CMPX

62,500 of the shares represents unvested restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 2, 2027.

150,000 of the shares represents unvested restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 2, 2027.

Represents the number of shares withheld by the Issuer to cover tax withholding obligations in connection with the vesting of restricted stock units ("RSUs").

125,000 of the shares represent unvested restricted stock units ("RSU") granted on February 8, 2023. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on February 8, 2024. 318,750 of the shares represent unvested restricted stock units ("RSU") granted on January 9, 2024. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 9, 2025. 250,000 of the shares represent unvested restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 2, 2027.

Represents the number of shares withheld by the Issuer to cover tax withholding obligations in connection with the vesting of restricted stock units ("RSUs").

250,000 of the shares represent unvested restricted stock units ("RSU") granted on February 8, 2023. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on February 8, 2024. 318,750 of the shares represent unvested restricted stock units ("RSU") granted on January 9, 2024. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 9, 2025. 250,000 of the shares represent unvested restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 2, 2027.

This grant vests in full upon the earlier of (i) June 10, 2026 or (ii) the date of the next annual meeting of the Company's stockholders.

This grant vests in full upon the earlier of (i) June 10, 2026 or (ii) the date of the next annual meeting of the Company's stockholders.

The Reporting Person is a member of OrbiMed Advisors LLC ("OrbiMed Advisors"). Pursuant to an agreement with OrbiMed Advisors, the Reporting Person is obligated to transfer any securities issued under any stock options or other awards, or the economic benefit thereof, to OrbiMed Advisors and OrbiMed Capital GP V LLC, which will in turn ensure that such securities or economic benefits are provided to OrbiMed Private Investments V-KA, LP.

The options were granted pursuant to the Compass Therapeutics, Inc. 2025 Inducement Plan as a material inducement to the Reporting Person's acceptance of employment with the Issuer in accordance with Nasdaq Rule 5635(c)(4).

The options will vest over four years, as follows: 25% of the shares underlying the option will vest and become exercisable on January 2, 2027, with the remaining 75% vesting in 36 substantially equal monthly installments thereafter.

The options vest over 48 substantially equal monthly installments starting February 2, 2026.

This grant vests in full upon the earlier of (i) June 10, 2026 and (ii) the date of the next annual meeting of the Company's stockholders.

The options were granted pursuant to the Compass Therapeutics, Inc. 2025 Inducement Plan as a material inducement to the Reporting Person's acceptance of employment with the Issuer in accordance with Nasdaq Rule 5635(c)(4).

The options will vest over four years, as follows: 25% of the shares underlying the option will vest and become exercisable on January 2, 2027, with the remaining 75% vesting in 36 substantially equal monthly installments thereafter.

This grant vests in full upon the earlier of (i) June 10, 2026 or (ii) the date of the next annual meeting of the Company's stockholders.

The options vest over 48 substantially equal monthly installments starting February 2, 2026.

The options vest over 48 substantially equal monthly installments starting February 2, 2026.

Represents restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first vesting on January 2, 2027.

150,000 of the shares represents unvested restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 2, 2027.

Represents restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first vesting on January 2, 2027.

300,000 of the shares represents unvested restricted stock units ("RSU") granted on December 9, 2024. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on December 9, 2025. 125,000 of the shares represents unvested restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 2, 2027.

This grant vests in full upon the earlier of (i) June 10, 2026 or (ii) the date of the next annual meeting of the Company's stockholders.

Represents restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first vesting on January 2, 2027.

250,000 of the shares represent unvested restricted stock units ("RSU") granted on February 8, 2023. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on February 8, 2024. 478,125 of the shares represent unvested restricted stock units ("RSU") granted on January 9, 2024. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 9, 2025. 250,000 of the shares represent unvested restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 2, 2027.

Represents restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first vesting on January 2, 2027.

62,500 of the shares represents unvested restricted stock units ("RSU") granted on January 2, 2026. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 2, 2027.

This grant vests in full upon the earlier of (i) June 10, 2026 or (ii) the date of the next annual meeting of the Company's stockholders.

The Reporting Person is a member of Enavate Sciences, LP ("Enavate"). Pursuant to an agreement with Enavate, the Reporting Person is obligated to transfer any securities issued under any stock options or other awards, or the economic benefit thereof, to Enavate, which will in turn ensure that such securities or economic benefits are provided to Enavate

The options vest over 48 substantially equal monthly installments starting February 2, 2026.

Represents the number of shares withheld by the Issuer to cover tax withholding obligations in connection with the vesting of restricted stock units ("RSUs").

250,000 of the shares represent unvested restricted stock units ("RSU") granted on February 8, 2023. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on February 8, 2024. 478,125 of the shares represent unvested restricted stock units ("RSU") granted on January 9, 2024. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 9, 2025.

The price reported in Column 4 is the weighted average purchase price. These shares were purchased in two transactions at prices of $2.105 and $2.115 per share. The reporting person hereby undertakes to provide, upon request, to the Company, any security holder of the Company, or the staff of the Securities and Exchange Commission, full information regarding the number of shares purchased and prices within the range set forth above.

150,000 of the shares represent unvested RSUs granted on November 16, 2021. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on November 15, 2022. 250,000 of the shares represent unvested RSUs granted on February 8, 2023. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on February 8, 2024. 478,125 of the shares represent unvested RSUs granted on January 9, 2024. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 9, 2025.

