Contract analysis

I. Purpose of This Letter I write in my capacity as Responsible Partner at Calderwood & Harkness LLP ("C&H" or the "Firm"), independent counsel to the Special Committee (the "Special Committee") of the Board of Directors (the "Board") of Penterra Pharmaceuticals Corp. ("Penterra" or the "Company"), a Delaware corporation whose common stock is listed on the New York Stock Exchange under the ticker symbol "PPHR" and wh

II. Background and Context To provide the necessary context for the recusal and coordination protocol described in this letter, I briefly summarize the relevant factual background. Dr. Marcus Hale, who serves as Chairman of the Board and Chief Executive Officer of Penterra, holds an equity interest of approximately 28.5% in Caliston BioSciences, Inc., a privately held Delaware corporation with its principal office at

III. Confirmation of ABC's Recusal In light of the foregoing, this letter serves as the formal confirmation that Alcott, Barringer & Cole LLP is recused from advising the Special Committee in connection with all matters relating to the Proposed Transaction — that is, the proposed acquisition of Caliston BioSciences, Inc. by Penterra Pharmaceuticals Corp. (Project Coriander) — in any capacity whatsoever. This recusal

IV. Scope of Information Barrier A. Excluded Persons and Information To effectuate the recusal described above, the following information barrier shall be established and maintained for the duration of the protocol: Access Restrictions. ABC personnel shall have no access to the Project Coriander workspace on Penterra's segregated document management system (the "Coriander Workspace"), which has been established on th

V. Permitted Coordination on Non-Conflicted Matters A. Categories of Permitted Coordination The establishment of the recusal and information barrier described herein is not intended to impair ABC's ability to serve as regular outside counsel to Penterra on non-conflicted matters. Accordingly, C&H and ABC may coordinate on the following categories of non-conflicted corporate matters relating to Penterra, provided that

VI. Handling of Pre-Existing Work Product As noted above, ABC provided governance process advice to the Penterra Board between April 12, 2023 and June 2, 2023 — the date on which the Special Committee was formally constituted and Calderwood & Harkness LLP was engaged as independent counsel. During that period, ABC may have prepared memoranda, analyses, board presentations, governance frameworks, or other work product

VII. Duration of the Protocol This recusal and coordination protocol shall remain in full force and effect from the date of this letter through the earliest to occur of the following: (a) the closing of the Proposed Transaction (i.e., the consummation of the merger of Caliston BioSciences, Inc. with and into a wholly owned subsidiary of Penterra, or such other transaction structure as may be agreed); (b) the terminat

VIII. Acknowledgment of Respective Roles For the avoidance of doubt, the respective roles and responsibilities of Calderwood & Harkness LLP and Alcott, Barringer & Cole LLP are as follows: Calderwood & Harkness LLP serves as independent counsel to the Special Committee of the Board of Directors of Penterra Pharmaceuticals Corp. In that capacity, C&H has sole authority and responsibility to advise the Special Committe

IX. Confirmation Request I respectfully request that you countersign this letter in the space provided below and return a signed copy to me by email (with the original to follow by first-class mail) to confirm Alcott, Barringer & Cole LLP's acknowledgment of and agreement to the recusal and coordination protocol set forth herein. Upon receipt of your countersignature, I will provide a copy of this fully executed lett

X. Closing Victoria, I appreciate your cooperation, professionalism, and understanding in supporting the integrity of the Special Committee process. The procedural safeguards reflected in this protocol are critical to protecting the interests of Penterra's stockholders and ensuring that the Special Committee's work is conducted with the rigor and independence that Delaware law requires. I am confident that the framew

XI. Acknowledgment and Agreement ACKNOWLEDGED AND AGREED: The undersigned, on behalf of Alcott, Barringer & Cole LLP, hereby acknowledges receipt of the foregoing letter dated June 5, 2023 from Renata Vasquez of Calderwood & Harkness LLP and confirms Alcott, Barringer & Cole LLP's agreement to the recusal and coordination protocol set forth therein. ALCOTT, BARRINGER & COLE LLP By: ________ Name: Victoria Shen Title: