(2	)%		0.0	%

The Company has applied the provisions of ASC 740, Income Taxes, which clarifies the accounting for uncertainty in tax positions and requires the recognition of the impact of a tax position in the financial statements if that position is more likely than not of being sustained on a tax return, based on the technical merits of the position, upon examination by the relevant taxing authority. At December 31, 2018 and 2017, the Company had unrecognized tax benefits related to Federal and state research tax credits of approximately $972,000 and $510,000, respectively. The Company is subject to Federal and state income tax examinations by tax authorities for all years since its incorporation in 2014. The Company is currently not under examination by any tax authority.

At December 31, 2018, the Company has available net operating loss carryforwards for Federal and state income tax purposes of approximately $57,532,000 and $57,845,000, respectively, which, if not utilized earlier, will begin to expire in 2035. The Company has Federal research credits of approximately $1,202,000, which, if not utilized earlier, will begin to expire in 2035, and state research credits of approximately $314,000, which, if not utilized earlier, will begin to expire in 2031. At December 31, 2018 the Company recorded $250,000 in research credits as prepaid to be offset against payroll tax liabilities associated with research and development personnel in 2018 in addition to the approximately $140,000 in research and development credits remaining in prepaid from 2017.

On December 22, 2017, the Tax Cuts and Jobs Acts was enacted into law. ASC 740 requires the Company to recognize the effect of the tax law change in the period of enactment. The lower tax rate requires the Company to remeasure its deferred tax assets and liabilities in fourth quarter of 2017. The total amount of the Company’s deferred tax assets before valuation allowance decreased by $4.3 million as a result of the decrease in the federal tax rate.

As permitted by SEC Staff Accounting Bulletin 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act, we recorded provisional estimates during the year ended December 31, 2017, and have subsequently finalized our accounting analysis based on the guidance, interpretations, and data available as of December 31, 2018 and no further adjustments were made upon finalization of our accounting analysis.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

14.	Commitments and Contingencies

Einstein License and Service Agreement

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 product 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 $4.4 million during the year ended December 31, 2018 and currently estimates that it will incur an additional $0.3 million of such costs during the year ended December 31, 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 Merck Agreement 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™ product 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™ product 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. For the years ended December 31, 2018 and 2017, the Company recorded approximately $1.1 million and $0 in collaboration revenue related to this agreement (Note 10).

Collaboration Agreement with LG Chem Life Sciences

On November 6, 2018, the Company entered into the LG Chem Agreement with LG Chem Life Sciences. 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 will make 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. There was no revenue recognized for the year ended December 31, 2018 related to this agreement.

Leased Facilities

On July 29, 2015, the Company entered into an operating lease agreement for its previous laboratory space for the period from August 1, 2015 through April 30, 2018. The lease contained escalating payments during the lease period. The Company records monthly rent expense on the straight-line basis.

On November 14, 2016 and January 16, 2018 the Company entered into an amendments to the operating lease agreement that each provided the Company with additional laboratory space. These amendments were effective beginning December 1, 2016 and January 16, 2018, respectively, and continued through the expiration of the lease on April 30, 2018.

On January 18, 2018, the Company entered into an operating lease agreement for its laboratory and office space in Cambridge, Massachusetts for the period from May 1, 2018 through April 30, 2021. The lease contains escalating payments during the lease period. Upon execution of this lease agreement the Company prepaid three months of rent, two of which will be held in escrow and credited against future rent payments and one month that was applied to the first months rent. The Company also prepaid seven and one half months rent pursuant to an amendment to the lease agreement executed on June 18, 2018. These amounts were recorded to deposits and prepaid expenses, respectively at December 31, 2018.

On June 18, 2018, the Company entered into an amended lease agreement that provided the Company with a reduction in rental fees for its office and laboratory space in exchange for prepayment of a portion of the fees. This amendment was effective beginning on May 15, 2018 and expires on April 14, 2021.

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. Upon execution of this lease agreement the Company prepaid three months of rent which will be held in escrow and credited against future rent payments. The Company also prepaid twelve months rent pursuant to the lease agreement executed on September 20, 2018. These amounts were recorded to deposits and prepaid expenses, respectively at December 31, 2018.

