Hympavzi boosts quality of life for hemophilia patients in trial
Bleeds reduced for adults, adolescents with inhibitors
Hympavzi (marstacimab) reduced bleeding rates and improved quality of life in adults and adolescents with hemophilia A or B who have inhibitors (antibodies against standard replacement therapies).
That’s according to final data from the Phase 3 BASIS study (NCT03938792), which demonstrated the treatment met its main goal of reducing the annualized number of bleeds requiring treatment.
The results were presented during the American Society of Hematology annual meeting, held earlier this month in Orlando, Florida, and described in the study, “Efficacy and Safety of Marstacimab Prophylaxis in Hemophilia A/B With Inhibitors: Results from the Phase 3 BASIS Trial,” published in Blood.
“It is encouraging that these data demonstrate the potential of Hympavzi to combine efficacy, safety, and straightforward administration for adults and adolescents living with hemophilia A or B with inhibitors and address a significant patient need,” Michael Vincent, MD, PhD, chief inflammation & immunology officer at Pfizer, the treatment’s developer, said in a company press release.
Hemophilia is caused by a deficiency in proteins needed for the blood to clot: FVIII, in the case of hemophilia A, and FIX in hemophilia B. Standard treatment for these types of hemophilia involves replacement therapy, in which a version of the missing clotting factor is administered to treat or prevent bleeding.
Preventing bleeds without factor replacement
Hympavzi is an antibody-based therapy that works by blocking the activity of tissue factor pathway inhibitor (TFPI), a protein that normally prevents unneeded clotting. This is expected to promote blood clotting and prevent bleeds through a mechanism that bypasses the need for factor replacement. It is approved to treat patients 12 and older with hemophilia A or B who do not have inhibitors.
The open-label BASIS trial enrolled 48 boys and men aged 12 to 74 with severe hemophilia A or B with inhibitors. They were treated with Hympavzi after a six-month observation phase on their current on-demand regimen with bypassing agents (medications that circumvent the need for conventional clotting factor replacement).
Hympavzi was administered for one year as a 300 mg subcutaneous (under-the-skin) loading dose, followed by weekly 150 mg dosing.
The treatment led to a significant and clinically meaningful 93% reduction in the annualized rate of treated bleeds (1.39 vs. 19.78), which was consistent across hemophilia types, age groups, and geographic locations. The median annualized bleeding rate was also reduced with Hympavzi (0 vs. 16.42).
Hympavzi also demonstrated superiority across all annualized bleeding-related secondary goals: spontaneous bleeds (0.87 vs. 15.27), joint bleeds (1.1 vs. 15.15), target joint bleeds (0.79 vs. 6.42), and total treated and untreated bleeds (4.36 vs. 27.29).
After six months of treatment, Hympavzi demonstrated superiority over on-demand therapy in improving health-related quality of life, with a reduced physical disease burden, including less joint and swelling pain, and improved ease of movement.
Patients also reported significant improvements in health, including enhanced mobility, self-care, daily activities, pain or discomfort, and emotional well-being, along with a more positive overall perception of their health.
Hympavzi was generally well tolerated, with no deaths or thromboembolic events, which occur when a blood clot breaks off and blocks another blood vessel. Overall, 38 participants experienced adverse events, most of them mild to moderate in severity. The most common were COVID-19 (21.6%), upper respiratory tract infection (15.7%), fibrin D-dimer increase (9.8%), an indicator of increased blood clotting, and headache (9.8%).
One patient reported a serious treatment-related skin rash that led to treatment discontinuation. Ten patients developed anti-drug antibodies, nine of which resolved by the end of the study, with no impact on the treatment’s safety and efficacy.
“In patients with inhibitors, this study demonstrates Hympavzi’s potential as a safe and efficacious treatment option that not only significantly reduced bleeding episodes … but also demonstrated improvement in certain aspects of health-related quality of life,” said Davide Matino, MD, a professor at McMaster University and the trial’s principal investigator.
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