Real-World Data Reveal Longer PFS With Elacestrant in Breast Cancer

Seth Wander, MD, PhD, a medical oncologist at the Massachusetts General Hospital and instructor in medicine at Harvard Medical School, discusses the efficacy of elacestrant (Orserdu) in real-world data for patients with ESR1-mutated breast cancer.

At the American Society of Clinical Oncology Annual Meeting (ASCO) and the San Antonia Breast Cancer Conference, Wander and his fellow investigators presented real-world data of patients treated with elacestrant. The initial findings focused on clinical outcomes, such as treatment duration and therapy line usage. Early post-approval use skewed toward later lines, but Wander anticipates a shift toward second-line use as clinicians become more familiar with the drug.

In real-world studies, surrogates like time to next treatment or discontinuation are used to estimate progression-free survival (PFS). Wander acknowledges the lack of uniform scans, but despite these limitations, elacestrant performed well, with PFS estimates of 5 to 7 months. This exceeds those from the EMERALD trial (NCT03778931) at a median PFS of 2.8 months on the overall population. This suggests clinicians are selecting appropriate patients—those with ESR1 mutations who responded well to prior endocrine and CDK4/6 inhibitor therapy—optimizing real-world outcomes, according to Wander.

TRANSCRIPTION

0:09 | What we've presented so far over the last 2 conferences at ASCO and San Antonio is a fairly large cohort of patients who received elacestrant in...the real-world setting. The first set of data we presented, we're looking at clinical outcomes. How long did patients stay on the drug? What line of therapy did they use the drug in? And as may not be surprising to you, these patients at the very beginning, when the drug was first approved, a lot of them were later line. They you know, it might have been [in their] third, fourth, or fifth line of therapy because the drug just came on and clinicians were looking for options for their patients. As time goes on, I suspect we'll see the average use of that drug drift back down toward the second-line setting.

0:56 | We use surrogates for PFS when we look at real-world data. We use measurements called time to next treatment or time to treatment discontinuation. These are sort of tried-and-true estimates of PFS, but because this isn't a prospective, randomized study, not everyone's being scanned at the same time. With that limitation in mind, we're actually seeing, regardless of line of therapy, that the patients are getting, elacestrant doing quite well. They're actually exceeding the estimated PFS on the EMERALD study, with numbers that are up in the neighborhood of sort of 5 to 7 months. Again, a little bit of variation based on line of therapy, but not much. That suggests to me that in the real world, clinicians are choosing this drug to some extent for the right patients, for patients that obviously have the ESR1 mutation, but also did well on their first-line endocrine and CDK4/6 inhibitor therapy, so they're likely to do well on subsequent endocrine therapy.