First Patients Dosed in Clinical Trial of VAX-24 for Prevention of Invasive Pneumococcal Disease, Pneumonia

The first participants have been dosed in a phase 1/2 clinical study of VAX-24, a 24-valent pneumococcal conjugate vaccine (PCV) candidate designed to prevent invasive pneumococcal disease and pneumonia in adults.

Pneumococcal disease is an infection caused by Streptococcus pneumoniae bacteria. According to a Vaxcytpress 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.

Although antibiotics are used to treat pneumococcal disease, some strains of the bacteria have developed resistance. The morbidity and mortality due to pneumococcal disease are highly significant, particularly for young children and older adults, highlighting the need for a more broad-spectrum vaccine.

VAX-24 is an investigational 24-valent PCV candidate 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.

According to Vaxcyte, the proof-of-concept study is expected to announce topline safety, tolerability, and immunogenicity results by the end of 2022. It is a randomized, observer-blind, dose-finding, controlled study in healthy adults.

“Initiating the VAX-24 phase 1/2 clinical study is an important step forward in the development of our lead, broad-spectrum PCV candidate, and for our company,” said Grant Pickering, CEO and co-founder of Vaxcyte, in the press release. “We developed VAX-24, using advanced chemistry and our novel XpressCF platform, with the intent to deliver the broadest spectrum PCV to effectively prevent pneumococcal disease and we look forward to announcing the topline safety, tolerability, and immunogenicity results from this clinical study by the end of the year.”

The phase 1 portion of the study will evaluate the safety and tolerability of a single injection at 3 dose levels and compared to Prevnar 20 in approximately 64 healthy adults aged 18 to 49 years. The phase 2 portion will then evaluate the safety, tolerability, and immunogenicity of a single injection at 3 dose levels and compared to Prevnar 20 in approximately 800 healthy adults between the ages of 50 and 64 years.

As part of the prespecified immunogenicity endpoints, researchers will assess the induction of antibody responses using immunoglobulin G and opsonophagocytic activity at each of the 3 VAX-24 doses and compared to Prevnar 20. Furthermore, for the additional 4 serotypes contained in VAX-24 and Pneumovax 23 but not in Prevnar 20, researchers will analyze the 4-fold rise in antibody titers. The trial will be conducted at approximately 13 sites in the United States.

“The global impact of pneumococcal disease remains significant and underscores the importance of advancing the development of VAX-24 and VAX-XP, our PCV candidate with an expanded breadth of coverage of greater than 30 strains,” said Jim Wassil, chief operating officer at Vaxcyte, in the press release. “Our PCV franchise is designed to improve upon the standard-of-care pneumococcal vaccines by covering the serotypes that are responsible for most of the residual pneumococcal disease currently in circulation.”

REFERENCE

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