Patients with intermediate-2 or high-risk myelofibrosis who received treatment with the novel JAK/ACVR1 inhibitor Jaktinib experienced a significant improvement in spleen-volume associated with myelofibrosis compared to those treated with hydroxyurea. These results were presented at the 2023 EHA Congress and met the primary end point of the trial.
About Myelofibrosis
Myelofibrosis is a type of blood cancer known as a myeloproliferative neoplasm that is chronic and progressive in nature. It involves the abnormal development and function of bone marrow cells that produce blood cells and leads to the formation of scar tissue in the bone marrow. When the bone marrow becomes scarred it can’t make enough blood cells and this can cause anemia, enlargement of the spleen and liver, fatigue, and other problems. In some patients with myelofibrosis, the condition progresses to acute myeloid leukemia. Myelofibrosis is rare and affects ~ 20,000 people in the U. S. Although it can occur at any age it most commonly occurs in individuals over 65. When myelofibrosis develops on its own (and not as the result of another bone marrow disease), it’s called primary myelofibrosis. Myelofibrosis can also result from a worsening of other bone marrow diseases, such as polycythemia vera and essential thrombocythemia. Learn more….
About Jaktinib
Jaktinib is a novel selective janus kinase 1-2 inhibitor. Roughly half of the people with primary myelofibrosis will test positive for a mutation in the Janus kinase 2 (JAK2) gene and a majority of individuals will have overactive JAK signaling even if they don’t have a JAK mutation. Increased production of JAK proteins causes the wrong number of blood cells and cytokines to be produced. Three small molecule JAK inhibitors have been approved for the treatment of myelofibrosis by the FDA: Jakafi (ruxolitinib), Inrebic (fedratinib), and Vonjo (pacritinib).
The current clinical trial directly compared Jaktinib to hydroxyurea in adult patients with intermediate-2 or high-risk myelofibrosis who had not previously been treated with a JAK inhibitor. At 24-weeks the proportion of patients achieving a 35% reduction in splenic volume was 72% for Jaktinib compared with 17% for those treated with hydroxyurea. Hemoglobin levels were also reported to increase with Jaktinib arm and decrease with hydroxyurea.
Treatment with Jaktinib was well tolerated and the most common side effects were low white cell, and platelet counts, anemia, respiratory tract infections, and fever. There were fewer cytopenias with Jaktinib group than with hydroxyurea. This interim report suggests that jaktinib could be a new treatment option for patients with myelofibrosis who are intermediate-2 or high-risk.
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Reference
Zhang Yi, Zhhuan J, He A, et al. A randomized double-blind phase 3 study of jaktinib versus hydroxyurea in patients with intermediate-2 or high-risk myelofibrosis. Hemasphere. 2023;7(suppl 3):S212.
