Merck strides onto Pfizer’s turf, posting pivotal vaccine data and heading to regulators

Merck & Co. has revealed data from a phase 3 trial designed to knock Pfizer’s pneumococcal vaccine off its perch. The vaccine candidate matched Prevnar 20 for shared serotypes and performed better for 10 of its 11 unique serotypes, positioning Merck to file for approvals around the world.

Pfizer is the dominant force in the adult U.S. pneumococcal vaccine market, with Prevnar 20 holding a 95% share in the third quarter, but Merck believes its V116 candidate provides broader protection than the competition. The drugmaker shared top-line data from a phase 3 trial of V116 in July and followed up Tuesday with a closer look at the results at the World Vaccine Congress West Coast.

In adults aged 50 years and older, V116 elicited non-inferior immune responses compared to PCV20, the generic name for Prevnar 20, for all 10 serotypes common to both vaccines. The immune responses in recipients of V116 were superior for 10 of the 11 serotypes that are included in Merck's asset but not in Prevnar 20.

Eight of the serotypes covered by V116 are completely unique to the candidate, with no approved vaccines designed to provide protection against them. Based on Centers for Disease Control and Prevention data, Merck estimates those eight serotypes account for approximately 30% of invasive pneumococcal disease (IPD) in individuals 65 years of age and older.

Merck executives have been out banging the drum for V116 in recent weeks. V116 only covers one serotype more than Prevnar 20, and covers fewer serotypes than 24-valent candidates in development at GSK—as a result of its $3.3 billion Affinivax buyout—and Vaxcyte. But Merck is trying to shift the numbers that people focus on.

“With one serotype more than PCV20, we're going to give about 30% more protection from an IPD perspective,” Jannie Oosthuizen, president, Merck U.S. Human Health, said at a conference earlier this month. “And if you compare that even to the 24-valent that is coming with Vaxcyte and Affinivax, we're still going to beat that by 25%. That will give them about 60% coverage of disease versus 85% with V116.”

Oosthuizen made the comment when an analyst at the UBS Biopharma Conference asked what investors are overlooking about Merck earlier this month. Caroline Litchfield, Merck’s chief financial officer, made a similar point at a Jefferies event, claiming the coverage of V116 is “much better than any other product out there today or any other product that is in development today.”

Merck is laying the foundation for a push to change thinking around pneumococcal vaccination. Talking to investors on a third-quarter results call last month, Dean Li, president of Merck Research Laboratories, framed V116 and its approved pediatric sibling Vaxneuvance as part of an attempt to bring a “precision medicine mindset” to vaccines, covering the right serotypes, at the right stage of life.