Pfizer’s RSV shot clears FDA adcomm; now it’s GSK’s turn

An FDA panel of experts has recommended approval of Pfizer’s respiratory syncytial virus (RSV) vaccine in a pair of votes, neither of which was a resounding win.

The Vaccines and Related Biological Products Advisory Committee (VRBPAC) voted by 7 to 4 with one extension that the RSVPreF shot was safe, and by the same margin that it was effective when used to reduce RSV-related lower respiratory infections (RTIs) in people aged 60 years and over.

The dissenting voices raised concerns about a link between the vaccine and Guillain Barré syndrome, a rare disorder in which the immune system attacks nerves that was highlighted in FDA reviewer documents published ahead of the meeting.

It is a rare condition, affecting up to 3 people per 100,000 in the over 60 age bracket, but there were two cases in Pfizer’s ongoing RENOIR study of its vaccine, which enrolled around 37,000 subjects.

Some advisors also said they would like to see the final data from the vaccine first, particularly as the number of RTI cases in RENOIR is fairly low.

There was also debate about the population of patients in the trial, with some panellists arguing that it included too few subjects who were vulnerable to RSV complications, such as those with heart disease or chronic obstructive pulmonary disease (COPD).

Pfizer presented interim results from RENOIR last August, showing 66.7% efficacy in preventing RSV-related RTIs with two or more symptoms, and 85.7% efficacy against three or more symptoms.

The FDA will now have to take its experts’ advice as it works towards completing its review of RSVPreF, which has the proposed trade name Abrysvo. It is expected to make a decision in May.

Currently, there are no approved vaccines for RSV on the market, and Pfizer is in a close race with GSK to bring the first one to market.

GSK’s rival jab now in the spotlight

GSK’s RSVPreF3 jab will come under the scrutiny of the VRBPAC later today, and showed similar, but slightly higher, levels of efficacy in its AReSVi-006 trial reported in October. According to the FDA briefing document, it saw one case of Guillain Barré syndrome thought to be related to vaccination in around 25,000 subjects.

The rivalry between the two pharma companies has also spilled over into the courts. Last June, Pfizer filed a lawsuit seeking to invalidate three patents covering GSK’s vaccine in a UK court.

RSV causes around 177,000 hospitalisations in the over-60s in the US each year and 29,000 deaths, and analysts have predicted that vaccines could generate a market worth several billion dollars a year worldwide.

“In older adults, RSV can result in serious illness, hospitalisation, or even death, so there is a significant need to protect this at-risk population,” said Annaliesa Anderson, chief scientific officer of Pfizer’s vaccine division.

“We are encouraged by the outcome of today’s VRBPAC meeting, as it is a testament to the strength of our science and dedication to bringing this important vaccine candidate to the market,” she added.