Contract analysis

I. Purpose and Executive Summary This memorandum summarizes the results of Calderwood & Harkness LLP’s review and analysis of the completed Director Independence Questionnaires submitted by the three members of the Special Committee of Penterra Pharmaceuticals Corp. (“Penterra” or the “Company”) (NYSE: PPHR): Diane Prescott, James Okafor, and Dr. Helen Ng. As the Committee is aware, the Special Committee was establis

II. Background A. The Proposed Transaction Penterra Pharmaceuticals Corp. is a Delaware corporation headquartered at 400 Innovation Drive, Suite 1200, Princeton, New Jersey 08540. The Company is evaluating a proposed acquisition of 100% of the outstanding equity interests of Caliston BioSciences, Inc., a Delaware corporation with its principal office at 88 Harbor Point Road, Cambridge, Massachusetts 02142. Based on t

1. NYSE Listed Company Manual Section 303A, including both the bright-line disqualification tests and the broader board determination of absence of material relationships;

2. Delaware common law standards of independence and disinterestedness applicable to interested-director transactions, including principles reflected in Aronson v. Lewis, Rales v. Blasband, and the MFW line of cases; and

3. SEC Rule 10A-3 audit committee independence concepts, which, while not directly controlling for this purpose, provide a useful analogous framework for identifying compensatory and affiliative relationships that could impair independent judgment. Following receipt of the completed questionnaires, we conducted supplemental inquiries by telephone with each of the three directors on June 4 and June 5, 2023. Those call

III. Applicable Independence Standards A. NYSE Listing Standards

Section 303A.02 of the NYSE Listed Company Manual provides that a director is “independent” only if the board affirmatively determines that the director has no material relationship with the listed company, either directly or as a partner, shareholder, or officer of an organization that has a relationship with the company. This standard combines bright-line disqualifications with a broader facts-and-circumstances inq

1. A director who is, or has been within the prior three years, an employee of the listed company is not independent.

2. A director who has received, or whose immediate family member has received, during any twelve-month period within the prior three years, more than $120,000 in direct compensation from the listed company, other than director and committee fees and certain forms of deferred compensation, is not independent.

3. A director who is affiliated with or employed by the company’s internal or external auditor, or who has an immediate family member falling within the specified audit-firm categories, within the relevant three-year period is not independent. Penterra’s independent auditor is Harwick & Tolliver LLP.

4. A director is not independent if the director or an immediate family member is employed as an executive officer of another company where any present Penterra executive officer serves on that other company’s compensation committee, creating an interlocking compensation committee relationship.

5. A director is not independent if the director is a current employee, or an immediate family member is a current executive officer, of a company that has made payments to, or received payments from, Penterra for property or services in an amount which, in any of the prior three fiscal years, exceeds the greater of $1 million or 2% of that other company’s consolidated gross revenues. Penterra’s board previously dete

IV. Director-by-Director Independence Analysis A. Diane Prescott (Special Committee Chair)

1. Background and Qualifications Diane Prescott has served as an independent director of Penterra since 2016, giving her approximately seven years of service on the board as of the date of this memorandum. She is the former Chief Executive Officer of Windbridge Health Systems, Inc., from which she retired in 2014. Her prior executive experience appears to have been substantial, and her current professional activities

2. Relationships with Interested Parties With respect to Dr. Marcus Hale, Ms. Prescott reported that she has no familial, financial, or personal relationship with him beyond their shared board service at Penterra. She reported no prior professional relationship predating her Penterra board service, no history of co-investment with Dr. Hale, no joint participation in private investment vehicles, and no co-venture, cha

3. Compensation from Penterra Ms. Prescott receives standard non-employee director compensation from Penterra, consisting of a board retainer and committee fees, together with standard equity compensation in the form of restricted stock units. Based on the materials reviewed, the amount of her annual cash compensation is below $120,000 per year, excluding the equity component and ordinary board fees. She confirmed th

4. NYSE Bright-Line Tests Based on the information reviewed, Ms. Prescott satisfies each of the NYSE bright-line independence criteria. She is not, and has not within the prior three years been, employed by Penterra. She has not received direct compensation from Penterra in excess of the applicable threshold, other than standard board and committee fees and equity awards of the type expressly contemplated for non-emp

5. Delaware Law Analysis For Delaware-law purposes, Ms. Prescott appears both independent and disinterested. She does not have any direct or indirect financial interest in Caliston or in the proposed merger consideration. She will share in any impact of the transaction on Penterra stock solely in her capacity as a stockholder or holder of ordinary director equity awards, in the same general manner as other stockholde

