Detection of ALK Gene Rearrangement in Cell-free RNA from Lung Cancer Malignant Pleural Effusion

The aim of this study was to evaluate the feasibility of measuring ALK gene rearrangement in cell-free RNA (cf-RNA) of the supernatant from malignant pleural effusion (MPE). Supernatant, cell blocks, and matched sera samples were collected. Cf-RNA was isolated from the supernatant and sera, and cellular RNA was isolated from cell blocks. The ALK gene rearrangement in the cf-RNA was tested by the real-time polymerase chain reaction. Results showed that the concentration of cf-RNA was higher in the supernatant than in matched sera. ALK status concordance rates were 100% between the supernatant and cell blocks, while they were 0% between sera and cell blocks in ALK gene rearrangement cases. This suggests that using cf-RNA in MPE supernatant, but not in sera, could offer a reliable and robust surrogate strategy for the detection of ALK gene rearrangement.