Pioneering Medicines: Senior Director, Head of Toxicology

Flagship Pioneering•Cambridge, MA

14h

About The Position

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. 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.

Requirements

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
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

Nice To Haves

Experience leading or building a toxicology function or team, including management of internal scientists and/or external partners, is a plus

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