Approved treatment controls bleeding for up to 5 years in hemophilia A

Long-term treatment with Hemlibra (emicizumab) provided sustained protection against bleeding for up to five years in people with hemophilia A, with no new safety concerns identified, according to a large real-world study from Canada.

The study, which analyzed data from 710 people with hemophilia A, found that more than 60% of participants experienced no recorded bleeding episodes during treatment with Hemlibra. The number of bleeding episodes people experienced each year fell by more than half after starting treatment, with the benefit maintained for up to five years.

“Continued follow-up will allow for greater quantification of this impact over time, providing valuable information to healthcare practitioners and regulatory authorities,” researchers wrote.

The study, “Long-term experience with emicizumab in people with hemophilia A in the Canadian Bleeding Disorders Registry,” was published in Blood Advances.

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Hemlibra mimics function of activated FVIII to aid blood clotting

In hemophilia A, genetic mutations result in a shortage or dysfunction of factor VIII (FVIII), a protein needed for blood to clot properly. As a result, people with the disease experience excessive, prolonged bleeding episodes.

Standard prophylactic (preventive) treatment involves regular infusions of factor replacement therapy, which provides the body with a working version of FVIII. However, about 30% of previously untreated people with severe hemophilia A develop FVIII inhibitors, which are antibodies that block replacement FVIII and make these therapies less effective.

Instead of replacing FVIII, Hemlibra mimics the function of activated FVIII to help support the body’s ability to form blood clots. Given as an injection under the skin, it’s approved in many countries, including the U.S. and Canada, as routine preventive treatment for people of all ages with hemophilia A, with or without FVIII inhibitors.

In Canada, public reimbursement for Hemlibra became available in 2019 for people with severe hemophilia A and FVIII inhibitors, and in 2021 for those without inhibitors. Access expanded further in 2024 to include, through exceptional access requests, people with moderate disease and severe bleeding already receiving prophylaxis, as well as some people with mild disease on a case-by-case basis.

“Data from routine clinical practice can help to further understand national practice patterns for the treatment of [hemophilia], as well as the safety and effectiveness of drugs outside of controlled clinical trials,” the researchers wrote. “Importantly, these data can be used as clinical evidence to help overcome access and reimbursement challenges.”

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Only 2 adverse events were possibly related to Hemlibra

To evaluate Hemlibra’s long-term safety and effectiveness in routine care, researchers analyzed data from the Canadian Bleeding Disorders Registry (CBDR), a national database that collects information from hemophilia treatment centers across Canada.

The study included 710 people with hemophilia A who received at least one dose of Hemlibra before the end of 2023. At the start of treatment, 60.7% of participants were adults and 39.3% children or adolescents. Most (92.8%) had severe disease, while 5.8% had moderate and 1.4% had mild hemophilia.

Before switching to Hemlibra, 89% were receiving routine FVIII replacement therapy, while Hemlibra was the first treatment for 17 children (2.4%) younger than 2. Most (72.5%) had no history of FVIII inhibitors, while 13.1% had current inhibitors and 14.4% had a previous history of inhibitors. By the time of the analysis, 75.9% had been receiving Hemlibra for more than one year.

Overall, treatment with Hemlibra was well tolerated. Over a median follow-up of about 18 months (roughly 1.5 years), researchers recorded 34 adverse events. Only two — intermittent headache and ankle or knee joint pain — were considered possibly related to Hemlibra. No participants discontinued Hemlibra or required dose modifications because of adverse events, and no cases of anti-drug antibodies were reported.

Data from the CBDR found no new safety signals following the switch to [Hemlibra], with a notable decrease in bleeds and sustained bleed control being observed for up to 5 years. These findings suggest that emicizumab has the potential to greatly reduce the impact on both patient quality of life and healthcare system burden.

The therapy also provided sustained protection against bleeding. Overall, 61.8% of participants experienced no recorded bleeding episodes while receiving Hemlibra, and the median annualized bleeding rate (ABR) was zero. The ABR estimates the number of bleeds a person experiences each year.

Compared with the period before starting Hemlibra, the mean ABR fell from 1 to 0.47, a 53% reduction. Bleeding rates declined regardless of FVIII inhibitor status, but the improvement was greatest among participants with current inhibitors, whose mean ABR dropped from 3.21 to 0.30 — a 91% reduction. Among those without current inhibitors, the mean ABR decreased from 0.88 to 0.53, a 40% reduction. All of these reductions were statistically significant.

The benefits of Hemlibra also persisted over time. Mean ABRs fell from 0.56 during the first year of treatment to 0.43 in the second year and 0.25 in the third year, then remained consistently low in the fourth (0.33) and fifth (0.17) years, indicating sustained protection against bleeding with long-term use.

“Data from the CBDR found no new safety signals following the switch to [Hemlibra], with a notable decrease in bleeds and sustained bleed control being observed for up to 5 years,” the researchers concluded. “These findings suggest that emicizumab has the potential to greatly reduce the impact on both patient quality of life and healthcare system burden.”