Ipsen agreed to acquire Kartos Therapeutics in a deal valued at up to $1.75 billion, centered on navtemadlin, an investigational oral MDM2 inhibitor designed to restore p53 function. Ipsen will pay $450 million upfront at close, with additional milestone payments tied to development, regulatory, and commercial outcomes. Kartos’ navtemadlin is in Phase 3 testing in myelofibrosis in the POIESIS program (oral add-on therapy to ruxolitinib for patients with suboptimal response). Ipsen positioned the acquisition as a late-stage oncology pipeline reinforcement and highlighted the program’s regulatory pathway and trial scale.