Mosaic Therapeutics has appointed Stephen Shuttleworth as chief scientific officer as the Cambridge oncology company accelerates its pipeline of synergistic precision oncology programmes and prepares for its first clinical studies. Shuttleworth joins the executive leadership team to lead scientific strategy, R&D and preclinical pipeline expansion, succeeding Barry Davies who retires at the end of November.

Shuttleworth has more than three decades of experience across drug discovery, biotech leadership and investment. Since 2019 he has been a venture partner at Samsara BioCapital, where he has focused on R&D due diligence, company creation and senior operational leadership. He previously spent over 10 years at Karus Therapeutics as CSO, COO and executive director, where he served as founding scientist and R&D lead for the company’s small molecule oncology programmes and worked with investors to secure venture funding.

His earlier career included scientific leadership roles in the UK, US and Canada at Piramed Pharma, Tularik, BioChem Pharma and CRUK, along with an early industry position at Chiroscience in Cambridge. Mosaic said Shuttleworth brings deep expertise in small molecule cancer therapeutics, medicinal chemistry and portfolio leadership. Across his career he has directed multiple research programmes in oncology, immunology, inflammation, metabolic disease and infectious disease.

Shuttleworth led the design and preclinical development of three small molecule cancer therapeutics that all completed Phase 1 studies: pictilisib, KA2237/CVL-237 and KA2507. Mosaic said this record of progressing discovery-stage assets into human studies is expected to support its plans to move its own combination therapies toward clinical evaluation.

Commenting on his appointment, Shuttleworth said: “I am delighted to be joining Mosaic, and for the opportunity to work with this world-class team in its pursuit of cutting-edge, precision combination therapies for the treatment of patients with cancer. Mosaic’s Synergistic Precision approach to the discovery of biomarker-defined, targeted therapies is truly innovative and I look forward to working alongside the team to realise the full potential of the Company’s discovery platform and capabilities.”

Chief executive Thomas Fuchs said Mosaic is pleased to bring Shuttleworth onto its leadership team as it advances its programmes toward the clinic. “He is a seasoned scientific leader and biotech investor, and I look forward to working with him as we bring our lead products into the clinic and work to build out our pipeline of precision oncology programmes,” Fuchs said. He added that the company is grateful for Davies’ contributions to platform and pipeline development and wished him well in his retirement.

Mosaic uses an experimental and computational discovery platform to identify oncology combinations with synergistic activity in biomarker-defined patient groups. Its pipeline includes two assets in-licensed from Astex Pharmaceuticals earlier this year: ASTX029, an ERK1/2 inhibitor, and ASTX295, an MDM2 antagonist. The company expects its first clinical combination study to begin in 2026, and said Shuttleworth’s appointment supports the transition toward clinical development.