Hemlibra Safe, Effective in Kids with Hemophilia A Regardless of Inhibitor Status, Data Show

Prophylactic (preventive) treatment with Hemlibra (emicizumab) safely and effectively reduces bleeding rates in children younger than 12 with hemophilia type A, regardless of development of inhibitors (antibodies) against synthetic factor VIII (FVIII), data from two Phase 3 studies show.

Hemlibra is a type of replacement therapy that mimics the activity of FVIII — the missing clotting factor in hemophilia A patients — helping blood to clot normally.  Initially developed by Japan-based Chugai Pharmaceutical, Hemlibra is now co-developed by Chugai, along with Roche and its subsidiary, Genentech.

Hemlibra is currently approved as a routine prophylactic treatment in the United States for adults and children with hemophilia A, with or without FVIII inhibitors, and in Europe for all hemophilia A patients with inhibitors, and for severe hemophilia A patients without inhibitors.

Results from the Phase 3 HOHOEMI study (JapicCTI‐173710), which evaluated Hemlibra in pediatric patients without FVIII inhibitors, were previously published in the journal Haemophilia.

HOHOEMI showed that subcutaneous (under the skin) administration of Hemlibra — every two weeks or once a month — was well-tolerated and effectively reduced the number of bleeding events in children younger than 12.

“The HOHOEMI study that we conducted in Japan is the first clinical study which examined the use of Hemlibra in hemophilia A children without inhibitors,” Yasushi Ito, Chugai’s executive vice president and co-head of project & lifecycle management unit, said in a press release.

Now, data from the global Phase 3 HAVEN 2 study (NCT02795767) appeared in the journal Blood, in an article titled “A multicenter, open-label, phase 3 study of emicizumab prophylaxis in children with hemophilia A with inhibitors.”

The multi-center, open-label trial evaluated the safety and effectiveness of Hemlibra prophylaxis in 85 children younger than 12 with hemophilia A and FVIII inhibitors.

Participants, who had been previously treated with factor VIII replacement therapy — either on an as-needed or prophylactis basis — were randomly assigned to receive Hemlibra subcutaneously either as 1.5 mg/kg once a week (65 children), 3 mg/kg every two weeks (10 children), or 6 mg/kg every four weeks (10 children).

Among children receiving Hemlibra once a week, the annualized bleeding rate (ABR) for treated bleeding events — according to the number of treated bleeding events reported during the study — was 0.3, and 77% of them had no treated bleeding events.

When looking at the bleeding events of the 15 children in this group who had previously received standard bypassing agents prophylaxis within a non-interventional study (NCT02476942), the researchers found that Hemlibra reduced the ABR by 99%, compared to previous standard therapy.

The ABR for treated bleeding events was 0.2 in children receiving Hemlibra injection every two weeks and 2.2 in those receiving Hemlibra every four weeks.

Hemlibra was well-tolerated, and the most common adverse events reported among the initially enrolled 88 children were nasopharyngitis, otherwise known as the common cold, (37.5%) and skin reactions at the injection site (29.5%).

Two out of these 88 children developed antibodies against Hemlibra, which was associated with reduced levels of Hemlibra in the blood. One child experienced a permanent loss of Hemlibra effectiveness. All the other children achieved effective Hemlibra blood levels, regardless of the treatment regimen.

The results of both Phase 3 studies confirm the appropriateness of administering Hemlibra with three dosing options in children with hemophilia A, regardless of their FVIII inhibitor status.

“Conventional standard treatment for hemophilia A requires intravenous injections multiple times a week, which can be a treatment hurdle especially for children with difficult vascular access,” Ito said, adding that “Hemlibra can be administered subcutaneously in a longer dosing interval.”

“We are very pleased that data on the use of Hemlibra in children were published in the international journals … [and] we will continue undertaking clinical studies with exceptional science so that patients and healthcare professionals may use Chugai’s products with more confidence,” Ito said.