Aoife Brennan
About Aoife Brennan
Aoife Brennan, M.D. (age 49) has served as an independent director of Xilio Therapeutics since June 2024; she is a physician–executive with 16+ years of drug development leadership. She is currently CEO, President and director of Climb Bio, Inc. (formerly Eliem Therapeutics, Inc.) since June 2024; previously CEO, President and director of Synlogic, Inc. (Oct 2018–Mar 2024), and earlier its Chief Medical Officer (Sep 2016–Oct 2018). Dr. Brennan trained in internal medicine and endocrinology/metabolism at the Royal College of Physicians in Ireland, completed post-doctoral training at Beth Israel Deaconess Medical Center, and is a graduate of the Harvard Medical School Scholars in Clinical Science Program; her medical degree is from Trinity College Dublin .
Past Roles
| Organization | Role | Tenure | Committees/Impact |
|---|---|---|---|
| Synlogic, Inc. | CEO, President, Director | Oct 2018–Mar 2024 | Led clinical strategy and corporate development |
| Synlogic, Inc. | Chief Medical Officer | Sep 2016–Oct 2018 | Built clinical programs |
| Biogen Inc. | VP & Head, Rare Disease Innovation Unit | Prior to joining Synlogic (dates not disclosed) | Led R&D across preclinical to commercial-stage rare disease portfolio |
External Roles
| Organization | Role | Tenure | Committees/Impact |
|---|---|---|---|
| Climb Bio, Inc. (public; formerly Eliem Therapeutics) | CEO, President, Director | Since Jun 2024 | Executive leadership; board role |
| FibroGen, Inc. (public) | Director | Current (dates not disclosed) | Not disclosed |
| Cerevance, LLC (private) | Director | Current (dates not disclosed) | Not disclosed |
| RA Pharmaceuticals, Inc. (public) | Director | Sep 2018–Apr 2020 | Not disclosed |
Board Governance
- Independence: The board determined in March 2025 that all directors except the CEO are independent under Nasdaq rules; all Audit and Compensation Committee members meet Exchange Act independence criteria. Dr. Brennan is independent and serves on the Audit Committee .
- Committee memberships: Audit Committee member; the Audit Committee comprises Sara M. Bonstein (Chair), Aoife Brennan, M.D., and Christina Rossi; it met five times during 2024 .
- Board structure: As of April 15, 2025, Brennan is a Class III director (age 49); Audit Committee membership is indicated for her .
- Attendance: The full board met seven times in 2024; each director attended at least 75% of board and applicable committee meetings. Six of eight directors attended the 2024 annual meeting .
Fixed Compensation
| Component | 2024 Amount | 2025 Policy (effective Apr 14, 2025) | Notes |
|---|---|---|---|
| Cash retainer (Director) | $23,352 | $40,000 annual (Chair: $70,000) | Paid quarterly; prorated for partial service |
| Committee fees – Audit (member) | Included in cash above (specific 2024 allocation not disclosed) | $7,500 annual (Chair: $15,000) | Paid quarterly |
| Committee fees – Compensation (member) | N/A | $5,000 annual (Chair: $10,000) | |
| Committee fees – Nominating/Governance (member) | N/A | $4,000 annual (Chair: $8,000) |
Performance Compensation
| Equity Element | Grant Size | Grant Date / Basis | Vesting | Exercise/Term | Notes |
|---|---|---|---|---|---|
| Option awards (2024) | $40,155 fair value | Options granted in 2024 per director program | Not disclosed for Brennan’s 2024 grant | Not disclosed for Brennan’s 2024 grant | Aggregate director option holdings shown below |
| Initial director option grant (policy) | 62,000 shares | Upon initial election (effective policy Apr 14, 2025) | 1/3 annually on grant date for 3 years, subject to service | Exercise price = Nasdaq closing price at grant; 10-year term | Accelerates 100% upon death, disability, or change in control |
| Annual director option grant (policy) | 31,000 shares | First board meeting after each annual meeting (continuing directors ≥6 months) | Full vest by first anniversary or immediately prior to next annual meeting | Exercise price = Nasdaq closing price; 10-year term | Accelerates on death, disability, or change in control |
Design features: Non-employee directors are excluded from the 2025 employee stock option repricing and 2025 Plan; clawback applies to options under certain plans, and insider trading policy prohibits hedging and pledging by directors .
