USA – Pfizer Inc. and Valneva SE, have announced additional positive Phase 2 data for their Lyme disease vaccine candidate, VLA15, the only Lyme disease vaccine candidate currently in clinical development, with a Phase 3 trial set to start in the third quarter of 2022.

The trial will evaluate VLA15 in adults and pediatric subjects aged five and up, and it is scheduled to begin in 2022, subject to regulatory approval.

Valneva sold the rights to the multivalent protein subunit vaccine VLA15 to Pfizer in 2020 for US$130 million up front.

The agreement was made while phase 2 clinical trials for a two-dose series of the vaccine were already underway.

Pfizer and Valneva launched a third midphase trial last year to compare two- and three-dose VLA15 regimens, yielding the data that has now convinced the partners to move into phase 3.

The phase 2 clinical trial discovered that VLA15 was immunogenic in adults when given in either regimen, adding to previous evidence.

Adding a third VLA15 dose, on the other hand, increased the level of antibodies against an outer surface protein. The three-dose elicited a stronger immune response in patients, propelling the study into phase 3.

Pfizer’s success in Phase 3 could give it a clear advantage in a growing market. If approved VLA15, has the potential to make a significant impact.

Based on the new findings, Valneva and Pfizer intend to proceed with a three-dose primary series vaccination schedule in a planned Phase 3 clinical trial after data showed that it successfully elicited immune responses in patients.

Since the late 1990s, the number of reported cases of Lyme disease in the United States has tripled, possibly due to changes in land use that have brought more humans into close contact with tick hosts.

Whatever the cause, the increase has prompted the Centers for Disease Control and Prevention to declare that new tools for preventing tick-borne diseases are urgently needed. VLA15 is a rare example of such a tool.

VLA15 Dose regimen

Pfizer’s three-dose regimen gives VLA15 the second dose at two months and the third at six months. The two-dose regimen misses out the shot at two months.

Because the third dose was found to be beneficial in the phase 2 trial, the partners intend to test that regimen in the late-phase study.

VLA15 is a protein that targets the outer surface protein A of the bacteria that cause Lyme disease. In July 2017, the FDA granted it fast track designation.

SmithKline Beecham received FDA approval for a Lyme disease vaccine LYMERix, in the late 1990s, but it was pulled from the market a few years later, due to insufficient demand, according to the company.

Around the same time, Pasteur Mérieux Connaught, now Sanofi, abandoned plans to seek approval for a Lyme vaccine.

Following vaccination, some patients who received LYMERix complained of arthritis. Despite the fact that an FDA investigation determined that the evidence was insufficient to establish a link between the two, demand fell and the drug was withdrawn.

VLA15 is now the only Lyme vaccine in clinical development, according to Valneva. This provides Pfizer with the opportunity to add a growth driver to its massive vaccine unit, but it will have to overcome the legacy of its previous commercial failure to do so.

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