Vaxcyte Vaccine Challenges Pfizer's Dominance: 31-Valent Vaccine Triumphs in Clinical Trials Over Prevnar 20, Market Landscape Set to Change Dramatically!

On September 3, Vaxcyte announced results from a direct comparison of its 31-valent pneumococcal conjugate vaccine, VAX-31, with Pfizer Prevnar 20. In Phase 1/2 clinical trials in adults 50 years of age and older, VAX-31 demonstrated excellent performance, meeting or exceeding immunogenicity standards for 31 serotypes in both the high-dose and medium-dose groups, and the vaccine was well tolerated. These results not only open up huge market potential for Vaxcyte, but also have the potential to reshape the pneumococcal vaccine landscape.

Pneumococcus is a major cause of invasive diseases, pneumonia and upper respiratory tract infections. Severe pneumococcal infection can lead to serious sequelae such as deafness, paralysis, and mental retardation. Pneumococcal vaccination is one of the most cost-effective and effective strategies to prevent such diseases. Pneumococcal vaccines are mainly divided into pneumococcal polysaccharide (PPV) vaccines and pneumococcal conjugate (PCV) vaccines, with the PCV vaccine dominating the market, while Pfizer's Prevnar series of vaccines occupy a leading position in the PCV vaccine market, including Prevnar 13 and Prevnar 20.

The Prevnar 20 vaccine is an iteration of the Prevnar 13 vaccine that covers seven additional serotypes (8, 10A, 11A, 12F, 15B, 22F, and 33F) that are associated with antibiotic resistance, disease severity, invasion potential, and prevalence of pediatric pneumococcal cases. The Prevnar 20 vaccine was approved by the U.S. Food and Drug Administration (FDA) in 2021 to prevent invasive disease and pneumonia caused by the 20 pneumococcal serotypes in the vaccine in adults 18 years of age and older, and was subsequently expanded to prevent pneumococcal infections in infants and young children.

In 2023, Pfizer's Prevnar series of vaccines reached $6.44 billion in sales, second only to Merck's HPV vaccine, and ranked second on the list of vaccine sales. The competitive focus of the next generation of PCV vaccines is mainly on the increase in the number of serotypes covered, which directly expands the protection of the vaccine.

According to a press release from Vaxcyte, the VAX-31 vaccine is a 31-valent pneumococcal conjugate vaccine capable of covering more than 95 percent of the invasive pneumococcal disease (IPD) serotypes prevalent in U.S. adults age 50 and older, with the potential to increase coverage by 12-40 percent over existing PCV vaccines. It is the broadest candidate for pneumococcal conjugate vaccine currently in clinical trials. The Phase 1/2 clinical study enrolled 1,015 healthy adults aged 50 years and older and was designed to evaluate the safety, tolerability and immunogenicity of VAX-31 versus Prevnar 20 (PCV20) at three doses. The study results showed that VAX-31 was well tolerated in all dose groups and showed a similar safety profile to Pfizer Prevnar 20 at all doses. For all 31 serotypes, VAX-31 exhibited a strong opsonophagocytosis (OPA) immune response in all dose groups.

For the 20 serotypes shared with PCV20, VAX-31 met the OPA response non-inferiority criteria at high doses for all 20 serotypes, with 18 serotypes having a geometric mean ratio (GMR) greater than 1.0 and 7 serotypes achieving a statistically higher immune response. At medium doses, all 20 serotypes met the OPA response non-inferiority criteria, 13 serotypes had GMR greater than 1.0, and 5 serotypes achieved a statistically higher immune response. At low doses, 18 serotypes met the OPA response non-inferiority criteria, 8 serotypes had GMR greater than 1.0, and 3 serotypes achieved a statistically higher immune response.

For the 11 additional serotypes unique to VAX-31, all three doses met the criteria for superiority. Based on these positive results, Vaxcyte plans to advance VAX-31 to a phase 3 clinical trial in adults. In addition to VAX-31, Vaxcyte is developing its 24-valent vaccine candidate, VAX-24, and expects to report safety and immunogenicity data from a Phase 2 infant study in the first quarter of 2025.