Urine Omics Predicting IO Therapy Responses in mUC Patients

Inclusion Criteria: * 1\. Age \> 20 years * 2\. Subjects diagnosed as metastatic urothelial carcinoma (mUC) * 3\. Subjects who are about to receive IO-based therapy * 4\. ECOG performance 0, 1, 2, and 3 * 5\. Life expectancy 3 months * 6\. eGFR \> 15 ml/min/1.73 m2 (Stage IV Chronic Kidney Disease or better) * 7\. Willing to sign the informed consent form Exclusion Criteria: * 1\. Subjects NOT willing to sign the informed consent form * 2\. Subjects with active infection or active urinary tract infection, as shown by urinary WBC \> 5/HPF * 3\. Subjects having co-existing other malignancies that need active treatment. Those with other malignancies that do not need active treatment are allowed to join the study. * 4\. Subjects taking any immune-modulating agents, including but not limited to corticosteroid, immune-suppressants, etc. at the discretion of recruiting investigators * 5\. Subjects who have taken any CPIs before. However, subjects who have received intravesical or intrapelvic BCG instillation are allowed to enroll. * 6\. Subjects who have received anti-FGFR therapy, enfortumab vedotin or other systemic therapies within 12 weeks of screening are not allowed. However, subjects who had a washout period of the above agents for \>12 weeks are allowed to enroll. Subjects who have received or are receiving cytotoxic chemotherapy are allowed to join the study.