ORBIMED ADVISORS LLC - 14 Feb 2024 Form 4 Insider Report for Theseus Pharmaceuticals, Inc.

Footnote F1

Pursuant to the terms of that certain Agreement and Plan of Merger (the "Merger Agreement"), dated as of December 22, 2023, by and among the Issuer, Concentra Biosciences, LLC, a Delaware limited liability company ("Parent") and Concentra Merger Sub II, Inc., a Delaware corporation and a wholly owned subsidiary of Parent ("Merger Sub"), Merger Sub completed a tender offer for shares of common stock of the Issuer (each, a "Share") and thereafter merged with and into the Issuer, effective as of February 14, 2024 (the "Effective Time") with the Issuer surviving the merger.

Footnote F2

At the Effective Time, each issued and outstanding Share was cancelled and converted into the right to receive (a) $4.05 per Share in cash (the "Cash Amount"), subject to any applicable withholding taxes and without interest, plus (b) one non-transferable contractual contingent value right per Share (each, a "CVR"), which represents the right to receive potential payments, in cash, subject to any applicable tax withholding and without interest, all upon the terms and subject to the conditions as set forth in the Offer to Purchase, as amended, and in the related Letter of Transmittal.

Footnote F3

These Shares are held of record by OrbiMed Private Investments VII, LP ("OPI VII"). OrbiMed Capital GP VII LLC ("GP VII") is the general partner of OPI VII and OrbiMed Advisors LLC ("OrbiMed Advisors"), a registered investment adviser under the Investment Advisors Act of 1940, as amended, is the managing member of GP VII. By virtue of such relationships, OrbiMed Advisors and GP VII may be deemed to have voting power and investment power over the securities held by OPI VII and, as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment 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 Shares held by OPI VII.

Footnote F4

Each of GP VII, OrbiMed Genesis GP LLC ("Genesis GP"), and OrbiMed Advisors 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 VII have designated a representative, Carl L. Gordon, a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report on Form 4 shall not be deemed an admission that any of the Reporting Persons is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

Footnote F5

These Shares are held of record by OrbiMed Genesis Master Fund, L.P. ("OrbiMed Genesis"). Genesis GP is the general partner of OrbiMed Genesis. OrbiMed Advisors is the managing member of Genesis GP. By virtue of such relationships, OrbiMed Advisors and Genesis GP may be deemed to have voting power and investment power over the securities held by OrbiMed Genesis and, as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment 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 Shares held by OrbiMed Genesis.