This study is a phase II clinical trial of SSGJ-612 combined with a human epidermal growth factor receptor 2 (HER2)-targeted antibody-drug conjugate (ADC) in patients with hormone receptor (HR)-positive, HER2-low or HER2-ultralow metastatic breast cancer.
Voluntary participation in this study, signed informed consent form, good treatment compliance, and willingness to cooperate to complete all trial procedures.
Expected survival duration ≥ 3 months.
Metastatic tumor;
Tumor samples tested by central laboratory confirmed as HER2-low or HER2 ultra-low expression;
Uncontrolled or severe cardiovascular disease.
History of interstitial lung disease (ILD)/pneumonia requiring corticosteroid therapy (non-infectious), or current ILD/pneumonia, or suspected ILD/pneumonia not excluded by screening imaging.
Presence of pulmonary-specific, clinically significant comorbid conditions.
Presence of spinal cord compression, or clinically active central nervous system metastases.