The discontinuation of US participants is due to violation of Good Clinical Practice (GCP) at certain clinical trial sites run by a third-party clinical trial site operator, but not due to safety concerns related to the vaccine candidate
Pfizer and Valneva partly discontinue Phase 3 VALOR trial. (Credit: AVAKA photo from Pixabay)
Pfizer and Valneva will stop testing their Lyme disease vaccine, VLA15, in half of the US participants enrolled for Phase 3 Vaccine Against Lyme for Outdoor Recreationists (VALOR) clinical study.
In August last year, the two companies have partnered to initiate a Phase 3 VALOR trial to evaluate the efficacy, safety, and immunogenicity of their investigational vaccine candidate.
The discontinuation of US participants follows violation of Good Clinical Practice (GCP) at certain clinical trial sites run by a third-party clinical trial site operator.
The US drugmaker said that the discontinuation was not due to safety concerns related to the vaccine candidate, or prompted by a participant-reported adverse event.
Pfizer, as the study sponsor, will continue the clinical trial with other sites not operated by the third party, and will continues to enroll new participants at those sites.
Pfizer, in its statement said: “GCP is the international ethical and scientific quality standard for clinical trials that all clinical researchers need to follow. These standards are designed to put participants’ interests first and ensure high scientific integrity.
“Once Pfizer learned of potential violations of GCP, it conducted a thorough review of the operations and data collection at the clinical trial sites run by the third party and followed standard operating safeguards to determine the correct course of action.”
Both Pfizer and Valneva intend to work with regulatory authorities.
Pfizer will potentially submit a Biologics License Application (BLA) to the US Food and Drug Administration (FDA) and Marketing Authorisation Application (MAA) to the European Medicines Agency (EMA) in 2025.
The submissions are subject to successful completion of the Phase 3 studies and the agreement of these regulatory agencies to proposed modifications of the clinical trial plan.
VLA15 is an investigational multivalent protein subunit vaccine, the only Lyme disease vaccine candidate currently in clinical development.
Valneva and Pfizer jointly develop the vaccine under a collaboration agreement signed in April 2020, which was later updated in June 2022.
VLA15 leverages a 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.
The vaccine is designed to cover six most common OspA serotypes expressed by the Borrelia burgdorferi sensu lato species that are prevalent in North America and Europe.
Furthermore, VLA15 has shown a strong immune response and satisfactory safety profile in pre-clinical and clinical studies, said Pfizer.