Complex tumor genomes inferred from single circulating tumor cells by array-CGH and next-generation sequencing
A partir d'échantillons sanguins prélevés sur 37 patients atteints d'un cancer colorectal de stade IV, cette étude évalue la faisabilité d'analyser le génome de cellules tumorales circulantes à l'aide d'une puce d'hybridation génomique comparative ou d'une technique de séquençage de prochaine génération
Circulating tumor cells (CTCs) released into blood from primary cancers and metastases reflect the current status of tumor genotypes, which are prone to changes. Here we performed the first comprehensive genomic profiling of CTCs using array-CGH and next-generation sequencing. We used the FDA-cleared CellSearchTM system, which detected CTCs in 21 of 37 patients (range 1-202 per 7.5 ml sample) with stage IV colorectal carcinoma (CRC). In total, we were able to isolate 37 intact CTCs from 6 patients and identified in those multiple CRC-associated copy number changes, many of which were also present in the respective primary tumor. We then used massive parallel sequencing of a panel of 68 CRC-associated genes to compare the mutation spectrum in the primary tumors, metastases, and the corresponding CTCs from two of these patients. Mutations in known driver genes (e.g., APC, KRAS, or PIK3CA) found in the primary tumor and metastasis were also detected in corresponding CTCs. However, we also observed mutations exclusively in CTCs. To address whether these mutations were derived from a small subclone in the primary tumor or represented new variants of metastatic cells, we performed additional deep sequencing of the primary tumor and metastasis and applied a customized statistical algorithm for analysis. We found that most mutations initially found only in CTCs were also present at subclonal level in the primary tumors and metastases from the same patient. Our study paves the way to use CTCs as a liquid biopsy in patients with cancer.
Cancer Research , résumé, 2013