These securities are held of record by OrbiMed Genesis Master Fund, L.P. ("Genesis Master Fund"). OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis Master Fund and OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisors Act of 1940, as amended, is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by Genesis Master Fund. OrbiMed Advisors exercises investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the securities held by Genesis Master Fund.

This report on Form 4 is jointly filed by GP V, OrbiMed Advisors, and Genesis GP. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. OrbiMed Advisors and GP V have designated Carl L. Gordon ("Gordon"), a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any of the Reporting Persons, or Gordon, is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

These securities are held of record by OrbiMed Genesis Master Fund, L.P. ("Genesis Master Fund"). OrbiMed Genesis GP LLC ("Genesis GP") is the general partner of Genesis Master Fund and OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisors Act of 1940, as amended, is the managing member of Genesis GP. By virtue of such relationships, Genesis GP and OrbiMed Advisors may be deemed to have voting and investment power with respect to the securities held by Genesis Master Fund. OrbiMed Advisors exercises investment and voting power through a management committee comprised of the Reporting Person, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the securities held by Genesis Master Fund.

Each of the Reporting Person, GP V, OrbiMed Advisors, and Genesis GP disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of his or its pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Person, GP V, OrbiMed Advisors, or Genesis GP is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

The price reported in Column 4 is the weighted average purchase price. These shares were purchased in multiple transactions at prices ranging from $1.42 to $1.43 per share. The reporting person hereby undertakes to provide, upon request, to the Company, any security holder of the Company, or the staff of the Securities and Exchange Commission, full information regarding the number of shares purchased and prices within the range set forth above.

The options vest over 48 substantially equal monthly installments starting March 11, 2025.

The options vest over 48 substantially equal monthly installments starting March 11, 2025.

The options vest over 48 substantially equal monthly installments starting March 11, 2025.

The options vest over 48 substantially equal monthly installments starting March 11, 2025.

The options vest over 48 substantially equal monthly installments starting March 11, 2025.

The options vest over 48 substantially equal monthly installments starting March 11, 2025.

The options vest over 48 substantially equal monthly installments starting March 11, 2025.

The Reporting Person is a member of OrbiMed Advisors LLC ("OrbiMed Advisors"). Pursuant to an agreement with OrbiMed Advisors, the Reporting Person is obligated to transfer any securities issued under any stock options or other awards, or the economic benefit thereof, to OrbiMed Advisors and OrbiMed Capital GP V LLC, which will in turn ensure that such securities or economic benefits are provided to OrbiMed Private Investments V-KA, LP.

The options vest over 48 substantially equal monthly installments starting March 11, 2025.

The Reporting Person is a member of Enavate Sciences, LP ("Enavate"). Pursuant to an agreement with Enavate, the Reporting Person is obligated to transfer any securities issued under any stock options or other awards, or the economic benefit thereof, to Enavate, which will in turn ensure that such securities or economic benefits are provided to Enavate.

The options vest over 48 substantially equal monthly installments starting March 11, 2025.

The options vest over 48 substantially equal monthly installments starting March 11, 2025.

Represents the number of shares withheld by the Issuer to cover tax withholding obligations in connection with the vesting of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of common stock.

125,000 of the shares represent unvested RSUs granted on November 16, 2021. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on November 15, 2022. 250,000 of the shares represent unvested RSUs granted on February 8, 2023. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on February 8, 2024. 478,125 of the shares represent unvested RSUs granted on January 9, 2024. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 9, 2025.

Represents the number of shares withheld by the Issuer to cover tax withholding obligations in connection with the vesting of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of common stock.

150,000 of the shares represent unvested RSUs granted on November 16, 2021. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on November 15, 2022. 375,000 of the shares represent unvested RSUs granted on February 8, 2023. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on February 8, 2024. 478,125 of the shares represent unvested RSUs granted on January 9, 2024. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vested on January 9, 2025.

The options vest as follows: 25% on December 9, 2025, with the remaining over 36 substantially equal monthly installments starting January 9, 2026.

Represents restricted stock units ("RSU") granted to the reporting person on December 9, 2024. Each RSU represents a contingent right to receive one share of common stock. The award is subject to service-based vesting conditions and vests in four equal annual installments, with the first installment vesting on December 9, 2025.

The options vest over 48 substantially equal monthly installments starting September 13, 2024.

The options vest over 48 substantially equal monthly installments starting April 8, 2024.

The Reporting Person is a member of Enavate Sciences, LP ("Enavate"). Pursuant to an agreement with Enavate, the Reporting Person has agreed to receive and hold for the benefit of Enavate any securities issued under any stock options or other awards granted to him for his services as a director on the Issuer's board of directors. As such, the Reporting Person disclaims beneficial ownership of, and all right, title and interest in, the reported securities.

The options vest over 48 substantially equal monthly installments starting March 9, 2024.

The options vest over 48 substantially equal monthly installments starting March 9, 2024.

The options vest over 48 substantially equal monthly installments starting March 9, 2024.

The options vest over 48 substantially equal monthly installments starting March 9, 2024.

The options vest over 48 substantially equal monthly installments starting March 9, 2024.

The Reporting Person is a member of OrbiMed Advisors LLC ("OrbiMed Advisors"). Pursuant to an agreement with OrbiMed Advisors, the Reporting Person is obligated to transfer any securities issued under any stock options or other awards, or the economic benefit thereof, to OrbiMed Advisors and OrbiMed Capital GP V LLC, which will in turn ensure that such securities or economic benefits are provided to OrbiMed Private Investments V-KA, LP.