Pfizer cans $500M staph vaccine hopeful after phase 2b trial failure

Pfizer in December stopped a midstage trial of its Staphylococcus aureus vaccine candidate. (Pixabay)

Pfizer had been hoping for big things from its Staphylococcus aureus vaccine candidate—until the shot failed a phase 2b trial, that is. And now, the company has pulled the plug, its new pipeline update (PDF) shows.

Analysts previously pinned the vaccine, known as PF-06290510, with a $489 million sales estimate by 2022, according to Evaluate. That would have been a welcome addition at a time when Pfizer is working to expand beyond the megasuccessful Prevnar 13.

But in December, the drug giant stopped the staph shot's phase 2b trial, which Pfizer had previously planned to expand into a phase 3 test. After sifting the data, an independent Data Monitoring Committee saw little chance the shot would hit its efficacy endpoint.

Pfizer had started the trial, designed to test the vaccine in adults who'd had spinal fusion surgery, way back in 2015. The vaccine was among a number of programs Pfizer hoped could help it expand its vaccines business beyond the megablockbuster pneumococcal shot Prevnar 13, whose sales growth has slowed.

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Though PF-06290510 is now history, Pfizer hasn't entirely given up on staph vaccines, at least not yet, a spokeswoman said Tuesday. The company is "evaluating next steps for the S. aureus vaccine development program and has not made a decision regarding its future."

Now, Pfizer will have to lean on other pipeline programs to fuel its vaccines future. The drugmaker is also advancing a Prevnar follow-up, a vaccine against C. diff, plus other candidates.

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Pfizer's vaccine sales for 2018 came in at $6.3 billion, up 6% over 2017’s $6 billion, the drugmaker reported (PDF) Tuesday. As it has in previous years, Prevnar made up the vast majority of the company’s haul in the field. Prevnar sales for the year were up 4% to $5.8 billion.