Background: PD-1/PD-L1 combined with vascular endothelial growth factor (VEGF) inhibitors improves survival in patients with advanced renal cell carcinoma (RCC), but the role of perioperative application in patients with localized RCC has not been established. In this phase II trial, we investigate the safety and role of tislelizumab and axitinib in downsizing tumors in patients with non-metastatic clear cell RCC prior to surgical resection. Methods: In this investigator-initiated study, 20 patients with high-risk non-metastatic ccRCC (clinical stage T2a-4 and/or N1, M0 lesions) were enrolled to receive 12 weeks of neoadjuvant ticelizumab and axitinib prior to nephrectomy. The primary endpoint was the objective response rate (complete and partial response) after neoadjuvant treatment according to RECIST v1.1. Secondary endpoints were disease-free survival (DFS), overall survival (OS), surgical outcome and safety. Results: By September 2023,13 eligible pts were enrolled. 11 pts have completed neoadjuvant therapy, with a median age of 60 (range 45-73) years, among whom 9 pts underwent surgery as planned without any delay. One patient progressed during treatment and received further systemic therapy. In 9 pts evaluable for efficacy, the investigator-assessed confirmed ORR was 55.5%. The median reduction of primary renal tumor size was 26.2% (range 12.5-45%). Pathologic results showed that one patient (11.1%) achieved a complete response (CR) by RECIST 1.1 and four patients achieved a partial response (PR). One patient who was considered unresectable became resectable at the end of treatment. Two patients were converted from radical to partial nephrectomy. The most common neoadjuvant therapy-related AEs were hematologic toxicity, hypothyroidism, nausea, vomiting, decreased appetite, fatigue, diarrhea, and elevated ALT/AST. There were no Gr4/Gr5 TRAEs. No direct intraoperative complications and no drug-related surgical complications postoperatively. Conclusions: As a neoadjuvant therapy for accRCC, the combination of tislelizumab and axitinib has clinical efficacy and a manageable safety profile. Clinical trial information: NCT05172440.