Phase III study evaluating palbociclib (PD-0332991), a Cyclin-Dependent Kinase (CDK) 4/6 Inhibitor in patients with hormone-receptor-positive, HER2-normal primary breast cancer with high relapse risk after neoadjuvant chemotherapy "PENELOPEB"

INTERVENTION: Arm A : palbociclib at a dose of 125 mg once daily, day 1 to day 21 followed by 7 days off treatment in a 28‐day cycle for thirteen cycles Arm B : Placebo of palbociclib once daily day 1 to day 21 followed by 7 days off treatment in a 28‐day cycle for thirteen cycles CONDITION: residual invasive breast cancer and high CPS‐EG score after neoadjuvant chemotherapy receiving standard adjuvant endocrine therapy for HRpositive/HER2‐normal primary breast cancer PRIMARY OUTCOME: Invasive Disease‐free survival INCLUSION CRITERIA: Histologically confirmed unilateral or bilateral primary invasive carcinoma of the breast. Residual invasive disease post‐neoadjuvant either in the breast or as residual nodal invasion. Centrally confirmed hormone‐receptor‐positive and HER2‐normal assessed preferably on tissue from post‐neoadjuvant residual invasive disease or core biopsy of the breast (Exception). In case of bilateral breast cancer status has to be confirmed centrally for both sides. Centrally assessed Ki‐67, pRB, and Cyclin D1 status assessed preferably on post‐neoadjuvant residual invasive disease of the breast (Exception). Neoadjuvant chemotherapy of at least 16 weeks. This period must include 6 weeks of a taxane ‐containing neoadjuvant therapy (Exception) Adequate surgical treatment (Specifics). R0 required in case of breast conserving surgery as the final treatment. Less than 16 weeks interval since the date of final surgery or less than 10 weeks from completing radioth