Surveillance of the Genetic Signature in Circulating Tumor DNA for Guiding Adjuvant Chemotherapy in Urothelial Carcinoma

Inclusion Criteria: 1. aged 18-70 years old; 2. a score of ≤1 for the Eastern Cooperative Oncology Group (ECOG) Performance Status; 3. receiving radical cystectomy (with lymph node dissection) or nephroureterectomy; 4. histologically confirmed (surgical specimen) muscle invasive urothelial carcinoma, and the major histological type should be transitional cell carcinoma; 5. Classification of tumour, node and metastasis (TNM): pT2-4a N0-2M0; 6. absence of microscopic (i.e., positive margin) or gross residual of the tumor (R0 resection) and absence of metastasis, confirmed by a negative CT or MRI scan of pelvis, abdomen and chest within 4 weeks prior to enrolment; 7. adequate hematologic and end-organ function, defined by the following laboratory results obtained within 28 days prior to the first study treatment: * ANC≥1500 cells/μL (without granulocyte colony-stimulating factor support within 2 weeks prior to Cycle 1, Day 1) * WBC counts \> 2500 cells/μL * Lymphocyte count ≥ 300 cells/μL * Platelet count ≥ 100,000 cells/μL (without transfusion within 2 weeks prior to Cycle 1, Day 1) * Hemoglobin ≥ 9.0 g/dL * AST, ALT, and alkaline phosphatase ≤ 2.5 × the upper limit of normal (ULN), * PTT ≤ 1.5 × ULN * PT ≤ 1.5 × ULN or INR \< 1.7 * Calculated creatinine clearance ≥ 30 mL/min (Cockcroft-Gault formula) 8. able to understand and provide written informed consent, and agree to receive the treatment arrangement and study procedures stated in the informed consent Exclusion Criteria: 1. receiving any approved anti-cancer treatment within 3 weeks prior to study enrolment; 2. participation in another clinical trial with therapeutic intent within 28 days prior to enrolment; 3. suffering from malignancies other than urothelial carcinoma within 5 years prior to study enrolment; 4. conditions that contraindicate chemotherapy, such as renal impairment with creatinine clearance rate (CCr) \<50 mL/min, hearing impairment, and inadequate marrow function; 5. anaphylactic or hypersensitivity reactions or other contraindication to cisplatin and gemcitabine; 6. active or uncontrolled infections, including human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), or tuberculosis; 7. pregnancy or breastfeeding.