1. Imlunestrant, an Oral Selective Estrogen Receptor Degrader, as Monotherapy and in Combination With Targeted Therapy in Estrogen Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer: Phase Ia/Ib EMBER Study.
- Author
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Jhaveri KL, Lim E, Jeselsohn R, Ma CX, Hamilton EP, Osborne C, Bhave M, Kaufman PA, Beck JT, Manso Sanchez L, Parajuli R, Wang HC, Tao JJ, Im SA, Harnden K, Yonemori K, Dhakal A, Neven P, Aftimos P, Pierga JY, Lu YS, Larson T, Jerez Y, Sideras K, Sohn J, Kim SB, Saura C, Bardia A, Sammons SL, Bacchion F, Li Y, Yuen E, Estrem ST, Rodrik-Outmezguine V, Nguyen B, Ismail-Khan R, Smyth L, and Beeram M
- Subjects
- Humans, Female, Middle Aged, Aged, Adult, Aromatase Inhibitors administration & dosage, Aromatase Inhibitors therapeutic use, Aromatase Inhibitors adverse effects, Thiazoles administration & dosage, Thiazoles therapeutic use, Thiazoles adverse effects, Administration, Oral, Aged, 80 and over, Progression-Free Survival, Molecular Targeted Therapy, Cyclin-Dependent Kinase 4 antagonists & inhibitors, Breast Neoplasms drug therapy, Breast Neoplasms pathology, Breast Neoplasms genetics, Breast Neoplasms metabolism, Antineoplastic Combined Chemotherapy Protocols therapeutic use, Antineoplastic Combined Chemotherapy Protocols adverse effects, Everolimus administration & dosage, Everolimus therapeutic use, Everolimus adverse effects, Benzimidazoles administration & dosage, Benzimidazoles therapeutic use, Benzimidazoles adverse effects, Receptors, Estrogen metabolism, Aminopyridines administration & dosage, Aminopyridines adverse effects, Aminopyridines therapeutic use, Receptor, ErbB-2 metabolism
- Abstract
Purpose: Imlunestrant is a next-generation oral selective estrogen receptor (ER) degrader designed to deliver continuous ER target inhibition, including in ESR1- mutant breast cancer. This phase Ia/b trial determined the recommended phase II dose (RP2D), safety, pharmacokinetics, and efficacy of imlunestrant, as monotherapy and in combination with targeted therapy, in ER-positive (ER+) advanced breast cancer (ABC) and endometrial endometrioid cancer. The ER+/human epidermal growth factor receptor 2-negative (HER2-) ABC experience is reported here., Methods: An i3+3 dose-escalation design was used, followed by dose expansions of imlunestrant as monotherapy or in combination with abemaciclib with or without aromatase inhibitor (AI), everolimus, or alpelisib. Imlunestrant was administered orally once daily and with the combination partner per label., Results: Overall, 262 patients with ER+/HER2- ABC were treated (phase Ia, n = 74; phase Ib, n = 188). Among patients who received imlunestrant monotherapy (n = 114), no dose-limiting toxicities or discontinuations occurred. At the RP2D (400 mg once daily), patients (n = 51) reported grade 1-2 nausea (39.2%), fatigue (39.2%), and diarrhea (29.4%). Patients at RP2D had received previous cyclin-dependent kinase 4/6 inhibitor (CDK4/6i; 92.2%), fulvestrant (41.2%), and chemotherapy (29.4%) for ABC and achieved a median progression-free survival (mPFS) of 7.2 months (95% CI, 3.7 to 8.3). Among patients who received imlunestrant + abemaciclib (n = 42) and imlunestrant + abemaciclib + AI (n = 43), most (69.4%) were treatment-naïve for ABC; all were CDK4/6i-naïve. Patients treated with imlunestrant + everolimus (n = 42)/alpelisib (n = 21) had received previous CDK4/6i (100%), fulvestrant (34.9%), and chemotherapy (17.5%) for ABC. No new safety signals or interactions with partnered drugs were observed. The mPFS was 19.2 months (95% CI, 13.8 to not available) for imlunestrant + abemaciclib and was not reached for imlunestrant + abemaciclib + AI. The mPFS with imlunestrant + everolimus/alpelisib was 15.9 months (95% CI, 11.3 to 19.1)/9.2 months (95% CI, 3.7 to 11.1). Antitumor activity was evident regardless of ESR1 mutation status., Conclusion: Imlunestrant, as monotherapy or in combination with targeted therapy, had a manageable safety profile with evidence of preliminary antitumor activity in ER+/HER2- ABC.
- Published
- 2024
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