Evaluation of a novel c-MET based circulating tumor cell (CTC) biomarker in patients with gastrointestinal malignancies.

84 Background: Multiple GI malignancies including gastric, pancreatic, and colorectal cancers harbor genetic alterations in the MET oncogene. MET amplification is associated with poor prognosis, and c-MET targeted therapies are in development. We aimed to capture and identify c-MET CTCs using a non-invasive, rapid test. Methods: We modified the CELLSEARCH platform by using nanomagnetic particles conjugated to antibodies against the extracellular domain of c-MET to capture c-MET-expressing CTCs. The method was validated by spiking MET-amplified gastric cancer cells, c-MET-overexpressing, nonamplified cancer cells, and MET-negative cancer cells into peripheral blood from healthy volunteers. Peripheral blood samples were obtained from patients (pts) with refractory metastatic gastric, pancreatic, and colorectal cancers, prepared in duplicate, and characterized by immunofluorescence staining for intracellular c-MET-PE, DAPI, and pan-CK-FITC. CD45 + cells were excluded. CTC enumeration with c-MET capture was c...