Detection of a Rare Intra-ALK Inversion and ALK Rearrangement in a Lung Adenocarcinoma Patient by FoundationOne Liquid CDx and Successful Treatment with Alectinib: Case Report

A 50-year-old woman with stage IVB lung adenocarcinoma tested negative for driver mutations using the Oncomine Dx Target Test Multi-CDx system (Thermo Fisher Scientific, Waltham, MA). After undergoing chemotherapy and immunotherapy, FoundationOne Liquid CDx (Foundation Medicine, Inc., Cambridge, MA) identified a rare <i>EML4</i>-<i>ALK</i> gene rearrangement. Treatment with alectinib led to rapid clinical improvement and sustained disease control for more than 7 months. This case highlights the value of next-generation sequencing-based profiling in detecting rare actionable alterations missed by standard tests. We also include a discussion on why the <i>EML4-AKL</i> fusion was not detected in the usual test.