Timing is everything: new trial seeks best sequence of targeted therapy for breast cancer

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Female patients aged 18-75 years; 2. Histologically confirmed advanced HER2-negative breast cancer, including IHC 2+/ISH-, IHC 1+/ISH-, and IHC 0/ISH- subtypes; 3. Completed first-line combination chemotherapy for advanced/metastatic disease (specific regimen not restricted), with disease progression (PD) evaluated per RECIST criteria (HR-positive patients must have received at least one line of endocrine therapy); 4. Electrocorticography (ECOG) performance status \< 2; 5. Estimated life expectancy ≥ 12 weeks; 6. Adequate bone marrow function, defined as: * ANC ≥ 1.5 × 10⁹/L * Platelets ≥ 90 × 10⁹/L * Hemoglobin ≥ 90 g/L 7. Adequate hepatic and renal function, defined as: * Total bilirubin ≤ 1.5 × upper limit of normal (ULN) * AST or ALT ≤ 2.5 × ULN (≤ 5 × ULN for patients with liver metastases) * Creatinine clearance ≥ 60 mL/min 8. Signed informed consent obtained prior to any study-related procedures or treatments, confirming the patient's willingness to participate and comply with study requirements. Exclusion Criteria: 1. Prior treatment with an ADC after disease recurrence or metastasis; 2. Pregnant or breastfeeding women; 3. No evaluable recurrent or metastatic lesions as defined by RECIST 1.1 criteria; 4. Symptomatic brain parenchymal and/or leptomeningeal metastases with symptoms not adequately controlled by treatment; 5. History of other malignancies within the past 5 years, except for adequately treated carcinoma in situ of the cervix, cutaneous squamous cell carcinoma, or well-controlled localized basal cell carcinoma of the skin; 6. Psychiatric disorders or other conditions that may interfere with patient compliance; 7. Recent history of serious and uncontrolled systemic diseases, such as clinically significant cardiovascular disease, pulmonary disease, metabolic disorders, or arterial/venous thromboembolic events; 8. Concurrent use of other investigational drugs, or participation in another clinical trial within 30 days prior to enrollment; 9. Known or suspected allergy to any study drug or its excipients; 10. Any other condition that, in the opinion of the investigator, renders the patient unsuitable for participation in this trial.