Results from 2 initial phase 3 studies evaluating an investigational 15-valent pneumococcal conjugate vaccine (PCV15; V114, Merck) were recently released, assessing its immunogenicity, safety, and tolerability.

These are 2 of 16 trials in a clinical development program, with the goal of assessing PCV15 in populations at increased risk of pneumococcal disease.

The results of the first study, the PNEU-WAY study, demonstrated that PCV15 elicited an immune response to all the 15 serotypes included in the vaccine in adults 18 years or older who are living with HIV. Additionally, the results of the second study, PNEU-FLU, showed that PCV15 can be given concomitantly with the quadrivalent influenza vaccine in adults 50 years or older.

The authors of the study said in a statement that pneumococcal disease, which is an infection caused by bacteria called Streptococcus pneumoniae, is evolving.

There are aggressive strains called serotypes that can increase the risk of invasive pneumococcal illnesses, such as bacteremia (infection in the bloodstream), bacteremic pneumonia (pneumonia with bacteremia), and meningitis, as well as non-invasive pneumococcal illnesses, such as otitis media (middle ear infection), pneumonia, and sinusitis.

Although healthy individuals can be negatively affected by pneumococcal disease, those that are most at risk are adults older than 65 years, children younger than 2 years, and individuals with certain chronic health or immunosuppressive conditions.

PCV15 is an updated pneumococcal conjugate vaccine, as it includes serotypes 22F and 33F among the 15 serotypes conjugated to a CRM197 carrier protein. Both 22F and 33F are associated with invasive pneumococcal disease, and they are not contained in the pneumococcal conjugate vaccine licensed for use in adults.

To assess PCV15 in adults, the investigators in the PNEU-WAY study assessed data from 302 participants who were randomized to receive PCV15 or the already available 13-valent pneumococcal conjugate vaccine (PCV13), followed by the pneumococcal vaccine polyvalent (PNEUMOVAX 23, Merck).

The results showed that at 30 days post-vaccination, PCV15 was able to meet its primary immunogenicity objective as measured by serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs), and Immunoglobulin G (IgG) geometric mean concentrations (GMCs) for all 15 serotypes that the vaccine contained.

The analysis of the OPA GMTs and IgG GMCs for the 13 shared serotypes between PCV15 and PCV13 were found to be comparable, with the immune responses in the PCV15 group shown to be higher than that of the PCV13 group for the 2 serotypes unique to PCV15. Additionally, PCV15 and PCV13 were found to have a similar safety profile.

In the PNEU-FLU study assessing PCV15’s use when administered concomitantly or non-concomitantly with the quadrivalent influenza vaccine (QIV) in adults 50 years or older, participants were randomized into 2 groups. Those in the concomitant group received PCV15 and the QIV at the first visit, and during the second visit about 30 days later they received the placebo. Those in the non-concomitant group received the placebo and QIV on day 1 and the PCV15 at the second visit about 30 days later.
Basing the results of the trial on the serotype-specific OPA GMTs at 30 days post-vaccination with PCV15, the findings showed that PCV15 when administered concomitantly with QIV was noninferior compared with PCV15 administered non-concomitantly with QIV. Additionally, the investigators found QIV administered concomitantly with PCV15 was noninferior to QIV administered non-concomitantly with PCV15, based on the influenza strain-specific hemagglutination inhibition (HAI) GMTs at 30 days post-vaccination with QIV. Between the 2 vaccination groups, the safety profiles were also comparable.

“Certain populations are at greater risk for pneumococcal disease, reinforcing the importance of investigating new interventions focused on their specific needs,” Luwy Musey, MD, executive director in biologics, vaccine clinical research at Merck Research Laboratories in Whitehouse Station, New Jersey, said in a statement. “Results from these first 2 Phase 3 studies of V114 are encouraging, and we look forward to sharing additional data in the future from our ongoing clinical development program, including our pivotal studies assessing the immunogenicity of V114 and its potential to protect against the serotypes most likely to cause invasive disease.”

Merck announces that V114, its investigational 15-valent pneumococcal conjugate vaccine, met safety and immunogenicity objectives in initial phase 3 studies in adults [news release]. Kenilworth, NJ: Merck Incorporated; June 22, 2020. Accessed July 1, 2020.