Clear cell urethral adenocarcinoma – a case report of an exceptional response to immunotherapy in a metastatic rare tumour

Primary clear cell adenocarcinoma of the urethra is extremely rare. Given the rarity of these tumours there is no high-level evidence available to guide treatments. Localized disease is typically treated with primary surgery or concurrent chemo-radiotherapy. In the advanced disease setting treatment options are limited and decisions are based on evidence in disease subtypes where similarities exist. Immuno-oncology and the use of checkpoint inhibitors, particularly for metastatic disease has transformed clinical practice over the past few years and patient outcomes continue to improve as a result of their introduction. Here we report the first case, to our knowledge, of a patient with advanced primary clear cell adenocarcinoma of the urethra who had a dramatic and almost complete response to anti-PD-1 therapy in the fourth line setting. Level of evidence: 4