FDA Clears First-in-Class Emicizumab for Hemophilia A

Megan Brooks

November 16, 2017

The US Food and Drug Administration (FDA) has approved emicizumab-kxwh (Hemlibra, Roche) to prevent or reduce the frequency of bleeding episodes in children and adults with hemophilia A with factor VIII inhibitors.

"Reducing the frequency or preventing bleeding episodes is an important part of disease management for patients with hemophilia. Today's approval provides a new preventative treatment that has been shown to significantly reduce the number of bleeding episodes in patients with hemophilia A with factor VIII inhibitors," Richard Pazdur, MD, acting director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research and director of the FDA's Oncology Center of Excellence, said in a news release.

Hemlibra is a first-in-class bispecific monoclonal antibody that bridges activated factor IX and X and thereby replaces the missing factor VIII. Hemlibra is a prophylactic treatment that can be self-administered once weekly via subcutaneous injection.

The safety and efficacy of Hemlibra were demonstrated in two clinical trials. The first trial included 109 males aged 12 years or older who had hemophilia A with inhibitors. Patients taking Hemlibra experienced about 2.9 treated bleeding episodes per year, compared to about 23.3 treated bleeding episodes per year for patients who did not receive prophylactic treatment. This represents an 87% reduction in the rate of treated bleeding episodes, the FDA said. Patients treated with Hemlibra also reported an improvement in hemophilia-related symptoms (painful swellings and joint pain) and physical functioning (pain with movement and difficulty walking).

The second trial was a single-arm trial of 23 boys younger than 12 years who had hemophilia A with inhibitors. During the trial, 87% of the patients taking Hemlibra did not experience a bleeding episode that required treatment.

"Nearly one in three people with severe hemophilia A can develop inhibitors to factor VIII replacement therapies, putting them at greater risk for life-threatening bleeds or repeated bleeds that can cause long-term joint damage," Roche notes in news release.

"People with hemophilia A who develop inhibitors face significant challenges preventing bleeds and typically require infusions of medicine multiple times a week, which can be especially difficult for young children and their families," Guy Young, MD, of Children's Hospital Los Angeles and the Keck School of Medicine, University of Southern California, said in the release. "This new medicine has been shown to reduce the frequency of bleeds compared to the currently available medicines and only needs to be injected once a week. This could make a meaningful difference for these children."

Common side effects of Hemlibra include injection site reactions, headache, and arthralgia.

Hemlibra carries a boxed warning noting that severe blood clots (thrombotic microangiopathy and thromboembolism) have been observed in patients who were given a rescue treatment (activated prothrombin complex concentrate) to treat bleeds for 24 hours or longer while taking Hemlibra.

Hemlibra was given priority review and breakthrough therapy designations by the FDA. The drug also received orphan drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases.

According to the National Institutes of Health, hemophilia affects 1 in every 5000 males born in the United States, approximately 80% of whom have hemophilia A.

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