Pioneering Medicines: Senior /Executive Director, Head of Toxicology

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

Functional Leadership & Capability Building

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

Portfolio & Program Strategy

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

External Partnerships & Regulatory

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