Contract analysis

I. Introduction Calderwood & Harkness LLP acts as counsel to Penterra Pharmaceuticals Corp., a Delaware corporation ("PPC" or the "Company"), in connection with the registered selling-stockholder secondary offering (the "Offering") of 6,250,000 shares of common stock, par value $0.001 per share (the "Shares"), of PPC. The Offering is being conducted pursuant to the Prospectus Supplement dated October 12, 2023 (the "P

II. Reference to Initial Comfort Letter We refer to the initial comfort letter dated October 2, 2023 (the "Initial Comfort Letter") delivered by Graystone & Whitmore to the Underwriters and the Company in connection with the filing of the preliminary prospectus supplement with the SEC on October 2, 2023. We understand that the Initial Comfort Letter was prepared and delivered in accordance with the standards set fort

III. Request for Bring-Down Comfort Letter Pursuant to Section 7(d) of the Underwriting Agreement, as a condition precedent to the obligations of the several Underwriters to consummate the purchase of the Shares at the closing of the Offering, we hereby request that Graystone & Whitmore deliver a bring-down comfort letter (the "Bring-Down Comfort Letter") dated as of October 17, 2023, the scheduled closing date of th

IV. Scope and Content of the Bring-Down Comfort Letter We respectfully request that the Bring-Down Comfort Letter include the following elements, each of which is discussed in greater detail below. A. Reaffirmation of Initial Comfort Letter The Bring-Down Comfort Letter should reaffirm and update all statements, conclusions, and procedures set forth in the Initial Comfort Letter, with the date of the Bring-Down Comfo

V. Delivery Instructions We request that the Bring-Down Comfort Letter be executed and delivered on October 17, 2023, the Closing Date, prior to or simultaneously with the closing of the Offering. The closing is currently expected to take place at the offices of Caldwell, Pearce & Strauss LLP, 1251 Avenue of the Americas, 40th Floor, New York, New York 10020, at 10:00 a.m. Eastern Time on October 17, 2023, or at such

VI. Over-Allotment Option Provision We wish to bring to your attention that the Underwriting Agreement grants the Underwriters a 30-day option, exercisable in whole or in part, to purchase up to an additional 937,500 shares of common stock from the Selling Stockholders to cover over-allotments, if any (the "Over-Allotment Option"). The Over-Allotment Option expires on November 11, 2023. In the event that the Over-All

VII. Cooperation of the Company The Company has advised us that it will cooperate fully with Graystone & Whitmore in connection with the preparation and delivery of the Bring-Down Comfort Letter and will make available such books, records, financial information, and personnel of the Company as may be reasonably necessary to enable Graystone & Whitmore to complete the procedures described herein and to deliver the Bri

VIII. Closing We appreciate Graystone & Whitmore's prompt attention to this request, particularly in light of the approaching Closing Date of October 17, 2023, and the importance of the timely delivery of the Bring-Down Comfort Letter as a condition to the closing of the Offering. We recognize the time constraints involved and are prepared to work cooperatively with your team to facilitate the completion of the neces