Netupitant/Palonosetron for Prevention of Nausea and Vomiting in Breast Cancer ADC Therapy

Netupitant/Palonosetron for Prevention of Nausea and Vomiting in Breast Cancer ADC Therapy

Inclusion Criteria: Age ≥ 18 years. Histologically or cytologically confirmed breast cancer. Planned to initially receive one of the following antibody-drug conjugate (ADC) agents: trastuzumab deruxtecan (T-DXd), trastuzumab rezetecan (SHR-A1811), or datopotamab deruxtecan (Dato-DXd). Planned to use netupitant/palonosetron capsules (NEPA) prophylactically as an antiemetic prior to ADC therapy. Eastern Cooperative Oncology Group (ECOG) performance status of 0-2. Expected survival ≥ 3 months. Adequate organ function, defined as: Absolute neutrophil count (ANC) ≥ 1.5 × 10⁹/L; Platelet count ≥ 100 × 10⁹/L; Hemoglobin ≥ 90 g/L; Serum total bilirubin ≤ 1.5 × ULN; ALT and AST ≤ 2.5 × ULN (≤ 5 × ULN for patients with liver metastases); Serum creatinine ≤ 1.5 × ULN or creatinine clearance ≥ 60 mL/min. Able to understand and voluntarily sign written informed consent. Able and willing to use an electronic patient-reported outcome (ePRO) device to complete daily diary records. Exclusion Criteria: * Currently participating in another clinical trial that may affect the antiemetic evaluation or drug exposure of this study. Nausea (Visual Analog Scale \[VAS\] ≥ 5 mm) or vomiting within 24 hours prior to enrollment. Use of any antiemetic medication within 2 weeks prior to enrollment, including 5-HT3 receptor antagonists, NK1 receptor antagonists, glucocorticoids, metoclopramide, olanzapine, etc. Use of benzodiazepines, opioids, or opioid-like medications within 1 week prior to enrollment or planned use during the study period (especially the Day 1-21 observation window), except single doses of midazolam, temazepam, or triazolam. Known allergy to netupitant, palonosetron, or excipients of the NEPA capsule. Symptomatic brain metastases or leptomeningeal metastases (patients who have received treatment and been stable for ≥ 4 weeks are eligible). Uncontrolled serious medical conditions, including but not limited to: uncontrolled hypertension (systolic blood pressure ≥ 160 mmHg or diastolic blood pressure ≥ 100 mmHg), uncontrolled diabetes (HbA1c ≥ 8.0%), New York Heart Association (NYHA) functional classification ≥ III, myocardial infarction or unstable angina within 6 months, or history of clinically significant QT interval prolongation. Psychiatric disorder or cognitive impairment that may affect the reliability of nausea/vomiting assessment or ePRO completion. Pregnant or lactating women. Any other condition that, in the investigator's judgment, makes the participant unsuitable for this study.