Phase 3 trial supports PCV20 in adults
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Pfizer’s 20-valent pneumococcal conjugate vaccine induced robust immune responses that were comparable to other vaccines currently on the market, according to results from a phase 3, randomized, double-blind trial.
“PCV20 is being developed to expand pneumococcal serotype coverage beyond PCV13,” Brandon Essink, MD, CPI, principal investigator and medical director for Meridian Clinical Research in Omaha, Nebraska, said during an IDWeek presentation. “Streptococcus pneumoniae causes serious disease, including bloodstream infections and pneumonia. The risk of disease is increased in young children, the elderly and those with immunocompromised or other chronic medical conditions.”
Although the amount of disease caused by the 13 serotypes included in PCV13 has been reduced following its introduction, “there remains a substantial disease burden due to serotypes not in the vaccine,” Essink said. PCV20 includes all 13 serotypes in PCV13, along with seven additional serotypes “that are responsible for a substantial amount of the residual disease burden,” he added. Moreover, PCV20 offers “immunologic advantages” over the 23-valent unconjugated pneumococcal polysaccharide vaccine, or PPSV23, which contains the same seven additional serotypes that PCV20 does, plus three other pneumococcal serotypes.
The FDA granted breakthrough therapy designation to PCV20 in 2018.
In the study, which was conducted in the United States and Sweden, 3,880 adults naive to pneumococcal vaccination were enrolled into three age cohorts. Those aged 60 years or older (n = 3,000) were administered either PCV20 and saline 1 month later, or PCV13 and PPSV23 1 month later. Those aged 50 to 59 years (n = 440) and 18 to 49 years (n = 440) received either a dose of PCV20 or PCV13.
According to the researchers, the immunogenicity of PCV20 was noninferior to all 13 serotypes included in PCV13 and six of the seven additional serotypes shared with PPSV23. Serotype 8 missed noninferiority by a narrow margin in the comparison between PCV20 and PPSV23 in adults aged older than 60 years, but the researchers said this is unlikely to be clinically significant. Further analysis showed that the response to serotype 8 induced by PCV20 was consistent with that observed with the serotypes in PCV13.
Results also showed that PCV20 immune responses in adults aged 50 to 59 years and 18 to 49 years were noninferior to those in adults aged 60 to 64 years.
“The immunogenicity of PCV20 in adults 18 to 59 years of age was bridged to that in adults 60 to 64 years of age,” supporting PCV20’s use in adults aged older than 18 years, Essink said.
According to the researchers, the safety profile of PCV20 was similar to that of PCV13, and they identified no safety concerns.
“These findings provide confidence that PCV20 is likely to be as effective as [PCV13] in helping prevent invasive pneumococcal disease and pneumonia due to the 13 serotypes in [PCV13], and also effective against disease due to seven additional pneumococcal serotypes in adults aged 18 years or older,” Essink concluded.
Perspective
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Eugene Shapiro, MD
That PCV20 induces a robust antibody response to all serotypes in the vaccine in adults is encouraging. However, a major question is when the results of similar studies in children will be available and how these results will affect recommendations for the routine use of pneumococcal vaccines. Relatively recently, the Advisory Committee on Immunization Practices (ACIP) walked back its recommendation for routine administration of PCV13 to adults aged older than 65 years; it is now optional (to be guided by shared decision-making between patients and their health providers). The reason is that in populations in which a high proportion of young children (who are the major vectors of pneumococcal infections) are immunized, administration of PCV13 to adults provides little incremental benefit, and it is expensive. Even if PCV20 is highly immunogenic, it is uncertain whether the ACIP would again alter its recommendation and endorse routine immunization of adults, especially if PCV20 will eventually replace PCV13 in the routine immunization schedule for children.
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Essink B, et al. Abstract 3. Presented at: IDWeek; Oct. 21-25, 2020 (virtual meeting).
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