Positive Phase II booster results for Lyme disease vaccine candidate

French biotech Valneva and U.S. big pharma company Pfizer today announced positive Phase II results for the second booster vaccination of their Lyme disease vaccine candidate VLA15, one year after the first booster was administered. The results from the VLA15-221 Phase II study revealed strong immunogenicity and safety data in adult and pediatric study participants.

“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,” the companies wrote in a press statement.

Lyme disease is a bacterial infection mainly caused by the bacterium Borrelia burgdorferi​ that can spread to humans when they are bitten by ticks, external parasites that feed on blood. Lyme disease has been reported in almost all states in the U.S., Central Europe, and Asia.

In 2022, more than 63,000 Lyme disease cases were reported to the U.S. Centers for Disease Control and Prevention (CDC). However, more recent estimates show that almost half a million people​ are diagnosed and treated for Lyme disease in the U.S. annually, with approximately 130,000 cases reported in Europe each year.

Typical symptoms of Lyme disease are fever, headache, fatigue, and a characteristic skin rash around the tick bite called erythema migrans. While the infection can be treated with a course of antibiotics, if left untreated, Lyme disease can become dangerous, affecting the joints, heart, and nervous system.

There is currently no approved vaccine for Lyme disease in humans. Valneva and Pfizer’s VLA15 is the most advanced vaccine candidate in clinical development, with two Phase III trials ongoing. The VLA15 vaccine targets a surface protein called OspA (outer surface protein A), which is expressed in the bacteria Borrelia burgdorferi ​when it is active in a tick. By blocking OspA, the bacteria is prevented from leaving the tick’s body and cannot infect humans. VLA15 covers the six most common serotypes of OspA expressed by the species Borrelia burgdorferi​ in North America and Europe.

The latest result from the VLA15-221 Phase II study showed a significant immune response – measured by antibodies in the blood – across all six serotypes in children, adolescents, and adults. The immune response was measured one month after the second booster dose was administered and was in line with that of the first booster. An independent Data Monitoring Committee has observed no safety concerns to date.

“We are encouraged by these data, which support the potential benefit of booster doses across all examined age groups,” said Juan Carlos Jaramillo, Chief Medical Officer of Valneva, in a press statement.

“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 two companies began a currently ongoing Phase III study in August 2022, in which they are investigating the efficacy, safety, and immunogenicity of VLA15 in children and adults in regions within the U.S. and Europe where Lyme disease is common. For this study, the primary vaccination was administered to all participants by July 2024.

A second Phase III study that is collecting further evidence and observing the safety profile of VLA15 in children is currently ongoing.

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

Should the data for these Phase III studies be positive, Pfizer plans to submit a Biologics License Application to the FDA, EMA, and MAA in 2026.