Rabies srRNA Vaccine Demonstrates Robust Immune Response
RBI-4000 is a self-replicating RNA (srRNA) vaccine developed to stimulate virus-neutralizing immune responses to rabies for prophylactic use.
Positive results have been announced from a phase 1 trial evaluating the safety, reactogenicity, and immunogenicity of the rabies vaccine candidate RBI-4000, Replicate Bioscience announced in a release.1 Data from the study, which was previously presented at the 2024 American Society of Gene and Cell Therapy Annual Meeting, was also published in Nature Communications.2
Rabies srRNA Vaccine Demonstrates Robust Immune Response / PEDROMERINO - stock.adobe.com
Data from the study showed a single dose of the RBI-4000 vaccine elicited immune responses in healthy patients, attaining an immune threshold of protection against rabies established by the World Health Organization (WHO) across all dose levels tested. The vaccine candidate was also seen to have good tolerability, with no serious adverse events, dose-limiting toxicities, or maximum tolerated dose level observed in the study.
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“These clinical results position RBI-4000 as a promising alternative capable of inducing rabies protective immunity at unprecedentedly low doses and with a single dose," Parinaz Aliahmad, PhD, head of Research and Development at Replicate, said in a release.1 "Furthermore, the data showcase RBI-4000's favorable safety profile, which we attribute to our optimized and scalable manufacturing processes. We are encouraged by the strength of the robust clinical data package supporting continued development of RBI-4000 and look forward to advancing it into further clinical studies."
RBI-4000 is a self-replicating RNA (srRNA) vaccine, which elicit robust immune responses with superior durability and can be administered at much lower doses than messenger RNA (mRNA) vaccines. RBI-4000 was developed to stimulate virus-neutralizing immune responses to rabies for prophylactic use.
The trial (NCT06048770) included 89 healthy patients between the ages of 18 to 45 years who had no prior exposure or vaccination to rabies. Patients were put into 4 cohorts: 0.1 mcg, 1 mcg, 10 mcg, and an active comparator of the commercially available rabies vaccine RabAvert. Those in the first 2 cohorts also received a prime-boost dosing schedule 8 weeks apart.
The study found that the majority of participants across all cohorts achieved the established WHO threshold. Of the patients in the single 10 mcg dose group, 89% to 94% either achieved or surpassed the WHO serological metric for protection. RBI-4000 also elicited immune responses that were equivalent to those elicited by RabAvert. Additionally, RBI-4000 demonstrated higher protein production and robust immune responses at significantly lower dose levels than linear, nucleoside-modified mRNA.
"The RBI-4000 Phase 1 data demonstrate compelling immunogenicity and a broad therapeutic index for Replicate's srRNA platform," Phil Dormitzer, MD, PhD, founder and president of Dormitzer Biologics, said in a release.1 "The vaccine candidate's high potency and the boostable immunity elicited by well tolerated dose levels suggest the potential utility of Replicate's srRNAs to prevent complex infectious diseases, for which targeting of multiple antigens may be needed."
READ MORE: Immunization Resource Center
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