Ipsen moved to deepen its myelofibrosis pipeline by agreeing to acquire Kartos Therapeutics for $450 million upfront, taking control of navtemadlin in Phase 3 testing. The oral small molecule aims to restore p53 function—an approach positioned as an add-on and potential next option for patients with suboptimal responses to JAK inhibition. The Kartos program is being tested in a Phase 3 study enrolling more than 600 patients with intermediate- and high-risk TP53 myelofibrosis who have had an inadequate response to Jakafi. Ipsen expects a topline readout next year, targeting an eventual launch around 2028 if results hold. The deal reinforces Ipsen’s strategy to pad oncology pipeline depth with assets that can expand the standard-of-care framework, while signaling continued appetite among larger biopharma for p53-reactivation approaches beyond earlier oncology attempts.