Elacestrant Proves Effective in Advanced, Co-Mutated Breast Cancer

Elacestrant is effective in patients with advanced breast cancer that has both an ESR1 and other mutation.

Following progression or relapse, it is key for providers to test for ESR1, as well as potential co-mutations, to guide second-line treatment decisions for patients with estrogen receptor (ER)-positive, HER2-negative advanced or metastatic breast cancer.

In particular, elacestrant (Orserdu) has proven effective in this patient population who previously received at least 1 line of endocrine therapy.

“Findings suggest that observed benefit with elacestrant versus standard of care [endocrine therapy] was not impacted by the presence of the common co-existing mutations or molecular expressions,” Erica Doubleday, MS, FNP-C, BSN, RN, said.

In a recent Community Case Forum event, , Doubleday of Oschner MD Anderson Cancer Center, led a discussion about the evolving landscape of second-line treatment for HR-positive, HER2-negative metastatic breast cancer.

Elacestrant in Co-Mutated, Metastatic Breast Cancer

Elacestrant may be the best option for patients whose disease is positive for more than 1 mutation; however, it is essential to consider other patient characteristics when determining a treatment plan, Doubleday said.

She discussed a patient case, in which the individual expressed co-mutations of ESR1 and PIK3. The patient is 90 years old, so, at the time, she is only being treated with fulvestrant.

“However, when she does progress—and she will progress on it—we will most likely go with elacestrant … just for ease of use and less side effects,” Doubleday said. “We have to make it easy for her because she’s 90. … I think it’s important to look at the patient, look at their background, their age, performance status and really make the [treatment] decision off of that.”

The use of elacestrant in patients with ESR1 and PIK3CA co-mutations is supported by findings from the EMRALD trial (NCT03778931). Data showed that among a subgroup of patients with the co-mutations who were previously treated with a CDK4/6 inhibitor, the median progression-free survival (PFS) was 5.45 months (95% CI, 2.14-10.84) with elacestrant, compared with 1.94 months (95% CI, 1.84-3.94) with standard endocrine monotherapy^.1

Patient Assistance in Biomarker Testing

To determine the best treatment available, biomarker testing is needed to identify ESR1 following each progression of the disease. Advanced practice providers (APPs) who attended the session mentioned that they sometimes face difficulty getting coverage for the testing.

READ MORE: ESR1 Testing Is Crucial in Second-line HR+, HER2- Metastatic Breast Cancer

“We had a very [heavily populated] Medicaid population and—as we know—Medicaid is strategic in what they will and will not cover. So a lot of things we want to do, we cannot because we do not have payment for it,” one attendee said.

Doubleday mentioned that APPs may be able to encourage patients to apply for patient assistance programs that will help lower the cost of the procedure.

“Depending on what company is used, they may have patient assistance [programs],” she said.

References

Bardia A, O'Shaughnessy J, Bidard F-C, et al. Elacestrant vs standard-of-care in ER+/HER2- advanced or metastatic breast cancer (mBC) with ESR1 mutation: key biomarkers and clinical subgroup analyses from the phase 3 EMERALD trial. Presented at the 2023 San Antonio Breast Cancer Symposium; December 5-9, 2023; San Antonio, TX. Abstract PS17-02.