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Vaxcyte (PCVX) is soaring today after announcing topline results from the pivotal Phase 3 OPUS-1 trial evaluating VAX-31. VAX-31 is PCVX's investigational 31-valent pneumococcal conjugate vaccine candidate and its most advanced clinical program, designed to prevent invasive pneumococcal disease and pneumococcal pneumonia.

• OPUS-1 enrolled 4,047 adults and was designed to establish a new PCV standard of care through head-to-head safety, tolerability and immunogenicity comparisons with Pfizer's Prevnar 20 and Merck's Capvaxive in adults 50 and older, while separately evaluating immunobridging in adults 18-49.
• VAX-31 met all prespecified co-primary immunogenicity endpoints, achieving noninferiority across all 28 shared-serotype assessments and superiority across all four assessments involving its three unique serotypes and cross-reactive 20B. All 32 immunobridging comparisons also met noninferiority, while safety was similar to the licensed comparators.
• Importantly, VAX-31 cleared a more stringent noninferiority standard than historically used for PCV20 and PCV21, supporting its potential to deliver broader disease coverage while maintaining robust immune responses. VAX-31 is designed to expand disease coverage, with PCVX estimating coverage of 95% of IPD and 88% of pneumococcal pneumonia in U.S. adults 50 and older.
• Looking ahead, PCVX expects OPUS-2 and OPUS-3 results in 1H27, supporting a planned BLA submission in 1H28. The OPUS-1 results will serve as the cornerstone of the planned filing and further validate PCVX's carrier-sparing platform.

Briefing.com Analyst Insight

The important development from today's trial results is that PCVX demonstrated it can substantially broaden pneumococcal disease coverage while maintaining robust immune responses, even under a more stringent noninferiority standard. This supports a potentially differentiated profile versus PCV20 and PCV21 in a large and growing pneumococcal vaccine market, while also validating PCVX's carrier-sparing platform. While additional Phase 3 and manufacturing work remain, OPUS-1 serves as the cornerstone of the planned BLA, with OPUS-2 and OPUS-3 results in 1H27 representing the next key catalysts as PCVX works toward a planned 1H28 submission.