FDA Grants Accelerated Approval for New Breast Cancer Drug

Why it matters locally: This federal approval of a new breast cancer drug could significantly impact healthcare providers and patients across Massachusetts, offering a new treatment option for individuals with advanced HR-positive, HER2-negative breast cancer with ESR1 mutations.

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The U.S. Food and Drug Administration (FDA) approved a new medication for adult patients with advanced breast cancer today. The drug, elacestrant, received accelerated approval for individuals whose hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer progressed after at least one line of endocrine therapy. Patients must also have ESR1 mutations, as detected by an FDA-approved test. Accelerated approval allows the FDA to approve drugs for serious conditions that address unmet medical needs. This approval happens based on a surrogate endpoint, such as tumor response rate, that researchers believe will predict clinical benefit. Confirmatory trials are required to verify the anticipated clinical benefit. Researchers evaluated elacestrant in a clinical trial involving 223 postmenopausal men and women. All participants had advanced HR-positive, HER2-negative breast cancer with ESR1 mutations. They had previously received one or two lines of endocrine therapy and one to two lines of chemotherapy. In the trial, 27.9% of patients who received elacestrant experienced a partial or complete response to the treatment. The median duration of response for these patients was 8.6 months. Common side effects observed in patients included musculoskeletal pain, nausea, vomiting, fatigue, diarrhea, indigestion, and hot flashes. The FDA advises healthcare professionals to monitor patients for potential elevated cholesterol and triglyceride levels. The agency also noted that elacestrant can cause fetal harm when administered to pregnant individuals. The FDA granted the approval to Stemline Therapeutics, Inc. The agency reviewed the application under its Project Orbis initiative, which facilitates concurrent review among international partners.