Ipsen agreed to acquire Kartos Therapeutics, a Redwood City, California-based clinical-stage biopharmaceutical company developing a treatment for myelofibrosis, a rare blood cancer, for $450 million upfront and up to $1.3 billion in additional milestone payments, bringing the total potential deal value to $1.75 billion.
According to Reuters, the acquisition centers on navtemadlin, an oral MDM2 inhibitor being evaluated as an add-on therapy to ruxolitinib, the current standard of care for myelofibrosis, in patients who have a suboptimal response to that treatment. The drug is currently in a Phase III trial called POIESIS, which is enrolling more than 600 patients across more than 250 sites globally. Top-line data from that trial are expected in 2027, the company said.
Ipsen CEO David Loew said in a statement that the deal “further strengthens our late-stage oncology pipeline” and that navtemadlin has the potential to become a new treatment option as early as 2028.
Myelofibrosis is a rare blood cancer in which the bone marrow becomes scarred, forcing blood production to shift to the spleen and causing significant symptoms including fatigue, night sweats, and progressive splenomegaly. Approximately 50% to 75% of patients on ruxolitinib discontinue treatment within three years, and median overall survival after discontinuation is roughly one to two years, the company said.
The milestone payments to Kartos shareholders include a significant regulatory approval payment and sales-based milestones, Ipsen said. The deal is expected to close by the end of the third quarter, subject to antitrust clearance under the Hart-Scott-Rodino Antitrust Improvements Act.
Starting in 2029, the acquisition is projected to add to Ipsen’s core operating income, and the company does not anticipate meaningful impact on its guidance for the current year.
The navtemadlin program traces its origins to a 2016 licensing agreement with Amgen that gave rise to Kartos as a company, The Wall Street Journal reported. The transaction extends Ipsen’s oncology expansion following its purchase of ImCheck Therapeutics last year in a deal worth up to 1 billion euros.
Goldman Sachs & Co. LLC and PJT Partners are serving as financial advisors to Kartos. Orrick Herrington & Sutcliffe LLP is acting as legal counsel to Ipsen, and DLA Piper LLP is serving as legal counsel to Kartos, the company said.
