Ribociclib vs. Palbociclib in Patients With Advanced Breast Cancer Within the HER2-Enriched Intrinsic Subtype

Main Inclusion Criteria:

• Histologically documented HR-positive and HER2-negative breast cancer by localtesting

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1.

• advanced (loco regionally recurrent not amenable to curative therapy or metastatic)breast cancer.

• Availability of FFPE tumor block for biomarker analysis, obtained during metastaticperiod.

• HER2-E or Basal-like subtype as per central PAM50 analysis.

• Measurable disease or non-measurable disease, as defined by RECIST v1.1

• Adequate hematologic and end-organ function

• Patient must be willing and able to comply with scheduled visits, treatment plans,laboratory tests, and other trial procedures.

• Women of childbearing potential must have confirmed negative serum pregnancy testwithin 7 days prior to randomization.

• Women of CBP must be willing to use highly effective methods of contraception.

• Patient must have a 6-lead or 12-lead ECG with ALL of the following parameters atscreening:

• QTcF interval (QT interval using Fridericia's correction) at screening < 450msec.

• Resting heart rate 50-90 beats per minute (determined from the ECG).

Main Exclusion Criteria:

• Prior therapy with any CDK4/6 inhibitors.

• Patient has received prior treatment with chemotherapy for advanced/metastaticbreast cancer