A multicenter study of noninvasive genotyping and dynamic monitoring of ROS1+NSCLC receiving treatment with crizotinib by next generation sequencing

Abstract

Background: ROS1 rearrangement has been identified in 1-2% of NSCLC cases. Noninvasive genotyping of driver genes and monitoring of tumor dynamics help make better personalized therapeutic decisions. The aim of this study is to investigate the feasibility and performance of capture-based sequencing on ROS1 fusion detection, we developed a targeted region capture combined sequencing panel to detect and quantify rearrangement events, along with other driver mutation variants in plasma. Methods: We screened 2617 patients with NSCLC for ROS1 rearrangements, and collected blood samples from 67ofthem with confirmed ROS1rearrangements based on their tissue biopsies. We obtained longitudinal blood samples of 16 ROS1 positive NSCLC patients after crizotinib treatment for disease monitoring. Results: In total, we identified 62 genetic alterations with a median of 3.9 mutations per patient. 93% of patients still exhibit rearrangements, and 31% of patients acquired ROS1 required point mutations. Besides other known resistance mechanisms, we identified CDKN2A mutations in 19% of patients. Interestingly, we also observed TERT, PTPRD, NFE2L2 and OR5L2 mutations in ROS1 required point mutations negative patients, which were restricted to crizotinib resistance. In addition to detecting ROS1 rearrangements, we also detected one kind of crizotinib resistant mutations, ROS1 G2032R from 5 patients. ROS1 rearrangements were successfully blood samples detected in 42 of 67 patients at baseline with 62.7% sensitivity and 100% specificity. ctDNA concentration correlates with responses and disease progression, reflecting its ability as a biomarker. Conclusions: The suitable sensitivity and the high specificity between tissue and plasma ROS1 determination supports the blood-based ROS1 rearrangements testing to determinate the eligibility of NSCLC patients for crizotinib treatment. Blood is a good screening substitute when tumor tissue is absent or insufficient for testing ROS1 rear-rangements to guide crizotinib treatment in NSCLC. ROS1 rearrangement in blood could be used to recommend crizotinib treatment, but the blood negativity should be confirmed with other sample, biopsy tissue, pleural effusion, etc.