Table 1.
Clinical Trials That Evaluated the Use of Elacestrant in Advanced Breast Cancer
| Study | Study Setting | Study Population | Number of Patients | Intervention | Primary Endpoint(s) | Results |
|---|---|---|---|---|---|---|
| RAD1901-10619 | Phase Ib | Post-menopausal women with ER-positive HER2-negative advanced breast cancer who had disease progression after ≥ 6 months of 1–3 lines of endocrine therapy for advanced disease No prior CDK4/6i |
16 | Elacestrant 400 mg daily Elacestrant 200 mg daily with escalation to 400 mg after 2 weeks |
Percentage difference in FES uptake in tumor lesions after 14 days of treatment, compared to baseline | Median reduction in FES uptake in tumor lesions from baseline to day 14: 89% (similar in both dose cohorts) ORR: 11.1% CBR: 30.8% Median PFS: 5.3 months |
| RAD1901-00520 | Phase I | Post-menopausal women with ER-positive HER2-negative advanced breast cancer, heavily pre-treated (median of 3 prior lines of therapy for advanced disease) Allowed prior CDK4/6i and prior SERD |
57 | Elacestrant 200–1000 mg daily | Frequency of dose-limiting toxicities (DLT) during the first 28 days | No DLT up to 600 mg daily Most common side effects: nausea, increase triglycerides, decreased serum phosphorus ORR: 19.4% CBR: 42.6% Median PFS: 4.5 months |
| EMERALD21 | Phase III | Men and post-menopausal women with ER-positive HER2-negative advanced breast cancer who had progressed on 1 or 2 lines of endocrine therapy for advanced disease Prior CDK4/6i was required |
477 | Elacestrant 400 mg daily versus standard of care endocrine therapy (fulvestrant or AI) | PFS in all patients and PFS in patients with ESR1 mutation | PFS in all patients: relative reduction in progression or death of 30% (HR 0.70; P = 0.002) vs SoC PFS in patients with ESR1 mutation: relative reduction in progression or death of 45% (HR 0.55; 95%; P = 0.0005) vs SoC 12-month PFS in all patients: 22.3% with elacestrant vs 9.4% with SoC 12-month PFS in patients with ESR1 mutation: 26.8% with elacestrant vs 8.2% with SoC |
Abbreviations: ER-positive, estrogen receptor positive; HER2-negative, human epidermal growth factor receptor 2 negative; CDK4/6i, cyclin-dependent kinase 4/6 inhibitor; FES, 16α-18F-fluoro-17β-estradiol; ORR, objective response rate; CBR, clinical benefit rate; PFS, progression free survival; SERD, selective estrogen receptor degrader; DLT, dose-limiting toxicities; AI, aromatase inhibitor; SoC, standard of care; ESR1, estrogen receptor gene α.