Second-line abemaciclib and endocrine therapy

The MONARCH 2 study (NCT02107703) tested abemaciclib (CDK4/6 inhibitor) in a phase III, placebo-controlled trial that randomly assigned 669 patients with HER2-negative, hormone receptor–positive, advanced breast cancer (with previous progression on endocrine therapy) to receive abemaciclib plus fulvestrant or placebo plus fulvestrant.[23]

The MONARCH 2 study (NCT02107703) tested abemaciclib (CDK4/6 inhibitor) in a phase III, placebo-controlled trial that randomly assigned 669 patients with HER2-negative, hormone receptor–positive, advanced breast cancer (with previous progression on endocrine therapy) to receive abemaciclib plus fulvestrant or placebo plus fulvestrant.[23]

The primary end point (investigator-assessed PFS) was met, with median duration of follow-up of 19.5 months. The median PFS was 16.4 months for the abemaciclib-fulvestrant arm versus 9.3 months for the placebo-fulvestrant arm (HR, 0.55; 95% CI, 0.45–0.68; P < .001).[23][Level of evidence B1]

The MONARCH 2 study (NCT02107703) tested abemaciclib (CDK4/6 inhibitor) in a phase III, placebo-controlled trial that randomly assigned 669 patients with HER2-negative, hormone receptor–positive, advanced breast cancer (with previous progression on endocrine therapy) to receive abemaciclib plus fulvestrant or placebo plus fulvestrant.[23]

OS data are mature and demonstrate an improvement in OS for patients receiving abemaciclib, and showed a median OS of 46.7 months for abemaciclib plus fulvestrant versus 37.3 months for placebo (HR, 0.757; 95% CI, 0.606–0.945; P = .01).[24][Level of evidence A1]

The MONARCH 2 study (NCT02107703) tested abemaciclib (CDK4/6 inhibitor) in a phase III, placebo-controlled trial that randomly assigned 669 patients with HER2-negative, hormone receptor–positive, advanced breast cancer (with previous progression on endocrine therapy) to receive abemaciclib plus fulvestrant or placebo plus fulvestrant.[23]

Adverse events included diarrhea in the abemaciclib group (86.4%) and in the placebo group (24.7%), neutropenia (46% and 4%), nausea (45.1% and 22.9%), fatigue (39.9% and 26.9%), and abdominal pain (35.4% and 15.7%).

The MONARCH 2 study (NCT02107703) tested abemaciclib (CDK4/6 inhibitor) in a phase III, placebo-controlled trial that randomly assigned 669 patients with HER2-negative, hormone receptor–positive, advanced breast cancer (with previous progression on endocrine therapy) to receive abemaciclib plus fulvestrant or placebo plus fulvestrant.[23] › Adverse events included diarrhea in the abemaciclib group (86.4%) and in the placebo group (24.7%), neutropenia (46% and 4%), nausea (45.1% and 22.9%), fatigue (39.9% and 26.9%), and abdominal pain (35.4% and 15.7%).

These events were mostly grade 1 to 2. Grade 1 to 2 diarrhea occurred in 73% of the patients in the abemaciclib group and in 24.2% of the placebo group. Anti-diarrheal medicine effectively managed this symptom in most cases, according to the study report.

The MONARCH 2 study (NCT02107703) tested abemaciclib (CDK4/6 inhibitor) in a phase III, placebo-controlled trial that randomly assigned 669 patients with HER2-negative, hormone receptor–positive, advanced breast cancer (with previous progression on endocrine therapy) to receive abemaciclib plus fulvestrant or placebo plus fulvestrant.[23] › Adverse events included diarrhea in the abemaciclib group (86.4%) and in the placebo group (24.7%), neutropenia (46% and 4%), nausea (45.1% and 22.9%), fatigue (39.9% and 26.9%), and abdominal pain (35.4% and 15.7%).

Grade 3 diarrhea occurred in 13.4% of patients in the abemaciclib group and 0.4% of patients in the placebo group. No grade 4 diarrhea was reported.

The MONARCH 2 study (NCT02107703) tested abemaciclib (CDK4/6 inhibitor) in a phase III, placebo-controlled trial that randomly assigned 669 patients with HER2-negative, hormone receptor–positive, advanced breast cancer (with previous progression on endocrine therapy) to receive abemaciclib plus fulvestrant or placebo plus fulvestrant.[23] › Adverse events included diarrhea in the abemaciclib group (86.4%) and in the placebo group (24.7%), neutropenia (46% and 4%), nausea (45.1% and 22.9%), fatigue (39.9% and 26.9%), and abdominal pain (35.4% and 15.7%).

Grade 3 to 4 neutropenia occurred in 25.5% of patients in the abemaciclib group and 1.7% of patients in the placebo group. Febrile neutropenia was reported in six patients in the abemaciclib arm.