The US Food and Drug Administration (FDA) approved fulvestrant with abemaciclib for patients with hormone receptor–positive, HER2-negative advanced or metastatic breast cancer, according to a press release.1 Patients who progress on endocrine therapy are eligible for the combination.

The approval was based on results from the phase 3 MONARCH 2 trial ( Identifier: NCT02107703), for which patients were randomly assigned to receive fulvestrant plus abemaciclib (446 patients) or fulvestrant plus placebo (223 patients).2 Patients in the abemaciclib group had double the objective response rate of those in the placebo group (48.1% vs 21.3%, respectively) and more than a 7-month improvement in progression-free survival (16.4 months vs 9.3 months).

Some adverse events were, however, much more common in the abemaciclib arm, including diarrhea, neutropenia, nausea, and fatigue.

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Abemaciclib is a CDK4/6 inhibitor that was granted Breakthrough Designation by the FDA in 2015. It was approved in September 2017 for patients with hormone receptor–positive, HER2-negative breast cancer previously treated with hormone therapy.

Fulvestrant is an estrogen-targeting therapy that was approved for some patients with breast cancer in 2002.


  1. Faslodex receives US FDA approval for the treatment of advanced breast cancer in combination with abemaciclib [news release]. AstraZeneca: November 15, 2017. Accessed November 15, 2017.
  2. Sledge GW Jr, Toi M, Neven P, et al. MONARCH 2: abemaciclib in combination with fulvestrant in women with HR+/HER2- advanced breast cancer who had progressed while receiving endocrine therapy. J Clin Oncol. 2017;35(25):2875-84. doi: 10.1200/JCO.2017.73.7585