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A Study to Evaluate Efficacy and Safety of Giredestrant Compared With Fulvestrant (Plus a CDK4/6 Inhibitor), in Participants With ER-Positive, HER2-Negative Advanced Breast Cancer Resistant to Adjuvant Endocrine Therapy (pionERA Breast Cancer)
Trial Status: active
This is a Phase III, randomized, open-label multicenter study that will evaluate the
efficacy and safety of giredestrant compared with fulvestrant, both in combination with
the investigator's choice of a CDK4/6 inhibitor (palbociclib, ribociclib or abemaciclib),
in participants with estrogen receptor-positive (ER+), human epidermal growth factor
receptor 2-negative (HER2-) advanced breast cancer who have developed resistance to
adjuvant endocrine therapy.
Inclusion Criteria
Locally advanced or metastatic adenocarcinoma of the breast, not amenable to treatment with curative intent
Documented estrogen receptor-positive (ER+), HER2-negative (HER2-) tumor assessed locally on the most recent tumor biopsy (or an archived tumor sample if a recent tumor sample is not available for testing)
Confirmed ESR1 mutation status (ESR1m versus ESR1nmd) in baseline circulating tumor DNA (ctDNA) through central laboratory testing
Resistance to prior adjuvant endocrine therapy (ET), which is defined as having relapsed with prior standard adjuvant ET, on-treatment after >/=12 months or off-treatment within 12 months of completion. Prior use of adjuvant CDK4/6i is allowed (if relapse occurred >/=12 months since completion).
No prior systemic anti-cancer therapy for advanced disease
Measurable disease as defined per RECIST v.1.1 or non-measurable (including bone-only) disease
Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0-1
For pre/perimenopausal women and for men: willing to undergo and maintain treatment with approved LHRH agonist therapy (as per local guidelines) for the duration of study treatment
Exclusion Criteria
Prior systemic therapy (e.g., prior chemotherapy, immunotherapy, or biologic therapy) for locally advanced unresectable or metastatic breast cancer
Prior treatment with another SERD (e.g., fulvestrant, oral SERDs) or novel ER-targeting agents
Advanced, symptomatic, visceral spread that is at risk of life-threatening complications in the short term
Active cardiac disease or history of cardiac dysfunction
Clinically significant history of liver disease
Additional locations may be listed on ClinicalTrials.gov for NCT06065748.