FDA adcomm backs Pfizer’s RSV vaccine, preps for GSK

Published: Mar 01, 2023

By Tristan Manalac

BioSpace

Tuesday, the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) deemed there were enough data to support Pfizer’s respiratory syncytial virus (RSV) vaccine RSVpreF in adults aged 60 and older.

This vote comes a day before the same panel will deliberate over GSK’s investigational RSV shot.

Voting 7-4, the VRBPAC found Pfizer’s data sufficiently demonstrates the safety of its RSV vaccine candidate. The panel was split the same way for Pfizer’s efficacy data. Both safety and efficacy votes had one abstention.

The FDA’s advisory committee is a recommending body comprised of independent experts. The Agency is not required to follow its counsel, though it often does. The final regulatory verdict for Pfizer’s RSV vaccine is due May 2023.

In a briefing document submitted before the meeting, Pfizer presented key Phase III efficacy and safety data for its RSV shot. The candidate had a 66.7% efficacy in preventing RSV-associated lower respiratory tract infections (LRTI) with at least two symptoms during the first RSV season. This figure jumped to 85.7% when considering LRTI episodes with at least three symptoms.

As for safety, Pfizer pointed to the mostly mild or moderate local and systemic reactions associated with its candidate. Adverse events, including those that were serious or life-threatening, were balanced between treatment and placebo arms.

The panel, however, flagged two cases of Guillain-Barré syndrome (GBS) out of 19,942 vaccinated participants, potentially related to Pfizer’s candidate. Given a background rate of 1.5 to 3 cases per 100,000 people, these GBS cases were “considered an important potential risk,” the VRBPAC wrote in its briefing document.

The FDA has requested that Pfizer include GBS and other immune-mediated demyelinating conditions in its pharmacovigilance plan and run a post-marketing safety study for its RSV shot.

Pfizer won priority review for the Biologics License Application for its RSV vaccine candidate in December 2022.

Up Next: GSK

GSK is slightly ahead of Pfizer in the RSV race, winning its priority review a month earlier.

The VRBPAC is set to discuss Wednesday whether GSK’s safety and efficacy data support the approval of its RSV vaccine candidate.

In its briefing documents, GSK presented promising efficacy numbers for its candidate, with a vaccine efficacy of 82.6% in preventing RSV-confirmed lower respiratory tract disease (LRTD) in adults aged 60 years and above. The vaccine was even better at preventing severe LRTD in patients 70 to 79 years old.

As in the case of Pfizer, the VRBPAC also flagged one case of GBS, which it deemed related to GSK’s vaccine. GSK is not required to run a safety trial for GBS.

Source: BioSpace