Vaxcyte Initiates OPUS-3 Phase 3 Trial Of VAX-31 in Previously Vaccinated Adults, First Patients Dosed In Pneumococcal Vaccine

Vaxcyte has announced that the first participants have been dosed in OPUS-3, a Phase 3 clinical trial evaluating VAX-31, its investigational 31-valent pneumococcal conjugate vaccine (PCV), in adults who have previously received a pneumococcal vaccine. The study is designed to assess the safety, tolerability and immunogenicity of VAX-31, including its ability to boost serotype-specific immune responses while offering broad strain coverage in a single shot.

OPUS-3 is part of Vaxcyte’s broader Phase 3 adult development program intended to support a planned Biologics License Application (BLA) submission to the U.S. FDA. The full program includes three late-stage trials: OPUS-1, a pivotal noninferiority study evaluating prevention of invasive pneumococcal disease (IPD) and pneumonia; OPUS-2, assessing co-administration with a seasonal influenza vaccine in pneumococcal-naïve adults; and OPUS-3, focused on previously vaccinated individuals. Together, the studies are expected to enroll around 6,000 adults, with approximately 3,400 participants receiving VAX-31.

“The initiation of our Phase 3 study evaluating VAX-31 administered to adults with prior pneumococcal vaccination marks continued progress for the program as we work toward delivering a best-in-class, next-generation PCV with the potential to set a new standard-of-care for adults,” said Grant Pickering, Chief Executive Officer and Co-founder of Vaxcyte. “Given the potential for VAX-31 to significantly expand protection and provide substantial incremental coverage of approximately 19-31% against pneumococcal pneumonia relative to current standard-of-care vaccines, it is important to understand how VAX-31 may boost immune responses in adults who previously received lower-valency pneumococcal vaccines and broaden serotype coverage.”

The OPUS-3 study is a randomized, double-blind, active-controlled trial enrolling approximately 720 healthy U.S. adults aged 50 years and older who were vaccinated against pneumococcus at least six months prior. Conducted across roughly 30 U.S. sites, the trial will generate descriptive data on safety and immune response following a single dose of VAX-31.

In addition to these clinical trials, Vaxcyte plans to conduct a manufacturing consistency (lot-to-lot) study as part of its regulatory strategy. The company aims to position VAX-31 as a next-generation PCV candidate that can deliver expanded serotype coverage in adults through a single vaccine.