New anti-hormonal therapy could be a new treatment option for early-stage breast cancer



Early results from a UCLA-led clinical trial revealed treatment of women with early breast cancer estrogen receptor (ER) positive and human epidermal growth factor (HER2) receptor 2 negative with a new type of anti-hormone therapy, called selective oral estrogen receptor degrading therapy (SERD), has led to clinically significant reductions in tumor activity before surgery. Activity was assessed by measuring the levels of Ki67, which is a protein that is expressed when the cancer cell divides. Reducing Ki67 levels gives researchers information about the likelihood of a good outcome.

Women treated with two weeks of oral SERD giredestrant had a greater than 80% decrease in their Ki67 tumor, compared to a 67% reduction in patients who were treated with anastrozole, an aromatase inhibitor. (IA) standard, which are pills that lower estrogen. levels.

This is encouraging data from the first reported trial comparing an oral SERD to an AI. Our results provide an early indication that giredestrant may reduce the division of cancer cells to a greater extent than our standard treatment. And we know from other studies that when a tumor loses its Ki67 after two weeks of hormone therapy, the patient has a lower chance of long-term disease recurrence. These data provide a strong rationale for further evaluating giredestrant in larger randomized trials in curative or late-stage settings. “

Dr Sara Hurvitz, Principal Study Author and Director, Clinical Breast Cancer Research Program, Jonsson Comprehensive Cancer Center, University of California – Los Angeles Health Sciences


ER-positive breast cancer accounts for more than two-thirds of all breast cancers diagnosed; over 180,000 women are diagnosed with this subtype each year in the United States. Up to half of women with ER-positive disease will eventually develop resistance to current treatments.

Oral SERDs, which are downregulators of estrogen receptors taken in pill form instead of injection, are becoming an increasingly studied alternative to aromatase inhibitors, which are currently the gold standard treatment for women with ER-positive early breast cancer, but don’t always do so. work long term. Researchers continue to develop new generations of oral SERDs to better overcome drug resistance.


Researchers recruited 202 postmenopausal women with untreated, ER-positive and HER2-negative early breast cancer to assess the efficacy, safety and pharmacokinetics of giredestrant. Half of the patients received two weeks of giredestrant and the other half received two weeks of anastrozole in the window of opportunity phase. After two weeks, palbociclib was administered in combination with giredestrant or anastrozole during the 14 week neoadjuvant phase before surgery. Biopsies were taken before the start of therapy and at the two week time point to see if the percentage of cells expressing Ki67 had dropped. Data from the interim analysis were presented, which included 108 patients evaluable for safety and 83 patients evaluable for efficacy.


Interim analysis shows that giredestrant may be another treatment option for women with ER positive breast cancer. The data also gives researchers evidence that they should move forward with the full primary analysis and that giredestrant should be studied in larger randomized trials.


University of California – Los Angeles Health Sciences

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