Merck pits its pneumococcal shot against Pfizer's mammoth Prevnar in head-to-head phase 3

Merck
Merck pushed its 15-valent pneumococcal shot V114 into phase 3 testing. (Merck on YouTube)

Merck & Co. has a big target in mind for its pneumococcal conjugate vaccine V114: no less than Prevnar 13, the world's best-selling shot. And now, the U.S. drugmaker has put V114 a phase 3 course that includes a head-to-head trial against the Pfizer shot.

The New Jersey drugmaker rolled out plans Tuesday for two phase 3 studies of its shot. For one trial, investigators will recruit 600 participants and test Merck's vaccine against the Pfizer shot. Both cohorts will receive Merck's Pneumovax 23 one year after their initial immunizations. In the second study, the team will test V114, followed by Pneumovax 23 after eight weeks, in 300 adults with HIV.

V114 is designed to protect against 15 serotypes of pneumococcal disease, including all of the serotypes included in Pfizer's blockbuster shot.

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V114 is among a group of pipeline shots Merck executives have praised in recent months. The company is also pinning hopes on its personalized cancer vaccine partnership with Moderna, plus programs in cytomegalovirus, RSV and dengue.

Merck's vaccines business needs a next wave of products to keep growth coming. Among Merck's marketed shots, the HPV vaccine Gardasil 9 is continuing its upward drive, generating a 6% sales increase last year to $2.3 billion. In fact, strong Gardasil demand has created a shortage in the U.K., a spokesperson recently confirmed. 

But at least one Merck shot is expected to struggle in the face of new competition. The shingles vaccine Zostavax pulled in $688 million last year but it's facing a new rival in key markets—GlaxoSmithKline's Shingrix. And that rivalry is already starting to take a toll. After Shingrix's U.S. launch, Zostavax's fourth-quarter sales slipped 45%. 

RELATED: Don't sweat Prevnar's problems, Pfizer R&D chief says. New vaccines are on their way 

If Merck's in-development pneumococcal conjugate vaccine generates strong data and wins FDA approval, though, it could challenge Prevnar 13 in a multibillion-dollar market. Datamonitor Healthcare analysts currently project a second quarter 2020 launch for the Merck product in the U.S. and Europe.

But that doesn't mean the challenge would be easy. Pfizer is working on a midstage 20-valent pneumococcal shot intended to follow the ultrasuccessful Prevnar 13. In a recent conversation with Bernstein analyst Tim Anderson, Pfizer R&D head Mikael Dolsten told the analyst he believes the shot "will position the company well for the next decade." 

Plus, the market itself presents its own challenges. The Prevnar franchise has seen growth slip in recent quarters, thanks to a shrinking pool of patients not yet vaccinated. Pfizer executives recently said they expect sales for the vaccine to be flat this year. Last year, the Prevnar franchise pulled in $5.6 billion in global sales, a sizable decrease from 2015's high point of $6.25 billion.