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Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2020	Aug. 01, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Entity Registrant Name	COMPASS THERAPEUTICS, INC.
Entity Central Index Key	0001738021
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		52,151,798
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity File Number	000-55939
Entity Tax Identification Number	82-4876496
Entity Address, Address Line One	245 First Street
Entity Address, Address Line Two	3rd Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	617
Local Phone Number	500-8099
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Title of each class	Common Stock, $0.0001 par value per share
No Trading Symbol	true

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 65,371	$ 25,303
Prepaid expenses and other current assets	1,917	935
Total current assets	67,288	26,238
Property and equipment, net	2,829	3,751
Restricted cash	263	263
Other assets	69	129
Total assets	70,449	30,381
Current liabilities:
Current portion of long-term debt	7,454	5,576
Accounts payable	1,581	629
Accrued expenses	2,574	3,122
Derivative liability related to loan		494
Total current liabilities	11,609	9,821
Long-term debt, net of current portion	5,590	9,293
Total liabilities	17,199	19,114
Commitments and contingencies (Note 2 and 11)
Convertible preferred stock - 0 and 207,164,404 authorized, issued, and outstanding as of June 30, 2020 and December 31, 2019, respectively		129,870
Stockholders' equity (deficit):
Preferred stock, $0.0001 par value: 10,000,000 and 0 shares authorized; no shares issued and outstanding as of June 30, 2020 and December 31, 2019, respectively
Common stock, $0.0001 par value: 300,000,000 shares authorized; 52,151,798 and 9,073,002 shares issued at June 30, 2020 and December 31, 2019, respectively; 50,896,833 and 7,034,047 shares outstanding at June 30, 2020 and December 31, 2019, respectively	5	1
Additional paid-in-capital	187,112	3,304
Accumulated deficit	(133,867)	(121,908)
Total stockholders' equity	53,250	(118,603)
Total liabilities and stockholders' equity	$ 70,449	$ 30,381

Condensed Consolidated Balance Sheets (Parenthetical) (unaudited) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Convertible preferred stock, shares authorized	0	207,164,404
Convertible preferred stock, shares issued	0	207,164,404
Convertible preferred stock, shares outstanding	0	207,164,404
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	52,151,798	9,073,002
Common stock, shares outstanding	50,896,833	7,034,047

Condensed Consolidated Statements of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses:
Research and development	$ 2,985	$ 5,389	$ 6,556	$ 12,632
General and administrative	2,085	3,284	4,345	6,635
Total operating expenses	5,070	8,673	10,901	19,267
Loss from operations	(5,070)	(8,673)	(10,901)	(19,267)
Other income (expense):
Interest income	7	237	48	471
Interest expense	(242)	(314)	(518)	(632)
Change in fair value of derivative liability	(236)	(32)	(556)	(89)
Realized foreign exchange loss		(1)		(8)
Total other expense	(471)	(110)	(1,026)	(258)
Loss before income tax expense	(5,541)	(8,783)	(11,927)	(19,525)
Income tax expense	(16)	(26)	(32)	(55)
Net loss	$ (5,557)	$ (8,809)	$ (11,959)	$ (19,580)
Net loss per share - basic and diluted	$ (0.41)	$ (1.33)	$ (1.16)	$ (3.00)
Basic and diluted weighted average shares outstanding	13,602,793	6,615,140	10,334,589	6,525,611

Condensed Consolidated Statements of Changes in Convertible Preferred Stock and Stockholders' Equity (Deficit) (unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Convertible Preferred Stock
Temporary equity, Beginning Balance at Dec. 31, 2018					$ 129,870
Temporary equity, Beginning Balance, Shares at Dec. 31, 2018					207,164,404
Temporary equity, Ending Balance at Mar. 31, 2019					$ 129,870
Temporary equity, Ending Balance, Shares at Mar. 31, 2019					207,164,404
Beginning Balance at Dec. 31, 2018	$ (84,774)	$ 1	$ 2,389	$ (87,164)
Beginning Balance, Shares at Dec. 31, 2018		6,355,377
Vesting of share-based awards		223,072
Stock-based compensation expense	255		255
Net loss	(10,771)			(10,771)
Ending Balance at Mar. 31, 2019	(95,290)	$ 1	2,644	(97,935)
Ending Balance, Shares at Mar. 31, 2019		6,578,449
Temporary equity, Beginning Balance at Dec. 31, 2018					$ 129,870
Temporary equity, Beginning Balance, Shares at Dec. 31, 2018					207,164,404
Temporary equity, Ending Balance at Jun. 30, 2019					$ 129,870
Temporary equity, Ending Balance, Shares at Jun. 30, 2019					207,164,404
Beginning Balance at Dec. 31, 2018	(84,774)	$ 1	2,389	(87,164)
Beginning Balance, Shares at Dec. 31, 2018		6,355,377
Net loss	(19,580)
Ending Balance at Jun. 30, 2019	(103,914)	$ 1	2,829	(106,744)
Ending Balance, Shares at Jun. 30, 2019		6,683,576
Temporary equity, Beginning Balance at Mar. 31, 2019					$ 129,870
Temporary equity, Beginning Balance, Shares at Mar. 31, 2019					207,164,404
Temporary equity, Ending Balance at Jun. 30, 2019					$ 129,870
Temporary equity, Ending Balance, Shares at Jun. 30, 2019					207,164,404
Beginning Balance at Mar. 31, 2019	(95,290)	$ 1	2,644	(97,935)
Beginning Balance, Shares at Mar. 31, 2019		6,578,449
Vesting of share-based awards		105,127
Stock-based compensation expense	185		185
Net loss	(8,809)			(8,809)
Ending Balance at Jun. 30, 2019	(103,914)	$ 1	2,829	(106,744)
Ending Balance, Shares at Jun. 30, 2019		6,683,576
Temporary equity, Beginning Balance at Dec. 31, 2019	$ 129,870				$ 129,870
Temporary equity, Beginning Balance, Shares at Dec. 31, 2019	207,164,404				207,164,404
Temporary equity, Ending Balance at Mar. 31, 2020					$ 129,870
Temporary equity, Ending Balance, Shares at Mar. 31, 2020					207,164,404
Beginning Balance at Dec. 31, 2019	$ (118,603)	$ 1	3,304	(121,908)
Beginning Balance, Shares at Dec. 31, 2019		7,034,047
Vesting of share-based awards		88,080
Stock-based compensation expense	247		247
Net loss	(6,402)			(6,402)
Ending Balance at Mar. 31, 2020	(124,758)	$ 1	3,551	(128,310)
Ending Balance, Shares at Mar. 31, 2020		7,122,127
Temporary equity, Beginning Balance at Dec. 31, 2019	$ 129,870				$ 129,870
Temporary equity, Beginning Balance, Shares at Dec. 31, 2019	207,164,404				207,164,404
Temporary equity, Ending Balance, Shares at Jun. 30, 2020	0				0
Beginning Balance at Dec. 31, 2019	$ (118,603)	$ 1	3,304	(121,908)
Beginning Balance, Shares at Dec. 31, 2019		7,034,047
Conversion of Compass Therapeutics LLC preferred shares into common shares upon consummation of the reverse merger, Shares		30,629,606
Net loss	(11,959)
Ending Balance at Jun. 30, 2020	$ 53,250	$ 5	187,112	(133,867)
Ending Balance, Shares at Jun. 30, 2020		50,896,833
Temporary equity, Beginning Balance at Mar. 31, 2020					$ 129,870
Temporary equity, Beginning Balance, Shares at Mar. 31, 2020					207,164,404
Temporary equity, Conversion of Compass Therapeutics LLC preferred shares into common shares upon consummation of the reverse merger					$ (129,870)
Temporary equity, Conversion of Compass Therapeutics LLC preferred shares into common shares upon consummation of the reverse merger, Shares					(207,164,404)
Temporary equity, Ending Balance, Shares at Jun. 30, 2020	0				0
Beginning Balance at Mar. 31, 2020	$ (124,758)	$ 1	3,551	(128,310)
Beginning Balance, Shares at Mar. 31, 2020		7,122,127
Common shares issued to former shareholders of Olivia Ventures Inc., Shares		1,000,000
Conversion of Compass Therapeutics LLC preferred shares into common shares upon consummation of the reverse merger	129,870	$ 3	129,867
Conversion of Compass Therapeutics LLC preferred shares into common shares upon consummation of the reverse merger, Shares		30,629,606
Common shares issued in private placement, net of issuance costs of $6,902	53,581	$ 1	53,580
Common shares issued in private placement, net of issuance costs of $6,902, Shares		12,096,442
Payment to non-participating Compass Therapeutics LLC members upon consummation of Merger	(69)		(69)
Payment to non-participating Compass Therapeutics LLC members upon consummation of Merger, Shares		(13,641)
Vesting of share-based awards		62,298
Stock-based compensation expense	183		183
Net loss	(5,557)			(5,557)
Ending Balance at Jun. 30, 2020	$ 53,250	$ 5	$ 187,112	$ (133,867)
Ending Balance, Shares at Jun. 30, 2020		50,896,833

