Noninvasive genotyping of driver genes and monitoring of tumor dynamics help make better personalized therapeutic decisions. However, neither PCR-based assays nor amplicon-based targeted sequencing can detect fusion genes like anaplastic lymphoma kinase (ALK) rearrangements in blood samples. To investigate the feasibility and performance of capture-based sequencing on ALK fusion detection, we developed a capture-based targeted sequencing panel to detect and quantify rearrangement events, along with other driver mutation variants in plasma. In this perspective study, we screened 364 patients with advanced non-small cell lung cancer (NSCLC) for ALK rearrangements, and collected blood samples from 24 of them with confirmed ALK rearrangements based on their tissue biopsies. ALK rearrangements were successfully detected in 19 of 24 patients at baseline with 79.2% (95% CI 57.9%, 92.9%) sensitivity and 100% (36/36) specificity. Among the 24 patients, we obtained longitudinal blood samples from 7 of them after either chemotherapy and/or Crizotinib treatment for disease monitoring. The by-sample detection rate of ALK rearrangements after treatment drops to 69.2% (9 of 13). In addition to detecting ALK rearrangements, we also detected 3 Crizotinib resistant mutations, ALK L1152R, ALK I1171T and ALK L1196M from patient P4. ctDNA concentration correlates with responses and disease progression, reflecting its ability as a biomarker. Our findings suggest capture-based sequencing can detect and quantify ALK rearrangements as well as other somatic mutations, including mutations mediated drug resistance, in plasma with high sensitivity, paving the way for its application in identifying driver fusion genes and monitoring tumor dynamics in the clinic.

BackgroundAberrant Rad51 expression is implicated in the progression of human malignancies. However, the role of Rad51 in colorectal cancer (CRC) remains undefined. This study aimed to establish a relationship between Rad51 and clinicopathologic features of CRC.MethodsWe retrospectively examined the paraffin-embedded tissue samples obtained from 54 patients with CRC who had received surgical therapies at our institution during 2006–2008. Rad51 expression in adenocarcinoma, paracancerous tissue, and normal colonic tissue was determined by immunohistochemistry. The correlation between Rad51 immunoreactivity and clinicopathologic features of these patients was evaluated.ResultsRad51 immunoreactivity was detected in 67% of adenocarcinoma, 48% of paracancerous tissue, and 27% of normal colonic mucosa. Rad51 expression in adenocarcinoma was significantly higher than normal colonic tissue (p < 0.05). Rad51 was also overexpressed in poorly differentiated tumors and tumor samples from patients with lymph node metastasis (p < 0.05). Patients with Rad51 overexpression had a 69% two-year survival, 49% three-year survival, and 16% five-year survival, considerably worse than patients with negative Rad51 expression (p < 0.05).ConclusionOur data suggest that Rad51 overexpression is correlated with malignant phenotypes of CRC and may predict poor prognosis for these patients.