Core Insights - Vaxcyte, Inc. is advancing its VAX-31 infant Phase 2 randomized, dose-finding study to the final stage, focusing on a 31-valent pneumococcal conjugate vaccine designed to prevent invasive pneumococcal disease (IPD) in infants [1][2][3] - The VAX-31 Optimized Dose aims to elicit stronger immune responses in infants, with the majority of serotypes dosed at 4.4mcg and the balance at 3.3mcg, potentially covering approximately 92% of IPD and 93% of acute otitis media in U.S. children under five [1][3][6] - The company plans to release topline data from the primary immunization series and booster dose by the end of the first half of 2027 [1][2] Company Overview - Vaxcyte is a clinical-stage vaccine innovation company focused on developing high-fidelity vaccines to combat bacterial diseases [1][8] - The company is also developing VAX-24, a 24-valent PCV candidate, which aims to cover more serotypes than any existing infant PCV on the market [8][9] - Vaxcyte utilizes the XpressCF platform for cell-free protein synthesis, enhancing its ability to produce complex vaccines [9] Study Details - The VAX-31 infant Phase 2 study is a randomized, double-blind, active-controlled trial evaluating safety, tolerability, and immunogenicity compared to Prevnar 20 (PCV20) [4][10] - The study will enroll approximately 900 participants, including those previously in the Low Dose arm, and will assess immune responses through serotype-specific immunoglobulin G (IgG) seroconversion rates [2][10] - The study consists of three stages, with the first stage completed and the second stage modified to include the new Optimized Dose arm [4][10] Disease Context - Pneumococcal disease, caused by Streptococcus pneumoniae, is a leading cause of vaccine-preventable deaths among children under five, with significant morbidity and mortality [5][6] - The disease can lead to severe conditions such as meningitis and bacteremia, highlighting the urgent need for a broader-spectrum vaccine [5][6] Regulatory Status - The FDA has expanded the Breakthrough Therapy designation for VAX-31 to include the prevention of pneumonia caused by Streptococcus pneumoniae, indicating potential substantial improvement over existing therapies [7]

VAX-31 Phase 1/2 Study Results Overview - VAX-31 demonstrated a safety profile similar to Prevnar 20® (PCV20) at all doses studied[14] - VAX-31 induced robust OPA immune responses for all 31 serotypes (STs) at all doses studied, with all three doses advanceable to Phase 3[14] - The VAX-31 data validate the potential of Vaxcyte's carrier-sparing platform to deliver the broadest-spectrum PCVs[15] Immunogenicity Data - High and Middle doses of VAX-31 met or exceeded OPA regulatory immunogenicity criteria for all 31 STs, while the Low dose met the criteria for 29 of 31 STs[17] - For the 20 STs common with PCV20, the High dose had 18 with GMR greater than 10, the Middle dose had 13 with GMR greater than 10, and the Low dose had 8 with GMR greater than 10[17] - For the 11 additional STs unique to VAX-31, all 11 met the superiority criteria at all doses[17] Clinical Development Plan - Vaxcyte plans to initiate a Phase 3 pivotal, non-inferiority study for VAX-31 in adults by mid-2025, with topline results expected in 2026[18] - Vaxcyte plans to initiate a VAX-31 infant Phase 2 study in 1Q:2025 following IND submission and clearance[18] Market Opportunity - The pneumococcal vaccine market is expected to reach approximately $13 billion by 2027[105] - VAX-31 is designed to increase coverage to more than 95% of IPD circulating in U S adults[104]