This study retrospectively analyzes the clinical data of HER2-low breast cancer (IHC 1+/2+ and FISH-negative) patients treated with sequential antibody-drug conjugates (ADCs). Key variables include patient demographics, tumor characteristics, ADC regimens (e.g., trastuzumab deruxtecan, sacituzumab govitecan), treatment sequencing, survival outcomes, and safety profiles. Genomic data (e.g., HER2 expression dynamics, TROP2 levels) are integrated to explore resistance mechanisms and prognostic biomarkers.mechanisms.
This study aims to investigate the efficacy of different ADC sequential regimens in HER2-low breast cancer patients.
Diagnosed with HER2-low breast cancer, defined as immunohistochemistry (IHC) score of 1+ or IHC score of 2+ with negative in situ hybridization (FISH-negative)
Received sequential administration of two or more ADCs
Complete data for patient's character, laboratory and imaging test, treatment and follow-up are available.
Concomitant with other tumor components at the time of diagnosis;
Have a history of any other malignant tumors;
Lack of complete data
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Treatment groupsSee each treatment group below.