Pfizer and Paris-based partner Valneva have decided to discontinue testing their Lyme disease vaccine in roughly half of U.S. participants, citing a breach of clinical trial guidelines by a third-party contractor.
The VALOR phase 3 clinical study is investigating the efficacy, safety and immunogenicity of Lyme disease vaccine candidate, VLA15.
Pfizer learned of potential violations of Good Clinical Practice (GCP) at certain clinical trial sites run by a third-party clinical trial site operator. After conducting a review of the operations and data collection at the sites, Pfizer determined that approximately half of the total recruited participants will be discontinued.
According to Pfizer, the discontinuation was not due to any safety concerns with the investigational vaccine and was not prompted by a participant-reported adverse event.
Pfizer did not disclose specific numbers. When the partners kicked off the trial back in August, they noted a goal of enrolling approximately 6,000 participants 5 years of age and older in Lyme disease-endemic regions in Europe and the U.S. The Clinicaltrials.gov registry notes a goal of 18,000 participants, and lists 79 different trial sites.
VLA15 — an investigational multivalent protein subunit vaccine — 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. In April 2020, Pfizer bought the rights to commercialize VLA15 from Valneva in co-development deal worth up to $308 million. The deal was signed when phase 2 clinical trials testing a two-dose series of the vaccine were already in progress. According to Pfizer, VLA15 is the only Lyme disease vaccine candidate currently in clinical development.
The VALOR clinical trial remains ongoing with other sites not operated by the third party, and Pfizer continues to enroll new participants at those sites.
