SABR Combined With Axitinib and Toripalimab for Oligometastatic Renal Cell Carcinoma

Inclusion Criteria: Histologically confirmed diagnosis of clear cell renal cell carcinoma (ccRCC). Age ≥ 18 years. Eastern Cooperative Oncology Group (ECOG) performance status of 0-2. Radiological evidence of distant metastasis meeting the MD Anderson (MDA) definition of oligometastatic disease: ≤5 metastatic lesions, all amenable to curative-intent local therapy. Lesions must be measurable per RECIST 1.1 criteria. Prior definitive local therapy to the primary tumor, including surgery, stereotactic radiotherapy, or ablation. Either no prior systemic therapy for metastatic disease (first-line naïve), or prior first-line tyrosine kinase inhibitor (TKI) therapy only with subsequent oligoprogression (≤5 progressive lesions with remaining lesions stable). Adequate organ function: Hemoglobin (Hb) ≥ 80 g/L Absolute neutrophil count (ANC) ≥ 1.5 × 10⁹/L Platelet count (PLT) ≥ 75 × 10⁹/L Serum total bilirubin ≤ 1.5 × upper limit of normal (ULN) Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3 × ULN Prothrombin time (PT) and activated partial thromboplastin time (aPTT) ≤ 1.5 × ULN Voluntary written informed consent obtained, with commitment to complete all treatment and follow-up visits. Exclusion Criteria: Target lesions previously treated with radiotherapy with a biologically effective dose (BED₃) ≥ 60 Gy (calculated with α/β = 3 Gy). Target lesions deemed unsuitable for radiotherapy by the treating radiation oncologist (e.g., lesions invading the gastrointestinal tract or penetrating the bronchus). Uncontrolled malignant pleural effusion or ascites. Presence of other uncured malignancies. History of severe psychiatric illness interfering with understanding of informed consent or compliance with study procedures. Severe cardiovascular disease: New York Heart Association (NYHA) class III-IV heart failure, uncontrolled arrhythmia, or myocardial infarction within the past 6 months. Any other serious medical condition that, in the investigator's judgment, may pose significant risk or interfere with radiotherapy. Pregnancy, breastfeeding, or planned pregnancy during the study period. Any other reason determined by the investigator that makes the participant unsuitable for study participation.