Study Supports Rabies Immunoglobulin For Post-Exposure Prophylaxis In Kids

In children with confirmed or suspected rabies, human rabies immunoglobulin (HRIG) appears to be an effective part of the post-exposure prophylactic (PEP) treatment, researchers say.

"We know the incidence of kids being exposed to animals that may transmit rabies is high," Dr. Novinyo Amega of Kedrion Biopharma, in Fort Lee, New Jersey, told Reuters Health by email. "However, little data exist that can help clinicians better understand the safety profiles of the various HRIG products currently available."

Dr. Amega and colleagues conducted a phase-4 prospective, single-arm clinical trial of KEDRAB, an HRIG distributed by Kedrion Biopharma and approved by the U.S. Food and Drug Administration (FDA) in 2017, in 30 patients under 17.

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All participants had confirmed or suspected rabies exposure in which PEP was indicated. This included standard-of-care wound washing, passive immunization with HRIG, and induction of active immunity through initiation of the rabies vaccine series. No placebo group was used, as this would have been ethically unacceptable due to the high fatality rate of rabies, the researchers say.

Participants received 20 IU/kg of HRIG150 (150 IU/mL) infiltrated into the wound site or sites. Any remainder was injected intramuscularly, concomitantly with the first of a four-dose series of rabies vaccine. Rabies virus neutralizing antibody (RVNA) titers and tolerability were assessed on day 14 following administration of the last vaccine dose.

There were no serious adverse events, rabies infections, or deaths, the researchers report in Human Vaccines and Immunotherapeutics. Twelve participants experienced a total of 13 adverse events deemed related to the study treatment, but all were mild.

By day 14, RVNA levels had reached at least 0.5 IU/mL in all but two of the participants. However, say the investigators, testing was "not repeated subsequently; thus, it remains possible that the two subjects that did not attain the cutoff by day 14 seroconverted by day 30."

The study results have been submitted to the FDA for review, Dr. Amega said, adding, "we are pleased to see that top-line results of this pediatric study support KEDRAB's safety profile. Importantly, we believe that meeting the primary objective of this study could further differentiate KEDRAB from other currently available HRIGs in the U.S."

Kamada Ltd, which manufactures KEDRAB, and Kedrion Biopharma funded the study. Most of the authors are employees of these companies.

—David Douglas

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