This single-center single-arm, open-label prospective clinical trial aimed to evaluate the efficacy and safety of entinostat combined with chemotherapy as second-line therapy for unresectable locally advanced or metastatic bladder cancer.

Inclusion Criteria:

• Histopathologic confirmed unresectable advanced or metastatic bladder cancer, except for those with squamous differentiation, glandular differentiation or both;
• Failure of first-line treatment;
• There is at least one measurable lesion according to RECIST 1.1;
• Archived tumor tissue samples or tumor biopsies must be provided;
• ECOG score of 0-1 an an estimated survival of at least 6 months;
• Adequate organ function;
• Patients voluntarily participated in this study, signed the informed consent form, and had good compliance;
• Women with fertility must consent to contraception during the study and for 6 months after the last dose of study drug.

Exclusion Criteria:

• Patients who received platinum-based chemotherapy after failure of first-line treatment;
• Patients who received platinum-based chemotherapy withnin a 24 month before this trial;
• Those who have received other anti-tumor treatment or participated in other clinical studies within 4 weeks before the start of the study, or have not recovered from the last toxicity (except grade 2 hair loss and grade 1 neurotoxicity);
• Concomitant disease such as uncontrolled hypertension or diabetes, renal inadequacy, myocardial infarction, severe angina;
• Female subjects who are pregnant, breastfeeding or planning to become pregnant during the study;
• Patients with serious physical or mental illnesses.