Vaxcyte said its lead adult vaccine candidate, VAX-31, hit all prespecified primary endpoints in the pivotal OPUS-1 phase 3 trial, with the strongest readout coming in adults 50 and older.
In that age group, all 28 serotypes shared with Prevnar 20 and/or Capvaxive met the trial’s noninferiority bar, and the three serotypes unique to VAX-31 plus cross-reactive serotype 20b met superiority criteria. Among the 11 serotypes shared by VAX-31, Prevnar 20 and Capvaxive, the vaccine met all 11 noninferiority comparisons. It also met 9 of 9 noninferiority comparisons for serotypes shared only with Prevnar 20 and 8 of 8 for serotypes shared only with Capvaxive.
Against Prevnar 20, VAX-31 met the noninferiority criterion for all 20 shared serotypes. Against Capvaxive, it met the criterion for 17 of 19 shared serotypes; serotypes 3 and 12f missed the >0.667 threshold but cleared the company’s historical >0.5 threshold.
The immunobridging endpoint also came in positive: across all 321 serotype comparisons, VAX-31 met noninferiority in adults 18 to 49 compared with adults 50 to 64.
On safety, Vaxcyte said VAX-31 was well tolerated and showed a profile similar to Prevnar 20 and Capvaxive across all ages studied. The company said there were no serious adverse events related to the study vaccines and no discontinuations due to adverse events.
The trial enrolled 4,047 participants across about 30 U.S. sites, including 3,572 adults age 50 and older and 475 adults age 18 to 49.
Vaxcyte said it expects OPUS-2 and OPUS-3 adult phase 3 results in the first half of 2027, with a planned biologics license application submission in the first half of 2028. Following these announcements, the company's shares moved 0.77%, and are now trading at a price of $56.48. For more information, read the company's full 8-K submission here.
