An unprecedented leprosy vaccine, LepVax, is set to undergo clinical trials in Brazil, led by the Oswaldo Cruz Institute (IOC/Fiocruz). This marks the first time a leprosy vaccine will be assessed in clinical trials within the country, following authorization from the National Health Regulatory Agency (Anvisa). Brazil has the second highest number of leprosy cases in the world, behind only India.
LepVax: A New Hope for Leprosy Prevention
LepVax, developed by the Access to Advanced Health Institute (AAHI), represents a significant advancement as the first specific vaccine against Mycobacterium leprae, the bacterium responsible for leprosy. The vaccine utilizes protein subunit technology, a modern approach to immunizer production.
Pre-clinical studies have demonstrated encouraging results. Vaccinated mice exhibited a significant reduction in infection rates, even when exposed to high levels of the bacteria. Furthermore, when administered post-infection in armadillos (a model for neurological leprosy studies), LepVax delayed motor and sensory nerve damage. These findings suggest the vaccine's potential for both preventing and treating the disease.
Clinical Trial Design and Objectives
The initial Phase 1a trial, conducted in the United States with 24 healthy volunteers, established the vaccine's safety profile, with no serious adverse events reported, and demonstrated its immunogenicity. The upcoming trial in Brazil, classified as a Phase 1b clinical trial, aims to confirm these findings within a leprosy-endemic context. This is crucial as prior exposure to mycobacteria among Brazilians may influence the immune response to the vaccine.
The Phase 1b study will involve 54 healthy volunteers, randomly divided into three groups: two receiving low and high doses of the vaccine, respectively, and one receiving a placebo. The trial will be conducted as a randomized, double-blind, placebo-controlled study, considered the gold standard for research. Participants will receive three vaccinations, spaced 28 days apart, and will be followed for a year (421 days total).
Addressing a Global Health Challenge
Leprosy, a neglected disease affecting primarily vulnerable populations, remains a significant global health concern. According to the World Health Organization (WHO), approximately 200,000 new cases occur annually across 120 countries. While multidrug therapy has significantly reduced the global burden of leprosy since 1981, new cases and permanent deformities persist, highlighting the need for innovative control measures.
Verônica Schmitz, deputy head of the Leprosy Laboratory at IOC/Fiocruz and scientific leader of the LepVax clinical trial, emphasized the importance of this study, stating, "Brazil concentrates 90% of leprosy cases in the Americas... The WHO has already pointed out that we need new tools to control leprosy and people affected by leprosy deserve a vaccine."
Future Implications
If the Phase 1b trial yields positive results, researchers plan to proceed with a Phase 2a clinical trial in Brazil, involving 582 leprosy patients. This trial will assess the vaccine's safety in infected individuals and its potential therapeutic effects. The ultimate goal is to integrate LepVax into Brazil's national immunization schedule, contributing to the WHO's strategy to interrupt leprosy transmission by 2030.
