Clinical Research Directory

Dynamic ctDNA Monitoring in Advanced Malignant Phyllodes Tumors of the Breast

Malignant phyllodes tumor of the breast is a rare fibroepithelial tumor. Patients with metastatic or unresectable disease have limited systemic treatment options, and there remains a need for biomarkers that can dynamically reflect disease changes during treatment. Circulating tumor DNA (ctDNA) may provide additional information on tumor burden and disease progression through a minimally invasive blood-based approach. This prospective, multicenter, observational cohort study will enroll approximately 50 patients with advanced malignant phyllodes tumors of the breast who have distant metastases or are currently not candidates for curative surgery and are planning to start systemic therapy. Peripheral blood samples will be collected before treatment and at predefined time points during the current systemic treatment line, including time points corresponding to routine imaging assessments. Individualized tumor-informed ctDNA monitoring panels will be established using patient-specific somatic variants identified from tumor whole-exome sequencing obtained during routine clinical care. The study will primarily evaluate the relationship between dynamic changes in ctDNA during the current systemic treatment line and progression-free survival (PFS), and will explore the potential value of longitudinal ctDNA monitoring for disease monitoring and prognostic assessment in advanced malignant phyllodes tumors. Study ctDNA results will not be used independently to guide clinical treatment decisions.