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).