Ormutivimab a promising alternative for postexposure rabies prophylaxis

The antirabies monoclonal antibody (mAb) ormutivimab, when administered with vaccine, is noninferior to human rabies immunoglobulin (HRIG) for postexposure prophylaxis, with no safety concerns, according to a phase III study.

The double-blind, noninferiority study included 720 adult participants (mean age 40.5 years) with suspected WHO category III rabies exposure. These participants were randomly assigned to receive vaccine plus either ormutivimab (20 IU/kg) or HRIG (20 IU/kg). Ormutivimab or HRIG was administered after thorough wound washing on day 0, while the vaccination was administered on days 0, 3, 7, 14, and 28.

On day 7, the primary endpoint of the adjusted geometric mean concentration (GMC) of rabies virus neutralizing activity (RVNA) was similar in the ormutivimab and HRIG groups (0.41 IU/mL for both). The corresponding adjusted-GMC ratio of 1.01 established the noninferiority of ormutivimab. Seroconversion rates were higher in the ormutivimab group than in the HRIG group on days 7, 14, and 42.

In terms of safety, adverse events occurred in 70.33 percent of participants in the ormutivimab group and 74.44 percent in the HRIG group. The respective frequencies of adverse reactions were 64.44 percent and 69.44 percent. These adverse reactions included swelling, erythema, and pain at the injection site, with most of them being mild and resolved without intervention.

Serious adverse events occurred in 18.61 percent of participants in the ormutivimab group and 25.83 percent in the HRIG group.