In September 2024, Valneva and Pfizer announced positive immunogenicity and safety data from the VLA15-221 Phase II study investigating a second booster vaccination of their Lyme disease vaccine candidate. The vaccine, VLA15, is administered one year after receipt of the first booster dose. The immune response and safety profile one month after the VLA15 booster dose were similar to those reported after the first booster dose, which shows “compatibility with the anticipated benefit” of a booster vaccination before each Lyme season.
VLA15
VLA15 is the most advanced Lyme disease vaccine candidate; there are no approved human vaccines for the disease. It is an investigational multivalent protein subunit vaccine that uses an established mechanism of action for a Lyme disease vaccine to target the outer surface protein A (OspA) of Borrelia burgdorferi, the Lyme disease-causing bacteria. OspA is expressed by the bacteria when present in a tick, so blocking it inhibits the bacterium’s ability to leave the tick and cause infection in humans.
The vaccine targets the six most prevalent OspA serotypes expressed by the Borrelia burgdorferi sensu lato species in North America and Europe. It is tested as an alum-adjuvanted formulation and administered intramuscularly.
Phase II study
VLA15-221 is a randomised, observer-blind, placebo-controlled Phase II study, the first clinical study of VLA15 to enrol a paediatric population (5-17 years). 560 healthy participants received either VLA15 in two immunisation schedules or placebo. The study is being conducted at US sites in areas where Lyme disease is endemic.
The most recent results “demonstrated a significant anamnestic antibody response” for all six serotypes in paediatric, adolescent, and adult participants. This was measured one month after administration of the second booster. Many participants seroconverted after the second booster dose, yielding seroconversion rates (SCRs) above 90% for all OspA serotypes in all age groups. Geometric Mean Titres were “comparably high” at one month post first and second booster.
Encouraging data
Dr Juan Carlos Jaramillo, Valneva’s Chief Medical Officer, is “encouraged” by the data, which “support the potential benefit of booster doses across all examined age groups”.
“As Lyme disease continues to spread, it represents a significant unmet medical need, affecting numerous individuals throughout the Northen Hemisphere. Each new set of positive data brings us one step closer to potentially bringing this vaccine to both adults and children living in areas where Lyme disease is endemic.”
Dr Annaliesa Anderson, Senior Vice President and Head of Vaccine Research and Development at Pfizer, reflected that the “only recommended strategies” for protection against Lyme disease are “personal preventive behaviours”.
“These data from the VLA15-221 study are an important step towards a potential vaccine that could help prevent the disease and ease the burden of acute, severe, and sometimes persistent consequences. Together with our partner Valneva, we look forward to progressing our vaccine candidate in the ongoing Phase III clinical trials.”
The ongoing Phase III clinical study, Vaccine Against Lyme for Outdoor Recreationists (VALOR) was initiated in August 2022 to investigate the efficacy, safety, and immunogenicity of VLA15 in participants aged 5 years and older in highly endemic regions in the US and Europe. There is also a second ongoing Phase III study (VLA15-1012) to provide further evidence on the safety profile of VLA15 in the paediatric population. Pfizer intends to submit a Biologics License Application (BLA) to the US FDA and Marketing Authorisation Application (MAA) to the European Medicines Agency (EMA) in 2026, subject to positive Phase III data.
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