Pfizer Posts Strong Phase 3 Data for Hemophilia Drug HYMPAVZI
Once-weekly treatment shows a 93% reduction in bleeding rates for patients with inhibitors, positioning Pfizer in a competitive market.
Pfizer Inc. (NYSE: PFE) announced positive topline results from a pivotal Phase 3 trial for its hemophilia treatment, HYMPAVZI™ (marstacimab), marking a significant step forward for a key candidate in its rare disease pipeline as the company navigates a shifting post-pandemic landscape.
The study, which evaluated the drug in patients with hemophilia A or B with inhibitors, found that the once-weekly subcutaneous injection reduced the annualized bleeding rate (ABR) by a statistically significant 93% compared to on-demand treatment. The results position Pfizer to compete more aggressively in a lucrative market currently dominated by established therapies.
According to the company's press release, patients receiving HYMPAVZI as a prophylactic treatment experienced an ABR of 1.39 over 12 months, a dramatic improvement from the 19.78 ABR observed in the on-demand treatment arm. The trial met all its bleeding-related secondary endpoints, demonstrating superiority in reducing spontaneous, joint, and total bleeds. The drug was reported to be generally well-tolerated, with no deaths or thromboembolic events.
This clinical success is a much-needed boost for Pfizer's pipeline, particularly after the company scaled back its gene therapy ambitions for hemophilia. Earlier this year, Pfizer discontinued the global development of its hemophilia B gene therapy, Beqvez, citing low market demand. The strong data for HYMPAVZI reaffirms a different, but potentially more commercially viable, path forward in the space.
“These encouraging results demonstrate HYMPAVZI's potential to help people living with hemophilia A or B with inhibitors, meeting an important need for patients with antibodies that neutralize most factor-based prophylactic options,” said Michael Vincent, Chief Inflammation & Immunology Officer at Pfizer, in a statement.
Hemophilia patients with inhibitors present a significant treatment challenge, as their immune systems develop antibodies that render standard factor-replacement therapies ineffective. HYMPAVZI works through a different mechanism, targeting an inhibitor of coagulation known as TFPI to help re-establish the body's ability to form clots.
Davide Matino, a principal investigator for the BASIS trial and an Associate Professor of Medicine at McMaster University, highlighted the drug's potential impact. “The strong bleed reduction with HYMPAVZI... coupled with its weekly administration method, offers exciting potential for these patients who are in critical need of treatment options,” he noted.
Despite the promising data, Pfizer enters a competitive field. The current standard of care for many hemophilia patients, particularly those with inhibitors, is Roche’s blockbuster drug Hemlibra (emicizumab), which has set a high bar for efficacy and safety. Other key competitors include Novo Nordisk's Concizumab and Sanofi's Fitusiran, both of which also target different pathways in the coagulation cascade.
Pfizer’s drug, with its subcutaneous, once-weekly dosing in a pre-filled pen, aims to offer convenience and a strong efficacy profile that could capture a meaningful share of the multi-billion dollar hemophilia market. The company has already secured approval for HYMPAVZI for patients without inhibitors and is expected to submit these new data to regulatory authorities for label expansion.
Investors will be watching closely as Pfizer prepares for its upcoming earnings report on November 4. The company's stock has faced headwinds amid declining revenues from its COVID-19 products and concerns over patent expirations for key drugs like Eliquis and Ibrance. Positive developments from its pipeline, such as the recent mid-stage trial data for a weight-loss drug acquired via Metsera and these HYMPAVZI results, are critical to shaping the narrative around Pfizer’s long-term growth prospects.