Pfizer's Prevnar 13 follow-up hits the mark in phase 3, aims for 2020 approval filing

Pfizer building
Pfizer is planning to file its 20-valent pneumococcal shot by the end of 2020. (Tracy Staton)

Pfizer has set out on a costly quest to improve on its Prevnar 13 and capture the next-gen pneumococcal vaccine market. Now, the company has reported positive top-line results for a pivotal trial, potentially setting up a filing by the end of 2020. 

The study tested the vaccine in 3,880 adults 18 and older who haven’t previously been vaccinated against pneumococcal disease. Investigators looked at immune responses for each of the 20 serotypes included in the candidate vaccine.

The 20-valent shot met its primary endpoint for 19 of 20 strains compared with the same strains covered by existing vaccines—including 13 strains in Pfizer's own Prevnar 13. It narrowly missed the mark on the last strain.

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The vaccine matched up to all 13 strains in Prevnar 13, plus 6 of 7 additional strains covered by Merck’s Pneumovax 23. 

For the secondary endpoint, investigators looked at immunogenicity for adults specifically in the 18-to-59 age range, and the vaccine met the endpoint for all 20 strains. Based on its discussions with the FDA, Pfizer says the data are “expected to meet licensure criteria.” 

“We are encouraged by the results from this study and remain on track to file the adult 20vPnC indication with the FDA by the end of 2020,” Pfizer’s senior vice president and head of vaccine R&D Kathrin Jansen said in a statement

The results show the vaccine is “expected to have a comparable safety profile and likely be as effective as Prevnar 13 in helping prevent invasive pneumococcal disease and pneumonia due to the 13 serotypes in Prevnar 13, and also effective against disease due to the seven additional pneumococcal serotypes in adults 18 years of age or older," she added.

RELATED: Pfizer 'all in' on advancing next-generation pneumococcal vaccine candidate: CFO 

RBC Capital Markets analyst Randall Stanicky said the results “provide some comfort around the derisking of 20-valent in protecting the vaccine franchise.” 

Despite the “narrow miss on one of the seven additional serotypes,” the analyst believes Pfizer will point to the “totality” of the evidence and the “narrowness” of the lone miss. Even Prevnar 13 missed on three of 13 serotypes in a pivotal study, he added. 

The drugmaker is conducting two more phase 3 studies of the vaccine in adults with prior history of pneumococcal vaccination and those without. In total, the phase 3 program has enrolled more than 6,000 people. Results from the other two studies are expected in the next few months, Pfizer said. 

RELATED: Racing with Merck, Pfizer wins FDA 'breakthrough' tag for 20-valent pneumococcal vaccine 

Racing with rival Merck, Pfizer is advancing the vaccine as a follow-up to Prevnar 13. The vaccine franchise generated $5.85 billion globally last year.

Meanwhile, Merck has a 15-valent candidate in phase 3 studies. Both vaccine programs have won FDA breakthrough therapy designations.

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