Future minimum lease payments under these leases at December 31, 2018 are as follows:

Year
2019		4,461,349
2020		4,910,521
2021		1,432,234
Total	$	10,804,104

Total rent expense of approximately $3,311,000 and $1,976,000 was included in the statement of operations for the years ended December 31, 2018 and 2017, respectively.

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 December 31, 2018, 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.

Cue Biopharma 401(k) Plan

12 Months Ended

Dec. 31, 2018

Compensation And Retirement Disclosure [Abstract]

Cue Biopharma 401(k) Plan

15.	Cue Biopharma 401(k) Plan

Effective as of January 1, 2017, the Company adopted the Cue Biopharma 401(k) Plan (the “Plan”) for all employees of the Company. Employees may participate in the Plan upon complying with the Plan’s eligibility requirements, subject to limitations imposed by the Internal Revenue Service. Under the Plan, the Company may match employee contributions at its discretion. The Company did not make any contributions to the Plan during the year ended December 31, 2018 or 2017.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation

Cash and Cash Equivalents

Marketable Securities

Restricted Cash

Property and Equipment

Laboratory equipment		5 years
Computer 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

Rent Expense and Deferred Rent Liability

Stock-Based Compensation

Income Taxes

Comprehensive Income (Loss)

Earnings (Loss) Per Share

	December 31,
	2018		2017
Common stock warrants		1,252,441		1,252,441
Common stock options		4,540,321		2,732,221
Total		5,792,762		3,984,662

Fair Value of Financial Instruments

Recent Accounting Pronouncements

	December 31,
in thousands	2018		2017
Cash and cash equivalents	$	20,800	$	63,533
Restricted cash included in prepaid expenses and other current assets		50		50
Restricted cash included in other non-current assets		150	—
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	$	21,000	$	63,583

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

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 equipment		3 years
Furniture and fixtures		3-8 years

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

	December 31,
	2018		2017
Common stock warrants		1,252,441		1,252,441
Common stock options		4,540,321		2,732,221
Total		5,792,762		3,984,662

Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash

The following table provides a reconciliation of cash, cash equivalents, and restricted cash within the statement of financial position that sum to the total of the same such amounts shown in the statement of cash flows.

	December 31,
in thousands	2018		2017
Cash and cash equivalents	$	20,800	$	63,533
Restricted cash included in prepaid expenses and other current assets		50		50
Restricted cash included in other non-current assets		150	—
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	$	21,000	$	63,583

Fair Value (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Fair Value Assets Measured on Recurring Basis

	Fair Value Measurements as of December 31, 2018
	Level 1		Level 2		Level 3		Fair Value
Cash equivalents	$	10,547,628	$	—	$	—	$	10,547,628
Marketable securities		—		18,412,500		—		18,412,500
Total	$	10,547,628	$	18,412,500	$	—	$	28,960,128

Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2018

Investments Debt And Equity Securities [Abstract]

Schedule of Fair Value of Available-for-Sale 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
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury Securities	$	18,423,458	$	—	$	(10,958	)	$	18,412,500
	$	18,423,458	$	—	$	(10,958	)	$	18,412,500

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Summary of Property and Equipment

Property and equipment as of December 31, 2018 and 2017 is summarized as follows:

	December 31,
	2018			2017
Laboratory equipment	$	3,872,233		$	2,205,410
Furniture and fixtures		93,321			9,606
Computer equipment		181,844			82,958
Leasehold improvements		—			53,718
		4,147,398			2,351,692
Less accumulated depreciation and amortization		(1,365,939	)		(661,153	)
Net property and equipment	$	2,781,459		$	1,690,539

Summary of Depreciation Expense

Depreciation expense for the years ended December 31, 2018 and 2017 was included in the statement of operations as follows:

	Years Ended December 31,
	2018		2017
General and administrative	$	35,287	$	15,163
Research and development		724,724		404,405
Total	$	760,011	$	419,568

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2018

Accrued Liabilities Current [Abstract]

Summary of Accrued Expenses

Accrued expenses as of December 31, 2018 and 2017 is summarized as follows:

	December 31,
	2018		2017
Accrued compensation	$	1,195,749	$	824,349
Contract manufacturing services		160,650		95,657
Professional Services		207,440		111,750
Contract research services		145,035		21,472
Other expenses		79,188		97,857
	$	1,788,062	$	1,151,085

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Estimated Fair Value of Each Stock Option Award

