Merck Announces Positive Results From Phase 3 Pneumococcal Vaccine Trials

V116, an investigational 21-valent pneumococcal conjugate vaccine manufactured by Merck, showed positive topline results from a pair of phase 3 trials evaluating its response in vaccine-naïve and previously vaccinated individuals, according to a company press release.

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Two trials, STRIDE-3 and STRIDE-6, investigated the immune responses and interaction with pneumococcal serotypes. In STRIDE-3, a randomized, double-blind, active comparator-controlled study, participants were randomized to receive either V116 or pneumococcal 20-valent conjugate vaccine (PCV20).

The primary endpoints included safety, serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) 30 days post-vaccination, and a percentage of participants with a ≥ 4-fold rise from baseline in serotype-specific OPAs. V116 was observed to result in statistically significant immune responses compared to PCV20 in vaccine-naïve adults for serotypes common to both vaccines, the results indicated. Additionally, positive immune responses were also observed for serotypes unique to V116.

STRIDE-6 was a randomized, double-blind, active comparator-controlled study that evaluated the safety, tolerability, and immunogenicity of V116 in adults who were 50 years of age or older and previously were given a pneumococcal vaccination at least 1 year before enrollment.

The participants were randomized to receive 1 dose of either V116, pneumococcal 15-valent conjugate vaccine (PCV15) or pneumococcal vaccine, polyvalent (23-valent). Similar to STRIDE-3, the primary endpoints were safety and geometric mean titer (GMT) of serotype-specific OPA responses 30-days post vaccination.

The results demonstrated that V116 was immunogenic for all 21 pneumococcal serotypes in the vaccine among adults who received a pneumococcal vaccine at least 1 year prior to the study taking place, according to Merck. Pre-pandemic 2019 data from the CDC indicate that the 21 serotypes covered by the V116 vaccine are responsible for 85% of invasive pneumococcal disease in adults 65 years of age and older.

Notably, Merck’s V116 includes 8 serotypes that are not currently approved by pneumococcal vaccines, including 15A, 15C, 16F, 23A, 23B, 24F, 31, and 35B. Those serotypes were responsible for approximately 30% of invasive pneumococcal disease in individuals 65 years of age and older, based on the previously mentioned CDC data, according to Merck.

If approved, V116 would be the first pneumococcal conjugate vaccine specifically designed for adults, according to Merck. The company said that study results would be shared with the scientific community soon.

“These results support the potential for V116 to become an important new preventative option for adults, regardless of prior pneumococcal vaccination status, by expanding coverage to include eight serotypes not currently included in any licensed vaccine. We are very grateful to the patients and investigators who contributed to these studies,” said Eliav Barr, MD, senior vice president, head of global clinical development, and chief medical officer of Merck Research Laboratories, in a press release.

Reference

Merck announces V116, an investigational, 21-valent pneumococcal conjugate vaccine specifically designed for adults, met key immunogenicity and safety endpoints in two phase 3 trials. Merck. News release. July 27, 2023. Accessed July 28, 2023. https://www.merck.com/news/merck-announces-v116-an-investigational-21-valent-pneumococcal-conjugate-vaccine-specifically-designed-for-adults-met-key-immunogenicity-and-safety-endpoints-in-two-phase-3-trials/