It targets resistant cancers.
A new experimental hormone therapy pill has demonstrated potential in extending the lives of women with advanced breast cancer that is difficult to treat, according to a recent clinical trial. The drug, imlunestrant, has been shown to improve progression-free survival in patients whose cancers are driven by the hormone estrogen. The treatment was especially effective in cases where the cancer carried a mutation in the ESR1 gene, which encodes estrogen receptors, as reported in findings published on December 11 in the New England Journal of Medicine and presented at the San Antonio Breast Cancer Symposium.
Imlunestrant is a selective estrogen receptor degrader (SERD) that works by reducing the effectiveness of estrogen receptors in breast cancer cells, making them less responsive to estrogen. The clinical trial included 874 women with advanced, recurrent, or treatment-resistant breast cancer that was estrogen receptor-positive (ER-positive), meaning their cancer growth was fueled by estrogen. Approximately 70% of all breast cancers are ER-positive, according to the Cleveland Clinic.
In the trial, one-third of the participants were assigned to receive imlunestrant alone, another third received a combination of imlunestrant and the targeted therapy drug Verzenio (abemaciclib), and the final group received standard hormone therapy. Verzenio, a CDK4/6 inhibitor, helps to stop cancer cells from dividing and multiplying. For women with ESR1 mutations, imlunestrant alone reduced the risk of cancer progression or death by 38% compared to standard hormone therapy, and the combination therapy with Verzenio was even more effective, reducing the risk by 43%.
The combination therapy proved particularly promising, with women who received both drugs experiencing a median progression-free survival of 9.4 months, compared to 5.5 months for imlunestrant alone and 3.8 months for standard therapy. The combination treatment was also deemed safe, with only about 6% of participants needing to discontinue due to side effects. Both imlunestrant and Verzenio are taken orally, and imlunestrant has the added benefit of being able to cross the blood-brain barrier, potentially aiding in the treatment of breast cancers that have spread to the brain.
These encouraging results suggest that imlunestrant, either alone or in combination with Verzenio, could provide an effective oral treatment option for women with ER-positive, HER2-negative advanced breast cancer, especially those who have not responded to other therapies.
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