Hemophilia A Patients With Inhibitors Benefit from Emicizumab

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Highlights:

• Hemophilia A is characterized by severe bleeding; current standard treatment for the condition requires intravenous administration of clotting factor two or three times a week
• Prolonged administration of clotting factor can result in the development of antibodies (called inhibitors) that attack and destroy them
• A new therapy involving Emicizumab could prevent bleeding episodes in hemophilia patients with inhibitors, according to a phase II clinical trial

A novel therapy called Emicizumab can reduce the incidence of bleeding episodes by 87 percent in patients with hemophilia A inhibitors, finds a Phase II clinical trial.

Patients with hemophilia A -- caused by deficiency of coagulation factor VIII -- often experience excessive bleeding in the event of a cut or injury and require prophylactic treatment with intravenously administered factor VIII three times a week. However, repeated administration of clotting factor can increase the development of antibodies called inhibitors. These inhibitors attack and destroy the necessary factor that affects the treatment.

‘Emicizumab could be a novel therapy for hemophilia A patients who no longer respond to conventional clotting therapies.’

By-passing agents

Medications called �by-passing agents' are the standard treatment for patients with hemophilia A and inhibitors.

Dr Guy Young, MD, director of the Hemostasis and Thrombosis Program and lead physician for study efforts at Children's Hospital Los Angeles, said, "While the standard medications allow us to 'bypass' the need for Factor VIII, they don't do the job as efficiently or as well for these patients. Bleeding is harder to stop, and episodes last longer and do more damage to the patients. A patient treated with this new therapy had been in a wheelchair for three years because of joint damage from repeated bleeding incidents. Now, he's walking."

Treating Hemophilia Patients with Emicizumab

Emicizumab (ACE910) is a bispecific monoclonal antibody. In phase I study, emicizumab markedly reduced the rate of bleeding among patients with hemophilia A with or without inhibitors.

The phase III study called HAVEN 1 was conducted by an international team of hematologists. The research team recruited 109 males, 12 years and older with hemophilia A with inhibitors. The participants were randomly divided into three groups.

The first group treated with Emicizumab prophylaxis experienced 87 percent lesser bleeds when compared to the group that did not receive any prophylactic treatment. The third group comprised of participants who had previously received prophylactic treatment with bypassing agents and were now assigned to Emicizumab prophylaxis. The third group experienced 79 percent fewer bleeds compared to prior prophylactic by-passing agents.

Benefits of Emicizumab

• Emicizumab is more effective at preventing severe bleeding in hemophilia A patients
• It has an improved safety profile, according to the study (no anti-drug antibodies were detected)
• Compared to by-passing agents, Emicizumab is easier to administer (subcutaneous) and requires only a once a week dosage

"This is the most significant advancement I have seen during my 20 years working in the field of hemophilia," said Young, who is also a professor of Pediatrics at the Keck School of Medicine of USC and treats the most pediatric patients with hemophilia in California. "We've had families flying in from all over the country to get access to this medication."

The research team plans to investigate the use of emicizumab in hemophilia A patients without inhibitors. Currently, Emicizumab is only available to patients as part of the clinical trial while the Food and Drug Administration (FDA) is in the process of evaluating the drug.

The study published in the New England Journal of Medicine was presented at the International Society of Thrombosis and Hemostasis.

Hemophilia

Hemophilia A is also known as factor VIII (FVIII) deficiency, which is caused by a defective or missing factor VIII, a clotting protein. Hemophilia occurs in 1 in 5,000 live births. It is a genetic disorder passed down from parents to children. However, one-third of hemophilia cases are caused by a spontaneous mutation.

The standard treatment for hemophilia A is prophylactic intravenous infusions of factor VIII two to three times a week to prevent severe bleeding. Hemophilia A is four times more common than hemophilia B. Most of the patients with hemophilia A experience severe bleeding in case of a cut or injury.

References:

1. Gallia G. Levy et al. Emicizumab Prophylaxis in Hemophilia A with Inhibitors. New England Journal of Medicine (2017). DOI: 10.1056/NEJMoa1703068
2. Hemophilia A - (https:www.hemophilia.org/Bleeding-Disorders/Types-of-Bleeding-Disorders/Hemophilia-A)

Source: Medindia

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