The patient was clinically diagnosed as stage IV-T1bN3M1...lung nodule biopsy confirmed PD-L1-negative lung adenocarcinoma....biopsy tissue samples revealed a CD74-ROS1 gene fusion and tumor mutation burden (TMB) of 12.6 mutations/megabase...A partial response, including a 60.2% reduction in the primary target lesion and 74.7% reduction in the metastatic lymph nodes, was observed on the first computed tomography scan evaluation after two cycles of treatment with pembrolizumab combined with carboplatin/pemetrexed...