Pfizer and Valneva have blamed “fewer than anticipated” Lyme disease cases for the failure of their phase 3 trial to hit its key goal. But the companies still plan to file the vaccine with regulators.
The partners had been assessing the six-valent vaccine, dubbed PF-07307405 or VLA15, in the late-stage Valor study of 9,437 individuals aged 5 years and older in areas of the U.S., Canada and Europe with high incidence of Lyme. After receiving the first dose of either PF-07307405 or a saline placebo, participants received a second dose at Month 2, a third dose between Months 5-9 and a fourth dose shortly before the start of the following Lyme season.
The study’s primary endpoint assessed the vaccine’s efficacy in reducing the rate of Lyme 28 days after the fourth and final dose. While the study demonstrated efficacy of 73.2% at this point, the lower bound of the 95% confidence interval was only 15.8%—below the required 20% threshold—meaning the study missed the mark.
The companies blamed this miss on the fact that “fewer than anticipated Lyme disease cases were accrued over the study period.”
It’s not the first time recruiting participants for the study has caused problems. Back in 2023, the companies were forced to pull half of the participants originally enrolled from the study when good clinical practice violations were discovered at some sites in the U.S. that were run by a third-party trial operator.
At the time, Valneva and Pfizer said this would delay their plans to file the vaccine for approval by a year.
Now, the companies aren’t willing to let the primary endpoint miss delay their approval ambitions any longer. In this morning’s release, the partners pointed to the fact that the lower bound of the 95% confidence interval was just above the required 20% mark for another pre-specified goal, where efficacy of 74.8% was demonstrated one day after the fourth dose.
“Given the clinically meaningful efficacy and the fact that the 95% confidence interval lower bound was above 20 in the second pre-specified analysis, Pfizer is confident in the vaccine’s potential and is planning submissions to regulatory authorities,” the Big Pharma said in the release.
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Pfizer Chief Vaccine Officer Annaliesa Anderson, Ph.D., said the efficacy of more than 70% is “highly encouraging and creates confidence in the vaccine’s potential to protect against this disease that can be debilitating.”
Lyme is a vector-borne illness most commonly found in the Northern Hemisphere and affects an estimated 476,000 people in the U.S. each year and an estimated 129,000 people in Europe, the companies said.
No vaccines are currently approved in the U.S. to protect against Lyme, with GSK having withdrawn a product in 2002 because of poor sales. The geographic range of the disease has expanded since then.
Valneva has a lot riding on the success of the vaccine, with CEO Thomas Lingelbach telling analysts last year that the VLA15 program is “the single largest catalyst for the company and its future development and strategic optionality.”
Under a 2020 deal between the two companies, Valneva received a $130 million upfront payment and was eligible for $35 million in development milestones, another $143 million in early commercialization milestones and tiered royalties on sales starting at 19%. In return, Valneva was required to fund 30% of all development costs while Pfizer has sole control over the vaccine’s commercialization.
