A Phase 3, Randomized, Open-label, Noninferiority Trial Evaluating Anti-Rabies Monoclonal Antibody Cocktail (TwinrabTM) Against Human Rabies Immunoglobulin (HRIG)

Background: Limited supply, cost and potential for severe adverse effects observed with the blood derived rabies immunoglobulin products has led to search for alternative therapies. This issue has been addressed by developing an anti-rabies monoclonal antibody cocktail.

Methods: This is a phase 3, randomized, open-label, noninferiority trial conducted in patients with World Health Organization (WHO) category III exposure with suspected rabid animal. Eligible patients were assigned to either the test arm, TwinrabTM (docaravimab and miromavimab) or the reference arm, human rabies immunoglobulin (HRIG; Imogam® Rabies-HT), in a ratio of 1:1. The primary endpoint was the comparison of responder rates between the 2 arms assessed as percentage of those with rabies virus neutralizing Antibodies titers ≥0.5 IU/mL on day 14.

Results: A total of 308 patients were equally randomized into the 2 arms. In the per-protocol (PP) population, there were 90.21% responders in the TwinrabTM arm and 94.37% in the HRIG arm. The geometric mean of rapid fluorescent foci inhibition test titers in the PP on day 14 were 4.38 and 4.85 IU/mL, for the TwinrabTM and HRIG arms, respectively. There were no deaths or serious adverse events reported.

Conclusions: This study confirmed that TwinrabTM is noninferior to HRIG in terms of providing an unbroken window of protection up to day 84. This trial in healthy adults with WHO category III exposure from suspected rabid animal also establishes the safety of TwinrabTM in patients with 1 WHO approved vaccine regimen (Essen).

Clinical trials registration: CTRI/2017/07/009038.

clinical trial; monoclonal antibodies; post exposure prophylaxis; rabies.