Condensed Consolidated Statements of Changes in Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) (unaudited)	3 Months Ended
	Jun. 30, 2020 USD ($)
Statement Of Stockholders Equity [Abstract]
Stock issuance costs	$ 6,902

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net loss	$ (11,959)	$ (19,580)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	900	1,060
Loss on disposal of equipment	8
Noncash interest expense	50	62
Share-based compensation	430	440
Change in fair value of derivative liability	556	89
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(982)	(328)
Other long-term assets	32	(82)
Accounts payable	952	(1,280)
Accrued expenses	(1,998)	173
Settlement of derivative liability	(1,050)
Net cash used in operating activities	(13,061)	(19,446)
Cash flows from investing activities:
Purchases of property and equipment	(16)	(254)
Proceeds from sale of fixed assets	55
Net cash used in investing activities	39	(254)
Cash flows from financing activities:
Proceeds from issuance of common units	60,482
Issuance costs from issuance of common units	(5,517)
Repayment of borrowings under loan	(1,875)
Net cash provided by financing activities	53,090
Net change in cash, cash equivalents and restricted cash	40,068	(19,700)
Cash, cash equivalents and restricted cash at beginning of period	25,566	57,773
Cash, cash equivalents and restricted cash at end of period	65,634	38,073
Supplemental disclosure of cash flow information
Cash paid for interest	486	$ 567
Supplemental disclosure of financing activities
Unpaid offering costs included in accrued expenses	(1,384)
Payment to non-participating Compass LLC investors within accrued expenses	$ (69)

Nature of Business and Basis of Presentation

6 Months Ended

Jun. 30, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Nature of Business and Basis of Presentation

1.	Nature of Business and Basis of Presentation

Compass Therapeutics, Inc. (“Compass” or the “Company”) is a clinical-stage biopharmaceutical company developing proprietary antibody therapeutics intended to engage the immune system to treat both solid tumors and hematological malignancies. The Company immuno-oncology product candidates include a clinical-stage monoclonal antibody and a portfolio of bispecific antibodies. The Company was incorporated as Olivia Ventures, Inc. (“Olivia”) in the State of Delaware on March 20, 2018. Prior to the Merger (as defined below), Olivia was a “shell company” (as defined in Rule 12b-2 of the Securities Exchange Act of 1934, as amended).

On June 17, 2020, the Company’s Board of Directors and the Company’s pre-Merger (defined below) stockholders, approved an amended and restated certificate of incorporation, which, among other things, increased authorized capital stock from 50,000,000 shares of common stock par value $0.0001 and 5,000,000 shares of preferred stock, par value $0.0001 per share, to 300,000,000 shares of common stock, par value $0.0001 per share, and 10,000,000 shares of preferred stock, par value $0.0001 per share.

On June 17, 2020, the Company completed a merger (the “Merger”) of a wholly-owned subsidiary Compass Therapeutics LLC (“Compass LLC”) pursuant to an Agreement and Plan of Merger and Reorganization (the “Merger Agreement”), by and among the Company, Olivia Ventures, Inc., Acquisition Sub, Compass Therapeutics, Blockers, Blockers Merger Subs and Blocker Holders and, as a result of, Compass LLC became a wholly-owned subsidiary of the Company.

At the effective time of the Merger and the applicable effective time of each Blocker Merger, collectively, the Effective Time, an aggregate of 31,627,139 shares of its common stock were issued to holders of common membership interests of Compass LLC (including common membership interests issued upon the conversion of preferred membership interests) and 7,428,217 shares of its common stock were issued to the holders of equity interests of the Blockers. The issuances of shares of the Company’s common stock to the security holders of Compass LLC and the Blockers are collectively referred to as the Share Conversion.

In addition, 2,930,836 shares of the Company’s common stock were reserved for issuance under its 2020 Stock Option and Incentive Plan. Immediately prior to the Effective Time, an aggregate of 4,000,000 of the 5,000,000 shares of the Company’s common stock held by pre-Merger stockholders of Olivia Ventures, Inc. were forfeited and surrendered for cancellation, or the Stock Forfeiture. No fractional shares of the Company’s common stock were issued in connection with the Merger, and holders of Compass LLC Units received cash in lieu thereof.

On June 19, 2020, the Company sold 12,096,442 shares of its common stock pursuant to the initial closing of a private placement offering for up to 14,000,000 shares of its common stock at a purchase price of $5.00 per share, or the Offering Price. The aggregate gross proceeds from the initial closing of the Offering were approximately $60.5 million (before deducting placement agent fees and total expenses in connection with the initial closing of the Offering, which are estimated at approximately $6.9 million).

The Merger and the Blocker Mergers were treated as a recapitalization and reverse acquisition for financial reporting purposes. Compass Therapeutics is considered the acquirer for accounting purposes, and the Company’s historical financial statements before the Merger will be replaced with the historical financial statements of Compass Therapeutics before the Merger in future filings with the SEC. As a result, the vested and outstanding common units held by Compass LLC members have been presented as outstanding shares of the Company’s common stock for all periods presented. All outstanding preferred units of Compass LLC are presented as convertible preferred stock for all presented and until such units were converted into shares of the Company’s common stock at the time of the Merger.

The Company is subject to risks and uncertainties common to companies in the biotechnology and pharmaceutical industries. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s technology will be obtained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees and consultants.

Liquidity Uncertainties and Going Concern

6 Months Ended

Jun. 30, 2020

Liquidity Uncertainties And Going Concern [Abstract]

Liquidity Uncertainties and Going Concern

2.	Liquidity, Uncertainties and Going Concern

The Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date that the condensed consolidated financial statements are issued.

Since its inception, the Company has funded its operations primarily with proceeds from the sale of its equity securities and borrowings under loan agreements. The Company has incurred recurring losses since its inception and had an accumulated deficit of $133.9 million at June 30, 2020. The Company expects to continue to generate operating losses for the foreseeable future. The Company expects that its cash and cash equivalents will be sufficient to fund its operating expenses and capital expenditure requirements through the fourth quarter of 2021. The future viability of the Company beyond that point is dependent on its ability to raise additional capital to finance its operations.

