- STEP 2: an expansion cohort part to confirm the safety and tolerability of ribociclib and capecitabine association on a longer follow-up, and to obtain preliminary evidence of anti-tumor activity on two expanded cohorts of HR positive and HR negative patients. Up to 14 patients in each cohort, taking into account patients already included in step one at this DL, may be enrolled, for a total of 28 at the RP2D.