VAX-24 Phase 2 Trial Enrollment Complete for Infant IPD Prevention

On March 4, 2024, Vaxcyte, Inc., a company specializing in vaccine innovation and listed on Nasdaq under PCVX, announced the successful completion of enrollment for its Phase 2 trial of VAX-24, a 24-valent pneumococcal conjugate vaccine (PCV). This vaccine, intended to protect against invasive pneumococcal disease (IPD), is currently being tested in healthy infants. The company plans to release initial safety, tolerability, and immunogenicity data from the primary three-dose immunization series by the end of the first quarter of 2025, with further data on the booster dose expected by the end of that year.

The CEO and Co-founder of Vaxcyte, Grant Pickering, highlighted that completing the enrollment represents a significant developmental milestone for both VAX-24 and VAX-31 PCV candidates. He stated that VAX-24 aims to cover more serotypes than existing infant vaccines. Jim Wassil, the Executive Vice President of Vaxcyte, noted the continuing need for vaccines like VAX-24 and VAX-31 that offer broader protection given IPD's impact on infants, where current vaccines fall short.

The VAX-24 Phase 2 study includes 802 infants and is designed to assess the safety, tolerability, and immunogenicity of three different doses of VAX-24 compared to VAXNEUVANCE™ in the initial stage and to Prevnar 20® in the subsequent stage. The study follows a three-dose primary vaccination series administered at two, four, and six months, with a booster at 12–15 months, in alignment with ACIP guidelines. The trial's endpoint will evaluate immune responses 30 days after the third and fourth doses, focusing on achieving a specific level of anti-pneumococcal polysaccharide serotype-specific IgG responses.

The study is being held at 32 locations across the United States. More information can be found on the ClinicalTrials.gov website with the identifier NCT05844423.

Pneumococcal disease is caused by Streptococcus pneumoniae and can lead to severe conditions such as meningitis and bacteremia, as well as non-invasive diseases like pneumonia and otitis media. Each year in the U.S., pneumococcal pneumonia infects approximately 320,000 people, leading to around 150,000 hospitalizations and 5,000 deaths. The disease causes about half of all bacterial meningitis cases in the country. Antibiotic resistance among pneumococcal strains elevates the need for advanced vaccines.

Vaxcyte’s PCV franchise includes VAX-24 and the next-generation 31-valent VAX-31, which are designed to cover more serotypes than existing vaccines, maintaining coverage of previously circulating strains while also addressing new variants associated with high mortality and antibiotic resistance. The company employs modern synthetic techniques, such as the XpressCF™ cell-free protein synthesis platform, to develop high-fidelity vaccines.

Vaxcyte holds a special designation for expedited development from the U.S. Food and Drug Administration for VAX-24, based on promising early results for adults. The company is determined to tackle bacterial infections that, if untreated, can have serious health and economic impacts.