Oral selective estrogen receptor degraders for breast cancer treatment: focus on pharmacological differences.

Purpose: The management of hormone receptor-positive (HR +) breast cancer (BC) relies on endocrine therapy (ET), with a primary focus on disrupting estrogen receptor (ER) signaling due to its critical role in BC tumorigenesis and progression. While effective for both early-stage and advanced breast cancers, ET frequently encounters resistance mechanisms, including both ligand-dependent and ligand-independent trajectories, ultimately leading to disease progression.
Methods: We searched PubMed, EMBASE and Scopus databases to review the current evidence on the use of novel oral selective estrogen receptor degraders (SERDs) for the treatment of HR+ BC.
Conclusions: Somatic activating mutations of the estrogen receptor 1 (ESR1) gene are known to sustain ER activity, boost ER-dependent gene transcription, and foster resistance to ET. The most significant gap remains after treatment failure with ET and cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors, where fulvestrant monotherapy typically results in a median progression-free survival of 2-3 months. Novel compounds, including oral SERDs, have been explored for their potential to overcome therapeutic resistance, both as monotherapy and in combination with other targeted therapies. Herein, we provide an overview on the latest findings on oral SERDs, examining their mechanism of action, safety data, and pharmacokinetics and pharmacodynamics profiles.
Competing Interests: Declarations. Competing interests: C.C. consulting/advisory role/speaker bureau: Pfizer, Roche, MSD, Lilly, Novartis, Seagen, Gilead, AstraZeneca, Daiichi Sankyo. A.M. has received honoraria as a consultant, advisor or speaker from Roche and Menarini/Stemline; and has received travel and accommodation support from AstraZeneca. G.C. received honoraria for speaker’s engagements from Roche, Seattle Genetics, Novartis, Lilly, Pfizer, Foundation Medicine, NanoString, Samsung, Celltrion, BMS, and MSD; honoraria for providing consultancy from Roche, Seattle Genetics, and NanoString; honoraria for participating in Advisory Board for Roche, Lilly, Pfizer, Foundation Medicine, Samsung, Celltrion, and Mylan; honoraria for writing engagement from Novartis and BMS; honoraria for participation in Ellipsis Scientific Affairs Group; Institutional research funding for conducting phase I and II clinical trials from Pfizer, Roche, Novartis, Sanofi, Celgene, Servier, Orion, AstraZeneca, Seattle Genetics, AbbVie, Tesaro, BMS, Merck Serono, Merck Sharp Dome, Janssen-Cilag, Philogen, Bayer, Medivation, and Medimmune. The other authors have no relevant financial or non-financial interests to disclose. Ethical approval: Not Applicable. Consent to participate: Not Applicable. Consent to publish: Not Applicable.
(© 2025. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)