Merck (NYSE: MRK), known as MSD outside of the United States and Canada, announced results from STRIDE-8, a Phase 3 trial evaluating CAPVAXIVE™ (Pneumococcal 21-valent Conjugate Vaccine), at IDWeek 2024 in Los Angeles, California. The trial evaluated the immunogenicity, safety and tolerability of CAPVAXIVE compared to PCV15 (pneumococcal 15-valent conjugate vaccine) in combination with PPSV23 (pneumococcal 23-valent polysaccharide vaccine) in vaccine-naïve adults 18-64 years of age with certain chronic conditions that put them at an increased risk of pneumococcal disease.

Key findings from the STRIDE-8 trial include:

• CAPVAXIVE was immunogenic for all 21 serotypes (or strains) included in the vaccine, as measured by serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) (primary immunogenicity objective) and immunoglobulin G (IgG) geometric mean concentrations (GMCs) (secondary immunogenicity objective) at Day 30;
• Immune responses elicited by CAPVAXIVE were comparable to PCV15 followed by PPSV23 for the 13 common serotypes and higher for the eight serotypes unique to CAPVAXIVE, as measured by serotype-specific OPA GMTs and IgG GMCs 30 days post-vaccination;
• The proportions of participants with adverse events (AEs), including injection-site, systemic, and vaccine-related AEs, were numerically lower in the V116 + placebo group than in the PCV15 + PPSV23 group.

“Adults with chronic medical conditions, such as kidney disease or diabetes, are particularly vulnerable to invasive pneumococcal disease, which may increase their risk of severe illness,” said Dr. Walter Orenstein, professor emeritus of medicine, epidemiology, global health and pediatrics at Emory University and member of Merck’s Scientific Advisory Committee. “These data further demonstrate that the broad serotype coverage CAPVAXIVE provides can help prevent invasive disease among vulnerable adults.”

CAPVAXIVE is indicated for:

• Active immunization for the prevention of invasive disease and pneumonia caused by Streptococcus pneumoniae serotypes 3, 6A, 7F, 8, 9N, 10A, 11A, 12F, 15A, 15B, 15C, 16F, 17F, 19A, 20A, 22F, 23A, 23B, 24F, 31, 33F and 35B in adults individuals 18 years of age and older;
• Active immunization for the prevention of pneumonia caused by S. pneumoniae serotypes 3, 6A, 7F, 8, 9N, 10A, 11A, 12F, 15A, 15C, 16F, 17F, 19A, 20A, 22F, 23A, 23B, 24F, 31, 33F and 35B in individuals 18 years of age and older.

The indication for the prevention of pneumonia caused by S. pneumoniae serotypes 3, 6A, 7F, 8, 9N, 10A, 11A, 12F, 15A, 15C, 16F, 17F, 19A, 20A, 22F, 23A, 23B, 24F, 31, 33F and 35B is approved under accelerated approval based on immune responses as measured by opsonophagocytic activity (OPA). Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.

CAPVAXIVE should not be administered to individuals with a history of a severe allergic reaction (e.g., anaphylaxis) to any component of CAPVAXIVE or to diphtheria toxoid; see additional Select Safety Information below.

“The data presented during IDWeek build on the robust clinical profile of CAPVAXIVE and illustrate the importance of improving equitable access for those at high risk for invasive pneumococcal disease,” said Dr. Macaya Douoguih, Therapeutic Area Head, Vaccines Clinical Research, Merck Research Laboratories. “Our commitment to prioritizing research and advancements that benefit populations at highest risk of invasive pneumococcal disease remains critical.”

In addition to STRIDE-8, Merck also presented results from a targeted literature review of the clinical and economic burden of pneumococcal disease in U.S. adults. The findings concluded that Black adults and adults in rural areas with lower levels of education and income face higher disease burden and lower rates of pneumococcal vaccination.

Data from a modeling study evaluating the health impact of the introduction of CAPVAXIVE in U.S. adults were also presented. The modeling study concluded that the use of CAPVAXIVE in adults reduced IPD incidence by 33.9% in the U.S. after 10 years, in the setting of continued pediatric PCV vaccination. This equated to approximately 14,000 fewer cases with CAPVAXIVE than PCV20 (pneumococcal 20-valent conjugate vaccine) after 10 years.

CAPVAXIVE is specifically designed to help protect adults against the serotypes that cause the majority of invasive pneumococcal disease (IPD) cases. Based on CDC data from 2018-2021, the serotypes covered by CAPVAXIVE are responsible for more cases of IPD in adults compared to PCV20.