This is an open-label, multicenter Phase II clinical study aimed at evaluating the efficacy, safety, PK profile, and immunogenicity of QLS31905 for Injection combined with Chemotherapy ± QL2107 in Patients with CLDN18.2-positive Advanced Biliary Tract Cancer

Inclusion Criteria:

• Subjects with unresectable locally advanced or metastatic Biliary Tract Cancer confirmed by histopathological or cytological examination;
• Subjects with at least one measurable lesion designated as a target lesion, as assessed by the investigator according to RECIST v1.1. Lesions that have received radiotherapy or other local treatments may be considered measurable if they demonstrate imaging PD;
• No prior systemic anti-tumor treatment for locally advanced or metastatic Biliary Tract Cancer.

Exclusion Criteria:

• Subjects with a known history of severe or repeated allergy, intolerance, or contraindication to QLS31905, QL2107, or other large molecule protein preparations, as well as Gemcitabine Hydrochloride for Injection, Cisplatin for Injection, Oxaliplatin Injection or Capecitabine Tablets and any components in their preparations;
• Subjects had other second primary malignancies within 5 years prior to the first dose;
• Subjects with clinically significant hemorrhage within 3 months before the first dose;