how many cycles of ibrance before disease regresses?

i just finished cycle 2 with zero side effects and feel great physically. 3 of my 4 tumor marker tests went down, (still waiting on the 4th) but scan shows slight progression in bladder and colon. can ibrance take more than two cycles to start regression of disease? my doctor wants to put me in a trial to target the exact mutation of the recurrence cells. the bladder and colon are strange places for bc recurrence, and we thought i'd do well on the ibrance. any thoughts?