Phase II Study of Neoadjuvant Tislelizumab Plus Radiotherapy and GP Chemotherapy for Borderline/Unresectable Hilar Cholangiocarcinoma

This is a phase II, single-arm, prospective clinical trial designed to evaluate the efficacy and safety of neoadjuvant therapy combining stereotactic body radiotherapy (SBRT), GP chemotherapy (gemcitabine and cisplatin/oxaliplatin), and tislelizumab in patients with borderline resectable or unresectable hilar cholangiocarcinoma. Eligible patients will receive SBRT followed by three cycles of tislelizumab plus GP chemotherapy. Patients with resectable disease after evaluation may undergo surgery and receive postoperative treatment as recommended by the multidisciplinary team. Those who remain unresectable will receive three additional cycles of systemic therapy. The primary endpoint is overall survival (OS); secondary endpoints include R0 resection rate, pathological complete response (pCR), surgical difficulty, progression-free survival (PFS), local control rate, and treatment-related safety.