Contract analysis

1. Beneficial ownership is determined in accordance with Rule 13d-3 under the Securities Exchange Act of 1934, as amended. The number of shares beneficially owned by each Selling Stockholder includes shares held directly by such Selling Stockholder and shares over which such Selling Stockholder has sole or shared voting or dispositive power, but does not include any shares issuable upon the exercise of stock options

2. Dr. Marco Castellano serves as the Manager of Castellano Family Holdings LLC. The shares listed as beneficially owned by Dr. Marco Castellano in the table above do not include the shares beneficially owned by Castellano Family Holdings LLC. Dr. Marco Castellano disclaims beneficial ownership of the shares held by Castellano Family Holdings LLC, except to the extent of his pecuniary interest therein.

3. In the event the over-allotment option is not exercised or is exercised only in part, the number of shares owned post-offering by each Selling Stockholder will be greater than the amounts shown in the "Shares Owned Post-Offering (Full Exercise)" column by the number of Option Shares not sold by such Selling Stockholder.

4. The allocation of Option Shares among the Selling Stockholders shall be determined in accordance with Section 2(b) of the Underwriting Agreement, which provides for allocation on a pro rata basis based on each Selling Stockholder's proportion of the total Option Shares, unless otherwise agreed by the Selling Stockholders and the Representative.

5. Each of the Selling Stockholders listed above has entered into a lock-up agreement with the Representative, dated as of October 12, 2023, restricting the sale or other disposition of shares of Common Stock for a period of 90 days following the date of the Prospectus, subject to certain customary exceptions as set forth in such lock-up agreement. CERTIFICATION OF COMPILATION CALDERWOOD & HARKNESS LLP One Liberty Pl

1. The foregoing pages constitute true and complete copies of all executed signature pages to the Underwriting Agreement dated as of October 12, 2023 (the "Underwriting Agreement"), among Penterra Pharmaceuticals Corp., a Delaware corporation, the Selling Stockholders named therein, and the several Underwriters named in Schedule I thereto, for which Ridgeline Securities LLC acts as the Representative of the several U

2. The Underwriting Agreement governs the offering of 6,250,000 shares of common stock, par value $0.001 per share (the "Shares"), of Penterra Pharmaceuticals Corp. at a public offering price of $41.60 per share, for an aggregate base offering size of $260,000,000. The Selling Stockholders have also granted the Underwriters an over-allotment option to purchase up to an additional 937,500 shares of common stock.

3. Each executed signature page set forth herein was received by Calderwood & Harkness LLP on or before October 12, 2023, and each such signature page bears the genuine signature of the individual or authorized signatory identified thereon.

4. The trade date for the offering is October 12, 2023. The settlement date for the offering is October 17, 2023 (T+3), with delivery of the Shares against payment in immediately available funds through the facilities of The Depository Trust Company.

5. The Underwriting Agreement is governed by, and shall be construed in accordance with, the laws of the State of Delaware, without regard to conflicts of law principles thereof that would result in the application of the law of any other jurisdiction.

6. This certification is furnished in connection with the closing of the offering and is not intended to, and does not, constitute a legal opinion of Calderwood & Harkness LLP with respect to any matter. Compiled and certified by: /s/ Brendan Walsh ________________________________________ Brendan Walsh, Partner Calderwood & Harkness LLP One Liberty Plaza, 52nd Floor New York, NY 10006 Date of Compilation: October 12,