Vaxcyte, Inc. announced that the U.S. Food and Drug Administration has cleared the Company?s adult Investigational New Drug application for VAX-31, a 31-valent pneumococcal conjugate vaccine candidate designed to prevent invasive pneumococcal disease. Vaxcyte expects to initiate the VAX-31 Phase 1/2 clinical study in adults in the fourth quarter of this year and announce topline safety, tolerability and immunogenicity results in the second half of 2024. The VAX-31 Phase 1/2 clinical study is a randomized, observer-blind, active-controlled, dose-finding clinical study designed to evaluate the safety, tolerability and immunogenicity of VAX-31 compared to Prevnar 20® (PCV20) in approximately 1,000 healthy adults aged 50 and above.

The Phase 1 portion of the study will evaluate the safety and tolerability of a single injection of VAX-31 at three dose levels (low, middle and high) administered to approximately 64 healthy adults 50 to 64 years of age before the study progresses to Phase 2. Phase 1 participants will also be evaluated for immunogenicity, and the Phase 1 safety, tolerability and immunogenicity data will be pooled with the participants in the Phase 2 portion of the study. The Phase 2 portion of the study will evaluate the safety, tolerability and immunogenicity of a single injection of VAX-31 at the same three dose levels compared to that of PCV20 in approximately 936 healthy adults 50 years of age and older. Pneumococcal disease is an infection caused by Streptococcus pneumoniae bacteria.

It can result in IPD, including meningitis and bacteremia, and non-invasive PD, including pneumonia, otitis media and sinusitis. In the United States, approximately 320,000 people get pneumococcal pneumonia each year, which is estimated to result in approximately 150,000 hospitalizations and 5,000 deaths. Pneumococci also cause over 50% of all cases of bacterial meningitis in the United States.

Antibiotics are used to treat PD, but some strains of the bacteria have developed resistance to treatments. The morbidity and mortality due to PD are significant, particularly for young children and older adults, underscoring the need for a more broad-spectrum vaccine. VAX-31, an investigational 31-valent PCV candidate, is designed to prevent IPD, which is especially serious in infants, young children, older adults, and those with immune deficiencies or certain chronic health conditions.

The public health community continues to affirm the need for vaccines that offer broader protection to prevent IPD. Both VAX-31 and VAX-24, Vaxcyte?s 24-valent PCV candidate entering late-stage clinical development, are designed to improve upon the standard-of-care PCV vaccines for both children and adults by covering the serotypes that are responsible for a significant portion of IPD currently in circulation and are associated with high case-fatality rates, antibiotic resistance and meningitis. VAX-31 was designed to provide coverage for approximately 95% of the IPD currently circulating in the U.S. adult population.

Vaxcyte aims to efficiently create and deliver high-fidelity, broad-spectrum vaccines by using modern synthetic techniques, including advanced chemistry and the XpressCF? cell-free protein synthesis platform. With VAX-31 and VAX-24, Vaxcyte is deploying this approach with the intent of adding more pneumococcal strains without compromising the overall immune response.