1. Background and Qualifications James Okafor has served as an independent director of Penterra since 2019, representing approximately four years of board service. He is the retired managing director of Fielding Capital Partners, LLC, a private equity firm, from which he retired in 2018. His background includes healthcare and life sciences investing, which may be particularly valuable in evaluating a clinical-stage b

2. Relationships with Interested Parties Mr. Okafor reported no familial, financial, or personal relationship with Dr. Marcus Hale beyond their shared service on the Penterra board. He specifically confirmed that he has never co-invested with Dr. Hale in any venture, private placement, syndicate, or fund vehicle, and that he has no private business relationship with him. During supplemental inquiry, Mr. Okafor stated

3. Compensation from Penterra Mr. Okafor receives standard non-employee director compensation from Penterra. Based on the information reviewed, such compensation is below $120,000 annually, exclusive of ordinary board-related equity awards and fees. He reported no consulting agreement, strategic advisory retainer, transaction bonus, or other separate compensatory arrangement with Penterra. As with Ms. Prescott, there

4. NYSE Bright-Line Tests Based on the information available to us, Mr. Okafor satisfies the NYSE bright-line independence criteria. He is not currently employed by Penterra and has not been employed by Penterra within the prior three years. He has not received compensation from Penterra in excess of the applicable threshold, other than standard director compensation. He has no affiliation with Harwick & Tolliver LLP

5. Delaware Law Analysis Under Delaware-law principles, Mr. Okafor appears independent and disinterested. He has no direct or indirect financial interest in Caliston or in the transaction consideration, and there is no indication he will receive any non-ratable benefit from consummation of the merger. Like other Penterra stockholders, he may be affected by the transaction to the extent he holds Penterra shares or RSU

1. Background and Qualifications Dr. Helen Ng has served as an independent director of Penterra since 2020, approximately three years as of the date hereof. She is a professor of pharmacology at Wexford University and previously served on an FDA advisory committee, bringing relevant scientific and regulatory expertise to the Special Committee’s work. Based on the information provided, Dr. Ng’s career is principally a

2. Relationships with Interested Parties Dr. Ng reported no familial, financial, or personal relationship with Dr. Marcus Hale beyond ordinary board service at Penterra. She further noted that Dr. Hale holds an MD/PhD from Kellmore University, whereas she is affiliated with Wexford University; the institutions are distinct, and she reported no overlapping academic connection, alumni activity, faculty collaboration, o

3. Compensation from Penterra Dr. Ng receives standard non-employee director compensation from Penterra, below the $120,000 annual threshold referenced in the NYSE bright-line tests, excluding ordinary board fees and equity awards. She reported no consulting fees, advisory compensation, sponsored research support, or other compensatory arrangement with Penterra beyond ordinary director pay. Dr. Ng indicated that her

4. NYSE Bright-Line Tests Dr. Ng satisfies the NYSE bright-line criteria based on the information reviewed. She is not employed by Penterra and has not been employed by Penterra within the prior three years. She has not received direct compensation from Penterra above the applicable threshold other than ordinary director compensation. She has no affiliation with Harwick & Tolliver LLP and no identified immediate fami

5. Delaware Law Analysis For Delaware-law purposes, Dr. Ng is both independent and disinterested. She has no financial interest in Caliston, no involvement with CLT-4019, no consulting or advisory arrangement with either party, and no non-ratable benefit tied to the proposed acquisition. Her interest as a holder of ordinary Penterra equity received through director compensation does not distinguish her from stockhold

V. Additional Cross-Checks and Considerations A. Relationships with Transaction Advisors As an additional diligence measure, we reviewed whether any of the three directors has a material relationship with the principal advisors and institutions presently associated with the proposed transaction or likely to appear in the transaction process. Specifically, we confirmed the absence of material relationships between any

VI. Conclusion and Recommendation Based on the completed questionnaires, supplemental inquiries, and our independent review, we reach the following conclusions: • Diane Prescott: Independent and disinterested under NYSE listing standards and Delaware law. Qualified to serve as Chair of the Special Committee. • James Okafor: Independent and disinterested under NYSE listing standards and Delaware law. Qualified to serv

VII. Attachments The following materials accompany or are referenced by this memorandum and should be maintained in the Project Coriander files: • Attachment A: Completed Director Independence Questionnaire — Diane Prescott (dated June 4, 2023) • Attachment B: Completed Director Independence Questionnaire — James Okafor (dated June 4, 2023) • Attachment C: Completed Director Independence Questionnaire — Dr. Helen Ng