Switching to Hemlibra can control bleeds better in young patients

Real-world study finds use of replacement therapies dropped by more than 97%

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by Steve Bryson, PhD |

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In real-world settings, Hemlibra (emicizumab-KXWH) can safely control bleeds in children with hemophilia A better than previous treatment regimens, a study reports.

Hemlibra’s improved efficacy was more pronounced among patients with inhibitors, or neutralizing antibodies targeting factor VIII (FVIII), which is the clotting protein missing in people with hemophilia A.

Moreover, the use of FVIII replacement therapies dropped by more than 97% after children started receiving Hemlibra, and no life-threatening bleeds were noted.

“Our data confirms the safety of [Hemlibra] prophylaxis and suggests improved bleeding control among prospectively followed paediatric patients in a large real-world cohort of children with [hemophilia A],” researchers wrote.

The study, “Bleeding control improves after switching to emicizumab: Real-world experience of 177 children in the PedNet registry,” was published in the journal Haemophilia.

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Preventive Hemlibra for hemophilia A infants favored by HTC directors

Hemlibra approved to prevent or reduce frequency of bleeds in hemophilia A

Hemophilia A is caused by genetic mutations that lead to a deficiency or dysfunction of FVIII, a protein involved in blood clotting. Standard hemophilia treatment consists of replacing the missing clotting factor — which in the case of hemophilia A is FVIII — with a lab-made version to prevent or lower the occurrence of bleeding episodes.

However, despite significantly reducing bleeding rates, FVIII replacement therapies are associated with the development of inhibitors that can render treatment ineffective.

Hemlibra is a therapy approved to prevent or reduce the frequency of bleeds in hemophilia A patients. It is an antibody-based therapy that works by binding to clotting factors IX and X, mimicking the action of FVIII. First approved in the U.S. in 2017 for children and adults with hemophilia A with inhibitors, Hemlibra’s approval was extended in 2018 to include hemophilia A patients without FVIII inhibitors.

Since its approval, many patients have switched to Hemlibra from standard therapies. Still, real-world data on the treatment’s safety and efficacy is limited.

To address this gap, researchers at several European sites examined data extracted from the PedNet Registry (NCT02979119), a multicenter study collecting data from 33 hemophilia treatment centers in 19 countries. Of note, most of the researchers have links to pharmaceutical companies, including Hemlibra’s original developer Chugai Pharmaceutical, a Roche subsidiary.

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Hemlibra controls hemophilia A bleeds over nearly 5 years: Analysis

Analysis focused on 177 children with hemophilia A

The analysis focused on 177 children with hemophilia A, with inhibitors or who had been exposed to FVIII replacement therapies for at least 50 days, and who were currently receiving prophylactic or preventive treatment with Hemlibra.

A total of 91 (52%) patients had no history of inhibitors. At the start of treatment with Hemlibra, 64 (36%) had active inhibitors, and 22 (12%) had undergone immune tolerance induction, a treatment to eliminate inhibitors.

Before Hemlibra treatment, patients with FVIII inhibitors had a higher annualized bleeding rate (ABR) (5.08 vs. 2.41 bleeds per year) and a higher joint bleeding rate (1.90 vs. 0.74 bleeds per year) than those without inhibitors. Similar bleeding rates were seen among patients who had undergone induction therapy and those without inhibitors.

During Hemlibra treatment, patients with inhibitors had fewer bleeding episodes in general compared with those without inhibitors (mean ABR of 0.75 vs. 1.11 bleeds per year), but joint bleeding rates were similar.

Accordingly, the most pronounced reduction in ABR was seen among patients with inhibitors, whose ABR dropped from 5.08 to 0.75. Joint ABR also dropped from 1.90 to 0.34. While Hemlibra’s efficacy was less pronounced in those without inhibitors, the mean overall ABR significantly dropped from 2.41 to 1.11 and the joint ABR from 0.74 to 0.31.

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Severe bleeds seen in small number of young patients on Hemlibra

No life-threatening bleeds reported during Hemlibra treatment

No life-threatening bleeds were reported during Hemlibra treatment, while 10 such events were reported in seven patients before they started on Hemlibra.

Before treatment, nearly half (48%) of the 64 patients with inhibitors received regular prophylactic treatment with bypassing agents, which circumvent the need for conventional clotting factors, and 26 (41%) underwent immune tolerance induction. This amounted to a median of 364 injections per year. After Hemlibra treatment, injection rates significantly dropped to 52 per year, and FVIII consumption by 97.6%.

Most (60%) of those without inhibitors were receiving long-acting FVIII prophylactic treatment before Hemlibra, at a median of 129 injections per year. With Hemlibra, injections were reduced to 35 per year, and replacement therapy consumption by 97.6%.

Five Hemlibra-related adverse events were reported in eight patients. Four patients experienced injection site reactions and one patient stopped Hemlibra treatment after seven months due to the development of antibodies against factors IX and X, even though bleed control was maintained. Inhibitors did not reoccur in the 22 patients who had undergone induction therapy, and no other blood-related events were reported.

“This study showed improved bleeding control compared to previous treatment and a favourable safety profile during [Hemlibra] therapy in paediatric haemophilia A patients,” the researchers wrote.