IDWeek 2024: Merck’s Investigational 21-Valent Pneumococcal Vaccine Shows Positive Immune Responses in At-Risk Adults

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An investigational, 21-valent pneumococcal conjugate vaccine was well tolerated and immunogenic in adults aged 18 to 64 years at increased risk of pneumococcal disease (PD), according to new findings presented at IDWeek in Los Angeles, CA (October 16-19, 2024).¹

The new data come from STRIDE-8, a phase 3 clinical trial evaluating the immunogenicity, safety, and tolerability of V116 (CAPVAXIVE™, Merck) compared to pneumococcal 15-valent conjugate vaccine (PCV15) in combination with pneumococcal 23-valent polysaccharide vaccine (PPSV23) in pneumococcal vaccine-naïve adults with certain underlying chronic conditions at increased risk of PD.¹

Researchers reported that V116 was immunogenic for all 21 serotypes included in the vaccine based on opsonophagocytic activity (OPA)geometric mean titers (GMTs) and immunoglobulin G (IgG) geometric mean concentrations (GMCs) at Day 30.¹

Also, investigators observed that the immune responses for V116 were comparable to PCV15 and PPSV23 for the 13 serotypes common to V116 and PCV15 plus PPSV23, and higher responses for the 8 serotypes unique to V116. IgG GMCs were consistent with OPA GMTs, added researchers in the study abstract.¹

The proportions of people with adverse events (AEs), which included injection-site, systematic, and vaccine-related AEs, were numerically lower for those who received V116 compared with those in the PCV15+PPSV23 group.¹

“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,” Dr. Walter Orenstein, professor emeritus of medicine, epidemiology, global health and pediatrics at Emory University and member of Merck’s Scientific Advisory Committee, said in a press release.² “These data further demonstrate that the broad serotype coverage CAPVAXIVE provides can help prevent invasive disease among vulnerable adults.”

The STRIDE-8 trial included 518 vaccine-naïve adults at increased risk of PD, including those with diabetes, cardiovascular disease, kidney disease, liver disease, and lung disease. Participants were randomly assigned 3:1 to receive a single dose of V116 on day 1 followed by placebo at day 8, or a single dose of PCV15 on day 1 followed by one dose of PPSV23 at week 8. The primary objectives were serotype-specific OPA GMTs and IgG GMCs at day 1 and 30-days post-vaccination.¹

In June 2024, the US FDA approved V116 for the prevention of PD in adults aged 18 years and older. The novel vaccine includes 8 unique serotypes that are not covered by currently FDA-approved pneumococcal vaccines. These 8 serotypes (15A, 15C, 16F, 23A, 23B, 24F, 31 and 35B) were responsible for approximately 27% of invasive pneumococcal disease (IPD) cases in people aged 50 years and older and 31% in those aged 65 years and older.

Following the approval, the CDC’s Advisory Committee on Immunization Practices (ACIP) unanimously voted to recommend a single dose of V116 for adults aged 19 years and older who are currently recommended to received either 15- or 20-valent pneumococcal conjugate vaccine.

References:

1. Scott P, Kato A, Tytus R, et al. A phase 3, randomized trial investigating the safety, tolerability, and immunogenicity of V116, an investigational adult-specific pneumococcal conjugate vaccine, in pneumococcal vaccine-naïve adults 18–64 years of age with increased risk for pneumococcal disease (P-45). Poster abstract presented at IDWeek 2024; October 16-19, 2024; Los Angeles, CA.
2. Merck’s CAPVAXIVE™ (pneumococcal 21-valent conjugate vaccine) demonstrates positive immune responses in adults with increased risk for pneumococcal disease. News release. Merck. October 16, 2024. Accessed October 18, 2024. https://www.merck.com/news/mercks-capvaxive-pneumococcal-21-valent-conjugate-vaccine-demonstrates-positive-immune-responses-in-adults-with-increased-risk-for-pneumococcal-disease/