Exploratory factors relevant to success of the Ion Torrent™ Oncomine™ Dx Target Test

Objective：Oncomine TM Dx Target Test® (ODxTT) has emerged as a companion diagnosing system for advanced non-small-cell lung cancer (NSCLC) using next generation sequencing. However, the test results instability due to　small-size biopsy samples is challenging in clinical use.

Methods：From June 2018 to December 2020, NSCLC samples diagnosed in our hospital were evaluated. Fifty-one NSCLC samples were analyzed for BRAF mutations and 19 biopsy samples for multiplex analysis. The correlation between clinicopathological factors and success rate were analyzed into integration.

Results： Success rates according to procedure were 100% (25/25) in surgical samples, 100% in excisional biopsy, 75%  in transbronchial biopsy, 78% in endobronchial ultrasound-transbronchial needle aspiration, 57% in computed tomography guided biopsy, respectively. Analysis success biopsy samples for BRAF mutations showed larger quantity of DNA than failure group (median 279 ng vs 18 ng, p<0.01). In multiplex analysis, quantity of DNA and RNA in analysis  success samples showed larger quantity than the failure samples (median quantity of DNA 198 ng vs 46 ng, p<0.01, median quantity of RNA 180 ng vs 34 ng, p<0.01). Number of biopsies in transbronchial biopsy and tumor nuclei content in multiplex analysis the success samples also showed larger than the failure samples (median number of biopsies 6.5 vs 4, p<0.01, median tumor nuclei content 50 % vs 30 %, p=0.01).

Conclusion：　The quantity of nucleic acid was associated with analysis success rates of ODxTT. Tumor nuclei content and number of punctures in transbronchial biopsy might associate to analysis success rates of ODxTT.