Pneumococcal Vaccine Candidate Shows Promise in Adults Aged 65 Years and Older

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VAX-24 is designed to prevent invasive pneumococcal disease and pneumonia, which can be most serious for infants, young children, older adults, and those with immune deficiencies or some chronic health conditions.

VAX-24 (Vaxcyte, Inc), a broad-spectrum 24-valent pneumococcal conjugate vaccine (PCV) candidate under evaluation for the prevention of invasive pneumococcal disease (IPD), showed positive results in a phase 2 study among adults aged 65 years and older.1

Streptococcus pneumoniae or pneumococcus bacterias. Credit: Maksym Yemelyanov - stock.adobe.com

Streptococcus pneumoniae or pneumococcus bacterias. Credit: Maksym Yemelyanov - stock.adobe.com


“We believe the positive results from the phase 2 study in adults aged 65 and older confirm the clinical potential of VAX-24 in the adult population. Based on the overall strength of our data and the well-established regulatory pathway, we look forward to meeting with regulators and advancing VAX-24 into a pivotal phase 3 study for which we expect topline data in 2025,” said Grant Pickering, chief executive officer and co-founder, of Vaxcyte, in a press release.1 “We developed VAX-24 with the goal of creating a best-in-class PCV that provides broader coverage and better immune responses compared to the standard-of-care vaccines. These data support that objective and also demonstrate the potential of our PCV franchise, including VAX-31, our 31-valent PCV candidate.”

Pneumococcal disease is an infection caused by Streptococcus pneumoniae bacteria. According to a Vaxcyte press release, the global incidence of pneumococcal disease is driven largely by emerging serotypes not covered by currently available vaccines. In the United States, approximately 900,000 patients get pneumococcal pneumonia each year, which results in an estimated 400,000 hospitalizations and 28,000 deaths. Pneumococci also cause more than 50% of all cases of bacterial meningitis in the United States, according to the press release.2

The VAX-24 trial reported data from the full 6-month safety assessment and prespecified pooled immunogenicity analyses from both this study in adults aged 65 and older and a prior phase 1 study of individuals aged 18-49 years and a phase 2 study in adults aged 50-64 years. In the study of adults aged 65 years and older, the 2.2 mcg dose of VAX-24 produced robust OPA immune responses for all 24 serotypes at all doses studied, which is similar to prior study findings in adult subjects. The VAX-24 2.2 mcg dose will now advance to a phase 3 trial.1

VAX-24 2.2 mcg produced an overall improvement in immune responses compared with what PCV20 showed in a prior phase 2 study in adults aged 50-64 years, according to Vaxcyte. Six-month safety data from both studies indicated that the safety and tolerability profile for VAX-24 is similar to PCV20 at all doses studied.

VAX-24 produced robust immune responses across all 24 STs at doses of 1.1 mcg, 2.2 mcg, and 2.2 mcg/4.4 mcg, which confirm findings from a prior phase 2 study in adults aged 50-64 (n=771).

Further, the VAX-24 2.2 mcg dose achieved target responses, as measured by the geometric mean ratio (GMR) of OPA responses for VAX-24 compared with PCV20, for all 24 STs, met the OPA response non-inferiority criteriafor 18 of 20 STs common with PCV20 and achieved the superiority criteria for all 4 additional STs unique to VAX-24.

VAX-24 is designed to prevent invasive pneumococcal disease and pneumonia, which can be most serious for infants, young children, older adults, and those with immune deficiencies or some chronic health conditions. It is intended to improve upon the standard-of-care PCV vaccines for both children and adults by covering the serotypes that are responsible for most of the residual pneumococcal disease currently in circulation. The FDA granted VAX-24 with Breakthrough Therapy designation in January 2023 for the prevention of IPD in adults.

“The data from both studies demonstrate VAX-24 safety and tolerability results similar to PCV20 and across cohorts, including older adults evaluated in this most recent study who are at increased risk for complications from IPD,” said Jim Wassil, executive vice president and chief operating officer of Vaxcyte, in a press release. “The immunogenicity results from our phase 2 studies reinforce the potential utility of our carrier-sparing approach and give us confidence in the potential for VAX-24 to provide an additional 10%-28% of coverage of IPD in adults compared to the standard-of-care PCVs.”

References

1. Vaxcyte Reports Positive Data from Phase 2 Study of its 24-Valent Pneumococcal Conjugate Vaccine Candidate, VAX-24, in Adults Aged 65 and Older and Full Six-Month Safety Data from Adult Phase 1/2 and Phase 2 Studies. News release. Vaxcyte. April 17, 2023. Accessed April 20, 2023. https://investors.vaxcyte.com/news-releases/news-release-details/vaxcyte-reports-positive-data-phase-2-study-its-24-valent

2. Vaxcyte doses first participants in phase 1/2 clinical study evaluating VAX-24 for the prevention of invasive pneumococcal disease and pneumonia in adults. News release. Vaxcyte; February 23, 2022. Accessed March 3, 2022. https://investors.vaxcyte.com/news-releases/news-release-details/vaxcyte-doses-first-participants-phase-12-clinical-study

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