18F-FDG PET/CT Evaluation of Crizotinib and Lorlatinib Therapy in Metastatic ROS-1–Positive Non–Small Cell Lung Cancer

Abstract ROS-1–positive non–small cell lung cancers (NSCLCs) are rare (approximately 1% of all NSCLCs) and require a first-line treatment by crizotinib. Crizotinib resistance is frequent within the first 12 months of treatment. Lorlatinib is a novel tyrosine kinase inhibitor of ROS-1 recently indicated for metastatic or locally advanced crizotinib-resistant NSCLC. We report the use of lorlatinib as second-line with a complete tumoral response after only 3 months of treatment. This case shows the major role of 18 F-FDG PET/CT in treatment evaluation and monitoring targeted therapy in metastatic NSCLC.