Table 1.

Clinical trials of cyclin‐dependent kinase 4/6 inhibitors in premenopausal patients with hormone receptor–positive/human epidermal growth receptor 2–negative mBC 30, 43, 44, 45, 46, 48, 49

	Trial
Characteristic	PALOMA‐3NCT01942135	MONALEESA‐7NCT02278120	MONARCH 2NCT02107703
Inclusion criteria	Age >18 years Endocrine therapy resistant Line of therapy for mBC: ≥2 (35% 2nd line or later)	Pre/perimenopausal women (age 18–59 years) Endocrine therapy sensitive and resistant Line of therapy for mBC: 1–2 (14% 2nd line after chemotherapy for metastatic disease)	Age ≥18 years Endocrine therapy sensitive and resistant Line of therapy for mBC: 1–2 (38% 2nd line after prior endocrine therapy for metastatic disease)
Treatment arms	Palbociclib + fulvestrant Placebo + fulvestrant Pre/perimenopausal women received goserelin	Ribociclib + tamoxifen, anastrozole, or letrozole Placebo + tamoxifen, anastrozole, or letrozole All women received goserelin	Abemaciclib + fulvestrant Placebo + fulvestrant Pre/perimenopausal women received GnRH agonist
Pre/perimenopausal women enrolled, n (% of total population)	108 (21)	672 (100)	114 (17)
Prior chemotherapy for ABC/mBC, %a	33	14	0
Patients with visceral disease, %a	59	58	55
Median PFS, mo, experimental vs. control	11.2 vs. 4.6	23.8 vs. 13.0	16.4 vs. 9.3
Median OS, mo, experimental vs. control (hazard ratio: 95% CI)	34.9 vs. 28.0 (0.81; 0.64–1.03; p = .09)	NR vs. 40.9 (0.71; 0.54–0.95; p = .01)	46.7 vs. 37.3 (0.76; 0.61–0.94; p = .01)

^aExperimental group only.

Abbreviations: ABC, advanced breast cancer; CDK, cyclin‐dependent kinase; GnRH, gonadotropin‐releasing hormone; HER2−, human epidermal growth receptor 2 negative; HR+, hormone receptor–positive; mBC, metastatic breast cancer; NR, not reached; OS, overall survival; PFS, progression‐free survival.