Contract analysis

ARTICLE I — APPOINTMENT OF ATTORNEY-IN-FACT

Section 1.1 — Appointment Each Selling Stockholder hereby irrevocably constitutes and appoints David Orenstein, General Counsel & Corporate Secretary of Penterra Pharmaceuticals Corp., as such Selling Stockholder's true and lawful attorney-in-fact (the "Attorney-in-Fact"), with full power of substitution and resubstitution, to act in such Selling Stockholder's name, place, and stead in connection with and for the pur

Section 1.2 — Powers Granted Each Selling Stockholder hereby grants to the Attorney-in-Fact full power and authority to do and perform, on behalf of and in the name of such Selling Stockholder, each and every act and thing necessary, appropriate, or desirable to consummate the Offering and the transactions contemplated by the Underwriting Agreement, including, without limitation, the power and authority to: (a) execu

Section 1.3 — Scope and Limitation Notwithstanding the broad powers granted in Section 1.2, the authority of the Attorney-in-Fact is subject to the following express limitations: (a) The Attorney-in-Fact shall act solely in connection with the Offering and shall not have authority to bind, commit, or obligate any Selling Stockholder with respect to any matter unrelated to the Offering, the Underwriting Agreement, or

Section 1.4 — Ratification Each Selling Stockholder hereby ratifies and confirms, and agrees to ratify and confirm, all acts and things that the Attorney-in-Fact may lawfully do or cause to be done by virtue of this power of attorney. Each Selling Stockholder acknowledges that third parties dealing with the Attorney-in-Fact are entitled to rely on this power of attorney as conferring the authority set forth herein wi

ARTICLE II — APPOINTMENT OF CUSTODIAN

Section 2.1 — Appointment of Custodian Each Selling Stockholder hereby appoints Pinnacle Trust & Transfer Co. as custodian (the "Custodian") of the Shares to be sold by such Selling Stockholder in the Offering. The Custodian hereby accepts such appointment on the terms and conditions set forth in this Agreement. The Custodian shall hold the Shares (in book-entry form through DTC or its nominee, Cede & Co.) for the ac

Section 2.2 — Delivery of Shares to Custodian Each Selling Stockholder shall cause such Selling Stockholder's respective Shares (being the number of Base Shares set forth opposite such Selling Stockholder's name in the table above and, to the extent the Over-Allotment Option is exercised, the applicable number of Option Shares) to be delivered or made available in book-entry form to the Custodian through DTC no later

Section 2.3 — Custodian's Duties The Custodian shall perform the following duties in connection with the Offering: (a) Delivery of Base Shares. Upon receipt of written instructions from the Attorney-in-Fact (or upon receipt of instructions delivered in accordance with the Underwriting Agreement and the direction letter to the transfer agent in the form attached hereto as Exhibit B), the Custodian shall deliver the Ba

Section 2.4 — Disbursement of Net Proceeds The net proceeds per share payable to the Selling Stockholders shall be $40.56 (being the public offering price of $41.60 per share less the underwriting discount of $1.04 per share). The aggregate net proceeds from the sale of the Base Shares shall total $253,500,000, to be allocated and disbursed to the Selling Stockholders as follows: In the event the Over-Allotment Optio

Section 2.5 — Custodian Compensation and Expenses The Custodian shall be entitled to reasonable compensation for its services hereunder in accordance with its standard fee schedule as in effect from time to time, a copy of which has been provided to the Selling Stockholders. Such compensation shall be borne by the Selling Stockholders, allocated among them in proportion to their respective Base Shares sold in the Off

Section 2.6 — Standard of Care; Limitation of Liability The Custodian shall exercise reasonable care in the custody, safekeeping, and delivery of the Shares and in the receipt and disbursement of the net proceeds, applying the same degree of care as it would exercise with respect to its own property of a similar nature. The Custodian shall not be liable for any action taken or omitted to be taken in good faith in the

ARTICLE III — REPRESENTATIONS AND WARRANTIES OF SELLING STOCKHOLDERS Each Selling Stockholder, severally and not jointly, hereby represents and warrants to the Attorney-in-Fact and the Custodian as of the date hereof and as of the Closing Date (and, if applicable, as of the Over-Allotment Closing Date) as follows:

Section 3.1 — Ownership Each Selling Stockholder is the sole beneficial and record owner of the number of shares of Common Stock of PPC set forth opposite such Selling Stockholder's name in the table set forth above under the heading "Pre-Offering Shares Held," free and clear of all liens, pledges, charges, security interests, encumbrances, equities, options, preemptive rights, rights of first refusal, claims, restri

Section 3.2 — Authority Each individual Selling Stockholder has full legal capacity and all requisite right, power, and authority to execute and deliver this Agreement, to sell, transfer, and deliver the Shares in the Offering, and to perform all of such Selling Stockholder's obligations hereunder and under the Underwriting Agreement. CFH LLC has been duly formed and is validly existing and in good standing as a limi

