Arthur O. Tzianabos, Ph.D.
About Arthur O. Tzianabos, Ph.D.
Arthur O. Tzianabos, Ph.D. (age 62) is Interim Executive Chair of Stoke Therapeutics’ Board (since March 2025), having previously served as Board Chair (since September 2024) and as a director since September 2018. He is CEO of Lifordi Immunotherapeutics (since June 2023), a Venture Partner at 5AM Ventures (since September 2022), and previously served as President & CEO of Homology Medicines (2016–2022), with earlier senior roles at Shire and on the Harvard Medical School faculty; he holds a B.S. from Boston College and a Ph.D. in Microbiology from the University of New Hampshire .
Past Roles
| Organization | Role | Tenure | Committees/Impact |
|---|---|---|---|
| Homology Medicines, Inc. (now part of Q32 Bio) | President & CEO | Apr 2016 – Sep 2022 | Led company from inception through IPO; focused on genetic medicines . |
| OvaScience, Inc. | President & Chief Scientific Officer | Sep 2013 – Mar 2016 | Senior R&D leadership at biotech developer . |
| Shire Plc | Senior management roles | Prior to 2013 | Development and launches of rare disease treatments; BD pipeline building . |
| Harvard Medical School | Faculty (associate professor) | ~15 years | Published 80+ scientific works; labs at Brigham & Women’s and HMS Microbiology . |
| Akouos, Inc. | Director (prior) | n/a | Former public company directorship (acquired by Lilly in 2022) . |
External Roles
| Organization | Role | Tenure | Notes |
|---|---|---|---|
| Lifordi Immunotherapeutics | Chief Executive Officer | Since Jun 2023 | Biopharma CEO role concurrent with STOK Board service . |
| 5AM Ventures | Venture Partner | Since Sep 2022 | Life sciences investing responsibilities . |
| Q32 Bio Inc. (formerly Homology Medicines, Inc.) | Director | Current | Public company directorship; post-merger position . |
| Univ. of New Hampshire – College of Life Sciences & Agriculture | Development Board member | Current | Academic board role . |
Board Governance
- Role and independence: Interim Executive Chair (executive role); Board determined six of nine directors are independent, and Dr. Tzianabos is not listed among them (i.e., not independent in current role) .
- Committee assignments (current): Not listed on Audit, Compensation, or Nominating & Corporate Governance committees in 2025 .
- Committee history: Served on Audit Committee until March 2025 (stepped off when named Interim Executive Chair); also previously chaired the Compensation Committee until September 2024 (succeeded by Julie Anne Smith) .
- Board leadership structure: CEO and Executive Chair roles are separated (Interim CEO Ian F. Smith; Interim Executive Chair Dr. Tzianabos) .
- Attendance: In 2024, each director attended at least 75% of the Board and applicable committee meetings .
- 2025 director election result (Class III): Votes for/withheld — Tzianabos: 29,241,848 For; 4,203,288 Withheld; broker non-votes 5,350,616 .
Fixed Compensation
Director compensation (2024 actual as a non-employee director; ceased when appointed Interim Executive Chair in March 2025):
| Year | Fees Earned (Cash) | Option Awards (ASC 718 FV) | Total |
|---|---|---|---|
| 2024 | $64,701 | $85,946 | $150,647 |
2025 Non-Employee Director Compensation Policy (market-aligned; not to exceed 65th percentile; directors can elect to take the Board retainer in RSUs vesting quarterly):
- Cash retainers: Board member $40,000; Non-Executive Chair $35,000; Committee chairs — Audit $20,000; Compensation $15,000; Nominating & Corporate Governance $10,000; Committee members — Audit $10,000; Compensation $7,500; Nominating & Corporate Governance $5,000 .
- Equity: New director initial option grant target FV ~$448,000 (12 quarterly vesting); annual option target FV ~$224,000 (one-year vest); strike set at closing price on grant date .
Performance Compensation
| Award Type | Metric(s) | Weight | Vesting / Terms | Notes |
|---|---|---|---|---|
| Non-employee director annual option (2024) | None (time-based) | n/a | Vests on 1-year anniversary (or next annual meeting) | ASC 718 FV $85,946 (grant post-June 5, 2024) . |
| Interim Executive Chair option (2025) | None (time-based) | n/a | 122,651 options vest monthly over 12 months; strike = closing price on grant date | Granted March 2025 per Interim Executive Chair Agreement . |
| New director initial option (policy) | None (time-based) | n/a | 12 equal quarterly installments | Target FV (2025): ~$448,000 . |
No performance metrics are tied to director pay; equity is time-based. Company-wide clawback policy (adopted Sept 2023) applies to incentive-based compensation in the event of a restatement, per SEC Rule 10D-1/Nasdaq .
