OncoMatch/Clinical Trials/NCT05851014
A Study of GB491 in Combination With Letrozole in Patients With HR Positive and HER2 Negative Advanced Breast Cancer
Is NCT05851014 recruiting? Yes, currently enrolling (May 2026). This Phase 3 trial studies GB491 combined with Letrozole for breast cancer.
Treatment: GB491 combined with Letrozole — The main purpose of this study is to evaluate the efficacy and safety of GB491 combined with Letrozole versus placebo combined with Letrozole in the treatment of HR+/HER2- locally advanced or metastatic breast cancer without prior systemic antitumor therapy
Check if I qualifyExtracted eligibility criteria
Cancer type
Breast Carcinoma
Biomarker criteria
Required: ESR1 hormone receptor-positive
hormone receptor-positive (HR+)
Required: HER2 (ERBB2) negative
human epidermal growth factor receptor 2-negative (HER2-)
Excluded: HER2 (ERBB2) positive
Confirmed diagnosis of HER2 positive disease
Performance status
ECOG 0–1(Restricted strenuous activity)
Prior therapy
Cannot have received: CDK4/6 inhibitor
Systematic treatment with any other CDK4/6 inhibitor
Cannot have received: chemotherapy
Exception: for locoregionally recurrent or metastatic breast cancer
Have previously received chemotherapy for locoregionally recurrent or metastatic breast cancer
Cannot have received: antitumor therapy
Exception: within 4 weeks prior to randomization
Had major surgery (or is expected to require major surgery during the study period), chemotherapy, radiation, any investigational drug, or other antitumor therapy within 4 weeks prior to randomization
Lab requirements
Blood counts
adequate organ and marrow function
Kidney function
adequate organ and marrow function
Liver function
adequate organ and marrow function
adequate organ and marrow function
Structured fields extracted by AI. May contain errors — verify against the official protocol.
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