	December 31,
	2018			2017
Risk-free interest rate	2.43 to 2.95%			1.71 to 2.22%
Expected dividend yield		0	%		0	%
Expected volatility	82.0-83.6%			80.9-83.0%
Expected life	4.0 to 7.0 years			3.2 to 7 years

Summary of Stock Option Activity

A summary of stock option activity for the years ended December 31, 2018 is as follows:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in Years)
Stock options outstanding at December 31, 2016		1,663,221		$	2.86		6.22
Granted		1,089,000			5.89
Exercised		(2,800	)		2.86
Cancelled		(17,200	)		2.86
Stock options outstanding at December 31, 2017		2,732,221		$	4.07		5.76
Granted		1,835,600			11.33
Exercised		(2,500	)		5.00
Cancelled		(25,000	)		7.79
Stock options outstanding at December 31, 2018		4,540,321		$	7.08		5.16
Stock options exercisable at December 31, 2018		1,422,014		$	4.81		4.68

Schedule of Stock-Based Compensation Included in Statement of Operations

Stock-based compensation for the years ended December 31, 2018 and 2017 was included in the statement of operations as follows:

	December 31,
	2018		2017
General and administrative	$	3,221,512	$	1,022,962
Research and development		3,952,201		1,752,401
Total	$	7,173,713	$	2,775,363

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Components of Deferred Tax Assets

Significant components of the Company’s deferred tax assets as of December 31, 2018 and 2017 are as follows:

	2018			2017
Deferred tax assets:
Net operating loss carryforwards	$	15,738,000		$	8,424,000
Research and other credits		1,450,000			867,000
Reserves and accruals		1,953,000			595,000
Other		3,000			—
Intangibles		—			4,000
Total gross deferred tax assets		19,144,000			9,890,000
Less valuation allowance		(19,004,000	)		(9,793,000	)
Total deferred tax assets		140,000			97,000
Deferred tax liability:
Depreciation		(140,000	)		(97,000	)
Net deferred tax assets	$	—		$	—

Schedule of Reconciliation of Federal Statutory Rate and Effective Tax Rate

A reconciliation of the difference between the income tax rate computed by applying the U.S. Federal statutory rate and the effective tax rate for the years ended December 31, 2018 and 2017 is as follows:

	Years Ended December 31,
	2018			2017
U. S. Federal statutory tax rate		(21	)%		(35	)%
State Taxes		(4	)%		0	%
Change in valuation allowance		24	%		16	%
Tax credits		(2	)%		(2	)%
Stock based compensation		3	%		2	%
Tax reform		0	%		18	%
Foreign withholding taxes		2	%		0	%
Other		0	%		1	%
Effective tax rate		(2	)%		0.0	%

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Schedule of Future Minimum Lease Payments for Operating Lease

Future minimum lease payments under these leases at December 31, 2018 are as follows:

Year
2019		4,461,349
2020		4,910,521
2021		1,432,234
Total	$	10,804,104

Organization and Basis of Presentation - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Abstract]
State of incorporation	Delaware
Date of incorporation	Dec. 31, 2014
Cash, cash equivalents and marketable securities	$ 39,213,000

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]
Restricted cash used to collateralize a credit card	$ 150,000
Acquired intangible asset, useful life	15 years
Disposal of equipment	$ 58,000	$ 16,000
Loss from disposal	(3,315)	(10,677)
Income tax expense	825,000
Cash equivalents	10,547,628
Short-term marketable securities	18,412,500
Collaboration revenue	1,142,604
ASC 606 \| Collaboration Agreement with Merck
Summary Of Significant Accounting Policies [Line Items]
Collaboration revenue	1,142,604
ASU 2016-02 \| Subsequent Event
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	$ 1,222,000	$ 592,000
Type of Cost, Good or Service [Extensible List]	us-gaap:LicenseMember	us-gaap:LicenseMember
Certificate of Deposit
Summary Of Significant Accounting Policies [Line Items]
Short-term restricted cash	$ 50,000	$ 50,000

