Valneva, a specialty vaccine company, and Pfizer Inc. (NYSE: PFE), today announced further positive Phase 2 results, including booster response, for Lyme disease vaccine candidate VLA15.
The Phase 2 study, VLA15-202, is evaluating the immunogenicity and safety of VLA15 in a Month 0-2-6 vaccination schedule. The study enrolled 246 healthy adults 18 to 65 years of age in the U.S. As announced in October 2020, the study met its primary endpoint of demonstrating that VLA15 was immunogenic across all dose groups tested and elicited high antibody responses across all serotypes (ST1 – ST6) at one month after completion of the primary vaccination series. Continued evaluation at Month 18 showed that antibody titers declined thereafter across all groups, remaining above baseline but confirming the need for a booster strategy.
VLA15 was safe and well-tolerated across all doses and age groups tested. No related Serious Adverse Events (SAEs) were observed in any treatment group.
Participants who received a complete primary vaccination series with 180 µg doses of VLA15, were invited to continue the study in a booster extension phase and were randomized to receive an additional 180 µg dose of VLA15 (N=39) or placebo (N=19) at Month 18.
VLA15’s acceptable safety profile was confirmed through one-month post-booster. Administration of a booster dose elicited a strong anamnestic response yielding a 2.9-fold (ST3) to 4.2-fold (ST1, ST4) increase (Geometric Mean Fold Rise) in anti-OspA IgG antibody titers compared with titers observed after primary immunization. All participants seroconverted to anti-OspA IgG after the booster dose, meaning Seroconversion Rates (SCRs) were 100% for all OspA serotypes. SCR was defined as the rate of subjects that changed from seronegative at baseline to seropositive. Additionally, subjects who were seropositive at baseline needed to show at least a 4-fold increase in anti-OspA IgG compared to baseline titer. Functionality of elicited antibodies was demonstrated by Serum Bactericidal activity Assays, leading to SCRs ranging from 86.8% (ST2) to 100.0% (ST3) after the booster. The study is continuing to monitor persistence of antibody responses.
Juan Carlos Jaramillo M.D., Chief Medical Officer of Valneva, commented, “Lyme disease represents a high unmet medical need which impacts the lives of millions of people in the Northern Hemisphere. We are excited by these additional Phase 2 results, which we believe take us a step closer to making a major contribution against this severe disease, subject to regulatory approval.”
“The prevalence and geographic reach of Lyme disease is growing, underscoring the major medical need for vaccination against the disease,” adds Kathrin Jansen, PhD, Senior Vice President and Head of Pfizer Vaccine Research and Development. “These positive results of the Phase 2 VLA15-202 study represent another important milestone in the development of VLA15, and we look forward to continue our development efforts in our quest to potentially protect people from Lyme disease in the future.”