Seattle took a 29-20 lead into the break and Sunderhaus scored six points during a 9-3 run to open the second half. San Jose State (2-9), which shot just 29 percent (13 of 45) from the field and was held below 44 points for the first time this season, trailed by double figures the rest of the way.
Seattle outrebounded San Jose State 40-19 and recorded 19 assists on 21 field goals.
Daryll Gaynor II scored a career-high 20 in the loss.
Rashad Muhammad, San Jose State's leading scorer at 12.1 per game, is serving an indefinite suspension due to a violation of team rules and did not play.