Complete response after radiation-assisted immunotherapy for metastatic urothelial carcinoma: a case report and literature review

Immunotherapy is emerging to be a new effective option in patients with metastatic urothelial carcinoma (UC) who are cisplatin-ineligible. However the feasibility of combinatory strategy in this setting is unknown. We reported our experience of treating one case of metastatic UC with radiation-assisted immunotherapy (RAIT). A 69-year-old male patient with end stage renal disease is a case of metastatic UC. The tumor was microsatellite stable. He was treated with six doses of triweekly pembrolizumab in four months. Hypofractionated radiotherapy to all metastatic lymphadenopathies (LAPs) was delivered between the second and the third dose of pembrolizumab. Complete response was confirmed with positron emission tomography/computed tomography one month after treatment. Metachronous bladder cancer was noticed nine months later and was successfully treated with transurethral resection of bladder tumor followed by adjuvant Bacillus Calmette-Guerin intravesical instillation. Genetic profiling from next generation sequencing (NGS) revealed high mutational burden (65.2 mutations/megabase) and CDH1 mutation. He remains disease free and dialysis free one and half year after treatment. Furthermore, circulating tumor cells (CTCs) dynamics correlates with the disease course precisely. This is a case of exceptional response and treating metastatic UC with RAIT in cisplatin-ineligible patients may warrant further investigation.