In December 2019, a novel strain of coronavirus (“COVID-19”) was reported to have surfaced in Wuhan, China. As of May 2020, COVID-19 has spread to Europe, the United States and many other countries, and has been declared a pandemic by the World Health Organization. In an effort to contain the spread of COVID-19, the United States, Europe and Asia have implemented severe travel restrictions, social distancing requirements, stay-at-home or shelter-in-place orders and have delayed the commencement of non-COVID-19-related clinical trials, among other restrictions. As a result, the COVID-19 pandemic has presented a substantial public health and economic challenge around the world and is affecting the Company’s employees, communities and business operations, as well as contributing to significant volatility and negative pressure on the U.S. economy and in financial markets. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition will depend on future developments that are highly uncertain and cannot be accurately predicted, including new information that may emerge concerning COVID-19, the actions taken to contain it or mitigate its impact, and the economic impact on local, regional, national and international markets.

The Company has been carefully monitoring the COVID-19 pandemic and its potential impact on its business, and has taken important steps to help ensure the safety of employees and their families and to reduce the spread of COVID-19 community-wide. A State of Emergency was declared in Massachusetts on March 10, 2020 and all non-essential businesses were ordered to close on March 23, 2020. Since biopharmaceutical companies are essential businesses, the Company was able to remain open and continue to pursue its operations, including the ongoing research and development activities. In mid-March 2020, the Company has established a work-from-home policy for all employees since, while ensuring essential staffing levels in the Company’s operations remain in place, including maintaining key personnel in its laboratory facilities and vivarium. Consistent with Federal and Massachusetts laws and regulations, and upon the reopening of businesses announced on May 18, 2020, the Company has gradually resumed its ordinary business and enabled its employees to return to back to work in its offices and labs, while maintaining flexibility with employees who have special situations or needs. The Company has implemented stringent safety measures designed to comply with applicable federal, state and local guidelines instituted in response to the COVID-19 pandemic.

To date, the Company has been able to continue to pursue its Phase 1 clinical trial without delays or major difficulties However, the Company is continuing to assess the potential impact of the COVID-19 pandemic to current and future business and operations, including expenses and clinical trials as well as the Company’s industry and the healthcare system.

Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

3.	Summary of Significant Accounting Policies

Basis of Presentation

The accompanying condensed consolidated financial statements are presented in U.S. dollars and have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and as amended by Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).

In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all normal and recurring adjustments (which consist primarily of accruals, estimates and assumptions that impact the financial statements) considered necessary to present fairly the Company’s financial position as of June 30, 2020 and its results of operations and changes in stockholders’ equity (deficit) for the three and six months ended June 30, 2020 and 2019 and cash flows for the six months ended June 30, 2020 and 2019. Operating results for the six months ended June 30, 2020 are not necessarily indicative of the results that may be expected for the year ending December 31, 2020.

The condensed consolidated balance sheet at December 31, 2019 has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by GAAP for complete financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with the consolidated financial statements of Compass Therapeutics LLC and related footnotes for the year ended December 31, 2019, included as Exhibit 99.1 in the Company’s Form 8-K filed with the SEC on June 23, 2020.

Principles of Consolidation

The accompanying condensed consolidated financial statements include the accounts of Compass Therapeutics, Inc., and its wholly-owned subsidiaries Compass Therapeutics LLC and Compass Therapeutics Advisors Inc. All intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, the accrual of research and development expenses, the valuation of the embedded derivative, the valuation of common stock and estimates associated with stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from those estimates. Changes in estimates are recorded in the period that they become known.

Segment Information

Operating segments are defined as components of an enterprise for which separate and discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company has one operating segment. The Company’s chief operating decision-maker, its chief executive officer, manages the Company’s operations on a consolidated basis for the purpose of allocating resources. All of the Company’s long-lived assets are held in the United States.

Cash and Cash Equivalents

The Company considers all highly liquid investments that are readily convertible into cash with original maturities of three months or less from the date of purchase to be cash equivalents. Cash and cash equivalents include cash held in banks and amounts held in money market funds. Cash equivalents are stated at cost, which approximates market value. Cash equivalents consisted of money market funds of $62.1 million and $22.8 million at June 30, 2020 and December 31, 2019, respectively.

Concentrations of Credit Risk and Off-Balance Sheet Risk

Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, cash equivalents and restricted cash. The Company maintains its cash, cash equivalents and restricted cash with financial institutions that management believes to be of high-credit quality. The Company has not experienced any losses related to its cash, cash equivalents and restricted cash.

Property and Equipment

Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization are recorded using the straight-line method over the estimated useful lives of the related assets as follows:

		Estimated
		Useful Life
Asset Classification
Equipment		5 years
Furniture and fixtures		7 years
Software		5 years
Leasehold improvements		Lesser of estimated
		useful life or lease term

Estimated useful lives are periodically assessed to determine if changes are appropriate. Maintenance and repairs are charged to expense as incurred. When assets are retired or otherwise disposed of, the cost of these assets and related accumulated depreciation or amortization are eliminated from the condensed consolidated balance sheet and any resulting gains or losses are included in the condensed consolidated statement of operations in the period of disposal. Costs for capital assets not yet placed into service are capitalized as construction-in-progress and depreciated once placed into service. Assets held under capital leases are stated at the lesser of the present value of future minimum lease payments or the fair value of the leased asset at the inception of the lease. Amortization of assets held under capital leases is computed using the straight-line method over the shorter of the estimated useful life of the asset or the period of the related lease.

Impairment of Long-Lived Assets

Long-lived assets consist of property and equipment. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized in the condensed consolidated statements of operations when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset group over its fair value, determined based on discounted cash flows. The Company did not record any impairment losses on long-lived assets during the six months ended June 30, 2020 and 2019.

Fair Value Measurements

Certain assets and liabilities of the Company are carried at fair value under GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable:

•

Level 1 – Quoted prices in active markets for identical assets or liabilities.

•

Level 2 – Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets and liabilities, or other inputs that are observable or can be corroborated by observable market data.

•

Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.

To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

An entity may choose to measure many financial instruments and certain other items at fair value at specified election dates. Subsequent unrealized gains and losses on items for which the fair value option has been elected are reported in earnings.

The Company’s cash equivalents are carried at fair value according to the fair value hierarchy described above and were determined based on Level 1 measurements (see Note 4). The Company’s restricted cash is carried at fair value according to the fair value hierarchy described above and were determined based on Level 2 measurements (see Note 4). The carrying values of other current assets and accounts payable approximate their fair value due to the short‑term nature of these assets and liabilities. The carrying values of the Company’s loan approximated its fair value as of June 30, 2020 and December 31, 2019 due to its variable interest rate. The fair value of the loan related embedded derivative (see Note 4) was determined based on Level 3 measurements.

Research and Development Costs

Costs associated with internal research and development and external research and development services, including drug development and preclinical studies, are expensed as incurred. Research and development expenses include costs for salaries, employee benefits, subcontractors, facility-related expenses, depreciation and amortization, stock-based compensation, third-party license fees, laboratory supplies, and external costs of outside vendors engaged to conduct discovery, preclinical and clinical development activities and clinical trials as well as to manufacture clinical trial materials, and other costs. The Company recognizes external research and development costs based on an evaluation of the progress to completion of specific tasks using information provided to the Company by its service providers.

Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. Such prepaid expenses are recognized as an expense when the goods have been delivered or the related services have been performed, or when it is no longer expected that the goods will be delivered, or the services rendered.

Costs associated with licenses of technology acquired as part of collaborative arrangements are expensed as incurred and are generally included in research and development expense in the condensed consolidated statements of operations if it is determined the license has no alternative future use.

Accrued Research and Development Expenses

The Company has entered into various research and development and other agreements with commercial firms, researchers, universities and others for provisions of goods and services. These agreements are generally cancelable, and the related costs are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research and development costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies or clinical trials, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ materially from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs.

