Contract analysis

1. Introduction and Purpose Calderwood & Harkness LLP acts as counsel to Penterra Pharmaceuticals Corp. in connection with the Offering. The underwriters participating in the Offering (collectively, the "Underwriters") are as follows: • Ridgeline Securities LLC — Lead Left Book-Running Manager • Broadmark Capital Inc. — Joint Book-Running Manager • Linden Groves & Co. — Co-Manager • Harborview Partners LLC — Co-Manag

2. Financial Statements to Be Covered The Comfort Letter should cover the following audited and unaudited financial statements and financial data of the Company that are included or incorporated by reference in the Preliminary Prospectus Supplement and/or the Registration Statement: 2.1 Audited Financial Statements The Comfort Letter should address the audited consolidated financial statements of PPC for the fiscal y

3. Financial Data and Other Information in the Prospectus Supplement In addition to the financial statements described in Section 2 above, the Comfort Letter should address certain specified financial data, financial information, and statistical data appearing in the Preliminary Prospectus Supplement (and, to the extent available and requested, in the final Prospectus Supplement), including, but not limited to, the f

4. Circle-Up Procedures / Agreed-Upon Procedures In addition to the procedures described in Sections 2 and 3 above, we request that the following specific agreed-upon procedures (commonly referred to as "circle-up" procedures) be performed by Graystone & Whitmore LLP in connection with the preparation and delivery of the Comfort Letter: 4.1 Reading of Minutes We request that Graystone & Whitmore LLP read the minutes

5. Cut-Off Date As referenced throughout this letter, the "Cut-Off Date" for purposes of the procedures to be performed in connection with the Comfort Letter shall be a date not more than five (5) business days prior to the date of delivery of the Comfort Letter. We currently expect that the Comfort Letter will be delivered on or about October 12, 2023, which is the anticipated date of pricing of the Offering and exe

6. Addressees The Comfort Letter should be addressed to the following parties: Addressees: (a) Ridgeline Securities LLC, as representative of the several underwriters named in the Underwriting Agreement 383 Madison Avenue New York, New York 10017 (b) Broadmark Capital Inc. 200 Park Avenue New York, New York 10166 (c) Linden Groves & Co. 745 Fifth Avenue New York, New York 10151 (d) Harborview Partners LLC 1 Federal S

7. Coordination and Deliverables In order to ensure that the Comfort Letter can be finalized and delivered in accordance with the anticipated timeline for the Offering, we respectfully request the following: (a) Draft Comfort Letter. Graystone & Whitmore LLP should provide a complete draft of the Comfort Letter to Calderwood & Harkness LLP and Caldwell, Pearce & Strauss LLP for review and comment as soon as practicab

8. Bring-Down Comfort Letter As noted above, the delivery of a bring-down comfort letter will be a condition to the closing of the Offering under the Underwriting Agreement. We anticipate that we will deliver a separate written request for the bring-down comfort letter to Graystone & Whitmore LLP on or about October 13, 2023. The bring-down comfort letter should be dated as of the Closing Date (expected to be October

9. Confidentiality This letter and the Comfort Letter (including any drafts thereof) are confidential and are provided solely for the benefit of the parties identified herein. Neither this letter nor the Comfort Letter, nor any portion thereof, should be disclosed, distributed, or made available to any party other than those identified in this letter without the prior written consent of Penterra Pharmaceuticals Corp.