Merck's 21-Valent Adult Pneumococcal Vaccine Meets Key Endpoints in Pair of Phase 3 Trials

An investigational 21-valent pneumococcal conjugate vaccine demonstrated statistically significant immune responses in both vaccine-naive adults and those previously vaccinated in 2 phase 3 trials, according to topline results released recently by Merck.

The novel vaccine (V116), indicated for the prevention of invasive pneumococcal disease and pneumococcal pneumonia, had a comparable safety profile to the comparator vaccines used in the STRIDE 3 and STRIDE 6 trials. V116 includes 8 Streptococcus pneumoniae serotypes associated with approximately 30% of cases of invasive pneumococcal disease (IPD) in people aged ≥65 years that are not currently covered by approved pneumococcal vaccines, according to the Centers for Disease Control and Prevention (CDC). CDC data also show that the 21 serotypes covered by V116 are responsible for 85% of IPD in this older population. If approved, V116 would be the only vaccine in its class “specifically designed for adults,” Merck states.

“Despite the availability of current pneumococcal conjugate vaccines, many adults remain vulnerable to pneumococcal disease, especially those who are older,” said Eliav Barr, senior vice president, head of global clinical development and chief medical officer, Merck Research Laboratories. “These results support the potential for V116 to become an important new preventative option for adults, regardless of prior pneumococcal vaccination status."

V116 is being investigated in the phase 3 STRIDE-3 and STRIDE-6 clinical trials, both of which are randomized, double-blind, active comparator-controlled studies. Full results will be shared in the near future, according to the company.

In STRIDE-3, statistically significant immune responses to V116 were demonstrated compared with PCV20 for serotypes common to both vaccines by geometric mean titer (GMT) of serotype-specific opsonophagocytic (OPA) activity 30 days post-vaccination in vaccine-naive adults (N=2600), with positive immune responses also recorded for the 8 serotypes unique to V116. A second primary endpoint of interest is the percentage of participants with ≥4-fold rise from baseline in serotype-specific OPAs.

In STRIDE-6, V116 was immunogenic for all 21 pneumococcal serotypes in the vaccine in adults aged ≥50 years (N=717) vaccinated against pneumococcus at least 1 year prior to the study with, alone or in combination, PPSV23, PCV13, and PCV15. Participants were randomly assigned to receive 1 dose of either V116, PCV15, or PPSV23. Primary end points included safety and geometric mean titer GMT of serotype-specific OPA responses 30 days post-vaccination.

Additional phase 3 clinical trials are examining the safety and immunogenicity of V116 in special populations, including individuals with HIV (STRIDE-7; NCT05393037) and those at increased risk for pneumococcal disease, including individuals with diabetes, chronic liver disease, chronic obstructive pulmonary disease, mild or moderate persistent asthma, chronic heart disease, and/or chronic kidney disease (STRIDE-8; NCT05696080). The STRIDE 4 (NCT05464420) trial is looking at use of V116 in adults aged 18 to 49 years and STRIDE 5 (NCT05526716) is assessing V116 when coadministered with influenza vaccine or administered sequentially with flu vaccine.

Source: Merck announced V116, an investigational, 21-valent pneumococcal conjugate vaccine specifically designed for adults, met key immunogenicity and safety endpoints in two phase 3 trials. News release. July 27, 2023. Accessed August 2, 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/