Governance > Board of Directors

Tim Clackson, Ph.D

Tim Clackson, Ph.D., is President and Chief Executive Officer of Theseus Pharmaceuticals. Tim most recently served as President and Chief Technology Officer at Xilio Therapeutics, a privately held oncology company developing tumor-selective immunotherapies, where he led the development of the company’s technology and product strategy. From 1994 to 2018, Tim was with ARIAD Pharmaceuticals, where he was President of Research & Development and Chief Scientific Officer. He played a key role in the company’s evolution from early research to a global commercial oncology company, and its subsequent acquisition by Takeda. He led the multi-disciplinary R&D team that internally discovered and developed five clinical-stage product candidates, including ICLUSIG® (ponatinib), approved for patients with treatment-resistant Ph+ leukemias; ALUNBRIG® (brigatinib), approved for ALK+ non-small cell lung cancer (NSCLC); and EXKIVITY® (mobocertinib), approved for EGFR Exon20 insertion+ NSCLC. Prior to ARIAD, Tim was a postdoctoral research fellow at Genentech. He received his Ph.D. in Biology from the University of Cambridge, and his B.A. in Biochemistry from the University of Oxford. Tim serves as a director on the boards of Forma Therapeutics, Theseus Pharmaceuticals, and the Massachusetts Biotechnology Council (MassBio).