P37.21 Improvement of PCR-Based Detection of ALK Rearrangements

ALK fusions can be detected by FISH (florescence is situ hybridization), IHC (immunohistochemistry), RT-PCR (reverse transcription polymerase chain reaction) and NGS (next generation sequencing). All these methods have advantages drawbacks. We aimed to improve the performance of PCR testing, which cost-efficient requires minimal amount material. assessed various test designs evaluated spectrum gene in 2620 EGFR mutation-negative formalin-fixed paraffin-embedded (FFPE) lung adenocarcinoma samples. found that results could significantly improved using ALK-specific primers instead random hexamers for cDNA synthesis. In addition, we revealed decrease fragment size below 100 bp also helpful preventing failures test. Single-tube variant-specific 4 most common rearrangements (V.1, V.2, V.3 V.9) identified 150 (6.8%) tumors. These ALK-positive samples were further analyzed unbalanced 5’/3’-end expression, range variations 5’/3’ ratio was comparison 261 control fusion-negative cDNAs; obtained data allowed reliable calculation threshold this assay. Subsequently, remaining adenocarcinomas expression; additional 109 samples, had evidence activation thus required validation an independent method. Thirteen cases tested analysis at time abstract submission; five proven rearrangement, each containing distinct translocation variant (EML4ex6-ALKex19, EML4ex21-ALKex20, EML4ex13-ALKex3-ALKex20, GCC2ex13-ALKex20 SFTPBex2-ALKex18). This study provides a roadmap adjustment assays detection actionable fusions.