Approved eight months ago for a certain class of patients with both hemophilia A or B, Pfizer’s Hympavzi has now shown its effectiveness in another group of patients with the bleeding disorder.
That's according to new top-line results released June 26 from a phase 3 trial. This test was specifically in patients with hemophilia A or B who are classified as “inhibitors” and saw the drug hitting its primary endpoint and key secondary endpoints. The study showed the superiority of once-weekly injections of Hympavzi compared to the performance of on-demand treatment in improving bleeding outcomes, Pfizer announced.
The results come on top of the FDA endorsing Hympavzi for patients with hemophilia A or B who are classified as “non-inhibitors.” In those with the disorder, inhibitors are patients who develop antibodies that counter the effectiveness of commonly used clotting factor replacement therapies to control bleeding.
“Patients with inhibitors tend to face frequent complications and navigating the treatment landscape can introduce complexities and increase disease burden,” Davide Matino, M.D., the principal investigator in the Basis study and a professor at McMaster University, said in a release.
Matino added that the bleed reduction demonstrated in the trial by Hympavzi “coupled with its weekly administration method, offers exciting potential for patients who are in critical need of treatment options.”
In the trial, 48 patients were given Hympavzi during a 12-month period versus an on-demand intravenous regimen with bypassing agents, as part of usual care in a six-month lead-in period. Hympavzi reduced the annual bleeding rate by 93% over 12 months.
Hympavzi also provided superior control in all bleeding-related secondary endpoint measures, including spontaneous bleeds, joint bleed, target joint bleeds and total bleeds. There were no deaths or thromboembolic events.
Pfizer said it will reveal full data at an upcoming medical meeting and will discuss the data with regulatory authorities, with the “goal of initiating regulatory filings” for hemophilia patients who are classified as inhibitors.
The only other treatment for hemophilia A and B which can be given to inhibitors and non-inhibitors is Sanofi’s Qfitlia, a small interfering RNA drug, which gained an FDA approval three months ago. It has an edge in that it is designed to be administered every two months, though the dosing period can be adjusted depending on the performance of the treatment.
Several new hemophilia therapies have hit the market in recent years, including Novo Nordisk’s daily injectable Alhemo, which was approved in December for A and B patients who are inhibitors.
Roche’s Hemlibra, which generated sales of $4.9 billion last year and can be used by inhibitors and non-inhibitors, rules the hemophilia A market but is being challenged by Sanofi and Sobi’s Altuviiio, which was approved in 2023 and achieved sales of $682 million last year.
Hympavzi was one of two Pfizer hemophilia treatments approved by the FDA in 2024. The company has already removed the other—hemophilia B gene therapy Beqvez—from the market, saying it was unable to attract customers or physicians to the $3.5 million one-time treatment.
Of the more than 800,000 people in the world with the disorder, roughly 20% of those with hemophilia A and 3% of those with hemophilia B are inhibitors, Pfizer said. Hemophilia inhibits the blood’s ability to clot properly, increasing the risk of repeated bleeding inside the joints, which can lead to hemophilic arthropathy, which may require surgery to repair or to replace damaged joints.