7591 Background: The implementation of new theranostic biomarkers in Oncology is leading to impressive therapeutic improvements. In patients with lung cancer, the possibility to use Circulating Tumor Cells (CTCs) as a non-invasive theranostic approach is a clinically appealing challenge. Adenocarcinomas with EML4-ALK rearrangement are a new molecular subgroup of lung tumors with very good response to Crizotinib, an ALK inhibitor. We have thus aimed at developing an informative assay characterizing the ALK-gene status in CTCs isolated from patients with lung cancer. Methods: CTCs were isolated preoperatively using Isolation by Size of Epithelial Tumor cells method (ISET) from 65 patients with lung adenocarcinoma and blindly screened for ALK-gene status. ALK break-apart fluorescence in situ hybridization (FISH) (LSI ALK dual colour probes set) and immunochemistry using an anti-ALK antibody (5A4 clone) were blindly performed on CTCs and corresponding tumor tissues and results were compared. Results: Two patients consistently showed ALK-gene rearrangement and strong ALK protein expression in CTCs and corresponding tumor samples. Negative results (both ALK FISH and ALK immunochemistry) were found in CTCs and corresponding tumor samples from the other 63 patients. Conclusion: We have developed an approach allowing to characterize ALK-gene status in CTCs from patients with lung cancer and shown consistent results in CTC and tumor tissues. These preliminary results encourage larger studies and open new avenues for non-invasive, real-time, theranostic monitoring of cancer patients.
Lung Adenocarcinoma with Concurrent Exon 19 EGFR Mutation and ALK Rearrangement Responding to Erlotinib