Stock-Based Compensation

Through December 2019, Compass Therapeutics LLC issued Class A and Class C common units to various employees, directors and consultants. The units constituted “profits interests” for tax purposes and were accounted for as share-based payment arrangements. Compass LLC measured the estimated fair value of the unit-based awards on the date of grant and recognized compensation expense over the requisite service period, which was generally the vesting period of the respective award. Upon consummation of the Merger, all outstanding vested units were converted into shares of common stock and all outstanding unvested units were converted into shares of restricted stock that will continue to vest over the remaining term of the original award.

The Company records compensation expense for all stock-based awards granted to employees and non-employees as stock-based at fair value and records compensation expense on a straight-line basis over the vesting period of the award. The Company measures the estimated fair value of the stock-based award on the date of grant. The Company accounts for forfeitures as they occur.

Net Loss per Share

Basic loss per share is computed by dividing net loss applicable to common stockholders by the weighted average number of shares of common stock outstanding during each period. Diluted loss per share includes the effect, if any, from the potential exercise or conversion of securities, such as unvested convertible preferred units and warrants that would result in the issuance of incremental shares of common stock. In computing the basic and diluted net loss per share applicable to common stockholders, the weighted average number of shares remains the same for both calculations due to the fact that when a net loss exists, dilutive shares are not included in the calculation as the impact is anti-dilutive.

The following potentially dilutive securities outstanding as of June 30, 2020 and 2019 have been excluded from the computation of diluted weighted average shares outstanding, as they would be anti-dilutive:

	June 30,
	2020		2019
Common stock issued upon vesting of share-based award		1,254,965		2,038,955
Preferred stock as converted		—		30,629,606
Warrants to purchase common stock		—		3,114,145
Total		1,254,965		35,782,706

Recently Issued Accounting Pronouncements

In February 2016, the FASB issued ASU No. 2016‑02, Leases, which requires a lessee to record a right‑of‑use asset and a corresponding lease liability on the balance sheet for all leases with terms longer than 12 months. A modified retrospective transition approach is required, applying the new standard to all leases existing at the date of initial application. An entity may choose to use either (1) its effective date or (2) the beginning of the earliest comparative period presented in the condensed consolidated financial statements as its date of initial application. If an entity chooses the second option, the transition requirements for existing leases also apply to leases entered into between the date of initial application and the effective date. The standard is effective for the Company beginning January 1, 2021, with early adoption permitted. The Company plans to adopt this standard on January 1, 2021 and is currently evaluating the expected impact that the standard could have on its financial position and results of operations upon adoption.

In August 2018, the FASB issued ASU No. 2018‑13, Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurements, which changes the fair value measurement disclosure requirements of ASC Topic 820. The goal of the ASU is to improve the effectiveness of ASC Topic 820’s disclosure requirements. The Company adopted this guidance on January 1, 2020 and was not material to its condensed consolidated financial statements and related disclosures.

In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606 (“ASU 2018-18”). The amendments in this update clarify that certain transactions between collaborative arrangement participants should be accounted for as revenue when the collaborative arrangement participant is a customer in the context of a unit of account and precludes recognizing as revenue consideration received from a collaborative arrangement participant if the participant is not a customer. The standard is effective for the Company beginning January 1, 2021. The Company is currently evaluating the potential impact ASU 2018-18 may have on its financial position and results of operations upon adoption.

In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ("ASU 2019-12"), which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. The new standard will be effective beginning January 1, 2022. The Company does not expect the adoption of ASU 2019-12 to have a material impact on its financial position and results of operations upon adoption.

Fair Value Measurements

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

4.	Fair Value Measurements

The following tables present information about the Company’s financial assets and liabilities that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values (in thousands):

	Fair Value Measurements as of June 30, 2020:
	Quoted
	Prices
	in Active		Significant
	Markets for		Other		Significant
	Identical		Observable		Unobservable
	Assets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Fair Value
Assets
Cash equivalents - money market funds	$	62,104	$	—	$	—	$	62,104
Restricted cash		—		263		—		263
Total assets	$	62,104	$	263	$	—	$	62,367
Liabilities
Derivative liability related to loan	$	—	$	—	$	—	$	—
Total liabilities	$	—	$	—	$	—	$	—

	Fair Value Measurements as of December 31, 2019:
	Quoted
	Prices
	in Active		Significant
	Markets for		Other		Significant
	Identical		Observable		Unobservable
	Assets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Fair Value
Assets
Cash equivalents – money market funds	$	22,784	$	—	$	—	$	22,784
Restricted cash		—		263		—		263
Total assets	$	22,784	$	263	$	—	$	23,047
Liabilities
Derivative liability related to loan	$	—	$	—	$	494	$	494
Total liabilities	$	—	$	—	$	494	$	494

Valuation of Derivative Liability

The Company’s derivative liability was comprised of the contingent interest rate reset features and a contingent feature to pay a success fee upon the occurrence of certain liquidity events, each of which met the definition of a derivative instrument, which terms are included in the loan and security agreement (refer to Note 7). The Company classified these instruments as a liability on the condensed consolidated balance sheets because these features were not clearly and closely related to its host instrument and met the definition of a derivative. The derivative liability was initially recorded at fair value upon issuance of the loan and was being subsequently remeasured to fair value at each reporting date. Changes in the fair value of the derivative liability were recognized as a component of other income (expense), net in the condensed consolidated statements of operations. The success fee was paid in full following the close of the Merger.

The fair value of the derivative liability recognized was determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The fair value of the derivative liability was determined using the probability-weighted expected return method, which considered as inputs the type, timing and probability of occurrence of a change-of-control event, the future equity financing and cash settlement of the loans; the potential amount of the payment under each of these potential settlement scenarios; and the risk-adjusted discount rate reflecting the expected risk profile for each of the potential settlement scenarios.

The following table provides a roll forward of the aggregate fair values of the Company’s derivative liability (in thousands):

	Derivative Liability
Balance at December 31, 2019	$	494
Change in fair value		556
Payment of success fee		(1,050	)
Balance at June 30, 2020	$	0

- 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

Property and Equipment

6 Months Ended

Jun. 30, 2020

Property Plant And Equipment [Abstract]

Property and Equipment

5.	Property and Equipment

Property and equipment consist of the following (in thousands):

	June 30,			December 31,
	2020			2019
Equipment	$	7,030		$	7,230
Furniture and fixtures		629			629
Leasehold improvements		896			896
Software		912			669
Assets not yet placed in service		—			230
Total property and equipment–at cost		9,467			9,654
Less: Accumulated depreciation and amortization		(6,638	)		(5,903	)
Property and equipment, net	$	2,829		$	3,751

Total depreciation and amortization expense for three months ended June 30, 2020 and 2019, was $0.4 million and $0.5 million, respectively. Total depreciation and amortization expense for six months ended June 30, 2020 and 2019, was $0.9 million and $1.1 million, respectively.

Accrued Expenses

6 Months Ended

Jun. 30, 2020

Payables And Accruals [Abstract]

Accrued Expenses

6.	Accrued Expenses

Accrued expenses consist of the following (in thousands):

	June 30,		December 31,
	2020		2019
Compensation and benefits	$	455	$	1,759
Research and development expenses		223		249
Legal and professional fees		957		417
Sales taxes		—		554
Other		939		143
Total accrued expenses	$	2,574	$	3,122

Loan Payable

6 Months Ended

Jun. 30, 2020

Debt Disclosure [Abstract]

Loan Payable

7.	Loan Payable

The aggregate principal amount of debt outstanding consisted of the following (in thousands):

	June 30,			December 31,
	2020			2019
Current portion of debt	$	7,500		$	5,625
Less: unamortized debt discount		(46	)		(49	)
Current portion of debt, net of debt discount	$	7,454		$	5,576

Long-term debt, net of current portion	$	5,625		$	9,375
Less: unamortized debt discount		(35	)		(82	)
Long-term debt, net of current portion	$	5,590		$	9,293

The Company entered into, and subsequently amended, a term loan facility with Pacific Western Bank, Inc. (“PWB”), and received $15.0 million debt proceeds. The loans bear interest at the greater of (i) 6.25% and (ii) the prime rate plus an applicable margin of 2.0%. The interest rate was 6.75% at June 30, 2020. In an event of default, as defined in the agreement, the interest rate applicable to borrowings would be increased by 5.0%. The Company made interest-only payments through March 31, 2020. Beginning in April 2020, the Company is obligated to make equal monthly principal payments of $625,000 through March 31, 2022 when the notes mature. The loan agreement allows for prepayment of the outstanding principal at any time, subject to a prepayment charge that is dependent on the prepayment date.

