31-valent Pneumococcal Conjugate Vaccine Candidate Compares Well

Vaxcyte, Inc. today announced positive topline results from the Phase 1/2 study evaluating the safety, tolerability, and immunogenicity of VAX-31, the Company’s 31-valent pneumococcal conjugate vaccine (PCV) candidate designed to prevent invasive pneumococcal disease (IPD).

In this Phase 1/2 study, VAX-31 was observed to be well tolerated and demonstrated a safety profile at all doses studied through the full six-month evaluation period similar to Prevnar 20® (PCV20).

The VAX-31 vaccine candidate showed robust opsonophagocytic activity (OPA) immune responses for all 31 serotypes at all doses studied.

At the middle and high doses, VAX-31 met or exceeded the OPA response non-inferiority criteria for all 20 serotypes common with PCV20.

At the VAX-31 high dose, average OPA immune responses were greater for 18 of 20 serotypes compared to PCV20 (geometric mean ratio (GMR) greater than 1.0), with seven of these serotypes achieving statistically higher immune responses compared to PCV20.

At the middle dose, 13 of 20 serotypes had a GMR greater than 1.0, and five serotypes achieved statistically higher immune responses compared to PCV20. For all 11 incremental serotypes unique to VAX-31 and not in PCV20, all three doses met the superiority criteria.

Based on the strength of the results from this study, the Company has selected VAX-31 to advance to an adult Phase 3 program. The Company plans to select the VAX-31 dose before initiating the adult Phase 3 program.

Grant Pickering, Chief Executive Officer and Co-Founder of Vaxcyte commented in a press release on September 3, 2024, “Based on the strength and clarity of these data, we have selected VAX-31 for the adult indication and plan to initiate the pivotal, non-inferiority Phase 3 study by mid-2025 and announce topline data in 2026."

"We intend to initiate the remaining VAX-31 Phase 3 studies in 2025 and 2026 and submit a Biologics License Application subject to the results of these studies.”

Pneumococcal disease is an infection caused by Streptococcus pneumoniae bacteria, leading to thousands of hospitalizations yearly in the U.S.