Summary of Significant Accounting Policies - Summary of Estimated Useful Lives of Assets (Details)	12 Months Ended
	Dec. 31, 2018
Laboratory Equipment
Property Plant And Equipment [Line Items]
Estimated useful lives	5 years
Computer Equipment
Property Plant And Equipment [Line Items]
Estimated useful lives	3 years
Furniture and Fixtures \| Minimum
Property Plant And Equipment [Line Items]
Estimated useful lives	3 years
Furniture and Fixtures \| Maximum
Property Plant And Equipment [Line Items]
Estimated useful lives	8 years

Summary of Significant Accounting Policies - Schedule of Anti-dilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	5,792,762	3,984,662
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	4,540,321	2,732,221

Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summary Of Significant Accounting Policies [Line Items]
Restricted cash included in prepaid expenses and other current assets	$ 50,068	$ 50,068
Restricted cash included in other non-current assets	150,000
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	21,000,352	63,583,717	$ 14,925,820
ASU 2016-18
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	20,800,000	63,533,000
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	21,000,000	63,583,000
ASU 2016-18 \| Prepaid Expenses and Other Current Assets
Summary Of Significant Accounting Policies [Line Items]
Restricted cash included in prepaid expenses and other current assets	50,000	$ 50,000
ASU 2016-18 \| Other Non-Current Assets
Summary Of Significant Accounting Policies [Line Items]
Restricted cash included in other non-current assets	$ 150,000

Fair Value - Schedule of Fair Value Assets Measured on Recurring Basis (Details)	Dec. 31, 2018 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 10,547,628
Marketable securities	18,412,500
Fair Value Measurements, Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	10,547,628
Marketable securities	18,412,500
Total	28,960,128
Fair Value Measurements, Recurring Basis \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	10,547,628
Total	10,547,628
Fair Value Measurements, Recurring Basis \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	18,412,500
Total	$ 18,412,500

Marketable Securities - Schedule of Fair Value of Available-for-Sale Marketable Securities (Details)	Dec. 31, 2018 USD ($)
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 18,423,458
Gross Unrealized Losses	(10,958)
Fair Value	18,412,500
U.S. Treasury Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	18,423,458
Gross Unrealized Losses	(10,958)
Fair Value	$ 18,412,500

Marketable Securities - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Investments Debt And Equity Securities [Abstract]
Marketable securities	$ 18,412,500	$ 0
Loss on investments	$ 612

Property and Equipment - Summary of Property and Equipment (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 4,147,398	$ 2,351,692
Less accumulated depreciation and amortization	(1,365,939)	(661,153)
Net property and equipment	2,781,459	1,690,539
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	3,872,233	2,205,410
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	93,321	9,606
Computer Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 181,844	82,958
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross		$ 53,718

Summary of Accrued Expenses (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities Current [Abstract]
Accrued compensation	$ 1,195,749	$ 824,349
Contract manufacturing services	160,650	95,657
Professional services	207,440	111,750
Contract research services	145,035	21,472
Other expenses	79,188	97,857
Accrued expenses	$ 1,788,062	$ 1,151,085

Einstein License and Service Agreement - Additional Information (Details)									12 Months Ended
	Jan. 14, 2022 USD ($)	Jan. 14, 2021 USD ($)	Jan. 14, 2020 USD ($)	Jan. 14, 2019 USD ($)	Jan. 14, 2018 USD ($)	Dec. 26, 2017 USD ($) shares	Jan. 14, 2017 USD ($)	Jan. 14, 2015 USD ($)	Dec. 31, 2018 USD ($) SupportingTechnology	Dec. 31, 2017 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Shares issued, fair value									$ 4,169,349
Einstein License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
License agreement entered date								Jan. 14, 2015
Number of supporting technology \| SupportingTechnology									2
Nonrefundable annual maintenance fees					$ 50,000		$ 25,000
Nonrefundable milestone payments									$ 0
Shares issued \| shares						671,572
Costs incurred									487,929	$ 5,084,708
Capitalized costs incurred									437,929
Einstein License Agreement \| Research and Development
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Shares issued, fair value						$ 5,036,789
Costs incurred									$ 50,000	$ 5,084,708
Type of Cost, Good or Service [Extensible List]									us-gaap:LicenseMember	us-gaap:LicenseMember
Einstein License Agreement \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Nonrefundable milestone payments								$ 5,000,000
Einstein License Agreement \| Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Product development costs									$ 250,000
Einstein License Agreement \| Scenario, Forecast
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Nonrefundable annual maintenance fees	$ 100,000	$ 75,000	$ 75,000
Einstein License Agreement \| Subsequent Event
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Nonrefundable annual maintenance fees				$ 50,000

