Formation and Business of the Company	12 Months Ended
Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Formation and Business of the Company	1. Formation and Business of the Company Compass Therapeutics, Inc. (“Compass” or the “Company”) is a clinical-stage, oncology-focused biopharmaceutical company developing proprietary antibody-based therapeutics to treat multiple human diseases. Our scientific focus is on the relationship between angiogenesis and the immune system. Our pipeline includes novel product candidates that leverage our understanding of the tumor microenvironment, including both angiogenesis-targeted agents and immune-oncology focused agents. These product candidates are designed to optimize critical components required for an effective anti-tumor response to cancer. These include modulation of the microvasculature via angiogenesis-targeted agents; induction of a potent immune response via activators on effector cells in the tumor microenvironment; and alleviation of immunosuppressive mechanisms used by tumors to evade immune surveillance. We plan to advance our product candidates through clinical development as both standalone therapies and in combination with our proprietary drug candidates as long as their continued development is supported by clinical and nonclinical data. References to Compass or the Company herein include Compass Therapeutics, Inc. and its wholly-owned subsidiaries. The Company was incorporated as Olivia Ventures, Inc. (“Olivia”) in the State of Delaware on March 20, 2018. Prior to the Company’s reverse merger with Compass Therapeutics LLC (the “Merger”), 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 completed the Merger of its wholly-owned subsidiary, Compass Therapeutics LLC, pursuant to an Agreement and Plan of Merger and Reorganization (the “Merger Agreement”), by and among Olivia Ventures, Inc., Compass Acquisition LLC, Compass Therapeutics LLC and as a result, Compass Therapeutics LLC became a wholly-owned subsidiary of the Company. Additionally, certain of the Company’s wholly-owned subsidiaries (each, a “Blocker Merger Sub”) merged with and into the applicable blocker entity (“Blockers”) in transactions that are referred to as “Blocker Mergers”. 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 the Company’s common stock were issued to holders of common membership interests of Compass Therapeutics 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 Therapeutics LLC and the Blockers are collectively referred to as the Share Conversion. 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.

Formation and Business of the Company

12 Months Ended

Dec. 31, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Compass Therapeutics, Inc. (“Compass” or the “Company”) is a clinical-stage, oncology-focused biopharmaceutical company developing proprietary antibody-based therapeutics to treat multiple human diseases. Our scientific focus is on the relationship between angiogenesis and the immune system. Our pipeline includes novel product candidates that leverage our understanding of the tumor microenvironment, including both angiogenesis-targeted agents and immune-oncology focused agents. These product candidates are designed to optimize critical components required for an effective anti-tumor response to cancer. These include modulation of the microvasculature via angiogenesis-targeted agents; induction of a potent immune response via activators on effector cells in the tumor microenvironment; and alleviation of immunosuppressive mechanisms used by tumors to evade immune surveillance. We plan to advance our product candidates through clinical development as both standalone therapies and in combination with our proprietary drug candidates as long as their continued development is supported by clinical and nonclinical data. References to Compass or the Company herein include Compass Therapeutics, Inc. and its wholly-owned subsidiaries. The Company was incorporated as Olivia Ventures, Inc. (“Olivia”) in the State of Delaware on March 20, 2018. Prior to the Company’s reverse merger with Compass Therapeutics LLC (the “Merger”), 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 completed the Merger of its wholly-owned subsidiary, Compass Therapeutics LLC, pursuant to an Agreement and Plan of Merger and Reorganization (the “Merger Agreement”), by and among Olivia Ventures, Inc., Compass Acquisition LLC, Compass Therapeutics LLC and as a result, Compass Therapeutics LLC became a wholly-owned subsidiary of the Company. Additionally, certain of the Company’s wholly-owned subsidiaries (each, a “Blocker Merger Sub”) merged with and into the applicable blocker entity (“Blockers”) in transactions that are referred to as “Blocker Mergers”.

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 the Company’s common stock were issued to holders of common membership interests of Compass Therapeutics 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 Therapeutics LLC and the Blockers are collectively referred to as the Share Conversion.

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.