AstraZeneca (AZ) will invest USD 2 billion as a strategic equity stake in Summit Therapeutics, while leading clinical work that combines Akeso's first-in-class tumour-immunology 2.0 backbone ivonescimab with AZ's sonesitatug vedotin, a potential first-in-class CLDN18.2 ADC, across several gastrointestinal tumours.

The companies have also signed a memorandum of understanding to explore ivonescimab with AZ's broader ADC and oncology portfolio, with each party supplying its own molecule, sharing development costs and retaining separate development and commercialisation rights in a non-exclusive framework that avoids milestones, royalties or profit splits.

The rationale is combinatorial, not acquisitive. sonesitatug vedotin showed statistically significant and clinically meaningful overall survival (OS) in pretreated CLDN18.2-positive gastric cancer in CLARITY-Gastric01, while ivonescimab delivered OS benefit over durvalumab plus chemo in first-line advanced biliary tract cancer in the Phase III HARMONi-GI1 study.