Section 3.3 — No Conflicts The execution and delivery of this Agreement by each Selling Stockholder, the sale and delivery of the Shares by each Selling Stockholder in the Offering, and the consummation of the transactions contemplated hereby and by the Underwriting Agreement do not and will not (a) conflict with, result in a breach or violation of, or constitute a default (or an event that with notice or lapse of ti

Section 3.4 — Lock-Up Waiver Each Selling Stockholder acknowledges that the shares of Common Stock held by such Selling Stockholder were subject to lock-up agreements (the "IPO Lock-Up Agreements") entered into in connection with the initial public offering of the Common Stock on April 17, 2023, pursuant to which each Selling Stockholder agreed not to offer, sell, contract to sell, pledge, grant any option to purchas

Section 3.5 — New Lock-Up Each Selling Stockholder acknowledges and agrees that, in connection with the Offering, such Selling Stockholder will enter into, or has concurrently herewith entered into, a new lock-up agreement (the "New Lock-Up Agreement") with Ridgeline Securities LLC and Broadmark Capital Inc., as representatives of the Underwriters, restricting the offer, sale, contract to sell, pledge, grant of any o

Section 3.6 — Accuracy of Information Each Selling Stockholder represents and warrants that all information furnished or to be furnished by such Selling Stockholder (or on such Selling Stockholder's behalf) expressly for inclusion or incorporation by reference in the Registration Statement, the Prospectus Supplement, any free writing prospectus, or any other offering document relating to the Offering is true, correct

ARTICLE IV — REPRESENTATIONS AND WARRANTIES OF ATTORNEY-IN-FACT

Section 4.1 — Acceptance David Orenstein hereby accepts his appointment as Attorney-in-Fact under this Agreement and agrees to act in accordance with the terms and conditions of this Agreement and to exercise the powers granted herein solely for the purposes and within the limitations set forth herein. The Attorney-in-Fact acknowledges that he has read and understands the terms of this Agreement and the Underwriting

Section 4.2 — Fiduciary Duty The Attorney-in-Fact shall act in good faith and in the best interests of the Selling Stockholders in carrying out his duties and exercising the powers granted to him under this Agreement. The Attorney-in-Fact shall exercise the degree of care, diligence, and skill that a reasonably prudent person would exercise in comparable circumstances. The Attorney-in-Fact shall promptly communicate

Section 4.3 — No Personal Liability The Attorney-in-Fact shall not be personally liable for any loss, damage, liability, cost, or expense suffered or incurred by any Selling Stockholder as a result of any action taken or omitted to be taken in good faith in the performance of his duties hereunder, except to the extent that such loss, damage, liability, cost, or expense directly results from the Attorney-in-Fact's own

Section 5.1 — Indemnification of Attorney-in-Fact Each Selling Stockholder, severally and not jointly (in proportion to such Selling Stockholder's respective Base Shares as a percentage of the total Base Shares), agrees to indemnify, defend, and hold harmless the Attorney-in-Fact from and against any and all losses, claims, damages, liabilities, costs, and expenses (including, without limitation, reasonable attorneys

Section 5.2 — Indemnification of Custodian Each Selling Stockholder, severally and not jointly (in proportion to such Selling Stockholder's respective Base Shares as a percentage of the total Base Shares), agrees to indemnify, defend, and hold harmless the Custodian and its officers, directors, employees, and agents from and against any and all Losses arising out of, relating to, or resulting from the Custodian's per

ARTICLE VI — TERM AND TERMINATION

Section 6.1 — Effective Date This Agreement shall become effective immediately upon execution and delivery by all parties hereto on October 12, 2023.

Section 6.2 — Termination This Agreement shall terminate automatically, without any action required on the part of any party, upon the latest to occur of: (a) the completion of the Closing, including the delivery of all Base Shares to the Underwriters and the receipt and full disbursement of all net proceeds to the Selling Stockholders in accordance with Section 2.4; (b) the expiration of the Over-Allotment Option (N

Section 6.3 — Revocability This power of attorney and custody agreement is irrevocable during its term. No Selling Stockholder may revoke, rescind, or terminate this Agreement, or any of the powers granted herein, without the prior written consent of the Underwriters (acting through Ridgeline Securities LLC as representative of the Underwriters). Any attempted revocation in violation of this Section 6.3 shall be null

Section 7.1 — Governing Law This Agreement shall be governed by, and construed and enforced in accordance with, the laws of the State of Delaware, without regard to principles of conflicts of law that would require the application of the laws of any other jurisdiction. Each party hereby irrevocably submits to the exclusive jurisdiction of the courts of the State of Delaware and the United States District Court for th

Section 7.2 — Notices All notices, requests, demands, consents, waivers, and other communications required or permitted to be given under this Agreement shall be in writing and shall be deemed to have been duly given when (a) delivered personally, (b) sent by registered or certified mail, return receipt requested, postage prepaid, (c) sent by nationally recognized overnight courier service, or (d) transmitted by elec

