Pioneering Medicines: Senior​/Executive Director, Head of Toxicology

Senior /Executive Director, Head of Toxicology

Cambridge, MA USA

What if... We could harness the power of Flagship's scientific platforms and create novel treatment options that benefit more patients, sooner?

About Pioneering Medicines

Pioneering Medicines, Flagship Pioneering's in-house drug development unit, is dedicated to conceiving and developing a broad portfolio of life-changing treatments for patients built from Flagship's innovative platforms. Harnessing the drug development expertise of its team together with the power of Flagship's multiple scientific platforms, Pioneering Medicines explores and identifies new product concepts which are then advanced jointly with Flagship's bioplatform companies.

Within Flagship's Innovation Supply Chain partnerships, Pioneering Medicines works with external collaborators to apply its unique approach to partners' R&D priorities. These partnerships are highly co-creative strategic alliances that accelerate therapeutic innovation by bringing together partners spanning the full spectrum of drug discovery, development, and production.

Position Summary

The Senior Director, Head of Toxicology will lead and build the toxicology function within Pioneering Medicines, defining and executing nonclinical safety strategies across a diverse and rapidly evolving portfolio. This role provides scientific and strategic leadership across both investigative and regulatory toxicology, supporting a broad range of therapeutic modalities.

Working in a dynamic venture creation environment, you will collaborate closely with multidisciplinary teams to optimize candidate selection, guide preclinical development, and ensure regulatory readiness. This is a high-impact role requiring strong analytical thinking, scientific rigor, and clear communication, influencing programs from discovery through early clinical development.

This role can be onsite at our Cambridge, MA site. Or if you are over 30 miles away remote with travel 3-4 days per month.

Key Responsibilities

• Lead, build, and scale the toxicology function, including internal team development and external partnerships
• Define fit-for-purpose operating models spanning investigative and regulatory toxicology
• Serve as the primary internal expert for nonclinical safety, ensuring quality, consistency, and scalability across the portfolio
• Define and drive toxicology strategies across multiple programs and modalities
• Translate findings into clear risk assessments, mitigation strategies, and IND/CTA-enabling plans
• Enable transparent, data-driven decision-making by articulating risks, assumptions, and trade-offs to program teams
• Oversee the design, execution, and interpretation of non-GLP and GLP toxicology studies
• Partner cross-functionally (DMPK, pharmacology, CMC, clinical) to integrate safety into development strategy
• Support diligence and evaluation of new programs within Flagship's ecosystem
• Build and manage a high-performing CRO and consultant network, ensuring quality, timelines, and cost efficiency
• Leverage and contribute to the Flagship ecosystem, fostering knowledge sharing and collaboration across platform companies
• Lead nonclinical regulatory strategy and documentation (INDs, IBs, briefing materials)
• Ensure regulatory readiness through clear and scientifically robust safety narratives
• Represent toxicology in regulatory interactions as appropriate

Qualifications

• PhD, DVM, or equivalent in Toxicology, Pathology, Pharmacology, or related field
• ~10-15+ years of experience in nonclinical safety in biotech/pharma
• Proven track record advancing programs through IND and into clinical development
• Experience across multiple modalities preferred
• Strong experience managing CROs and external collaborations
• Experience leading or building a toxicology function or team, including management of internal scientists and/or external partners, is a plus

Leadership Profile

• Enterprise mindset; able to operate across a portfolio in a fast-paced, collaborative environment
• Analytical and goal-oriented, with the ability to operate with urgency while maintaining high standards of scientific rigor and ethics
• Strong communicator who can translate complex toxicology into clear, audience-appropriate risk assessments, from early-stage teams to large pharma partners

About Flagship

Flagship Pioneering is a scientific innovation engine that invents and builds companies that change the world. We bring together the greatest scientific minds with entrepreneurial company builders and assemble the capital to allow them to take courageous leaps in human health, sustainability, and beyond. What sets Flagship apart is our ability to advance biotechnology by uniting life science innovation, company creation, and capital investment under one roof in a way that is largely without precedent.

Our team of scientists, entrepreneurial leaders, and professional capital managers are each aligned around an institutionalized process that enables us to innovate and create breakthroughs for the benefit of people and planet.…