Tim Clackson

About Tim Clackson

Tim Clackson is a scientist and biotechnology leader with 30 years of experience building teams and companies. He has led the development of multiple precision medicines for cancer patients, including several approved therapies, and created significant value through strategic capital formation, partnerships, and M&A. Tim was most recently CEO of IDRx, a precision oncology company developing a potential best-in-class therapy for GIST. He led IDRx through clinical proof-of concept, rapid organization growth, a $120m Series B financing, and acquisition of the company by GSK for up to $1.15bn. Before IDRx Tim was CEO of Theseus Pharmaceuticals, a company developing targeted therapies for GIST and NSCLC, which he grew into a clinical-stage, public company, raising $180m in an IPO. Prior to Theseus, he served as President at Xilio Therapeutics, where he initiated multiple tumor-selective immunotherapy programs now in clinical development.Previously Tim was President of R&D and CSO at ARIAD Pharmaceuticals, which was acquired by Takeda in 2017 for $5.2bn. During his 22 year career at ARIAD, Tim played a key role in the company’s evolution from early research to a global, commercial oncology company. From project conception to approval, he led the multi-disciplinary R&D team that discovered and developed ICLUSIG (ponatinib), a pan-BCR-ABL inhibitor approved globally for the treatment of CML and Ph+ALL; and ALUNBRIG (brigatinib), an ALK inhibitor approved globally for treatment of ALK+ NSCLC. His team also discovered and developed EXKIVITY (mobocertinib), a first-in-class oral EGFR inhibitor approved for treatment of Exon 20 mutant NSCLC; and ridaforolimus, an mTOR inhibitor partnered with Merck for oncology. Earlier in his ARIAD career, Tim helped develop a widely-used platform technology for control of gene and cell activity using bifunctional small molecules – one of the earliest applications of induced proximity. Tim trained as a postdoctoral fellow at Genentech, where his studies with Dr. Jim Wells on growth hormone receptor defined the now-established “hot spot” paradigm for how proteins interact. He obtained his Ph.D. in Biology from Cambridge University, for antibody engineering research under Dr. Greg Winter at the MRC Laboratory of Molecular Biology that included the development of antibody phage display technology. Tim received his B.A. in Biochemistry from Oxford University. Tim has served on the boards of multiple private and public companies as well as the Massachusetts Biotechnology Council (MassBio).

Experience

1. Board Member

   Kesmalea Therapeutics

   May 2025 — Present · London, GB

   Kesmalea is developing a new class of oral, CNS penetrant protein degraders based on its innovative SELFTAC platform.

Education

• University of Cambridge

  PhD, Biology

  1987 — 1990

• University of Oxford

  BA Hons., Biochemistry

  1983 — 1987