A Case of Granulocyte-Colony-Stimulating Factor-Producing Non-Small Cell Lung Cancer under Steroid Treatment and with Poor Performance Status That Responded to Pembrolizumab.

Introduction: There have been only a few cases showing the efficacy of pembrolizumab on granulocyte-colony Case Presentation: A 77-year-old woman was diagnosed with G-CSF-producing NSCLC-not otherwise specified, classified as clinical stage IVB, T2N3M1c. She had fever and her PS was 3, and her C-reactive protein (CRP) was 6.47 mg/dL due to inflammation by a G-CSF-producing tumor. Thus, we initiated the administration of dexamethasone (3.3 mg/day). Her fever abated the next day, and CRP dropped to 3.22 mg/dL after 4 days. Driver mutations were negative, and PD-L1, tumor proportion score, was highly expressed at 100%. Thus, pembrolizumab was started. Subsequently, the white blood cell count decreased, and the tumor shrank, indicating a partial response. After three cycles of pembrolizumab therapy, the anorexia improved, and she was discharged. The patient developed sclerosing cholangitis after discharge. Therefore, the pembrolizumab treatment was discontinued. The primary lesion was enlarged, indicating progressive disease. However, the patient and her family did not want additional treatment. Finally, her progression-free survival and overall survival were 6 and 7 months, respectively. Conclusion: Pembrolizumab may be effective against G-CSF-producing NSCLC with high PD-L1 expression. Corticosteroids seemed to inhibit inflammation induced by the tumor, and exert the efficacy of pembrolizumab.