Stock-Based Compensation - Additional Information (Details) - USD ($)		12 Months Ended
	Aug. 13, 2017	Dec. 31, 2018	Dec. 31, 2017	Aug. 12, 2017	Mar. 23, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted		1,835,600	1,089,000
Common stock reserved for issuance		648,450
Stock-based compensation		$ 7,173,713	$ 2,775,363
Unrecognized stock-based compensation		15,816,662
Intrinsic value of exercisable stock options		$ 1,682,014	$ 2,522,000
Intrinsic value of exercisable fair value per share		$ 4.70	$ 7.50
Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted		4,540,321
2016 Omnibus Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted		4,070,721
Common stock reserved for issuance		618,050
2016 Omnibus Incentive Plan \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized	2,800,000			2,000,000	2,000,000
Number of additional shares authorized for issuance	800,000
Percentage of number of common stock outstanding		20.00%
2016 Non-Employee Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted		469,600
Common stock reserved for issuance		30,400
2016 Non-Employee Equity Incentive Plan \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized					500,000

Stock-Based Compensation - Schedule of Estimated Fair Value of Each Stock Option Award (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	2.43%	1.71%
Risk-free interest rate, maximum	2.95%	2.22%
Expected dividend yield	0.00%	0.00%
Expected volatility, minimum	82.00%	80.90%
Expected volatility, maximum	83.60%	83.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life	4 years	3 years 2 months 12 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life	7 years	7 years

Stock-Based Compensation - Summary of Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward
Number of Shares, Outstanding Beginning Balance	2,732,221	1,663,221
Number of shares granted	1,835,600	1,089,000
Number of Shares, Exercised	(2,500)	(2,800)
Number of Shares, Cancelled	(25,000)	(17,200)
Number of Shares, Outstanding Ending Balance	4,540,321	2,732,221	1,663,221
Number of Shares, Exercisable	1,422,014
Weighted Average Exercise Price, Outstanding Beginning Balance	$ 4.07	$ 2.86
Weighted Average Exercise Price, Granted	11.33	5.89
Weighted Average Exercise Price, Exercised	5.00	2.86
Weighted Average Exercise Price, Cancelled	7.79	2.86
Weighted Average Exercise Price, Outstanding Ending Balance	7.08	$ 4.07	$ 2.86
Weighed Average Exercise Price, Exercisable	$ 4.81
Weighted Average Remaining Contractual Life (in Years)	5 years 1 month 28 days	5 years 9 months 3 days	6 years 2 months 19 days
Weighted Average Remaining Contractual Life (in Years), Exercisable	4 years 8 months 4 days

Stock-Based Compensation - Schedule of Stock-Based Compensation Included in Statement of Operations (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	$ 7,173,713	$ 2,775,363
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	3,221,512	1,022,962
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	$ 3,952,201	$ 1,752,401

Warrants - Additional Information (Details)	12 Months Ended
Warrants - Additional Information (Details)	Dec. 31, 2018 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]
Fair value of common stock	$ 4.70
Intrinsic value of common stock warrants \| $	$ 741,000
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 (Details1) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01	Dec. 31, 2018
Current Liabilities \| Maximum
Disaggregation Of Revenue [Line Items]
Revenue expected to be recognized	12 months
Current Liabilities \| Maximum \| Einstein License And Service Agreement \| Einstein
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 License And Service Agreement \| Einstein
Disaggregation Of Revenue [Line Items]
Revenue expected to be recognized	12 months

Revenue Recognition - Additional Information (Details) - USD ($)		12 Months Ended
	Nov. 06, 2018	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Transaction price recorded in liabilities		$ 2,500,000
Collaboration revenue		1,142,604
Short-term research and development contract liability		2,011,998	$ 2,500,000
Long-term research and development contract liability		5,174,752
Income tax expense		825,000
Prepaid expenses and other short-term assets		1,347,288	1,255,796
Other long-term assets		808,729	198,282
Collaboration Agreement with Merck \| Merck
Disaggregation Of Revenue [Line Items]
Collaboration revenue		1,142,605	$ 0
Short-term research and development contract liability		1,198,122
Long-term research and development contract liability		159,272
Collaboration Agreement with LG Chem Life Sciences \| LG Chem Life Sciences
Disaggregation Of Revenue [Line Items]
Collaboration revenue		0
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	5,000,000
Income tax expense	825,000
Premium paid for stock purchased	829,000
Collaboration Agreement with LG Chem Life Sciences \| LG Chem Life Sciences \| Maximum
Disaggregation Of Revenue [Line Items]
Additional amount receivable research development regulatory and sales milestones	$ 400,000,000
Einstein License And Service Agreement \| Einstein
Disaggregation Of Revenue [Line Items]
Transaction price recorded in liabilities		5,800,000
Collaboration revenue		0
Short-term research and development contract liability		813,876
Long-term research and development contract liability		5,015,479
Patent expenses		438,000
Prepaid expenses and other short-term assets		54,200
Other long-term assets		$ 383,729

Stockholders' Equity - Additional Information (Details) - USD ($)				12 Months Ended
	Dec. 04, 2017	Dec. 22, 2016	Jun. 15, 2015	Dec. 31, 2018	Dec. 31, 2017
Subsidiary Sale Of Stock [Line Items]
Preferred stock, shares authorized				10,000,000	10,000,000
Preferred stock, par value				$ 0.001	$ 0.001
Preferred stock, shares issued				0	0
Common stock, shares authorized				50,000,000	50,000,000
Common stock, par value				$ 0.001	$ 0.001
Common stock, shares issued				20,697,453	19,459,194
Common stock, shares outstanding				20,697,453	19,459,194
Antidilution rights in connection with any issuance of common stock				5,792,762	3,984,662
Amendment to Securities Purchase Agreements
Subsidiary Sale Of Stock [Line Items]
Antidilution rights in connection with any issuance of common stock	0
MDB
Subsidiary Sale Of Stock [Line Items]
Warrants to purchase shares of stock					833,312
Common stock warrants life					5 years
Exercise price of common stock warrants					$ 9.38
Warrants issued, cash consideration					$ 1,000
Private Placement \| Common Stock
Subsidiary Sale Of Stock [Line Items]
Sale of common stock		3,282,980	3,703,704
Sale of common stock price per share		$ 5.00	$ 2.70
Sale of stock, consideration received on transaction		$ 16,414,900	$ 10,000,000
Warrants to purchase shares of stock			370,370
Common stock warrants life			7 years
Exercise price of common stock warrants			$ 2.70
Warrants issued, cash consideration			$ 1,000
Warrants issued, additional paid-in-capital		1,409,864	1,911,529
Private Placement \| Common Stock \| Black-Scholes Option-Pricing Model
Subsidiary Sale Of Stock [Line Items]
Warrants, fair value			$ 773,941
Private Placement \| Common Stock \| MDB
Subsidiary Sale Of Stock [Line Items]
Placement agent fee percentage			10.00%
Placement agent fee amount		1,320,745	$ 1,000,000
Legal fees and reimbursable expenses		$ 89,119	$ 137,588

Related Party Transactions - Additional Information (Details) - MDB	12 Months Ended
	Dec. 31, 2018 USD ($) Director RelatedParty CurrentOfficerorDirector shares	Dec. 31, 2017 USD ($) $ / shares shares
Related Party Transaction [Line Items]
Cash placement agent fees paid	$ 0	$ 3,473,155
Warrants to purchase shares of stock \| shares		833,312
Exercise price of common stock warrants \| $ / shares		$ 9.38
Common stock warrants life		5 years
Warrants issued, cash consideration		$ 1,000
Beneficial ownership percentage		10.20%
Number of related parties, designated as directors \| Director	1
Employees
Related Party Transaction [Line Items]
Warrants assigned description	one-half
Number of related parties, to whom warrants issued \| RelatedParty	8
Number of current officers or directors to whom warrants issued \| CurrentOfficerorDirector	2
Current Officers or Directors
Related Party Transaction [Line Items]
Warrants issued \| shares	72,222
Chief Financial Officer
Related Party Transaction [Line Items]
Monthly compensation payable to officer	$ 6,000
Aggregate annual compensation payable to officer	$ 24,000	$ 72,000