The debt agreement contained provisions whereby the Company was obligated to pay a success fee of $1.1 million upon the achievement of certain liquidity events. Upon consummation of the Merger, the Company success fee payment became due and was paid in its entirety as of June 30, 2020.

The borrowings are collateralized by substantially all of the Company’s assets, excluding intellectual property and contains affirmative and negative covenants including restrictions on the Company’s ability to incur additional indebtedness, pay dividends, encumber its property, or engage in certain fundamental business transactions, such as mergers or acquisitions of other businesses. The Company was in compliance with its covenants as of June 30, 2020.

The Company recognized interest expense of $0.2 million and $0.3 million during the three months ended June 30, 2020 and 2019 and $0.5 million and $0.6 million during the six months ended June 30, 2020 and 2019, respectively.

As of June 30, 2020, the aggregate minimum future principal payments due in connection with the 2018 Loan Agreement, as amended, are as follows (in thousands):

Year Ending December 31,
2020	$	3,750
2021		7,500
2022		1,875
	$	13,125

Convertible Preferred Stock and Stockholders' Equity (Deficit)

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Convertible Preferred Stock and Stockholders' Equity (Deficit)

8.Convertible Preferred Stock and Stockholders’ Equity (Deficit)

Convertible Preferred Stock

In connection with the Merger, as discussed in Note 1, the Company issued 30,629,606 shares of its common stock to holders of convertible preferred membership interests of Compass Therapeutics LLC. No convertible preferred securities were outstanding as of June 30, 2020.

As of December 31, 2019, convertible preferred stock consisted of the following shares outstanding:

	Shares
Series A-1		64,704,832
Series A-2		36,782,734
Series A-3		23,467,151
Series A-4		15,253,415
Series A4B		22,216,583
Series A-5		44,739,689
		207,164,404

Common Stock

In connection with the Merger, as discussed in Note 1, the Company issued 8,425,750 shares of its common stock to holders of common membership interests of Compass Therapeutics LLC and issued 1,000,000 shares to the former shareholders of Olivia Ventures Inc. With respect to 15 holders of an aggregate of 131,472 Compass Therapeutics LLC common membership interests who were not accredited investors, the Company paid an aggregate of approximately $69 thousand in cash in consideration for cancelling such membership interests in connection with the Merger. In addition, 2,930,836 shares of the Company’s common stock were reserved for issuance under the 2020 Stock Option and Incentive Plan.

The Company also sold 12,096,442 shares of its common stock pursuant to the initial closing of a private placement offering for up to 14,000,000 shares of its common stock at a purchase price of $5.00 per share.

Stock-Based Compensation

6 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

9.	Stock-Based Compensation

Prior to the Merger, the Company issued profits interests and used an option pricing model to value the profits interests granted. The assumptions used to value profits interests granted during the six months ended June 30, 2020 and 2019 are as follows:

	June 30,			June 30,
	2020			2019
Expected term (in years)		6.0			6.0
Risk-free rate		0.36	%		2.43	%
Expected volatility		140.45	%		72.02	%
Expected dividend yield		0	%		0	%

Compass LLC unit-based awards granted to employees and non-employees were accounted for as unit-based compensation expense at fair value. The estimated fair value of the unit-based award was measured on the date of grant. The fair value of the underlying units based on input from Compass LLC management and approved by the Compass LLC Board, which utilized the Compass LLC enterprise value determined utilizing various methods including the back-solve method, the option-pricing method (“OPM”) or a hybrid of the probability-weighted expected return method (“PWERM”) and the OPM. The total enterprise value is then allocated to the various outstanding equity instruments, including the unit-based awards, utilizing the option-pricing model.

The fair value of each Compass LLC unit was estimated on the date of grant using the Black-Scholes option-pricing model, which required inputs based on certain subjective assumptions, including the expected unit price volatility, the expected term of the unit, the risk-free interest rate for a period that approximates the expected term of the units and Compass LLC’s expected dividend yield. The fair value of each restricted equity award is estimated on the date of grant based on the fair value of the Compass LLC’s common units on that same date. As there was no public market for its common units, Compass LLC determined the volatility for awards granted based on an analysis of reported data for a group of guideline companies that issued options with substantially similar terms. The expected volatility has been determined using a weighted-average of the historical volatility measures of this group of guideline companies. The Company expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded common stock. The expected term of the Compass LLC’s units granted to employees had been determined utilizing the “simplified” method for awards that qualified as “plain-vanilla” awards. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Compass LLC had not paid cash dividends on its common units; therefore, the expected dividend yield was assumed to be zero.

Following the closing of the Merger, the fair value of the Company’s awards for common stock to which market value is of the Company’s common stock must be determined, will be based on the closing price of the Company’s common stock as reported on the date of the grant.

The weighted-average grant-date fair value for profits interests granted was $0.23 per unit during the six months ended June 30, 2020. Compensation expense from profits interests for the three months ended June 30, 2020 and 2019 was $0.2 million and $0.2 million, respectively, and $0.4 million and $0.4 million for the six months ended June 30, 2020 and 2019, respectively.

Upon consummation of the Merger, all outstanding vested profits interests units were converted into shares of the Company’s common stock. Unvested profits interests units were converted into restricted shares of the Company’s common stock and will continue to vest under the same terms as the original profits interests.

A summary of the Company’s unvested restricted stock activity and related information during the six months ended June 30, 2020 is as follows:

Weighted Average
Grant Date
Fair Value
Nonvested, January 1, 2020	2,038,955		2.04
Granted	879		2.34
Vested	(150,379	)	0.57
Forfeited or canceled	(634,491	)	1.83
Nonvested, June 30, 2020	1,254,965		2.33

The Company has recognized the following compensation cost related to employee and non-employee stock-based compensation activities (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Research and development	$	31	$	61	$	112	$	175
General and administrative		152		124		318		265
Total	$	183	$	185	$	430	$	440

As of June 30, 2020, remaining unrecognized compensation cost related to unvested restricted stock awards to be recognized in future periods totaled $2.0 million, which is expected to be recognized over a weighted‑average period of 1.86 years.

In June 2020, the Company adopted the 2020 Stock Option and Incentive Plan (“2020 Plan”). The 2020 Plan allows for 2,930,836 shares of the Company’s common stock and will automatically increase each January 1, beginning on January 1, 2021, by the lesser of (i) 4% of the outstanding number of shares of our common stock on the immediately preceding December 31 or (ii) such number of shares as determined by the plan administrator no later than the immediately preceding December 31. No awards have been issued or are outstanding under the 2020 Plan as of June 30, 2020.

License, Research and Collaboration Agreements

6 Months Ended

Jun. 30, 2020

License Research And Collaboration Agreements [Abstract]

License, Research and Collaboration Agreements

10.	License, Research and Collaboration Agreements

Collaboration Agreements

Adimab Agreement

The Company entered into a collaboration agreement with Adimab, LLC on October 16, 2014. As of June 30, 2020, future milestone payments in connection with this agreement amounted to $2.0 million. The agreement also includes provisions for payment of royalties at rates ranging in the single digits as a percentage of future net sales within a specified term from the first commercial sale. The Company recorded no research and development during the three months ended June 30, 2020 and 2019, respectively, and $0 million and $0.5 million during six months ended June 30, 2020 and 2019, respectively.

