Contract analysis

1. Introduction and Purpose Calderwood & Harkness LLP ("C&H" or the "Firm") is pleased to confirm its engagement by Penterra Pharmaceuticals Corp. ("PPC" or the "Company"), a Delaware corporation headquartered in Princeton Junction, New Jersey, and publicly traded on the Nasdaq Stock Market (ticker symbol: PPCA), as outside tax counsel in connection with the matters described herein. This engagement letter (the "Lett

2. Scope of Representation 2.1 General Scope C&H will serve as outside tax counsel to PPC in defending against the IRS examination challenging the transfer pricing methodology employed in PPC's intercompany arrangements with its Irish subsidiary, Penterra Biopharma International Designated Activity Company ("PBI"), an Irish-incorporated entity. The defense will also encompass the intercompany transactions between PPC

3. Engagement Team and Staffing C&H has assembled an engagement team with extensive experience in transfer pricing controversy, IRS examination defense, and international tax matters. The members of the core engagement team are identified below. 3.1 Responsible Partner Leonard Cross, Partner, Tax Department, will serve as the Responsible Partner for this engagement. Mr. Cross will have overall responsibility for enga

4. Fee Arrangements 4.1 Hourly Billing Rates (2022) C&H's services in connection with this engagement will be billed on an hourly basis at the following rates, which are effective as of January 1, 2022: Paralegal and tax analyst rates vary depending on the seniority and experience of the individual assigned. A complete schedule of 2022 billing rates for all timekeepers who may work on this matter is set forth in Encl

5. IRS Power of Attorney In order to enable C&H to communicate directly with the IRS examination team, receive copies of IRS correspondence relating to the Examination, and represent PPC in IRS conferences and proceedings, PPC will execute IRS Form 2848 (Power of Attorney and Declaration of Representative) authorizing the following C&H attorneys to represent PPC before the IRS for tax years 2017, 2018, 2019, and 2020

6. Retention of Economic Experts — Kovel Arrangement Transfer pricing examinations of this nature invariably require the preparation of detailed economic analyses, including functional analyses, industry and comparable company benchmarking, and valuation studies. In order to ensure that such economic analyses are prepared under the protection of the attorney-client privilege and the work-product doctrine, C&H will re

7. Coordination with Other Advisors 7.1 Crestfield & Associates LLP C&H will coordinate closely with Crestfield & Associates LLP ("Crestfield"), PPC's independent auditor and the preparer of PPC's contemporaneous transfer pricing documentation for TY 2017–2020. The primary contacts at Crestfield for purposes of this engagement are Martin Ogilvy, Engagement Partner, and Susan Lam, Transfer Pricing Partner. Crestfield

8. Privilege and Confidentiality Protocols The preservation of the attorney-client privilege and the work-product doctrine is of paramount importance in connection with this engagement. The following protocols are designed to ensure the protection of privileged communications and work product. 8.1 Attorney-Client Privilege All communications between C&H and PPC in connection with this engagement are intended to be, a

9. Client Responsibilities The success of this engagement will depend in significant part on the timely and full cooperation of PPC and its personnel. PPC agrees to the following responsibilities: (a) Primary and Secondary Contacts. PPC will designate Marcus Whitfield, Vice President of Global Tax, as the primary client contact for day-to-day matters arising in connection with the Examination, including coordination

10. Conflicts of Interest C&H has conducted a comprehensive conflicts check in accordance with the Firm's standard procedures and the applicable Rules of Professional Conduct. Based on that review, C&H has determined that it has no conflicts of interest that would preclude its representation of PPC in connection with this engagement. The conflicts check encompassed PPC and its relevant affiliates, including PBI, PHL,

11. Termination Either party may terminate this engagement at any time upon written notice to the other party. C&H may also withdraw from the engagement in accordance with the applicable Rules of Professional Conduct, including in circumstances where continued representation would result in a violation of ethical obligations or where PPC fails to fulfill its obligations under this Letter, including the timely payment

12. File Retention At the conclusion of this engagement, C&H will retain the engagement file — including correspondence, memoranda, work product, and related materials — for a period consistent with the Firm's document retention policy, which currently provides for retention of closed matter files for a period of seven (7) years from the date of matter closure. PPC may request copies of the engagement file, or any po

13. Governing Law This engagement letter shall be governed by and construed in accordance with the laws of the State of New York, without regard to its principles of conflicts of law. Any dispute arising out of or relating to this engagement letter or the services provided hereunder shall be subject to the exclusive jurisdiction of the courts of the State of New York located in the County of New York or the United St

14. Acceptance and Execution We are honored that PPC has selected Calderwood & Harkness LLP to represent the Company in this important matter, and we look forward to working with you, Ms. Staines, and the PPC team throughout the course of this engagement. If the foregoing terms and conditions are acceptable to PPC, please indicate your agreement by signing and returning a copy of this Letter to the undersigned. This