Valneva & Pfizer Report Further Positive Phase 2 Booster Results for Lyme Disease Vaccine Candidate

Valneva SE and Pfizer Inc. recently announced positive immunogenicity and safety data from their VLA15-221 Phase 2 study following a second booster vaccination of their Lyme disease vaccine candidate, VLA15, given one year after receiving the first booster dose. The immune response and safety profile of VLA15 one month after receiving the second booster dose were similar to those reported after receiving the first booster dose, showing compatibility with the anticipated benefit of a booster vaccination prior to each Lyme season. There are currently no approved human vaccines for Lyme disease, and VLA15 is the Lyme disease vaccine candidate which has advanced the furthest along the clinical development timeline, with two Phase 3 trials in progress. The Centers for Disease Control and Prevention (CDC) has estimated that approximately 476,000 people in the US are diagnosed and treated for Lyme disease each year and 129,000 cases are reported annually in Europe.

These latest results from the VLA15-221 Phase 2 study again demonstrated a significant anamnestic antibody response across all six serotypes covered by the vaccine candidate in pediatric (5 to 11 years of age) and adolescent (12 to 17 years of age) participants, as well as in adults (18 to 65 years of age), measured one month after administration of this second booster dose (month 31). A high proportion of participants seroconverted after the second booster dose, yielding seroconversion rates (SCRs) above 90% for all outer surface protein A (OspA) serotypes in all age groups, in-line with SCRs after the first booster. Geometric Mean Titers at one month post first and second booster (i.e. month 19 vs. month 31) were comparably high.

The participants of this Phase 2 study received VLA15 or placebo during the primary vaccination phase in two immunization schedules (month 0-2-6 or month 0-6), followed by a first booster dose at month 18 and a second booster dose at month 30.

Juan Carlos Jaramillo, MD, Chief Medical Officer of Valneva, said “We are encouraged by these 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 Northern 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.”

The safety and tolerability profile of VLA15 after a second booster dose was comparable to the profile observed after the first booster. To date, no safety concerns were observed by an independent Data Monitoring Committee (DMC) in any treatment or age group.

“Personal preventive behaviors are currently the only recommended strategies to help protect yourself from Lyme disease. 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,” said Annaliesa Anderson, Ph.D., Senior Vice President and Head Vaccine Research and Development at Pfizer. “Together with our partner Valneva, we look forward to progressing our vaccine candidate in the ongoing Phase 3 clinical trials.”

In August 2022, Pfizer and Valneva initiated the currently ongoing Phase 3 clinical study, Vaccine Against Lyme for Outdoor Recreationists (VALOR) (NCT05477524), to investigate the efficacy, safety and immunogenicity of VLA15 in participants five years of age and older in highly endemic regions in the United States (U.S.) and Europe. The primary vaccination series for all participants was completed in July 2024. A second Phase 3 study (VLA15-1012), aiming to provide further evidence on the safety profile of VLA15 in the pediatric population, is also ongoing.

Pfizer aims to submit a Biologics License Application (BLA) to the US FDA and Marketing Authorization Application (MAA) to the European Medicines Agency (EMA) in 2026, subject to positive Phase 3 data.

VLA15 is an investigational multivalent protein subunit vaccine that uses an established mechanism of action for a Lyme disease vaccine that targets the outer surface protein A (OspA) of Borrelia burgdorferi, the bacteria that cause Lyme disease. OspA is a surface protein expressed by the bacteria when present in a tick. Blocking OspA inhibits the bacterium’s ability to leave the tick and infect humans. The vaccine candidate covers the six most prevalent OspA serotypes expressed by the Borrelia burgdorferi sensu lato species in North America and Europe.

VLA15-221 is a randomized, observer-blind, placebo-controlled Phase 2 study. It is the first clinical study with VLA15 which enrolled a pediatric population (5-17 years old). 560 healthy participants received either VLA15 in two immunization schedules (month 0-2-6 [N=190] or month 0-6 [N=181]) or placebo (month 0-2-6 [N=189]). Vaccine recipients received VLA15 at a dose of 180 µg, which was selected based on data generated in two previous Phase 2 studies. The main safety and immunogenicity readout (primary endpoint) was performed one month after completion of the primary series vaccination schedule. All eligible subjects received booster doses of VLA15 or placebo at month 18 and 30 (booster phase) and will be followed for an additional year to monitor antibody persistence. In addition, all eligible subjects will be asked to receive another booster dose of VLA15 or placebo at month 42, in order to assess the effect of periodic booster doses.

VLA15 is tested as an alum-adjuvanted formulation and administered intramuscularly. The study is being conducted at U.S. sites located in areas where Lyme disease is endemic and has enrolled both volunteers with a prior infection with Borrelia burgdorferi as well as Borrelia burgdorferi-naïve volunteers.

Lyme disease is a systemic infection caused by Borrelia burgdorferi bacteria transmitted to humans by the bite of infected Ixodes ticks. It is considered the most common vector-borne illness in the Northern Hemisphere. Early symptoms of Lyme disease (such as a gradually expanding erythematous rash called erythema migrans or other nonspecific symptoms like fatigue, fever, headache, mild stiff neck, muscle and joint pains) are often overlooked or misinterpreted. Left untreated, the disease can disseminate and cause more serious chronic complications affecting the skin, joints (arthritis), heart (carditis) or nervous system. The medical need for vaccination against Lyme disease is steadily increasing as the geographic footprint of the disease widens.

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