Table 1.

Comparison of key inclusion/exclusion criteria.

Parameter	MONALEESA-2	MONARCH 3
Disease	HR+/HER2− locally advanced/metastatic BC	HR+/HER2− locally advanced/metastatic BC
Menopausal status	Postmenopausal only	Postmenopausal only
Gender	Only female	Only female
Age	18 years and older	18 years and older
ECOG performance status	0 or 1	0 or 1
Patients included	Received no systemic treatment for ABC Have measurable disease as defined by RECIST 1.1 or ⩾1 predominantly lytic bone lesion • TFI > 12 months after prior (neo)adjuvant NSAIa	Received no systemic treatment for ABC Have measurable disease or non-measurable bone-only disease (blastic, lytic, or mixed) as defined by RECIST 1.1 Have had adequate organ function • TFI > 12 months after any prior (neo)adjuvant ET
Exclusions	Prior treatment with CDK4/6 inhibitors Presence of active cardiac disease or history of cardiac dysfunction, including QTcF >450 msec • Presence of inflammatory breast cancer	Prior treatment with everolimus or a CDK4/6 inhibitor Presence of visceral crisis, lymphangitic spread, or leptomeningeal carcinomatosis Presence of inflammatory breast cancer • Evidence or history of CNS metastases

^aML-2 allowed TFI ⩽ 12 months if the (neo)adjuvant therapy was tamoxifen.

ABC, advanced breast cancer; BC, breast cancer; CDK4/6; cyclin-dependent kinases 4 and 6; CNS, central nervous system; ECOG, Eastern Cooperative Oncology Group; ET, endocrine therapy; HR+/HER2-, hormone receptor-positive/human epidermal growth factor receptor 2-negative; NSAI, nonsteroidal aromatase inhibitor; QTcF, corrected QT interval by Fredericia’s formula; RECIST, Response Evaluation Criteria in Solid Tumors; TFI, treatment-free interval.