Merck & Co 21-valent Pneumococcal Conjugate Vaccine Ready for Phase III

The 21-valent pneumococcal conjugate vaccine targets 85% of invasive pneumococcal disease in adults aged ≥65 years; 8 serotypes are exclusive to this vaccine, says Merck.


An investigational 21-valent pneumococcal conjugate vaccine in development by Merck & Co produced “positive results” in adults participating in a phase 1/2 trial.

The vaccine, V116, is formulated to target serotypes responsible for 85% of all invasive pneumococcal disease in adults aged ≥65 years in the US as of 2019, according to a Merck & Co announcement made on June 21, 2022.

"Importantly, the eight serotypes in V116 that are not included in any currently-licensed pneumococcal vaccine account for over 30% of this disease burden alone," said Eliav Barr, chief medical officer at Merck Research Laboratories, in the statement.

On April 14, 2022, the FDA granted the investigational immunization breakthrough designation for prevention of invasive pneumococcal disease and pneumococcal pneumonia caused by Streptococcus pneumoniae serotypes 3, 6A/C, 7F, 8, 9N, 10A, 11A, 12F, 15A, 15B/C, 16F, 17F, 19A, 20, 22F, 23A, 23B, 24F, 31, 33F, 35B in adults aged ≥18 years.

According to Merck & Co, a "broad" Phase III program for V116 in vaccine-naïve and vaccine-experienced adults is anticipated to begin next month.

Merck presented the current findings at the International Symposium on Pneumococci and Pneumococcal Diseases (ISPPD-12), held June 19-23, 2022, in Toronto, Canada.

The 2-part V116-001 study evaluated the safety, tolerability, and immunogenicity of a single dose of V116 in healthy adults who have not previously received any pneumococcal vaccine.

In the first part of the study, investigators randomized 90 adults aged 18 to 49 years 1:1:1 to receive either a single dose of V116, given at 2 µg or 4 µg, or Merck's Pneumovax 23.

Similar to Pneumovax 23

After 30 days, according to Merck, immune responses for both V116 dose groups were "generally comparable" to Pneumovax 23 for serotypes common to both vaccines, and greater than Pneumovax 23 for serotypes unique to V116. The company noted that the 4-µg dose of V116 produced higher functional antibody activity compared to the lower dose for all serotypes except 9N.

Part 2 of the trial randomized 508 adults aged ≥50 years 1:1, stratified by age (50-64 years, 65-74 years, and 75 years or older), to receive either a single dose of V116 (4 µg) or Pneumovax 23. The company reports that V116 met noninferiority criteria compared to Pneumovax 23 for all shared serotypes and met superiority criteria for the unique serotypes based on assessment of the lower bound of the geometric mean titer (GMT) ratios.

The safety of V116-001 was evaluated based on post-vaccination adverse events. In both parts of the trial, Merck said V116 was well-tolerated with an overall safety profile "generally comparable" to Pneumovax 23

"Our encouraging data at ISPPD reflect the potential of V116 and Merck’s tailored approach to developing pneumococcal vaccines to meet the specific needs of different populations,” said SVP Barr in the Merck statement.

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