Combining a CDK4/6 inhibitor and fulvestrant improves overall survival consistently among patients with hormone receptor–positive, HER2-negative advanced or metastatic breast cancer, according to a U.S. Food and Drug Administration (FDA) analysis. The agency reported the findings in Lancet Oncology.

FDA conducted a pooled analysis of three phase III randomized clinical trials conducted as part of abemaciclib, palbociclib, and ribociclib’s marketing applications. The three studies involved 1,948 patients in total who received either one of the CDK4/6 inhibitors plus fulvestrant (n = 1,296) or a placebo plus fulvestrant (n = 652).

After a median follow-up of 45.1 months, the researchers found that overall median survival improved by 7.0 months in patients receiving the intervention versus the placebo as second-line or later systemic endocrine therapy. Two of the studies also evaluated the intervention as first-line therapy, but the survival benefit was not estimable in that setting.

“The addition of CDK inhibitors to fulvestrant resulted in a consistent overall survival benefit in all pooled patients and within most clinicopathological subgroups of interest,” the researchers concluded. “These findings support the existing standard of care of CDK inhibitors plus fulvestrant for the treatment of patients with hormone receptor–positive, HER2-negative advanced breast cancer."

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