Sanofi and SK bioscience advance their 21-Valent vaccine to Phase 3

Sanofi has announced a new step forward in its collaboration with SK bioscience, providing a €50 million ($52 million) upfront payment to propel their next-generation pneumococcal conjugate vaccine program into phase 3 clinical trials.
This development underscores the longstanding partnership between the two companies, which began in 2014 when Sanofi invested $23 million upfront to initiate vaccine development efforts.
The vaccine candidate, previously known as GBP410 and now renamed PCV21, achieved promising results in phase 2 trials last year. These trials demonstrated that PCV21’s immunogenicity was comparable to that of an existing control vaccine.

The new phase 3 study represents a milestone as it marks the first time a pneumococcal conjugate vaccine with more than 20 serotypes is being tested in late-stage trials involving infants and toddlers. By incorporating 21 serotypes, the partners aim to provide broader protection against pneumococcal infections compared to vaccines currently approved for children.
Sanofi and SK bioscience will share the costs associated with research and development for PCV21. As part of the agreement, SK bioscience will receive the €50 million upfront payment from Sanofi and the potential to earn additional milestone payments based on the vaccine’s development and commercial achievements. Once PCV21 reaches the market, Sanofi will handle global commercialization, except in South Korea, which remains SK bioscience’s exclusive territory.
“Given the vast unmet public health needs in [invasive pneumococcal disease], we’re delighted to expand this collaboration and continue our pursuit of innovative work in PCV,” said Thomas Triomphe, Sanofi’s head of vaccines, in a statement.
The collaboration is meant to bring together the complementary strengths of both companies. “Our collaboration leverages SK bioscience’s capabilities and Sanofi’s expertise in developing and bringing innovative vaccines to people worldwide with the collective aim of reducing the global impact of pneumococcal disease,” Triomphe added.

Currently, two pneumococcal conjugate vaccines are FDA-approved for pediatric use: Pfizer’s 20-valent Prevnar 20 and Merck & Co.’s 15-valent Vaxneuvance. These vaccines set the benchmark for current pneumococcal coverage, but Sanofi’s PCV21 aims to push the boundaries further by addressing a broader spectrum of serotypes.
Sanofi is not alone in seeking to expand the range of serotypes covered by pneumococcal vaccines. Merck recently secured FDA approval for Capvaxive, a 21-valent vaccine designed specifically for adults. GSK had also been pursuing a 24-valent candidate acquired through its $2.1 billion acquisition of Affinivax but discontinued the asset in October. Meanwhile, Vaxcyte has generated significant attention with its 31-valent candidate, which showed promising phase 1/2 data in adults earlier this year and recently entered phase 2 trials in infants.