Jeb Keiper

At Third Rock, Jeb brings more than two decades of experience in biotechnology leadership, company building, and strategic transactions. Jeb 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. Earlier in his career, Jeb held senior 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. He began his career at Pfizer R&D as a bench chemist and later worked at McKinsey and TransForm Pharmaceuticals.

Outside of work, Jeb enjoys wake surfing, mentoring others, and spending time with his family, including leading outdoor adventures with his children.