Japan’s Pharmaceuticals and Medical Devices Agency has approved a test from China-based Amoy Diagnostics as a companion diagnostic for Pfizer’s ROS1 inhibitor Xalkori (crizotinib). The AmoyDx ROS1 fusion kit is a polymerase chain reaction (PCR) assay that identifies advanced non-small cell lung cancer (NSCLC) patients who harbor an ROS1 gene fusion and might benefit from this therapy. ROS1 gene rearrangements occur in approximately 2.4% of Asian patients with NSCLC. The AmoyDx ROS1 fusion kit uses reverse transcription PCR to analyze tumor messenger RNA from tumor tissue or body fluids and detects 14 ROS1 gene fusions in total. It provides results within 2.5 hours on most commercially available real-time PCR instruments. The kit also previously obtained the CE mark in 2013 and Chinese Food and Drug Administration approval in 2014.