Emergent BioSolutions presented updated results from the interim analysis of its Phase 2 clinical study evaluating the safety and immunogenicity of the company’s chikungunya virus virus-like particle (CHIKV VLP) vaccine candidate across a series of dosing regimens. The presentation was made at the American Society of Tropical Medicine and Hygiene (ASTMH) annual meeting in Maryland held November 20 to 24, 2019.
This Phase 2 parallel-group, randomized, double-blind, dose-finding study enrolled 415 healthy adults at three U.S. sites. The subjects were randomized to one of several doses and regimens, including a single dose. Seroconversion occurred in 74% to 98% of subjects within seven days after one dose, and in all subjects by 28 days after the last dose. In the single-dose regimen arm, 96% of the single dose subjects had detectable antibodies within seven days of the vaccination. At the one-year visit, 98% of subjects receiving the single-dose regimen remained seropositive. Additionally, this arm had the highest Geometric Mean Titer at Days 7, 182, and 365 compared to the other arms, suggesting a durability of inducing high serum neutralizing titers with just a single dose. Subjects in three of the arms will be followed for at least two years to examine persistence of the response.
The vaccine candidate was well-tolerated across all study arms and no significant vaccine-related safety concerns have been identified in analyses to date. The most frequent adverse event was local injection site pain.
The CHIKV VLP vaccine candidate is licensed from the National Institute of Allergy and Infectious Diseases at the National Institutes of Health. The license was transferred to Emergent following the acquisition of PaxVax in 2018.
It received FDA Fast Track designation in May 2018 and EMA PRIME designation in September 2019.
About CHIKV VLP
Virus-like particle (VLP) vaccines are multi-protein structures that mimic the organization and conformation of naturally occurring viruses without the viral genome. Studies have shown that in general, other VLP vaccines are highly immunogenic, safe, and typically elicit high titer neutralizing antibodies, which are needed to protect against chikungunya virus. There is currently no vaccine, VLP or otherwise, to prevent chikungunya virus infection.
About the Chikungunya virus
Chikungunya virus is spread to people through infected mosquitoes. Symptoms include fever, joint pain, headache, muscle pain, joint swelling, or rash. Chikungunya outbreaks have occurred in countries in Africa, Asia, Europe, and the Indian and Pacific Oceans. The chikungunya virus was found for the first time in the Americas on islands in the Caribbean in 2013. According to the Centers for Disease Control and Prevention, there is a risk that the virus will be imported to new areas by infected travelers. Currently, there is no vaccine to prevent or medicine to treat chikungunya virus infection.