Conference Coverage

What’s hot at the world’s premiere breast cancer meeting



The San Antonio Breast Cancer Symposium (SABCS) 2021 will “be a great meeting,” according to Carlos Arteaga, MD, director of Simmons Comprehensive Cancer Center at UT Southwestern Medical Center, Dallas.

Dr. Arteaga, the meeting’s codirector, said the first-ever hybrid symposium will take place virtually from Dec. 7 to 10 as well as in person. Online availability appears to be a boon to attendance, with a record 9,325 registrants for the 2020 symposium, held only virtually because of the COVID-19 pandemic.

The meeting will have an app available, which can be accessed by searching “San Antonio Breast Cancer Symposium” (Google Play for Android, Apple for iOS) and downloading, or by going to from a desktop computer.

Dr. Arteaga provided a sneak peek of the most exciting research being presented at the upcoming meeting.

On the horizon for advanced breast cancer

A “very important” study of an investigational oral agent employed in heavily pretreated postmenopausal women with estrogen receptor–positive (ER+) advanced breast cancer headlines the meeting.

This international, multicenter trial could have “practice-changing implications,” Dr. Arteaga said in an interview.

The phase 3 EMERALD trial (abstract GS2-02) pits elacestrant, a selective estrogen receptor degrader (SERD), against standard endocrine therapy (fulvestrant or an aromatase inhibitor) in patients with metastatic breast cancer whose disease has progressed after treatment with at least one endocrine therapy and a CDK4/6 inhibitor.

The trial is important because many patients with breast cancer have estrogen receptor mutations, which are a “major mechanism of [drug] resistance” and thus progression on earlier therapy, Dr. Arteaga said.

Elacestrant is in good company among a plethora of oral SERDs under investigation in advanced breast cancer; however, currently, fulvestrant – which requires an intramuscular injection in the buttocks every month – is the only approved SERD.

“There’s plenty of preclinical data that suggest that these drugs [SERDs] may have activity against these mutant forms of the receptor, which occur in up to 40% of patients with advanced ER+ breast cancer,” he explained.

Researchers will present data on two primary outcome measures from the phase 3 trial: progression-free survival (PFS) based on mutations of the estrogen receptor 1 gene (ESR1-mut) and PFS in all subjects regardless of ESR1 status.

In addition to the EMERALD trial, PADA-1 (abstract GS3-05) is another important randomized, phase 3 trial focused on treating estrogen receptor mutations in patients with metastatic disease, said Dr. Arteaga.

The trial has enrolled patients with ER+ metastatic breast cancer who received an aromatase inhibitor (letrozole, anastrozole, or exemestane) and the CDK4/6 inhibitor palbociclib as first-line therapy.

In step 1 of the trial, approximately 1,000 patients were screened for circulating blood ESR1 mutation detection at regular intervals while being treated with palbociclib and an aromatase inhibitor in a continuous scheme until tumor progression or ESR1 mutation detection.

In step 2, up to 200 patients with a rising circulating ESR1 mutation and no tumor progression were randomized 1:1 to no change in therapy until tumor progression or to receive palbociclib plus fulvestrant until tumor progression.

The trial examines the safety and efficacy of “a clinical conundrum that we face” in this setting: whether or not to switch treatment from an aromatase inhibitor to fulvestrant while continuing a CDK4/6 inhibitor at the sign of mutation detection, Dr. Arteaga explained.


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