FDG-PET in the evaluation of response to nivolumab in recurrent non-small-cell lung cancer

BACKGROUND: Nivolumab, an immune checkpoint inhibitor, is recently clinically applied to non-small cell lung cancer (NSCLC) treatment, and this causes T cell activation and T cell infiltration to tumor tissue through the blockade of the interaction between programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1). 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) sometimes shows false positive because of the recruitment of neutrophils, lymphocytes, and macrophages. To date, there is only one report except our case, which described the correlation between FDG-PET and nivolumab. CASE PRESENTATION: We report on a 75-year-old man on nivolumab treatment for metastatic non-small cell lung cancer. He had undergone right lower lobectomy for lung adenocarcinoma in the right S8 segment 10 months prior to recurrence. Pathological findings revealed invasive adenocarcinoma, pT1bN2M0 stage IIIA. Epidermal growth factor receptor (EGFR) mutation was positive for de novo T790M and anaplastic lymphoma kinase (ALK) rearrangement was negative. Immunohistochemistry was negative for PD-L1. He underwent chemotherapy with a combination of cisplatin and pemetrexed for four cycles but developed progressive disease involving the right hemithorax, multiple lymph nodes, and multiple osseous sites. Nivolumab was instituted as a second-line chemotherapy. After six courses of this immunotherapy, FDG-PET scan showed decreased FDG uptake in each recurrent lesion despite T lymphocyte activation by nivolumab. Serum carcinoembryonic antigen (CEA) level was also remarkably decreased. CONCLUSIONS: Nivolumab’s effect on recurrent NSCLC may be monitored by PET; larger studies are needed.