A Phase II Study of Ivonescimab in Combination With GEMOX as Neoadjuvant and Conversion Therapy for Biliary Tract Cancer

The purpose of this study is to explore the efficacy and safety of Ivonescimab in combination with GEMOX chemotherapy as neoadjuvant and conversion therapy for patients with biliary tract cancer. It aims to evaluate the impact of this combination regimen on postoperative recurrence, patient survival, and medication safety. This is a single-center, phase II, interventional, single-arm, multi-cohort clinical study. A total of 87 eligible participants will be enrolled and assigned to either the neoadjuvant therapy cohort (45 participants) or the conversion therapy cohort (42 participants).

Inclusion Criteria: * 1\. Subjects voluntarily participate in the study, agree to sign a written informed consent form, demonstrate good compliance, and are willing to cooperate with follow-up. * 2\. Male or female aged \>= 18 and \ 5 cm; imaging suggests vascular invasion or hilar lymph node metastasis; tumor number \> 3 or any single tumor \> 3 cm; preoperative CA19-9 \> 37 U/mL or exceeding the upper limit of normal \[applicable to centers where the normal range is not \< 37 U/mL\]). * Conversion Therapy Cohort: The tumor is graded as locally advanced, unresectable, or combined with oligometastatic status (oligometastasis is defined as: metastatic lesions confined to a single organ or specific regional lymph nodes, and the number of metastatic lesions is \= 10 mm or the shortest diameter of enlarged lymph nodes \>= 15 mm). * 6\. No prior systemic therapy for biliary tract cancer. * 7\. Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 1. * 8\. Child-Pugh class A liver function. * 9\. Normal bone marrow, liver, and kidney function, meeting the following clinical laboratory evaluation criteria within 7 days prior to treatment (the conditions cannot be met by administering any blood components, cell growth factors, albumin, or other corrective medications within 14 days prior to obtaining the laboratory tests; patients developing obstructive jaundice after percutaneous transhepatic cholangial drainage \[PTCD\] or endoscopic retrograde cholangiopancreatography \[ERCP\] treatment may be considered for enrollment if liver function indicators meet the inclusion criteria): 1. Absolute neutrophil count (ANC) \>= 1.5 x 10\^9/L, platelet count \>= 90 x 10\^9/L, hemoglobin \>= 90 g/L; AST and ALT \