Antibodies Monoclonal Humanized/*therapeutic use *Carcinoma Transitional Cell/drug therapy Humans Prognosis Retrospective Studies *Urinary Bladder Neoplasms/drug therapy Metastatic urothelial carcinoma Pembrolizumab Prognostic factor Janssen and Pfizer. Takahiro Kimura is a paid consultant/advisor of Astellas Bayer Janssen and Sanofi. Shahrokh F. Shariat is a paid as follows: Honoraria: Astellas AstraZeneca Bayer BMS Cepheid Ferring Ipsen Janssen Lilly MSD Olympus Pfizer Pierre Fabre Richard Wolf Roche Sanochemia Sanofi Takeda Urogen. Consulting or Advisory Role: Astellas AstraZeneca Bayer BMS Cepheid Ferring Ipsen Janssen Lilly MSD Olympus Pfizer Pierre Fabre Richard Wolf Roche Sanochemia Sanofi Takeda Urogen. Speakers Bureau: Astellas Astra Zeneca Bayer BMS Cepheid Ferring Ipsen Janssen Lilly MSD Olympus Pfizer Pierre Fabre Richard Wolf Roche Sanochemia Sanofi Takeda Urogen Movember Foundation. The other authors declare no conflicts of interest associated with this manuscript.