Sophie Boer

Sophie de Boer is a Senior Principal at Flagship Pioneering, the Cambridge, Massachusetts venture-creation firm best known for founding and building breakthrough biotech companies such as Moderna. She joined Flagship through its selective 2017 Fellowship program and has risen steadily through the ranks — from Associate / VentureLabs Fellow to Senior Associate (2019–2021), to Principal (2021), and to Senior Principal (March 2024). In her role she "conducts explorations to discover unexplored biological mechanisms and new biotechnologies," working within Flagship Labs' teams of entrepreneurial scientists to develop the science, intellectual property, and business strategy that seed the firm's new startups.

Her scientific training is deep. She earned a B.S. in biomedical sciences and a master's in cancer genomics and developmental biology from Utrecht University (Netherlands), and a Ph.D. from Leiden University, conducting her thesis research at Harvard University. She completed postdoctoral work in the laboratory of Professor Kevin Eggan at Harvard University and the Broad Institute, focused on stem cells and regenerative biology and the mechanisms behind neurological diseases such as ALS and schizophrenia. She has also completed coursework at Harvard Business School.

Before Flagship, de Boer built industry and investing experience through a consulting engagement with Biogen's Corporate Development team and internships at PureTech Ventures (now PureTech Health) and NantKwest — a combination of bench science, corporate strategy, and venture exposure that maps directly onto Flagship's "scientist-founder-investor" model.

• Invests the Flagship way: rather than sourcing external deals, she helps originate and co-found companies from first-principles science developed inside Flagship Labs, then backs them from inception.
• Focus is squarely early-stage biotech and life sciences — platform companies built on novel biological mechanisms and new modalities (RNA medicines, generative-AI protein design, genetic medicines).
• Comfortable across company creation through Seed/Series A, with reported check sizes clustering in the low-to-mid single-digit millions and scaling up as Flagship's founding stake.
• Says "yes" to ideas that are platform-oriented and paradigm-shifting — where a new scientific insight can be translated into a durable, programmable technology, not a single-asset play.