Amélie Barthelemy

PURPOSE: The diagnostic test for ALK rearrangement in non-small-cell lung cancer (NSCLC) for crizotinib treatment is currently done on tumor biopsies or fine-needle aspirations. We evaluated whether ALK rearrangement diagnosis could be performed by using circulating tumor cells (CTCs). PATIENTS AND METHODS: The presence of an ALK rearrangement was examined in CTCs of 18 ALK-positive and 14 ALK-negative patients by using a filtration enrichment technique and filter-adapted fluorescent in situ hybridization (FA-FISH), a FISH method optimized for filters. ALK-rearrangement patterns were determined in CTCs and compared with those present in tumor biopsies. ALK-rearranged CTCs and tumor specimens were characterized for epithelial (cytokeratins, E-cadherin) and mesenchymal (vimentin, N-cadherin) marker expression. ALK-rearranged CTCs were monitored in five patients treated with crizotinib. RESULTS: All ALK-positive patients had four or more ALK-rearranged CTCs per 1 mL of blood (median, nine CTCs per 1 mL; range, four to 34 CTCs per 1 mL). No or only one ALK-rearranged CTC (median, one per 1 mL; range, zero to one per 1 mL) was detected in ALK-negative patients. ALK-rearranged CTCs harbored a unique (3'5') split pattern, and heterogeneous patterns (3'5', only 3') of splits were present in tumors. ALK-rearranged CTCs expressed a mesenchymal phenotype contrasting with heterogeneous epithelial and mesenchymal marker expressions in tumors. Variations in ALK-rearranged CTC levels were detected in patients being treated with crizotinib. CONCLUSION: ALK rearrangement can be detected in CTCs of patients with ALK-positive NSCLC by using a filtration technique and FA-FISH, enabling both diagnostic testing and monitoring of crizotinib treatment. Our results suggest that CTCs harboring a unique ALK rearrangement and mesenchymal phenotype may arise from clonal selection of tumor cells that have acquired the potential to drive metastatic progression of ALK-positive NSCLC.

AIMS: The common subtypes of renal tumours are conventional, papillary, chromophobe carcinoma and oncocytoma. The morphological differentiation between chromophobe carcinoma and oncocytoma may be difficult. The aim was to evaluate S100A1 as a new marker for the differentiation of the two subtypes. METHODS AND RESULTS: Thirty-nine tumour samples [nine clear cell renal cell carcinomas (RCCs), six papillary RCCs, nine chromophobe RCCs and 15 oncocytomas] were studied. The protein expression of S100A1 was evaluated by immunohistochemistry. The gene expression of S100A1 was analysed by reverse transcriptase-polymerase chain reaction. Nine oncocytomas showed strong immunoreactivity for S100A1. Four oncocytomas were scored as moderate and one as weak reactivity. In total, 14/15 (93%) of oncocytomas were considered to be immunopositive. In contrast, all nine chromophobe RCCs were considered to be immunonegative. There was a significant difference in the positive percentages of staining of S100A1 between these two subtypes (P < 0.01). S100A1 immunoreactivity was observed in 6/9 clear cell and 4/6 papillary carcinomas. The results of S100A1 gene expression corresponded well with the results of immunohistochemistry. CONCLUSION: S100A1 may be a potentially powerful marker to differentiate the chromophobe RCC from renal oncocytoma.

Circulating tumor cells (CTCs) have emerged as potential biomarkers in several cancers such as colon, prostate, and breast carcinomas, with a correlation between CTC number and patient prognosis being established by independent research groups. The detection and enumeration of CTCs, however, is still a developing field, with no universal method of detection suitable for all types of cancer. CTC detection in lung cancer in particular has proven difficult to perform, as CTCs in this type of cancer often present with nonepithelial characteristics. Moreover, as many detection methods rely on the use of epithelial markers to identify CTCs, the loss of these markers during epithelial-to-mesenchymal transition in certain metastatic cancers can render these methods ineffective. The development of personalized medicine has led to an increase in the advancement of molecular characterization of CTCs. The application of techniques such as FISH and RT-PCR to detect EGFR, HER2, and KRAS abnormalities in lung, breast, and colon cancer, for example, could be used to characterize CTCs in real time. The use of CTCs as a 'liquid biopsy' is therefore an exciting possibility providing information on patient prognosis and treatment efficacy. This review summarizes the state of CTC detection today, with particular emphasis on lung cancer, and discusses the future applications of CTCs in helping the clinician to develop new strategies in patient treatment.