Other License and Research Agreements

The Company has entered into several license agreements with various academic and healthcare institutions to in-license certain intellectual property rights and know-how relevant to its programs. As part of the consideration related to these license agreements, the Company made cash payments of $21 thousand and $0.1 million during the three and six months ended June 30, 2020, respectively.

The Company recorded research and development expense of $58 thousand and $0.1 million during the three months ended June 30, 2020 and 2019, respectively, and $0.2 million and $0.3 million during the six months ended June 30, 2020 and 2019, respectively. In addition, the Company also committed to make certain clinical and regulatory milestone payments in the aggregate of $0.5 million associated with the in-licensed technology.

Commitments and Contingencies

6 Months Ended

Jun. 30, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

11.	Commitments and Contingencies

Operating Leases

The Company leases laboratory and office space in Cambridge, MA. The Company also leases a vivarium and storage space in Cambridge, MA. All leases expire January 31, 2021. The future minimum rental payments under the leases as of June 30, 2020 are as follows:

	Amount
Year Ending December 31,
2020	$	962
2021		160
	$	1,122

Rental expense was $0.5 million and $0.5 million for the three months ended June 30, 2020 and 2019, respectively, and $1.0 million and $0.9 million for the six months ended June 30, 2020 and 2019, respectively.

Related Parties and Related-Party Transactions

6 Months Ended

Jun. 30, 2020

12.	Related Parties and Related-Party Transactions

On October 16, 2014, the Company entered into a collaboration agreement with Adimab, LLC. The Company’s co-founder has a direct ownership interest in Adimab, LLC. The Company recorded research and development expense of $0 million and $0.5 in connection with this agreement during six months ended June 30, 2020 and 2019, respectively.

On September 18, 2017, the Company entered into a software license and services agreement with StackWave, LLC. A former employee of the Company is the co-founder and has a direct ownership interest in StackWave, LLC. The Company recorded capitalized software of $0.2 million and $0.7 million for the six months ended June 30, 2020 and 2019, respectively.

Subsequent Events

6 Months Ended

Jun. 30, 2020

Subsequent Events [Abstract]

Subsequent Events

13.	Subsequent Events

In July 2020, the Company entered into a manufacturing agreement with a contract manufacturing organization, or CMO, for the good manufacturing practice, or GMP, of the Company’s second clinical candidate, the bi-specific antibody CTX-8371. The CMO is eligible to receive up to $4.85 million in payments as certain protocol and manufacturing stages are completed. The contract is cancelable by the Company or CMO upon written notification to the other party within a specified period of time.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2020

Accounting Policies [Abstract]

Basis of Presentation

Principles of Consolidation

Use of Estimates

Segment Information

Cash and Cash Equivalents

Concentrations of Credit Risk and Off-Balance Sheet Risk

Property and Equipment

		Estimated
		Useful Life
Asset Classification
Equipment		5 years
Furniture and fixtures		7 years
Software		5 years
Leasehold improvements		Lesser of estimated
		useful life or lease term

Impairment of Long-Lived Assets

Fair Value Measurements

•

Level 1 – Quoted prices in active markets for identical assets or liabilities.

•

Research and Development Costs

Accrued Research and Development Expenses

Stock-Based Compensation

Net Loss per Share

	June 30,
	2020		2019
Common stock issued upon vesting of share-based award		1,254,965		2,038,955
Preferred stock as converted		—		30,629,606
Warrants to purchase common stock		—		3,114,145
Total		1,254,965		35,782,706

Recently Issued Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2020

Accounting Policies [Abstract]

Schedule of Estimated Useful Lives of Assets

Depreciation and amortization are recorded using the straight-line method over the estimated useful lives of the related assets as follows:

		Estimated
		Useful Life
Asset Classification
Equipment		5 years
Furniture and fixtures		7 years
Software		5 years
Leasehold improvements		Lesser of estimated
		useful life or lease term

Schedule of Potentially Dilutive Securities Outstanding Excluded from Computation of Diluted Weighted Average Shares Outstanding

	June 30,
	2020		2019
Common stock issued upon vesting of share-based award		1,254,965		2,038,955
Preferred stock as converted		—		30,629,606
Warrants to purchase common stock		—		3,114,145
Total		1,254,965		35,782,706

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Summary of Financial Assets and Liabilities are Measured at Fair Value on Recurring Basis

	Fair Value Measurements as of June 30, 2020:
	Quoted
	Prices
	in Active		Significant
	Markets for		Other		Significant
	Identical		Observable		Unobservable
	Assets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Fair Value
Assets
Cash equivalents - money market funds	$	62,104	$	—	$	—	$	62,104
Restricted cash		—		263		—		263
Total assets	$	62,104	$	263	$	—	$	62,367
Liabilities
Derivative liability related to loan	$	—	$	—	$	—	$	—
Total liabilities	$	—	$	—	$	—	$	—

	Fair Value Measurements as of December 31, 2019:
	Quoted
	Prices
	in Active		Significant
	Markets for		Other		Significant
	Identical		Observable		Unobservable
	Assets		Inputs		Inputs
	(Level 1)		(Level 2)		(Level 3)		Fair Value
Assets
Cash equivalents – money market funds	$	22,784	$	—	$	—	$	22,784
Restricted cash		—		263		—		263
Total assets	$	22,784	$	263	$	—	$	23,047
Liabilities
Derivative liability related to loan	$	—	$	—	$	494	$	494
Total liabilities	$	—	$	—	$	494	$	494

Schedule of Aggregate Fair Values of Derivative Liability

The following table provides a roll forward of the aggregate fair values of the Company’s derivative liability (in thousands):

	Derivative Liability
Balance at December 31, 2019	$	494
Change in fair value		556
Payment of success fee		(1,050	)
Balance at June 30, 2020	$	0

Property and Equipment (Tables)

6 Months Ended

Jun. 30, 2020

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment

Property and equipment consist of the following (in thousands):

	June 30,			December 31,
	2020			2019
Equipment	$	7,030		$	7,230
Furniture and fixtures		629			629
Leasehold improvements		896			896
Software		912			669
Assets not yet placed in service		—			230
Total property and equipment–at cost		9,467			9,654
Less: Accumulated depreciation and amortization		(6,638	)		(5,903	)
Property and equipment, net	$	2,829		$	3,751

Accrued Expenses (Tables)

6 Months Ended

Jun. 30, 2020

Payables And Accruals [Abstract]

Components of Accrued Expenses

Accrued expenses consist of the following (in thousands):

	June 30,		December 31,
	2020		2019
Compensation and benefits	$	455	$	1,759
Research and development expenses		223		249
Legal and professional fees		957		417
Sales taxes		—		554
Other		939		143
Total accrued expenses	$	2,574	$	3,122

Loan Payable (Tables)

6 Months Ended

Jun. 30, 2020

Debt Disclosure [Abstract]

Schedule of Aggregate Principal Amount of Debt Outstanding

The aggregate principal amount of debt outstanding consisted of the following (in thousands):

	June 30,			December 31,
	2020			2019
Current portion of debt	$	7,500		$	5,625
Less: unamortized debt discount		(46	)		(49	)
Current portion of debt, net of debt discount	$	7,454		$	5,576

Long-term debt, net of current portion	$	5,625		$	9,375
Less: unamortized debt discount		(35	)		(82	)
Long-term debt, net of current portion	$	5,590		$	9,293