Other Directorships & Interlocks
| Company | Industry | Overlap/Interlock Considerations |
|---|---|---|
| Climb Bio, Inc. | Biopharma | Brennan is CEO and director; monitor for competitive/transactional overlaps with Xilio; no related-party transactions disclosed involving Brennan in proxy sections reviewed |
| FibroGen, Inc. | Biopharma | Public board service; potential industry network effects; no RPT involving Brennan disclosed |
| Cerevance, LLC | Biopharma (private) | Private board service; no RPT involving Brennan disclosed |
| RA Pharmaceuticals, Inc. | Biopharma | Prior public board (2018–2020); historical experience |
Expertise & Qualifications
- Clinical and development leadership across preclinical-to-commercial programs in rare diseases (Biogen) and synthetic biology therapeutics (Synlogic) .
- Physician training in internal medicine and endocrinology/metabolism; advanced clinical research training (Harvard Scholars in Clinical Science) .
- Current biopharma CEO experience (Climb Bio), adding operational and strategic perspective to Xilio’s audit and risk oversight .
Equity Ownership
| Metric | Mar 31, 2025 | Oct 1, 2025 |
|---|---|---|
| Shares owned (common) | — | — |
| Right to acquire within 60 days (options/warrants) | — | 16,666 |
| Total shares owned plus right to acquire | — | 16,666 |
| Beneficial ownership % | * (less than 1%) | * (less than 1%) |
| Director Option Holdings (Aggregate, as of Dec 31, 2024) | Options Outstanding |
|---|---|
| Aoife Brennan, M.D. | 50,000 |
- Anti-hedging and pledging: Company policy prohibits directors from hedging or pledging company securities, including short sales, derivatives, margin accounts, or collateral pledges .
- Ownership guidelines: The proxy discloses no formal equity ownership guidelines for executives; director ownership guidelines are not disclosed in the materials reviewed .
Governance Assessment
- Board effectiveness: Brennan brings clinical development depth and current CEO perspective; as an Audit Committee member, she contributes to financial oversight, internal controls, compliance, and cybersecurity risk discussions; the audit committee met five times in 2024 and issued its report recommending inclusion of audited financials in the 2024 Form 10-K .
- Independence and engagement: Confirmed independent under Nasdaq and Exchange Act rules; 2024 attendance thresholds met; directors expected to attend annual meetings .
- Compensation alignment: Director pay is modest with cash retainer plus options; clear vesting, 10-year terms, market-priced exercise, and acceleration only upon death/disability/change-in-control; non-employee directors excluded from 2025 employee option repricing and 2025 Plan—reducing perceived pay self-dealing risk .
- Equity alignment: Brennan’s beneficial ownership is less than 1% with limited near-term exercisability (16,666 options within 60 days as of Oct 1, 2025), though total outstanding director options for her were 50,000 at year-end 2024; alignment is moderate and typical for small-cap biotech boards .
- Related-party and conflicts: The company maintains a formal related person transaction policy under audit committee oversight; the DEF 14A related-party sections reviewed do not identify transactions involving Dr. Brennan. Nonetheless, given her active roles at Climb Bio and FibroGen, monitoring for any competitive or transactional overlaps is prudent .
RED FLAGS
- Low direct ownership: Beneficial ownership <1% and limited near-term exercisable options may temper perceived “skin in the game” .
- Multiple external commitments: Concurrent CEO role (Climb Bio) and public board service (FibroGen) could pose time/attention constraints or potential industry interlocks; no related-party transactions disclosed, but ongoing monitoring warranted .