The US Food and Drug Administration (FDA) approved abemaciclib for the treatment of adult patients with hormone receptor–positive, HER2-negative advanced or metastatic breast cancer who have progressed after receiving endocrine therapy.1

Abemaciclib was approved to be administered concomitantly with fulvestrant, an endocrine therapy, if the cancer had grown despite endocrine therapy. It was also approved as monotherapy for patients previously treated with endocrine therapy and chemotherapy after metastasis.

The FDA based its approval on evidence from the phase 3 MONARCH 2 study ( Identifier: NCT02107703), for which researchers randomly assigned 669 patients with advanced breast cancer to receive abemaciclib 150 mg twice daily with fulvestrant or placebo with fulvestrant.

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Patients in the abemaciclib arm had a median progression-free survival of 16.4 months compared with 9.3 months in the placebo arm (hazard ratio [HR], 0.553; 95% CI, 0.449-0.681; P < .001). Patients in the abemaciclib arm had an objective response rate of 48.1% (95% CI, 42.6%-53.6%) vs 21.3% (95% CI, 15.1%-27.6%) in the placebo arm.

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The most frequently reported adverse events with abemaciclib include diarrhea, nausea, vomiting, abdominal pain, neutropenia, anemia, infection, headache, and fatigue.

Abemaciclib was previously granted Breakthrough Therapy Designation and Priority Review.


  1. FDA approves new treatment for certain advanced or metastatic breast cancers [news release]. Silver Spring, MD: US Food and Drug Administration; September 28, 2017. Accessed September 28th, 2017.