Ipsen charts $1.75bn course for Kartos acquisition
Ipsen's chief executive David Loew.
French pharma company Ipsen has agreed to buy cancer biotech Kartos Therapeutics of the US for $450 million upfront, gaining control of a late-stage candidate for myelofibrosis.
Redwood City, California-based Kartos is running the pivotal phase 3 POIESIS trial of navtemadlin, an oral MDM2 inhibitor, as an add-on to standard treatment with Incyte's Jakafi (ruxolitinib) therapy in patients with myelofibrosis who do not respond well to Jakafi alone, with results due next year.
The proposed acquisition by Ipsen, which could swell to a value of $1.75 billion with regulatory approval and sales-related milestones, is expected to close in the third quarter of this year and start contributing to its profit in 2029.
Inhibiting MDM2 is thought to restore the activity of the tumour-suppressing protein p53, which helps to maintain DNA integrity in cells, and several drugs have been tested in humans, although most have been abandoned.
Both Boehringer Ingelheim's brigimadlin and Rain Oncology's milademetan reached phase 3 development for liposarcoma before being dropped, due to a lack of efficacy.
Sanofi was also active in this area with SAR405838, advancing the drug into clinical development in solid tumours before terminating the project due to the emergence of resistance mutations and modest efficacy. MSD took MK-8242 into phase 1 for solid tumours and AML, but subsequently stopped development, due to a challenging toxicity profile and an R&D pipeline reorganisation, while Taiho Oncology pulled a phase 2 trial of ASTX295, licensed from Astex Pharma.
Novartis was developing another candidate, siremadlin, for AML, other blood cancers, and solid tumours, but it no longer appears in the company's pipeline listing.
Undeterred by the challenges faced by other developers, Ipsen's chief executive, David Loew, said he is "excited by the potential of navtemadlin to define a new treatment paradigm for patients with myelofibrosis who have a suboptimal response to current standard of care, addressing a critical care gap and offering the potential for a new therapeutic option as early as 2028."
Many myelofibrosis patients don't respond well to Jakafi alone, leading to treatment discontinuations, and the prospects for those who abandon treatment are "dismal," according to Ipsen.
Continues building in oncology
The Kartos deal comes six months after the French company bought another blood cancer drug developer – ImCheck Therapeutics – in a €1 billion transaction that included an upfront fee of €350 million and added a midstage candidate for acute myeloid leukaemia (AML).
The company has been investing heavily in its oncology pipeline, licensing T-cell engager (TCE) therapies from Biomunex Pharma and Marengo Therapeutics in 2024 via deals valued at up to $610 million and $1.6 billion, respectively, and forging alliances to develop antibody-drug conjugates (ADCs) with Foreseen Bio and Sutro Biopharma. In the same year, it also acquired ex-US rights to Day One Biopharma's brain cancer therapy Ojemda (tovorafenib).
