Gemcitabine and Carboplatin After Progression on Enfortumab Vedotin and Pembrolizumab in Advanced/Metastatic Urothelial Carcinoma

The goal of this clinical trial is to learn if a chemotherapy combination called gemcitabine and carboplatin (GC) works to treat advanced urothelial cancer in people who have already been treated with enfortumab vedotin and pembrolizumab (EVP). It will also learn about the efficacy and safety of GC in these patients. The main questions it aims to answer are: * Does GC shrink the cancer or stop it from growing? * What medical side effects do participants have while receiving GC? Researchers will study how GC affects survival, cancer control, and quality of life. They will also collect blood samples to look at health-related markers and cancer DNA in the blood. \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Participants will: * Receive the GC chemotherapy (gemcitabine and cisplatin) after having been treated with EVP * Visit the clinic regularly for checkups, lab tests, and scans * Answer questions about their health, quality of life, and daily function * Provide blood samples for research This study may help researchers find better ways to treat advanced bladder and urinary tract cancer in the future-especially for older adults or those who have already tried other treatments.