Preliminary efficacy and safety results of tislelizumab (T) and axitinib (A) combined with stereotactic body radiation therapy (SBRT) in the treatment of oligometastatic renal cell carcinoma (omRCC): A single-center phase II study.

Abstract

e16503 Background: SBRT, a novel treatment modality by directly targeting tumor sites using high dose of radiation, has become standard of care for pts with omRCC. While it is believed that SBRT could prolong overall survival through reducing tumor burden, the role of SBRT in treating omRCC in the era of TKI/IO remains controversial. The aim of this study is to investigate the efficacy and safety of T and A combined with SBRT in the treatment of omRCC. Methods: Eligible pts had histologically confirmed clear cell renal cell carcinoma with oligometastases (≤5 lesions) and had ≤1 prior systemic therapy. All pts received SBRT to the metastatic lesions in 5-7 fractions at a dose of 30-50 Gy per lesion via CyberKnife with Synchrony Respiratory Tracking system. The lesions for SBRT were selected at the discretion of 2 independent radiologists. Concomitant T was given 200mg every 3 weeks and A 5mg twice a day. Primary endpoint was objective response rate (ORR) according to RECIST v1.1. Secondary endpoints included progression free survival (PFS) and overall survival (OS) estimated via Kaplan Meier method. Treatment-related adverse events (TRAE) were evaluated based on CTCAE 5.0. Results: From August 3 rd 2021 to October 12 th 2024, 17 pts met the inclusion criteria. Five pts had received TKI. Of 45 metastatic lesions, 28 were irradiated. Median follow-up was 8.9 months (range 2.8-24.1). Overall, ORR was 64.7%. 67.9% (19/28) of irradiated lesions and 58.8% (10/17) of non-irradiated lesions achieved objective response. Higher ORR was observed in pts with no prior systemic therapy than pts who had received TKI (75% and 40% respectively). Median PFS was 24.0 months (95%CI, 4.2-NR) and median OS was not reached. TRAEs of any grade were observed in 70.6% pts and no new safety signals were reported. Conclusions: The preliminary results of T plus A combined with SBRT demonstrated promising efficacy and safety in the treatment of omRCC. Higher objective response rate was seen in irradiated lesions and in pts who had not received TKI. Further recruitment is ongoing. Clinical trial information: ChiCTR2200067043 .