Vaxcyte's Phase 1/2 Trial Enrolling Adults 50+ for VAX-31 Pneumococcal Vaccine

On January 29, 2024, Vaxcyte, Inc., listed on Nasdaq under PCVX, announced the completion of participant enrollment in its Phase 1/2 clinical trial for VAX-31, a 31-valent pneumococcal conjugate vaccine (PCV) aimed at preventing invasive pneumococcal disease (IPD) in healthy adults aged 50 and older. The company expects to release data on safety, tolerability, and immunogenicity from the study by the third quarter of 2024.

Grant Pickering, CEO and co-founder of Vaxcyte, emphasized the importance of completing the study enrollment, noting that it involved more than one thousand adults over the age of 50. He highlighted the potential of VAX-31 to cover up to 95% of IPD strains circulating among the U.S. adult population while also targeting strains currently managed by existing vaccinations. Pickering stated that the company's progress with its PCV franchise, including VAX-24 and VAX-31, could lead to multiple Phase 3 data announcements in the coming years and, potentially, a Biologics License Application submission.

The VAX-31 Phase 1/2 study is now fully enrolled and involves a randomized, observer-blind, active-controlled, dose-finding clinical trial. The objective is to assess the safety, tolerability, and immunogenicity of VAX-31 at low, middle, and high doses, benchmarked against Prevnar 20® (PCV20) in 1,015 healthy adults aged 50 or older.

Phase 1 of the study focused on evaluating safety and tolerability through a single injection of VAX-31 at three different doses compared to PCV20 among 64 adults aged 50 to 64. An independent Data Monitoring Committee reviewed the safety and tolerability data and recommended proceeding to Phase 2. Participants in Phase 1 will also be assessed for immunogenicity alongside those in Phase 2.

In Phase 2, the study will evaluate the same safety, tolerability, and immunogenicity parameters in 951 adults aged 50 and older. This phase will measure the immune response, including opsonophagocytic activity (OPA) and immunoglobulin G (IgG), at the three VAX-31 doses and compared to PCV20 for 20 common serotypes, along with 11 additional serotypes present only in VAX-31. Safety evaluations will continue for six months post-vaccination, and the study is conducted across 25 sites in the United States.

Pneumococcal disease (PD), caused by the Streptococcus pneumoniae bacteria, can lead to serious conditions such as meningitis, bacteremia, and pneumonia, among others. In the U.S., the disease afflicts approximately 320,000 people annually, resulting in around 150,000 hospitalizations and 5,000 deaths. Pneumococcal meningitis accounts for over half of all bacterial meningitis cases in the country. Antibiotic resistance among some bacterial strains has further complicated treatment, highlighting the need for more advanced vaccines.

Vaxcyte's PCV franchise, particularly VAX-24 and VAX-31, is designed to offer more comprehensive protection against IPD for both children and adults. These vaccines aim to cover a wide range of serotypes while maintaining efficiency through modern synthetic techniques such as advanced chemistry and Vaxcyte's XpressCF™ cell-free protein synthesis platform. VAX-31, in particular, promises the broadest coverage among available PCVs, addressing about 95% of IPD strains found in the U.S. adult population.

Vaxcyte continues its efforts to combat bacterial diseases with innovative vaccines, utilizing cutting-edge technology to improve immunization strategies and outcomes.