GSK claims first positive Phase 3 result for an RSV vaccine

Dive Brief:

  • GSK’s experimental vaccine for respiratory syncytial virus prevented disease in adults 60 and older, the company said Friday, clearing the way for the British drugmaker to ask regulators later this year to approve the shot.
  • GSK didn’t provide specific details in its announcement. However, trial monitors determined success based upon an interim analysis that, per the study’s design, occurred once researchers identified lower respiratory tract infections in 56 participants. The drugmaker enrolled about 25,000 volunteers in 17 countries.  
  • The positive Phase 3 result is the first recorded for a prospective RSV vaccine after decades of research. At the same time, several other companies including Pfizer, Johnson & Johnson and Moderna are following GSK closely. Pfizer should report data from a late-stage trial by the end of the year. 

Dive Insight:

RSV is a common condition, causing infections that lead to 360,000 hospitalizations and 24,000 deaths every year, according to GSK. Preventing those outcomes represents a significant, untapped opportunity for vaccine developers and research has largely focused on three groups — older adults, pregnant women and children. Cowen analysts estimate the global market for adults alone may be worth $6.2 billion in 2028.

Previous efforts to develop a preventive shot have faltered. For example, one project stimulated antibodies that didn’t protect patients, and worse, triggered an enhanced form of the disease. However, development has accelerated in recent years because of a discovery by National Institutes of Health scientists that helped drugmakers better understand how to spur an immune response to the virus.

That discovery involved targeting a key protein, called F, before it changes shape and is able to enter human cells. GSK, Pfizer, J&J and Moderna all developed vaccines that focus on this “prefusion” form of the protein. GSK’s shot, the furthest along of the group, also includes an immune-boosting adjuvant.  

While GSK didn’t specify how well its shot prevented infections or poor health outcomes, the company did report that the study’s primary goal “was exceeded with no unexpected safety concerns observed,” that it worked equally well against two key strains of the virus and in patients aged 70 and older.

“Given the importance of these data, we plan to engage with regulators immediately and anticipate regulatory submissions in the second half of 2022,” said Hal Barron, GSK’s outgoing chief medical officer.

Still, Jefferies analyst Peter Welford wrote in a June 10 note to clients that based on previous comments from GSK executives, he believes the vaccine reduced the frequency of RSV cases by at least 75% in vaccinated volunteers when compared to those who received a placebo.

Welford forecasts potential peak sales of $2.5 billion a year from the vaccine, although that number will depend on how GSK’s shot compares to its close-following rivals. Use of an adjuvant “could contribute to higher protective immunity against lower respiratory tract disease, and hence hospitalizations” when compared to other shots, he added, although that has yet to be proven. 

GSK halted tests of its vaccine pregnant women in February because of an undisclosed safety finding.

The drugmaker began its Phase 3 trial in older adults in January 2021. Pfizer brought its shot into late-stage testing last August, while J&J and Moderna followed soon afterwards. Pfizer and J&J started their trials before the beginning of the winter respiratory infection season in the Northern Hemisphere, which could soon enable data readouts.

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