Board of Directors

Jeb Keiper is a Venture Partner of Third Rock Ventures, and has more than two decades of experience in biotechnology leadership, company building, and strategic transactions. He previously served as CEO at Nimbus Therapeutics, where he helped build the company from 2014 to 2025. During his time at Nimbus, the company raised over $600 million and advanced four medicines into late-stage clinical development. Additionally, he also oversaw the zasocitinib transaction with Takeda which included $4 billion upfront and up to $2 billion in downstream milestones. Prior to Nimbus, Mr. Keiper was VP of Business Development roles at GSK Oncology and spent a decade at GSK, where he led the oncology component of the $16 billion GSK–Novartis three-business transaction. Earlier in his career, he was a consultant at McKinsey and worked in business development at TransForm Pharmaceuticals. He began his career at Pfizer R&D as a bench chemist. He earned his academic degrees from MIT, including a BS in Chemistry, MS in Chemical Engineering, and MBA from MIT Sloan School of Management.