Regan shot 8 of 11 from the field, 3 of 4 from beyond the arc and 7 of 7 from the foul line for the Bulls (4-7). Tony Watson also scored 14 for Buffalo.
Buffalo never trailed in the second half, but Ameen Tanksley made two free throws to close the game to 56-54 with 10:18 remaining. Watson made a 3-pointer for a 62-56 advantage with 7:41 to go, and the Purple Eagles never got closer than five points the rest of the way.
Buffalo led 30-28 with 1:49 to go in the first half and used a 7-0 run to take a 37-28 halftime advantage.
Mike Brey is looking at former Notre Dame players to fill two assistant jobs that have opened up with the departures of Martin Ingelsby and Anthony Solomon.
Purdue's 2016-17 prospects got a jolt Wednesday when forward Caleb Swanigan announced he will return for his sophomore season.
Clemson's Jaron Blossomgame says he is withdrawing from the NBA draft and returning to school for a final season.