Preventive Hemlibra for hemophilia A infants favored by HTC directors

NBDF advisory council favors treatment's use in children under 12 months

Steve Bryson, PhD avatar

by Steve Bryson, PhD |

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Nearly all medical directors at hemophilia treatment centers in the U.S. said they would consider starting preventive Hemlibra (emicizumab-KXWH) in untreated infants with hemophilia A, ages 12 months and younger, a survey study reports.

Most respondents also said they’d transition from FVIII replacement therapies, used on-demand to treat early bleeds, to Hemlibra as a routine preventive agent. Preventing brain bleeds was the most common reason for starting Hemlibra early, according to the survey, details of which were reported in “Emicizumab use in infancy: A survey of United States Pediatric Hemophilia Treatment Center Medical Directors” and published in Haemophilia.

Hemlibra is an antibody-based therapy approved for people with hemophilia A, a bleeding disorder caused by the lack or malfunction of the blood clotting protein factor VIII (FVIII). Given as an injection under the skin, or subcutaneously, it mimics the action of FVIII to prevent or reduce bleeds. It can be used in patients with or without inhibitors, that is, neutralizing antibodies against FVIII that can develop with standard FVIII replacement therapies and render them ineffective.

While Hemlibra is approved for patients of all ages, few clinical trials have included infants 12 months and younger. Last year, interim results from the HAVEN 7 (NCT04431726) Phase 3 clinical trial called suggested preventive treatment with Hemlibra safely controlled bleeds in infants under 12 months with severe hemophilia A without inhibitors. The Medical and Scientific Advisory Council (MASAC) of the National Bleeding Disorders Foundation (NBDF) has supported using Hemlibra prophylaxis in this age group despite there being little data on its use in infants.

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Exploring why preventive Hemlibra is right for infants

Here, researchers in Texas and Ohio surveyed pediatric medical directors of hemophilia treatment centers (HTCs) in the U.S. to better understand the reasons for starting Hemlibra prophylaxis in infants. The survey was based on two patient scenarios with multiple-choice questions and comment options.

The first scenario involved a 9-month-old boy with severe hemophilia A who’d never had a bleeding event nor received FVIII replacement therapy. The second was about a 3-month-old boy with severe disease who’d been treated over three weeks for a spontaneous brain bleed. In both scenarios, the parents wanted to discuss future care.

Most of the 32 surveys were completed by respondents with more than 15 years of experience caring for hemophilia A patients and represented hemophilia treatment centers with more than 250 patients.

For case 1, 31 (96.9%) respondents said they would consider starting Hemlibra prophylaxis in infants with no or minimal treatment history, and 45.2% said they’d consider starting it in infants as young as a week, while 96.9% said they’d wait until age 6 months.

The most common reason for starting Hemlibra was to prevent brain bleeds (53.1%), followed by to avoid placing a tube, or central line, into a vein for treatment (21.9%).

All but one (96.9%) said they didn’t wait a minimum number of days on FVIII replacement therapies before starting Hemlibra. Moreover, nearly all (90.6%) said they did not regularly use FVIII concentrates in infants on Hemlibra until 50 days of exposure. About half (46.8%) said they would obtain FVIII inhibitor testing after FVIII treatment.

In the second case, 31 (96.9%) said they would transition to Hemlibra as a prophylactic agent in infants who’d been given FVIII replacement treatment for a brain bleed. Hemlibra was reported to be routinely used by six respondents (27.3%) and on a case-by-case basis by nine (40.9%) in patients with moderate hemophilia.

The comments by the participants showed a varied approach among the medical directors about initiating Hemlibra initiation in infants. Common differences emerged regarding FVIII treatment before Hemlibra to detect inhibitor risk or to promote immune tolerance to FVIII.

“We don’t require low-dose structured FVIII exposure but strongly encourage it,” one respondent said, while another said infants tended to be exposed to FVIII for 10 days “before starting [Hemlibra] regardless of bleeding.”

“Over the past year, we have had [six] new infants with severe hemophilia A, all have chosen to begin on prophylaxis with [Hemlibra], beginning at about 7-8 months of age,” another said.

Regardless, preventing spontaneous brain bleeds outweighed these concerns, the researchers said.

Lastly, many directors said it was important to share the decision-making process with families because of the factors that influence care.

“The majority of U.S. HTC Medical Directors would consider [Hemlibra] as prophylaxis in infants with hemophilia A under 12 months of age for a variety of reasons,” wrote the researchers, who favored research that would explore reasons for delaying Hemlibra.