Vaxcyte Announces Positive Phase 1/2 Results for VAX-31 Pneumococcal Vaccine in Adults 50+

Vaxcyte, Inc., a clinical-stage vaccine innovation company, has announced promising topline results from their Phase 1/2 study of VAX-31, a 31-valent pneumococcal conjugate vaccine (PCV) candidate aimed at preventing invasive pneumococcal disease (IPD). The study involved 1,015 healthy adults aged 50 and older. These results have prompted the company to advance VAX-31 to an adult Phase 3 program.

The Phase 1/2 study evaluated the safety, tolerability, and immunogenicity of VAX-31 at three different dose levels (low, middle, and high). The vaccine demonstrated robust opsonophagocytic activity (OPA) immune responses for all 31 serotypes across all doses. It met or exceeded the regulatory immunogenicity criteria compared to Prevnar 20 (PCV20), the current market standard. Specifically, at the middle and high doses, VAX-31 achieved non-inferiority criteria for all 20 serotypes shared with PCV20. Moreover, at the high dose, VAX-31 showed higher average OPA immune responses for 18 of 20 serotypes compared to PCV20, with seven of these serotypes achieving statistically higher immune responses. The middle dose also showed superior geometric mean ratios (GMRs) for 13 of 20 serotypes, with five achieving statistically higher immune responses.

Additionally, all three doses of VAX-31 met the superiority criteria for the 11 serotypes unique to this vaccine and not included in PCV20. The company plans to determine the optimal VAX-31 dose before initiating the adult Phase 3 program.

The safety profile of VAX-31 was similar to that of PCV20, and it was well tolerated at all doses throughout the six-month evaluation period. These results suggest that VAX-31 has the potential to be a best-in-class pneumococcal vaccine, offering broader protection against both currently circulating and historically prevalent pneumococcal strains.

Vaxcyte’s VAX-31 Phase 1/2 clinical study was a randomized, observer-blind, active-controlled, dose-finding study. It assessed the safety, tolerability, and immunogenicity of a single injection of VAX-31 compared to PCV20 in healthy adults aged 50 and older. Different doses were tested: low (1.1mcg), middle (2.2mcg), and high (3.3mcg) for most serotypes, with serotypes 1, 5, and 22F receiving slightly higher doses. The study was conducted at 25 sites across the United States.

Vaxcyte is now preparing for a Phase 3 study aimed at adult indications of VAX-31. They plan to initiate this pivotal, non-inferiority study by mid-2025, with topline safety, tolerability, and immunogenicity data expected in 2026. For pediatric indications, the company intends to start a Phase 2 study for infants in the first quarter of 2025.

Pneumococcal disease, caused by the bacteria Streptococcus pneumoniae, leads to conditions such as meningitis, bacteremia, pneumonia, otitis media, and sinusitis. The disease poses a significant health threat, particularly to young children and older adults, due to its high mortality rates, antibiotic resistance, and potential for severe complications like meningitis. Current treatment options include antibiotics, but the rise of resistant strains highlights the urgent need for more effective vaccines.

VAX-31, designed to cover 31 serotypes, aims to provide protection against over 95% of IPD circulating in adults aged 50 and older in the United States. It offers a significant increase in coverage compared to current adult PCVs.

Vaxcyte, known for engineering high-fidelity vaccines, is developing broad-spectrum conjugate and novel protein vaccines to combat bacterial diseases. Their innovative approach uses modern synthetic techniques and advanced chemistry to produce complex vaccines efficiently. Besides VAX-31, Vaxcyte's pipeline includes VAX-24, a 24-valent PCV for infants, and other vaccines targeting various bacterial infections.

How to obtain the latest research advancements in the field of biopharmaceuticals?

In the Synapse database, you can keep abreast of the latest research and development advances in drugs, targets, indications, organizations, etc., anywhere and anytime, on a daily or weekly basis. Click on the image below to embark on a brand new journey of drug discovery!