Contract analysis

1. Introduction and Context We have acted as counsel to Penterra Pharmaceuticals Corp., a Delaware corporation (the "Company" or "PPC"), in connection with the registered public offering (the "Offering") of shares of common stock, par value $0.001 per share (the "Common Stock"), of the Company by certain selling stockholders. This letter is being delivered to you in connection with the Underwriting Agreement dated Oc

2. Documents Reviewed In connection with the preparation of this letter, we have reviewed the following documents: (a) the Registration Statement on Form S-3 (File No. 333-274851) of the Company (the "Registration Statement"), including the base prospectus dated August 22, 2023, contained therein (the "Base Prospectus"), as filed with the Securities and Exchange Commission (the "SEC" or the "Commission") under the Se

3. Scope of Review and Participation In addition to our review of the documents described in Section 2 above, we have participated in the preparation of the Registration Statement, the Base Prospectus, the Preliminary Prospectus Supplement, the Prospectus Supplement, and the Pricing Term Sheet, including review of successive drafts of each such document. We have also participated in conferences and discussions with o

4. Limitations and Qualifications This letter is subject to the following limitations and qualifications: (a) This letter is not a guarantee, and the negative assurance set forth herein is not based on an independent investigation or verification of the facts stated in or omitted from the Registration Statement or the Prospectus. We have assumed the genuineness of all signatures, the legal capacity of all natural per

5. Negative Assurance Statement On the basis of the review and participation described in Sections 2 and 3 above, and subject to the limitations, qualifications, and exclusions set forth in Section 4 above and elsewhere in this letter, and in reliance upon the representations and warranties of the Company and the Selling Stockholders contained in the Underwriting Agreement and the certificates delivered to us by offi

6. Reliance and Benefit This letter is furnished to the Underwriters solely for their benefit and solely in connection with the Offering and may not be used, circulated, quoted, referred to, or relied upon by any other person or entity, or for any other purpose, without our prior written consent in each instance. Without limiting the generality of the foregoing, this letter may not be furnished to, or relied upon by,

7. No Attorney-Client Relationship with Underwriters We wish to clarify that Calderwood & Harkness LLP has acted solely as counsel to the Company in connection with the Offering. We do not represent, and have not represented, any of the Underwriters, the Selling Stockholders, or any other party in connection with the Offering. The Underwriters are separately represented by Caldwell, Pearce & Strauss LLP as counsel fo