Guillaume Pfefer

CEO-Partner & CEO of Senda Biosciences at Flagship Pioneering

Guillaume Pfefer is a Flagship Pioneering CEO-Partner and serves as Chief Executive Officer of Senda Biosciences. As a Partner, Guillaume is part of Flagship’s leadership team and provides expertise across the ecosystem. As Chief Executive Officer of Senda, he works closely with Ignacio Martinez, John Mendlein as well as the rest of the Flagship leadership to plan, drive and achieve the highest possible value creation for Flagship and for Senda.

Guillaume has more than 25 years of experience in the pharmaceutical industry leading R&D, Manufacturing, strategy, commercial, business development, and operations. Prior to joining Flagship, he was SVP, Global Vaccine Leader for Shingrix, GSK’s flagship biological against shingles. In this role, Guillaume had the accountability for the launch in the US. Under Guillaume’s leadership, his team delivered the best biopharma launch in North America over the past decade as independently assessed by IQVIA. Shingrix achieved multi-billion dollar revenue, 98% US market share, and received the Prix Galien for the best pharmaceutical product of 2019. Prior to GSK, Guillaume was President and CEO of Kala Pharmaceuticals. As CEO, he transformed Kala from a pre-clinical technology platform start-up to a leading ophthalmology company with four Phase III/II clinical trials and the foundation for a successful IPO. Prior to Kala, Guillaume held a number of ascending leadership positions over a nine-year career at Sanofi. In his last position, he served as General Manager of Sanofi Pasteur Mexico, one of the company’s largest worldwide affiliates. His previous positions included Vice President, Global Head of the Sanofi Pasteur’s Influenza and Pneumococcal Franchise and Global Head of Corporate Strategy.

Guillaume holds a Master’s degree in Chemical Engineering from the National School for Chemical Engineering (Nancy, France), a PhD in Materials Science from Centre National de la Recherche Scientifique (CNRS), France, and an MBA from the Wharton School at the University of Pennsylvania.



  • CEO-Partner & CEO of Senda Biosciences

    Current role

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