Section 7.3 — Successors and Assigns This Agreement shall be binding upon and shall inure to the benefit of the parties hereto and their respective successors, heirs, executors, administrators, legal representatives, and permitted assigns. No party may assign any of its rights or delegate any of its obligations under this Agreement without the prior written consent of the other parties hereto, and any attempted assig

Section 7.4 — Entire Agreement This Agreement, together with the Underwriting Agreement, the New Lock-Up Agreements, and the other documents and instruments executed and delivered in connection with the Offering, constitutes the entire agreement among the parties with respect to the subject matter hereof and supersedes all prior and contemporaneous agreements, understandings, negotiations, representations, and warran

Section 7.5 — Amendments and Waivers This Agreement may not be amended, modified, supplemented, or waived except by a written instrument duly executed by all parties hereto. No waiver of any provision of this Agreement shall operate as a waiver of any other provision, and no single or partial exercise of any right or remedy under this Agreement shall preclude any other or further exercise of such right or remedy or t

Section 7.6 — Counterparts This Agreement may be executed in one or more counterparts, each of which shall be deemed an original and all of which, when taken together, shall constitute one and the same instrument. Signatures delivered by facsimile transmission or by electronic transmission in portable document format (PDF) or other electronic imaging means shall be deemed to be original signatures for all purposes an

Section 7.7 — Severability If any provision of this Agreement is held to be invalid, illegal, or unenforceable by any court of competent jurisdiction, such invalidity, illegality, or unenforceability shall not affect any other provision of this Agreement, and this Agreement shall be construed as if such invalid, illegal, or unenforceable provision had never been contained herein, provided that the remaining provision

Section 7.8 — Headings The article and section headings contained in this Agreement are inserted for convenience of reference only and shall not in any way affect the meaning, construction, or interpretation of this Agreement. [Signature Pages Follow] SIGNATURE PAGES TO POWER OF ATTORNEY AND CUSTODY AGREEMENT IN WITNESS WHEREOF, the undersigned have duly executed this Power of Attorney and Custody Agreement as of the

1. Dr. Elena Castellano Bank Name: [To be provided separately] ABA/Routing Number: [To be provided separately] Account Number: [To be provided separately] Account Name: [To be provided separately] Reference: Penterra Pharmaceuticals Corp. — Secondary Offering Proceeds Contact: [To be provided separately]

2. Dr. Riccardo Castellano Bank Name: [To be provided separately] ABA/Routing Number: [To be provided separately] Account Number: [To be provided separately] Account Name: [To be provided separately] Reference: Penterra Pharmaceuticals Corp. — Secondary Offering Proceeds Contact: [To be provided separately]

3. Dr. Marco Castellano Bank Name: [To be provided separately] ABA/Routing Number: [To be provided separately] Account Number: [To be provided separately] Account Name: [To be provided separately] Reference: Penterra Pharmaceuticals Corp. — Secondary Offering Proceeds Contact: [To be provided separately]

4. Castellano Family Holdings LLC Bank Name: [To be provided separately] ABA/Routing Number: [To be provided separately] Account Number: [To be provided separately] Account Name: [To be provided separately] Reference: Penterra Pharmaceuticals Corp. — Secondary Offering Proceeds Contact: [To be provided separately] Note: Each Selling Stockholder shall provide complete wire transfer instructions to the Custodian no lat

1. Delivery of Base Shares. Please deliver, on October 17, 2023 (the Closing Date), through the facilities of The Depository Trust Company ("DTC"), the following number of shares of common stock of Penterra Pharmaceuticals Corp. (CUSIP: 70831X 10 5) to or for the accounts of the several Underwriters, against payment of the aggregate net purchase price in immediately available funds: DTC delivery instructions for the

2. Delivery of Option Shares (If Applicable). [To be completed upon exercise of the Over-Allotment Option, if applicable.] If the Over-Allotment Option is exercised by the Underwriters, in whole or in part, on or before November 11, 2023, please deliver, on the Over-Allotment Closing Date (expected to be on or about November 16, 2023), through the facilities of DTC, the following number of Option Shares (CUSIP: 70831

3. Disbursement of Net Proceeds. Upon receipt of the aggregate net purchase price from the Underwriters, please disburse the net proceeds to each Selling Stockholder by wire transfer of immediately available funds in accordance with the wire transfer instructions on file with you as provided in Exhibit A to the POA/Custody Agreement. The net proceeds per share are $40.56 (being the public offering price of $41.60 per

4. Confirmation. Please provide written confirmation to the undersigned upon (a) completion of the delivery of the Base Shares (and, if applicable, the Option Shares) through DTC and (b) completion of the wire transfers of net proceeds to each Selling Stockholder. If you have any questions regarding this direction letter, please contact the undersigned at the offices of Penterra Pharmaceuticals Corp. at 400 Meridian