Dr. Kaklamani on CDK4/6 Inhibition Prior to Elacestrant in ER+/HER2– Breast Cancer

Virginia Kaklamani, MD, professor of medicine, Division of Hematology/Oncology, leader, Breast Cancer Program, UT Health San Antonio MD Anderson Cancer Center, discusses the utilization of elacestrant (Orserdu) following treatment with CDK4/6 inhibitors in patients with estrogen receptor (ER)-positive, HER2-negative metastatic breast cancer.

At the 2022 San Antonio Breast Cancer Symposium (SABCS), investigators presented data from the phase 3 EMERALD trial (NCT03778931), Kaklamani begins. This is an international, multicenter, randomized, open-label trial, in which investigators compared elacestrant, an oral selective estrogen receptor degrader (SERD), with standard-of-care endocrine therapy, Kaklamani says. The standard-of-care approaches included either an aromatase inhibitor or fulvestrant (Faslodex), Kaklamani adds.

Data from the trial were previously presented at the 2021 San Antonio Breast Cancer Symposium, showing that elacestrant improved median progression-free survival (PFS), which was the trial’s primary end point, Kaklamani continues. Moreover, the trial showed that this treatment approach also improved median PFS in patients whose tumors have mutations in the ESR1 gene, and this outcome was another primary end point of the study, Kaklamani emphasizes.

At the 2022 SABCS, investigators shared data examining the effect of elacestrant in patients who received a prior CDK4/6 inhibitor, Kaklamani explains.

Investigators showed that among the 150 patients who received at least a 12-month duration of a CDK4/6 inhibitor prior to receiving elacestrant, the median PFS was 3.78 months, while the 160 patients who received prior endocrine therapy had a median PFS of 1.91 months.

This analysis was performed to understand whether certain groups of patients derive more or less benefit from elacestrant, Kaklamani notes. Overall, investigators showed that patients do derive a benefit from elacestrant whether they were on a shorter or longer duration of a CDK4/6 inhibitor. These results are even more pronounced in patients whose tumors have ESR1 mutations, Kaklamani concludes.