A Case of Metastatic Ureteral Cancer Treated with Pembrolizumab without Relapse of Ocular Myasthenia Gravis

A 77-year-old man complaining of gross hematuria was referred to our hospital for further examination and treatment. The contrast-enhanced computed tomographic (CT) scan revealed a left ureteral tumor, multiple bladder tumors, para-aortic lymph node metastasis, left supraclavicular lymph node metastasis, multiple liver metastases, and multiple lung metastases. Transurethral resection was performed. One of the multiple bladder tumors, located at the bladder neck, was pathologically diagnosed as urothelial carcinoma, pT1, high grade, G2．We diagnosed the patient with metastatic ureteral cancer (T4N2M1, stage IV). We stated gemcitabine, cisplatin (GC) therapy, but stopped after the first course due to gemcitabine drug eruption. We changed the regimen to methotrexate, vinblastine, doxorubicin, and cisplatin (MVAC) therapy and the cycle was completed without complications. However, CT scan showed disease progression. After palliative irradiation of the primary lesion, we administered pembrolizumab. Although he was asymptomatic, we diagnosed him with ocular myasthenia gravis because of a high level of serum anti-acetylcholine receptor antibodies and a temporary ptosis in his past history. In spite of the possibility of relapse of myasthenia gravis, treatment with pembrolizumab was continued with his consent since there were no other treatment options. After two courses of pembrolizumab, he was hospitalized due to disease progression and died about three weeks after admission. Myasthenia gravis is a possible immune-related adverse event of pembrolizumab, However, there have been few reports on the successful treatment with this agent in patients with previously diagnosed myasthenia gravis. We report, here, a case of metastatic ureteral carcinoma safely treated with pembrolizumab without relapse of ocular myasthenia gravis.