Schedule of Aggregate Minimum Future Principal Payments

As of June 30, 2020, the aggregate minimum future principal payments due in connection with the 2018 Loan Agreement, as amended, are as follows (in thousands):

Year Ending December 31,
2020	$	3,750
2021		7,500
2022		1,875
	$	13,125

Convertible Preferred Stock and Stockholders' Equity (Deficit) (Tables)

6 Months Ended

Jun. 30, 2020

Equity [Abstract]

Summary of Convertible Preferred Stock Shares Outstanding

As of December 31, 2019, convertible preferred stock consisted of the following shares outstanding:

	Shares
Series A-1		64,704,832
Series A-2		36,782,734
Series A-3		23,467,151
Series A-4		15,253,415
Series A4B		22,216,583
Series A-5		44,739,689
		207,164,404

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

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+ Details

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Value Profits Interests Granted

The assumptions used to value profits interests granted during the six months ended June 30, 2020 and 2019 are as follows

	June 30,			June 30,
	2020			2019
Expected term (in years)		6.0			6.0
Risk-free rate		0.36	%		2.43	%
Expected volatility		140.45	%		72.02	%
Expected dividend yield		0	%		0	%

Schedule of Unvested Restricted Stock Activity

A summary of the Company’s unvested restricted stock activity and related information during the six months ended June 30, 2020 is as follows:

Weighted Average
Grant Date
Fair Value
Nonvested, January 1, 2020	2,038,955		2.04
Granted	879		2.34
Vested	(150,379	)	0.57
Forfeited or canceled	(634,491	)	1.83
Nonvested, June 30, 2020	1,254,965		2.33

Schedule of Stock-Based Compensation Activity

The Company has recognized the following compensation cost related to employee and non-employee stock-based compensation activities (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Research and development	$	31	$	61	$	112	$	175
General and administrative		152		124		318		265
Total	$	183	$	185	$	430	$	440

Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2020

Commitments And Contingencies Disclosure [Abstract]

Future Minimum Rental Payments under Leases

The future minimum rental payments under the leases as of June 30, 2020 are as follows:

	Amount
Year Ending December 31,
2020	$	962
2021		160
	$	1,122

Nature of Business and Basis of Presentation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended	6 Months Ended
	Jun. 19, 2020	Jun. 17, 2020	Jun. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Entity incorporation, date of incorporation				Mar. 20, 2018
Common stock, shares authorized		300,000,000	300,000,000	300,000,000	50,000,000	300,000,000
Common stock, par value		$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, shares authorized		10,000,000	10,000,000	10,000,000	5,000,000	0
Preferred stock par value		$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Aggregate gross proceeds from the initial closing of offering				$ 60,482
2020 Stock Option and Incentive Plan
Class Of Stock [Line Items]
Number of common stock reserved for issuance		2,930,836
Common Stock
Class Of Stock [Line Items]
Common stock shares issued under common membership interests		31,627,139
Aggregate number of common stock forfeited and surrendered for cancellation		4,000,000
Common stock held by pre-merger stockholders		5,000,000
Shares of common stock sold			12,096,442
Common Stock \| Private Placement Offering
Class Of Stock [Line Items]
Shares of common stock sold	12,096,442			12,096,442
Purchase price per share	$ 5.00		$ 5.00	$ 5.00
Aggregate gross proceeds from the initial closing of offering	$ 60,500
Placement agent fees and expenses	$ 6,900
Common Stock \| Private Placement Offering \| Maximum
Class Of Stock [Line Items]
Shares of common stock sold	14,000,000			14,000,000
Common Stock \| 2020 Stock Option and Incentive Plan
Class Of Stock [Line Items]
Number of common stock reserved for issuance			2,930,836	2,930,836
Common Stock \| Blockers
Class Of Stock [Line Items]
Common stock shares issued under equity interest		7,428,217

Liquidity, Uncertainties and Going Concern - Additional Information (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Liquidity Uncertainties And Going Concern [Abstract]
Accumulated deficit	$ 133,867	$ 121,908

Summary of Significant Accounting Policies - Additional Information (Details)	6 Months Ended
	Jun. 30, 2020 USD ($) Segment	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments \| Segment	1
Impairment losses on long-lived assets	$ 0	$ 0
ASU 2018-13
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect	true
Money Market Funds
Summary Of Significant Accounting Policies [Line Items]
Cash equivalents	$ 62,100,000		$ 22,800,000

- Definition

Indicates (true false) whether accounting standards update was adopted.

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Date accounting standards update was adopted, in CCYY-MM-DD format.

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+ Details

Summary of Significant Accounting Policies - Schedule of Estimated Useful Lives of Assets (Details)	6 Months Ended
	Jun. 30, 2020
Equipment
Property Plant And Equipment [Line Items]
Estimated useful life	5 years
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Estimated useful life	7 years
Software
Property Plant And Equipment [Line Items]
Estimated useful life	5 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Estimated useful life	Lesser of estimated useful life or lease term

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Outstanding Excluded from Computation of Diluted Weighted Average Shares Outstanding (Details) - shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted weighted average shares outstanding	1,254,965	35,782,706
Preferred Stock as Converted
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted weighted average shares outstanding		30,629,606
Common Stock Issued upon Vesting of Share-based Award
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted weighted average shares outstanding	1,254,965	2,038,955
Warrants to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from computation of diluted weighted average shares outstanding		3,114,145

Fair Value Measurements - Summary of Financial Assets and Liabilities are Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Liabilities
Derivative liability related to loan		$ 494
Fair Value Measurements Recurring
Assets
Restricted cash	$ 263	263
Total assets	62,367	23,047
Liabilities
Derivative liability related to loan		494
Total liabilities		494
Fair Value Measurements Recurring \| Money Market Funds
Assets
Cash equivalents - money market funds	62,104	22,784
Fair Value Measurements Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Total assets	62,104	22,784
Fair Value Measurements Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1) \| Money Market Funds
Assets
Cash equivalents - money market funds	62,104	22,784
Fair Value Measurements Recurring \| Significant Other Observable Inputs (Level 2)
Assets
Restricted cash	263	263
Total assets	$ 263	263
Fair Value Measurements Recurring \| Significant Unobservable Inputs (Level 3)
Liabilities
Derivative liability related to loan		494
Total liabilities		$ 494

Fair Value Measurements - Schedule of Aggregate Fair Values of Derivative Liability (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($)
Fair Value Disclosures [Abstract]
Beginning balance	$ 494
Change in fair value	556
Payment of success fee	(1,050)
Ending balance	$ 0

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment–at cost	$ 9,467	$ 9,654
Less: Accumulated depreciation and amortization	(6,638)	(5,903)
Property and equipment, net	2,829	3,751
Equipment
Property Plant And Equipment [Line Items]
Total property and equipment–at cost	7,030	7,230
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment–at cost	629	629
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment–at cost	896	896
Software
Property Plant And Equipment [Line Items]
Total property and equipment–at cost	$ 912	669
Assets Not Yet Placed in Service
Property Plant And Equipment [Line Items]
Total property and equipment–at cost		$ 230

Property and Equipment - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Property Plant And Equipment [Abstract]
Total depreciation and amortization expense	$ 0.4	$ 0.5	$ 0.9	$ 1.1

Accrued Expenses - Components of Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Compensation and benefits	$ 455	$ 1,759
Research and development expenses	223	249
Legal and professional fees	957	417
Sales taxes		554
Other	939	143
Total accrued expenses	$ 2,574	$ 3,122

Loan Payable - Schedule of Aggregate Principal Amount of Debt Outstanding (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Current portion of debt	$ 7,500	$ 5,625
Less: unamortized debt discount	(46)	(49)
Current portion of debt, net of debt discount	7,454	5,576
Long-term debt, net of current portion	5,625	9,375
Less: unamortized debt discount	(35)	(82)
Long-term debt, net of current portion	$ 5,590	$ 9,293

