Ipsen completes acquisition of Kartos Therapeutics, strengthening late-stage Oncology pipeline

Ipsen (Euronext: IPN; ADR: IPSEY) announced today it has completed the acquisition of Kartos Therapeutics, a clinical-stage biopharmaceutical company adding late-stage MDM2 inhibitor navtemadlin in Phase III clinical development in myelofibrosis.

About navtemadlin
Navtemadlin is an investigational oral MDM2 inhibitor being developed as an add-on therapy to ruxolitinib for patients with myelofibrosis who have a suboptimal response to ruxolitinib. The Phase III POIESIS study is evaluating whether the addition of navtemadlin could improve clinical outcomes compared with ruxolitinib alone in this patient population. Early clinical data demonstrate navtemadlin has the potential to transform suboptimal responses to standard of care ruxolitinib into clinically meaningful responses in patients with intermediate and high risk TP53wt myelofibrosis, to provide both enhanced clinical outcomes and potential disease-modifying benefit.

About myelofibrosis
Myelofibrosis is a myeloproliferative neoplasm, frequently linked to alterations in the JAK/STAT pathway, in which patients develop bone marrow fibrosis due to the abnormal proliferation of hematopoietic stem cells and secretion of fibrogenic cytokines. As marrow function declines, blood production shifts to other organs, most often the spleen, leading to splenomegaly. Myelofibrosis is characterized by bone marrow failure, fibrosis, splenomegaly and a high symptom burden that can significantly affect quality of life, including fatigue, night sweats and other progressive symptoms. It also carries a risk of transformation to acute myeloid leukemia. The median age at diagnosis is approximately 67–69 years and the condition affects around 1.5 per 100,000 people in the U.S. and Europe. Approximately 75–89% of patients are intermediate- or high-risk at diagnosis and more than 95% are TP53wt. Ruxolitinib, a JAK inhibitor, is the first-line standard of care; however, it is estimated that a significant proportion of patients have an initial suboptimal response and approximately 50%-75% discontinue treatment after three years. Median overall survival is typically one to two years after treatment discontinuation, underscoring the need for new strategies that can increase the number of patients that can achieve optimal clinical outcomes.

About Ipsen
We are a global biopharmaceutical company with a focus on bringing transformative medicines to patients in three therapeutic areas: Oncology, Rare Disease and Neuroscience. Our pipeline is fueled by internal and external innovation and supported by nearly 100 years of development experience and global hubs in the U.S., France and the U.K. Our teams in more than 40 countries and our partnerships around the world enable us to bring medicines to patients in more than 100 countries.

Ipsen is listed in Paris (Euronext: IPN) and in the U.S. through a Sponsored Level I American Depositary Receipt program (ADR: IPSEY). For more information, visit ipsen.com.

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Navtemadlin Reduces Markers of Disease Burden in Relapsed/Refractory Myelofibrosis

December 9, 2024

Author(s): Morgan Bayer

Treatment with navtemadlin (KRT-232) lowered the levels of biomarkers of disease burden in patients with relapsed/refractory myelofibrosis, according to findings from the phase 3 BOREAS trial (NCT03930732) that were presented at the 2024 ASH Annual Meeting.1

“I want to emphasize the biology that drives this approach. MDM2 is a negative regulator of wild-type p53, which is a master determinant of cell fate, and this becomes very critical when you consider its influence over the 4 hallmarks of myelofibrosis: CD34-positive myelofibrosis cell proliferation, myelofibrosis driver gene variant allele frequency (VAF), bone marrow fibrosis, and pro-inflammatory cytokines,” said John O. Mascarenhas, MD, during a presentation of the data.

Mascarenhas is professor of medicine, hematology and medical oncology, director of the Center of Excellence for Blood Cancers and Myeloid Disorders, and director of the Adult Leukemia Program at the Mount Sinai Tisch Cancer Center in New York, New York.

In the randomized, multicenter, global phase 3 BOREAS trial, navtemadlin monotherapy was compared with best available therapy (BAT) that included hydroxyurea, peginterferon, immunomodulatory drugs, or supportive care. Patients included in the trial had TP53 wild-type myelofibrosis and were refractory or had relapsed on prior therapy with a JAK inhibitor. The data cutoff date was September 30, 2024.

In the study, 183 patients were randomly assigned 2:1 to receive navtemadlin (n =1 23) at 240 mg 7 days in a row for a 28-day cycle (with 21 days of drug holiday) or 1 cycle of BAT (n = 60) for 28 days. “The patients who were on a JAK inhibitor at the time had a 28-day washout period so that from a spleen and symptom perspective they were clear on day 1 of navtemadlin dosing,” Mascarenhas explained.

“What we saw in terms of biomarkers was a very significant potent, rapid reduction in circulating CD34 cells as a hallmark of myelofibrosis even within 12 weeks and sustained over 24 and 36 weeks,” Mascarenhas stated. At 12 weeks, CD34-positive cells showed a median reduction of 68% from baseline in 50 patients in the navtemadlin arm and 52% in 25 patients in the BAT arm. This trend continued at 24 weeks (n = 48, 70% reduction vs n = 19, 38% reduction) and at 36 weeks (n = 21, 76% reduction vs n = 9, 33% reduction).

The reduction in driver gene VAF by 50% or greater was observed in 21% (n = 17/82) of patients in the navtemadlin arm and 12% (n = 4/33) of patients in the BAT arm at 24 weeks, “nearly doubling the molecular response at 24 weeks,” Mascarenhas noted.

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