Other Directorships & Interlocks
| Company | Role | Public/Private | Potential Interlock/Conflict |
|---|---|---|---|
| Q32 Bio Inc. | Director | Public | None disclosed with Stoke in related-party section . |
| Akouos, Inc. (prior) | Director | Public (acquired) | Historical only; no current overlap . |
| Lifordi Immunotherapeutics | CEO | Private | No Stoke transactions disclosed . |
| 5AM Ventures | Venture Partner | Private VC | No Stoke transactions disclosed; related-party policy requires AC approval >$120k . |
Expertise & Qualifications
- Deep biotech operating experience (CEO roles at Homology and Lifordi; senior roles at Shire); extensive board governance in therapeutics/rare diseases .
- Scientific credentials and network (Harvard Medical School faculty; 80+ publications/patents) .
- Capital markets/strategic execution (led Homology through IPO; prior Chair of public biotech Akouos pre-acquisition) .
Equity Ownership
| As of | Common Shares Owned | Options Exercisable Within 60 Days | Total Beneficial Ownership | Ownership % |
|---|---|---|---|---|
| Mar 31, 2025 | 31,739 | 102,086 | 133,825 | <1% (asterisked in proxy) |
Additional reference points:
- Options outstanding as of Dec 31, 2024 (director table): 89,284 .
- Company policy prohibits hedging; pledging is prohibited absent Compliance Officer approval .
- No related-party transactions >$120,000 disclosed for directors/officers and >5% holders since Jan 1, 2024 .
Governance Assessment
-
Strengths
- Separation of Interim CEO and Interim Executive Chair roles; Board majority independent; independent directors meet in executive session .
- Compensation Committee uses independent consultant (Aon); committee determined no consultant conflicts; director pay targeted ≤65th percentile peer group, suggesting pay restraint .
- Robust policies: anti-hedging/anti-pledging and Dodd-Frank/Rule 10D-1-compliant clawback adopted in Sept 2023 .
- Strong shareholder support in 2025: Say-on-Pay passed 30,543,514 For vs 2,882,907 Against; shareholders preferred annual Say-on-Pay frequency (33,069,622 “one year”) .
- 2025 election support for Dr. Tzianabos (29,241,848 For vs 4,203,288 Withheld) indicates market confidence through the leadership transition .
-
Watch items / potential risks
- Independence: Serving as Interim Executive Chair renders him non-independent; he appropriately stepped off Audit and Compensation Committees upon appointment (good practice) but independence classification remains until he returns to a non-executive status .
- External roles: Concurrent CEO role at Lifordi and VC role at 5AM Ventures warrant ongoing monitoring for potential conflicts; the company discloses none to date and has a formal related-party approval policy .
- Director equity intensity increased under 2025 policy (annual option target FV ~$224,000; initial ~$448,000); while peer-aligned, higher option use increases dilution sensitivity; however, structure includes time-based vesting and shareholder-aligned upside .
Director-Related Voting and Engagement Signals
| Item | 2025 Outcome |
|---|---|
| Election (Class III) – Tzianabos | 29,241,848 For; 4,203,288 Withheld; 5,350,616 broker non-votes |
| Auditor Ratification (KPMG LLP) | 38,678,091 For; 67,754 Against; 49,907 Abstain |
| Say-on-Pay (Advisory) | 30,543,514 For; 2,882,907 Against; 18,715 Abstain; 5,350,616 broker non-votes |
| Say-on-Pay Frequency | “One year” received 33,069,622 votes |
Policies Relevant to Alignment and Risk
- Insider Trading Policy: prohibits hedging transactions and pledging (unless approved) .
- Clawback Policy: adopted Sept 2023; covers incentive-based compensation for the 3 fiscal years preceding any required restatement; administered by the Compensation Committee .
- Related-Party Transactions Policy: Audit Committee must approve any related-person transaction >$120,000; none disclosed since Jan 1, 2024 .
No director-specific stock ownership guidelines were disclosed in the 2025 proxy. Director attendance (2024) was ≥75% for all directors, indicating engagement .