Pfizer is dropping a significant portion of participants from a phase 3 vaccine trial, the company announced on Feb. 17.
Approximately half of the participants are being discontinued from the trial, which is examining the safety and efficacy of an experimental vaccine against Lyme disease, Pfizer and Valneva, a French company, said in a joint statement.
The companies blamed rules violations committed at some of the trial sites, which they said were being run by a third-party contractor.
Good Clinical Practice (GCP) is an international standard developed by the United States and other countries to guide clinical trials. The rules are aimed at running ethical trials.
The specific violations were not detailed, nor was the third-party contractor named.
Pfizer and Valneva did not immediately respond to requests for more information.
“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,” Pfizer and Valneva said in their statement.
The trial is continuing at sites that are not run by the contractor. Pfizer is enrolling new participants at those sites. Pfizer said it notified the U.S. Food and Drug Administration and other regulatory agencies, as well as the review board overseeing the study.
Pfizer and Valneva are preparing to submit applications to American and European regulators in 2025 for approval for the vaccine, pending completion of phase 3 trials.
Lyme Disease Trial
The companies announced the trial in 2022.In that announcement, they said the trial would enroll about 6,000 participants aged 5 and older and would be conducted at up to 50 locations across Europe and the United States. Some participants were going to receive the vaccine candidate, while others would receive placebo.
Data from phase 2 studies showed the vaccine produced a strong immune response, according to the companies.
No vaccine is currently available for Lyme disease in the United States. A vaccine called LYMERix was approved in the country in 1998, but was discontinued by the manufacturer, GlaxoSmithKline, in 2002.
GlaxoSmithKline cited a lack of demand. The withdrawal came amid increasing concerns of possible side effects, including arthritis.
Lyme disease is caused when an infected tick bites a person. Symptoms initially include fever and fatigue. If left untreated, Lyme disease can cause serious problems, including difficulty moving.
