A Case of Metastatic Urothelial Carcinoma Treated with Pemetrexed as Third-Line Chemotherapy with Discussion and Literature Review

Pemetrexed is an antifolate agent that is regarded as an alternative second-line chemotherapy against advanced or metastatic urothelial carcinoma (UC). However, there is limited information on pemetrexed in a third-line setting. We report a case of metastatic UC treated with pemetrexed as third-line chemotherapy following gemcitabine and cisplatin (GC) and gemcitabine and docetaxel (GD) therapies. A 73-year-old man with a history of transurethral resection of bladder carcinoma presented with pollakiuria. CT revealed a mass in the left renal pelvis that had invaded into the parenchyma of the left kidney, as well as para-aortic and mediastinum lymph node enlargement. Urinary cytology of the lesion in the left renal pelvis revealed UC. Thus, the patient was diagnosed with left renal pelvic carcinoma (cT3N2M0). After having received 4 courses of GC therapy, another mediastinum lymph node was enlarged. He subsequently received 3 courses of GD therapy as second-line chemotherapy, which showed little efficacy against the metastatic lesions. The patient was administered 3 courses of pemetrexed as third-line chemotherapy; however, its effect on tumor reduction was not sufficient. Finally, metastasis to the liver was observed, and he died 21 months after initiation of chemotherapy. For pathological confirmation, needle biopsy of a metastatic lymph node performed after death revealed high-grade UC and a high positivity of programmed death ligand 1 (PD-L1) in the tumor, which suggested that he could have benefited from anti-PD-L1 antibody immunotherapy. This report describes the outcome of pemetrexed treatment and proposes another possible candidate as third-line chemotherapy against metastatic UC.