In-Use Stability and Functional Efficacy of a Monoclonal Antibody Cocktail (TwinRab™) for Rabies Post-exposure Prophylaxis

Q: What problem does TwinRab™ aim to address in rabies post-exposure prophylaxis?

TwinRab™ targets limitations in access to human and equine rabies immunoglobulins, which restrict effective PEP coverage in resource-limited settings.

Q: How was TwinRab™ stability evaluated under simulated field-use conditions?

Samples from 300 IU/mL and 600 IU/mL batches were diluted in 0.9% sodium chloride and stored at room temperature for 4–24 hours, then tested for potency using the RFFIT method.

Q: How effective was TwinRab™ in vivo compared with Kamrab?

TwinRab™ achieved 90% survival when administered six hours after viral challenge and 70% when given after 24 hours, demonstrating comparable efficacy to Kamrab.

Sep 28, 2026

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Rabies remains a major public health problem in India, responsible for nearly one-third of global human deaths each year. Limited access to human and equine rabies immunoglobulins (RIGs) constrains effective post-exposure prophylaxis (PEP), especially where resources are limited. TwinRab™, a standardized two-antibody monoclonal cocktail of docaravimab and miromavimab, was tested for in-use stability and biological efficacy under simulated field conditions, including dilution, room-temperature storage, and in vivo efficacy compared with human RIG.

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CategoryHealthcare

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Abstract

In vitro stability and potency assessment

In vivo efficacy in a Syrian hamster model

Comparative efficacy vs. human RIG (Kamrab)

Public-health implications for field use

Review began 11/04/2025 Review ended 11/25/2025 Published 12/03/2025 © Copyright 2025 Kalita et al. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 4.0. , which permits unrestricted use , distribution , and reproduction in any medium , provided the original author and source are credited. DOI: 10.7759/cureus.98418 Open Access Original Article In-Use Stability and Functional Efficacy of a Monoclonal Antibody Cocktail (TwinRab™) for Rabies Post-exposure Prophylaxis Pankaj Kalita 1 , Sanjeev Kumar 1, Sanjay Bandyopadhyay 1 , Chintan Patel 1, Mihir Patel 1, Mr. Swagat Soni 1, Hiral Patel 1, Tushar Patel 1, Niraj Sakhrani 1, Trayambak Dutta 2, Manish Mahajan 3 1. Biotechnology, Zydus Lifesciences, Ahmedabad, IND 2. Infectious Disease, Zydus Lifesciences, Ahmedabad, IND 3. Medical Affairs, Zydus Lifesciences, Ahmedabad, IND Corresponding author: Trayambak Dutta, [trayambak.dutta@zyduslife.com](trayambak.dutta@zyduslife.com) Abstract Rabies remains a major public health problem in India, accounting for nearly one-third of global human deaths each year. Limited access to human and equine rabies immunoglobulins (RIGs) continues to restrict effective post-exposure prophylaxis (PEP) coverage, particularly in resource-limited settings. TwinRab™, a two-antibody monoclonal cocktail containing docaravimab and miromavimab, was developed as a standardized, scalable alternative to plasma-derived RIGs. This study evaluated the in-use stability and biological efficacy of TwinRab™ under simulated field-use conditions. In the in vitro arm, TwinRab™ samples from 300 IU/mL and 600 IU/mL batches were diluted in 0.9% sodium chloride to obtain twofold, fivefold, and 10-fold dilutions and stored at room temperature (25 ± 2 °C) for 4-24 hours. Potency was measured using the rapid fluorescent focus inhibition test (RFFIT) against the CVS-11 rabies virus strain. In the in vivo arm, undiluted TwinRab™ was administered six or 24 hours after viral challenge in a Syrian hamster model, and survival outcomes were compared with human RIG (Kamrab) . TwinRab™ retained its neutralizing potency after dilution and ambient storage for up to 24 hours. The 600 IU/mL batch showed no significant loss of activity across all dilutions (p > 0 .05), while minor but statistically significant differences were noted at higher dilutions ofthe 300 IU/mL batch (p < 0 .05) . In vivo, TwinRab™ achieved 90% survival when administered six hours post-challenge and 70% when administered after 24 hours, demonstrating comparable efficacy to Kamrab. These findings confirm that TwinRab™ maintains stability and functional efficacy under conditions that simulate routine clinical practice. Its thermostability, potency, and protective efficacy highlight its potential as a field-adaptable, next-generation alternative to conventional RIGs for PEP, particularly in high-burden regions with limited cold-chain infrastructure. Categories: Public Health, Internal Medicine, Infectious Disease Keywords: monoclonal antibodies, post-exposure prophylaxis (pep), rabies, rabies immunoglobulin, twinrab™ Introduction Rabies is a viral zoonotic disease that causes acute, progressive encephalitis and is almost invariably fatal once clinical symptoms appear. Globally, rabies accounts for an estimated 59,000 human deaths annually, with nearly 35% of these occurring in India [1,2] . The majority of fatalities result from dog bites in rural or underserved areas, where access to timely and complete post-exposure prophylaxis (PEP) remains limited. Despite the availability of effective vaccines and immunoglobulins, India continues to face challenges in achieving adequate PEP coverage due to infrastructure gaps, high costs, and supply chain limitations [3-5]. The World Health Organization (WHO) recommends combined active immunization with rabies vaccine and passive immunization using rabies immunoglobulin (RIG) for category III

FAQs

What problem does TwinRab™ aim to address in rabies post-exposure prophylaxis?

TwinRab™ targets limitations in access to human and equine rabies immunoglobulins, which restrict effective PEP coverage in resource-limited settings.

How was TwinRab™ stability evaluated under simulated field-use conditions?

Samples from 300 IU/mL and 600 IU/mL batches were diluted in 0.9% sodium chloride and stored at room temperature for 4–24 hours, then tested for potency using the RFFIT method.

How effective was TwinRab™ in vivo compared with Kamrab?

TwinRab™ achieved 90% survival when administered six hours after viral challenge and 70% when given after 24 hours, demonstrating comparable efficacy to Kamrab.

Sep 28, 2026

Uploaded by Hazel