Research concerning candidate VLA15 has been discontinued across certain trial sites.
Pfizer has decided to discontinue a significant percentage of participants in the US who had been enrolled in the Vaccine Against Lyme for Outdoor Recreationists (VALOR) phase 3 clinical study.
The research is investigating the safety, efficacy and immunogenicity of Lyme disease vaccine candidate, VLA15. Participants – representing approximately half of the total recruited participants in the trial – are being discontinued following violations of Good Clinical Practice (GCP) at certain clinical trial sites run by a third-party clinical trial site operator.
It has been noted that the cessation of these participants was not due to safety concerns with the vaccine and was not prompted by a participant-reported adverse event.
GCP is the international ethical and scientific quality standard for clinical trials that all clinical researchers need to abide by. Such standards are in place to put participant interests first and ensure a high standard of scientific integrity.
When Pfizer learned of potential violations of GCP, it conducted its own review of the operations and data collection at the clinical trial sites run by the third party and, thereafter, followed standard operating safeguards to determine the appropriate course of action.
Research participants are now being notified and Pfizer has contacted the US Food and Drug Administration, as well as other regulatory agencies and the independent Institutional Review Board.
While VLA15 is still under investigation, companies have been encouraged by the data from the phase 2 clinical studies, which have demonstrated strong immunogenicity, and acceptable safety and tolerability profiles.
Furthermore, VLA15 is the only Lyme disease vaccine candidate currently in clinical development. The vaccine uses an established mechanism of action that targets the outer surface protein A of Borrelia burgdorferi, the bacteria that cause Lyme disease.
Lyme disease is a systemic infection transmitted to humans by infected Ixodes ticks and is considered the most common vector-borne illness across the Northern Hemisphere.