Feasibility of PIK3CA Mutation Detection via Microfluidic Isolation of Disseminated Tumor Cells from Bone Marrow in Breast Cancer Patients

Abstract Disseminated tumor cells originating from the bone marrow serve as precursors of distant metastasis and are associated with increased mortality in breast cancer. With the emergence of targeted therapies for breast cancer, accurate procedures for enrichment of disseminated tumor cells are crucial to investigate the molecular heterogeneity between disseminated tumor cells and primary tumors. This study evaluated the feasibility of PIK3CA mutation analysis in disseminated tumor cells enriched using a microfluidic-based separation system.Bone marrow and primary tumor samples from 84 breast cancer patients were collected. Disseminated tumor cells were enriched from bone marrow aspirates using the Parsortix system, followed by PIK3CA mutation analysis via MassARRAY PIK3CA Breast Panel and digital droplet PCR. PIK3CA mutations were detected in 42.9% of primary tumors. PIK3CA mutations were neither detected via digital droplet PCR in disseminated tumor cells-positive bone marrow samples, nor in disseminated tumor cells-negative samples with a high allele frequency of PIK3CA mutations in the primary tumor.These findings suggest that current microfluidic enrichment methods, such as Parsortix, may be insufficient for reliable PIK3CA mutation detection in disseminated tumor cells. Additional research is required to investigate alternative enrichment techniques for the analysis of mutations in disseminated tumor cells.