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Tax provision related to foreign withholding tax	$ 825,000
Percentage of valuation allowance against deferred tax assets	100.00%	100.00%
Tax Cuts and Jobs Act of 2017, decrease in deferred tax assets before valuation allowance		$ 4,300,000
Federal
Income Taxes [Line Items]
Operating loss carryforwards	$ 57,532,000
Operating loss carryforwards expiration start year	2035
State
Income Taxes [Line Items]
Operating loss carryforwards	$ 57,845,000
Operating loss carryforwards expiration start year	2035
Research Tax Credit
Income Taxes [Line Items]
Prepaid amount to be offset against payroll tax liabilities	$ 250,000
Prepaid amount to be offset against payroll tax liabilities remaining from previous year	140,000
Research Tax Credit \| Federal
Income Taxes [Line Items]
Unrecognized tax benefits	972,000
Tax credits	$ 1,202,000
Tax credits carryforward expiration start year	2035
Research Tax Credit \| State
Income Taxes [Line Items]
Unrecognized tax benefits		$ 510,000
Tax credits	$ 314,000
Tax credits carryforward expiration start year	2031

Income Taxes - Schedule of Components of Deferred Tax Assets (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carryforwards	$ 15,738,000	$ 8,424,000
Research and other credits	1,450,000	867,000
Reserves and accruals	1,953,000	595,000
Other	3,000
Intangibles		4,000
Total gross deferred tax assets	19,144,000	9,890,000
Less valuation allowance	(19,004,000)	(9,793,000)
Total deferred tax assets	140,000	97,000
Deferred tax liability:
Depreciation	$ (140,000)	$ (97,000)

Income Taxes - Schedule of Reconciliation of Federal Statutory Rate and Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U. S. Federal statutory tax rate	(21.00%)	(35.00%)
State Taxes	(4.00%)	0.00%
Change in valuation allowance	24.00%	16.00%
Tax credits	(2.00%)	(2.00%)
Stock based compensation	3.00%	2.00%
Tax reform	0.00%	18.00%
Foreign withholding taxes	2.00%	0.00%
Other	0.00%	1.00%
Effective tax rate	(2.00%)	0.00%

Commitments and Contingencies - Additional Information (Details) - USD ($)							12 Months Ended
	Sep. 20, 2018	May 15, 2018	May 01, 2018	Jan. 18, 2018	Nov. 14, 2017	Dec. 01, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Nov. 06, 2018
Commitments And Contingencies [Line Items]
Collaboration revenue								$ 1,142,604
Lease agreement description								Upon execution of this lease agreement the Company prepaid three months of rent, two of which will be held in escrow and credited against future rent payments and one month that was applied to the first months rent. The Company also prepaid seven and one half months rent pursuant to an amendment to the lease agreement executed on June 18, 2018. These amounts were recorded to deposits and prepaid expenses, respectively at December 31, 2018
Additional lease agreement description								Upon execution of this lease agreement the Company prepaid three months of rent which will be held in escrow and credited against future rent payments. The Company also prepaid twelve months rent pursuant to the lease agreement executed on September 20, 2018. These amounts were recorded to deposits and prepaid expenses, respectively at December 31, 2018.
Rent expense								$ 3,311,000	$ 1,976,000
Amended Lease Agreement
Commitments And Contingencies [Line Items]
Lease agreement effective date		May 15, 2018		Jan. 16, 2018		Dec. 01, 2016
Lease expiration date		Apr. 14, 2021		Apr. 30, 2018
Operating Lease Agreement
Commitments And Contingencies [Line Items]
Lease agreement effective date	Oct. 15, 2018		May 01, 2018
Lease expiration date	Apr. 14, 2021		Apr. 30, 2021
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								$ 4,400,000
Anticipated contracted services to be received, period from date of payment								12 months
Catalent \| Agreements with Catalent \| Services on Development and Manufacture of Lead Drug Candidate \| Scenario, Forecast
Commitments And Contingencies [Line Items]
Total direct costs under agreement							$ 300,000
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
Collaboration revenue								$ 1,142,605	$ 0
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]
Collaboration revenue								$ 0
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
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

Commitments and Contingencies - Schedule of Future Minimum Lease Payments on Operating Leases (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 4,461,349
2020	4,910,521
2021	1,432,234
Total	$ 10,804,104

Cue Biopharma 401(k) Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
401(k) Plan
Defined Contribution Plan Disclosure [Line Items]
Company Contribution	$ 0	$ 0