The Role of Stereotactic Body Radiotherapy (SBRT) in Oligoprogressive Renal Cell Carcinoma (RCC) Treated with ICIs–TKIs: A Retrospective Multicentric Study

BACKGROUND: This multicentric, retrospective study investigated the use of stereotactic body radiotherapy (SBRT) in patients (pts) with metastatic renal cell carcinoma (mRCC) who experienced oligoprogression during a combination therapy with an immune checkpoint inhibitor (ICI) and a tyrosine-kinase inhibitor (TKI). METHODS: We retrospectively evaluated 34 pts affected by oligoprogressive RCC treated with an ICI-TKI combination between January 2020 and December 2023. SBRT was delivered to each site of oligoprogressive metastatic disease. After SBRT, pts were given follow-up clinical evaluations. 6-12-18-month local control (LC) rates and median next-line treatment-free survival (NEST-FS) were the primary endpoints. The secondary endpoints were overall response rate (ORR), clinical benefits and safety. RESULTS: After a median follow-up of 24 months, 6-12-18-month LC rates were 100%, 71% and 43%, respectively, and the median NEST-FS was 20 months. ORR was 90%, while clinical benefit was 100%. No > G2 adverse events related to SBRT were recorded. CONCLUSIONS: In our study, SBRT for oligoprogressive mRCC turned out to be a safe and useful treatment which was able to preserve current treatment. Further prospective studies are necessary to explore the effects of the ICIs-TKIs combination and SBRT upon oligoprogressive sites in mRCC.