Loan Payable - Additional Information (Details) - Term Loan Facility - Pacific Western Bank, Inc - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Debt Instrument [Line Items]
Debt proceeds			$ 15,000,000
Debt instrument, interest rate	6.25%		6.25%
Debt instrument, interest rate during period			6.75%
Increase in interest rate in case of default			5.00%
Term loan facility payment terms			The Company made interest-only payments through March 31, 2020. Beginning in April 2020, the Company is obligated to make equal monthly principal payments of $625,000 through March 31, 2022 when the notes mature.
Frequency of periodic payment			monthly
Date of first required payment			2020-04
Equal monthly principal payments			$ 625,000
Debt instrument, maturity date			Mar. 31, 2022
Success fee payment	$ 1,100,000		$ 1,100,000
Interest expense	$ 200,000	$ 300,000	$ 500,000	$ 600,000
Prime Rate
Debt Instrument [Line Items]
Debt instrument, applicable margin interest rate			2.00%

Loan Payable - Schedule of Aggregate Minimum Future Principal Payments (Details) - 2018 Loan Agreement $ in Thousands	Jun. 30, 2020 USD ($)
Debt Instrument [Line Items]
2020	$ 3,750
2021	7,500
2022	1,875
Long-term debt	$ 13,125

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Additional Information (Details) $ / shares in Units, $ in Thousands		3 Months Ended	6 Months Ended
	Jun. 19, 2020 $ / shares shares	Jun. 30, 2020 $ / shares shares	Jun. 30, 2020 USD ($) Holder $ / shares shares	Jun. 17, 2020 shares	Mar. 31, 2020 shares	Dec. 31, 2019 shares	Jun. 30, 2019 shares	Mar. 31, 2019 shares	Dec. 31, 2018 shares
Class Of Stock [Line Items]
Convertible preferred stock, shares outstanding		0	0			207,164,404
Common stock, shares issued		52,151,798	52,151,798			9,073,002
Olivia Ventures Inc
Class Of Stock [Line Items]
Common stock, shares issued		1,000,000	1,000,000
Number of holders membership interests cancelled with merger \| Holder			15
Number of membership interests cancelled as a result of not accredited investors with merger			131,472
Cash consideration for cancelling membership interests in connection with merger \| $			$ 69
2020 Stock Option and Incentive Plan
Class Of Stock [Line Items]
Common stock, shares issued		2,930,836	2,930,836
Common stock reserved for issuance				2,930,836
Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, shares outstanding		0	0		207,164,404	207,164,404	207,164,404	207,164,404	207,164,404
Common Stock
Class Of Stock [Line Items]
Conversion of Compass Therapeutics LLC preferred shares into common shares upon consummation of the reverse merger, Shares		30,629,606	30,629,606
Common stock, shares issued		8,425,750	8,425,750
Shares of common stock sold		12,096,442
Common Stock \| Private Placement Offering
Class Of Stock [Line Items]
Shares of common stock sold	12,096,442		12,096,442
Purchase price per share \| $ / shares	$ 5.00	$ 5.00	$ 5.00
Common Stock \| Private Placement Offering \| Maximum
Class Of Stock [Line Items]
Shares of common stock sold	14,000,000		14,000,000
Common Stock \| 2020 Stock Option and Incentive Plan
Class Of Stock [Line Items]
Common stock reserved for issuance		2,930,836	2,930,836

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Summary of Convertible Preferred Stock Shares Outstanding (Details) - shares	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Convertible preferred stock, shares outstanding	0		207,164,404
Series A-1
Class Of Stock [Line Items]
Convertible preferred stock, shares outstanding			64,704,832
Series A-2
Class Of Stock [Line Items]
Convertible preferred stock, shares outstanding			36,782,734
Series A-3
Class Of Stock [Line Items]
Convertible preferred stock, shares outstanding			23,467,151
Series A-4
Class Of Stock [Line Items]
Convertible preferred stock, shares outstanding			15,253,415
Series A4B
Class Of Stock [Line Items]
Convertible preferred stock, shares outstanding			22,216,583
Series A-5
Class Of Stock [Line Items]
Convertible preferred stock, shares outstanding			44,739,689
Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, shares outstanding	0	207,164,404	207,164,404	207,164,404	207,164,404	207,164,404

Stock-Based Compensation - Schedule of Value Profits Interests Granted (Details)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected term (in years)	6 years	6 years
Risk-free rate	0.36%	2.43%
Expected volatility	140.45%	72.02%
Expected dividend yield	0.00%	0.00%

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield				0.00%	0.00%
Weighted-average grant-date fair value for profits interests granted				$ 0.23
Stock-based compensation expense		$ 183	$ 185	$ 430	$ 440
Unrecognized compensation cost relating to unvested restricted stock awards	$ 2,000	$ 2,000		$ 2,000
Unvested stock expected to be recognized over a weighted-average period				1 year 10 months 9 days
Number of common stock issued	52,151,798	52,151,798		52,151,798		9,073,002
2020 Stock Option and Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock issued	2,930,836	2,930,836		2,930,836
Outstanding number of shares preceding percentage	4.00%
Number of awards issued or outstanding	0	0		0

Stock-Based Compensation - Schedule of Unvested Restricted Stock Activity (Details) - Restricted Stock	6 Months Ended
	Jun. 30, 2020 $ / shares shares
Shares
Nonvested at the beginning \| shares	2,038,955
Nonvested, Granted \| shares	879
Nonvested, Vested \| shares	(150,379)
Nonvested, Forfeited or canceled \| shares	(634,491)
Nonvested at the ending \| shares	1,254,965
Weighted Average Grant-Date Fair Value
Nonvested at the beginning \| $ / shares	$ 2.04
Nonvested, Granted \| $ / shares	2.34
Nonvested, Vested \| $ / shares	0.57
Nonvested, Forfeited or canceled \| $ / shares	1.83
Nonvested at the ending \| $ / shares	$ 2.33

Stock-Based Compensation - Schedule of Stock-Based Compensation Activity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Employee Service Share Based Compensation Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 183	$ 185	$ 430	$ 440
Research and Development
Employee Service Share Based Compensation Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	31	61	112	175
General and Administrative
Employee Service Share Based Compensation Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 152	$ 124	$ 318	$ 265

License, Research and Collaboration Agreements - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development	$ 2,985	$ 5,389	$ 6,556	$ 12,632
Adimab Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration agreement date			Oct. 16, 2014
Future milestone payments	2,000		$ 2,000
Research and development	0	0	0	500
Other License and Research Agreements
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development	58	$ 100	200	$ 300
Cash payment for license agreement	21		100
Clinical and regulatory milestone payments	$ 500		$ 500

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Lease expiration date			Jan. 31, 2021
Rental expense	$ 0.5	$ 0.5	$ 1.0	$ 0.9

Commitments and Contingencies - Future Minimum Rental Payments under Leases (Details) $ in Thousands	Jun. 30, 2020 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2020	$ 962
2021	160
Total future minimum rental payments	$ 1,122

Related Parties and Related-Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Related Party Transaction [Line Items]
Research and development	$ 2,985	$ 5,389	$ 6,556	$ 12,632
Adimab, LLC \| Collaboration Agreement
Related Party Transaction [Line Items]
Research and development			0	500
StackWave, LLC \| Software License and Services Agreement
Related Party Transaction [Line Items]
Capitalized software	$ 200	$ 700	$ 200	$ 700

Subsequent Events - Additional Information (Details)	Jul. 31, 2020 USD ($)
Maximum \| Manufacturing Agreement \| Subsequent Event
Subsequent Event [Line Items]
Payments receivable as certain protocol	$ 4,850,000