Phase III EMERALD study of RAD 1901 in breast cancer presented at San Antonio Breast Cancer Symposium
The Menarini Group will present additional data from the Phase III EMERALD study (NCT03778931) of elacestrant, an investigational oral SERD, during the upcoming San Antonio Breast Cancer Symposium (SABCS) being held from December 6-10
EMERALD is a Phase III registrational trial that demonstrated statistically significant progression-free survival (PFS) with elacestrant vs SOC endocrine monotherapy (fulvestrant, letrozole, anastrozole, exemestane), meeting both primary endpoints in all patients and in those patients harbouring ESR1 mutations (ESR1-mut), following progression on prior CDK4/6 inhibitors (CDK4/6i) in ER+, HER2- advanced or metastatic breast cancer.
A post-hoc analysis of the PFS results in the EMERALD trial based on the duration of prior CDK4/6i usage shows clinically meaningful results which favor monotherapy elacestrant, both in the total patient population as well as in patients with ESR1-mut. Increased duration of prior CDK4/6i in metastatic patients was positively associated with longer PFS on elacestrant but not with SOC. For those who were exposed to CDK4/6i at least 12 months prior to randomization on EMERALD, elacestrant achieved: In the all-patient population, a mPFS of 3.8 months on elacestrant vs 1.9 months on SOC, a 39% reduction in the risk of progression or death (HR=0.61 95% CI: 0.45-0.83). In the ESR1-mut population, a mPFS of 8.6 months on elacestrant vs 1.9 months on SOC, a 59% reduction in the risk of progression or death (HR=0.41 95% CI: 0.26-0.63). For those who were exposed with CDK4/6i of at least 18 months prior to randomization on EMERALD, elacestrant achieved: In the all-patient population, a mPFS of 5.5 months on elacestrant vs 3.3 months with SOC, a 30% reduction in the risk of progression or death (HR=0.70 95% CI: 0.48-1.02). In the ESR1-mut population, a mPFS of 8.6 months on elacestrant vs 2.1 months on SOC, a 53% reduction in the risk of progression or death (HR=0.47 CI: 0.20-0.79).
Updated safety data were consistent with previously reported results. Most of the adverse events (AEs), including nausea, were grade 1 and 2, and only 3.4% and 0.9% of the patients discontinued trial therapy because of an AE on elacestrant and SOC, respectively. A low percentage of patients received an antiemetic; 8.0% on elacestrant, 3.7% on fulvestrant, and 10.3% on AI, respectively. No hematological safety signal was observed and none of the patients in either of the two treatment arms had sinus bradycardia.