Investing.com -- Vaxcyte, Inc. (NASDAQ: PCVX) shares surged 50% Monday following positive topline results from the OPUS-1 pivotal adult phase 3 trial of VAX-31, the company’s 31-valent pneumococcal conjugate vaccine candidate.

VAX-31 met all prespecified primary endpoints across age groups studied compared to Prevnar 20 and Capvaxive. The vaccine demonstrated noninferiority at the >0.667 threshold for all 28 VAX-31 serotypes shared with the comparator vaccines in adults 50 and older, while three serotypes unique to VAX-31 and cross-reactive serotype 20B met superiority criteria.

The trial enrolled 4,047 participants at approximately 30 sites across the United States. Participants aged 50 years and older were randomized to receive a single dose of VAX-31, PCV20, or PCV21, while participants aged 18-49 received VAX-31 or PCV20.

VAX-31 was well tolerated and demonstrated a safety profile similar to PCV20 and PCV21 across all ages studied. No serious adverse events were considered related to study vaccines, and there were no study discontinuations due to adverse events.

In individual comparator analyses, VAX-31 met the noninferiority criterion for 20 of 20 serotypes shared with PCV20 and 17 of 19 shared with PCV21. Serotypes 3 and 12F missed the >0.667 noninferiority criterion against PCV21 but met the historical >0.5 threshold.

Vaxcyte expects to report results from OPUS-2 and OPUS-3 adult phase 3 trials in the first half of 2027, supporting a planned Biologics License Application submission in the first half of 2028.

Guggenheim analyst Seamus Fernandez raised the price target on Vaxcyte to $125 from $116 while maintaining a Buy rating. "The adult VAX-31 OPUS-1 Phase 3 was a major win not only vs. investor expectations and delivering our Best Case scenario, but also setting up VAX-31 for clear commercial leadership," the analyst commented.

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