Ipsen to acquire Kartos Therapeutics to strengthen late-stage haemato-oncology pipeline
Tuesday, June 30, 2026
Ipsen has entered into a definitive merger agreement to acquire Kartos Therapeutics, adding the investigational MDM2 inhibitor navtemadlin to its late-stage haemato-oncology pipeline.
Navtemadlin is designed to restore the tumour-suppressing function of the p53 protein and is being developed as an add-on treatment for patients with intermediate- and high-risk TP53 wild-type myelofibrosis who have an inadequate response to the current standard treatment, ruxolitinib.
Although ruxolitinib helps reduce enlarged spleen size and disease-related symptoms, many patients experience a limited response and eventually discontinue treatment. Outcomes after discontinuation remain poor, with a median overall survival of around one to two years.
Navtemadlin is currently being evaluated in the global Phase III POIESIS trial, which aims to enrol more than 600 patients across over 250 sites. The study is assessing the combination of navtemadlin with ruxolitinib in patients with intermediate- and high-risk TP53 wild-type myelofibrosis who have shown a suboptimal response to standard therapy.
The Phase III trial follows positive findings from the Phase Ib/II KRT-232-109 study. Results presented at the European Hematology Association Congress in 2023 showed that, after 24 weeks of treatment, 42% of patients achieved at least a 25% reduction in spleen volume, while 32% achieved at least a 35% reduction. In addition, 32% of patients experienced at least a 50% improvement in total symptom score.
The earlier study also suggested potential disease-modifying effects. Among evaluable patients, 71% achieved at least a 20% reduction in driver variant allele frequency, while 57% showed an improvement of at least one grade in bone marrow fibrosis by central review after 24 weeks.
According to Ipsen, the acquisition strengthens its oncology pipeline and supports the development of new treatment options for patients with myelofibrosis who have limited benefit from existing therapies. If approved, navtemadlin could become available as early as 2028.
Source: globenewswire.com
