Evaluation of appropriate conditions for Oncomine DxTT testing of FFPE specimens for driver gene alterations in non–small cell lung cancer

Abstract

BackgroundThe Oncomine Dx Target Test Multi‐CDx System (ODxTT) is a next‐generation sequencing panel approved as a companion diagnostic for drugs targeted to corresponding gene alterations in non–small cell lung cancer. However, appropriate slide conditions for ODxTT have remained unclear.MethodsWe focused on the production of the number of tumor cells on a formalin‐fixed paraffin‐embedded (FFPE) section and the number of prepared slides, designated the TS value, and determined a TS value of ≥4000 as a target slide condition for ODxTT. We evaluated the impact of this condition on ODxTT testing with tumor specimens found to have a TS of <4000 (n = 23) or a TS of ≥4000 (n = 142).ResultsA positive correlation was apparent between the TS value and the concentrations of both DNA and RNA. Among the 142 samples with a TS of ≥4000, a sufficient concentration of DNA or RNA for ODxTT analysis was achieved in 100% and 98% samples, respectively. Among samples explored for driver gene alterations after determination of the target slide condition (TS ≥4000), most (84.9%) had a TS of ≥4000 and were submitted for ODxTT analysis.ConclusionOur findings indicate that a TS of ≥4000 is a feasible and relevant criterion for ODxTT testing, and its adoption should help to improve the success rate of such testing in clinical practice.