• Males or females aged ≥18 years and ≤75 years.

• ECOG performance status of 0 - 2.

• Histologically confirmed invasive neuroendocrine carcinoma with or without urothelial carcinoma, with a neuroendocrine carcinoma component of \>50%; Formalin-fixed paraffin-embedded (FFPE) specimens (preferred) or at least 15 unstained, freshly cut, continuous slides should be submitted with related pathology reports prior to study enrollment. If fewer than 15 slides are available, patients may still be eligible for enrollment after confirmation by the principal investigator. If a tumor tissue section is not available, the tumor tissue must be obtained from the biopsy performed at the time of screening.

• Clinical stage T1-T4a N0 M0 (CT/MRI ± PET/CT) If the clinical stage is T1-4a N1-3 M0, it needs to be judged by the investigator. If cystectomy can still be performed, participants can be included in the study.

• Expected survival longer 3 months.

• Normal function of vital organs (14 days prior to enrollment). Meet the following criteria:

‣ Blood routine examination:

‣ HB≥90 g/L; ANC≥1.5×109 /L; PLT≥100×109 /L.

⁃ No functional organic disease:

∙ T-BIL≤1.5×ULN (upper limit of normal); ALT and AST≤2.5 x ULN; Serum creatinine ≤2×ULN, or endogenous creatinine clearance \> 20 mL /min (Cockcroft-Gault formula); International Standardized ratio (INR), activated partial thromboplastin time (aPTT) : ≤1.5× ULN.

• Fertile males or females must use a highly effective contraceptive approach (such as oral contraceptives, intrauterine devices, abstinence or barrier contraception combined with spermicides) during the trial and continue contraception for 12 months after the end of treatment.

• Participants who voluntarily join the study, sign informed consent, have good compliance, and cooperate with follow-up.