Mixed Phase III result for Pfizer's 20-valent pneumococcal conjugate vaccine in infants

US pharma giant Pfizer (NYSE: PFE) on Friday announced top-line results from its pivotal US Phase III study (NCT04382326) in infants evaluating its 20-valent pneumococcal conjugate vaccine candidate (20vPnC) for the prevention of invasive pneumococcal disease (IPD) caused by the 20 Streptococcus pneumoniae (pneumococcus) serotypes contained in the vaccine for the pediatric population.

The study had two co-primary objectives, associated with immunogenicity responses one month after the third and fourth doses of the four-dose vaccination series, respectively: non-inferiority (NI) of the percentage of participants with predefined serotype-specific immunoglobin G (IgG) concentrations after Dose 3 and NI of IgG geometric mean concentrations (GMCs) after Dose 4. All 20 serotypes met the co-primary objective of NI of IgG GMCs after Dose 4.

14 of the 20 serotypes met the co-primary objective of NI of the percentage of participants with predefined IgG levels after Dose 3 (two serotypes missed by a wider margin, while four narrowly missed), and all serotypes met non-inferiority for the key secondary objective of IgG GMCs after Dose 3. All 20 serotypes elicited robust functional responses (OPA) and increases in antibody responses after Dose 4, with the totality of data supporting the potential benefit of all serotypes in this 20-valent vaccine candidate.