Feasibility and effects of high-dose hypofractionated radiation therapy and simultaneous multi-kinase inhibition with sunitinib in progressive metastatic renal cell cancer.

Objectives: Radiotherapy (RT) is considered oncologically ineffective in metastatic renal cell cancer (mRCC). Inhibition of angiogenetic pathway may lead to radiosensitization in mRCC. The aim of this study was to evaluate the efficacy of the simultaneous combination of RT with systemic treatment of bulky (mRCC) using sunitinib.

Methods And Materials: We included 22 patients with progressive mRCC between 04/2007 and 08/2008 at the University Hospital Munich Großhadern. All patients underwent high-dose hypofractionated RT while they were simultaneously treated systemically with sunitinib 50 mg.

Results: Median age was 63.0 years (range 26.7-84.4). Median dose of radiation was 40 Gy (range 25-50) in a median of 8 fractions (range 5-30). Treatment sites were brain, retroperitoneal and mediastinal lymph nodes, spinal cord, bones, liver, and kidney. Median follow-up was 14.3 months. After 3 months, 2 patients had complete remission (CR), 9 patients showed partial remission (PR) as measured by response evaluation criteria in solid tumors (RECIST) criteria, 2 patients had minor response (MR), and 8 patients had stable disease (SD). Only 1 patient did not respond to therapy. Toxicity was very low with only 1 grade 4 hypertension. Skin toxicities were manageable with no grade 3 event during the combination period.

Conclusions: The combination of RT with simultaneous systemic treatment using sunitinib is effective in patients with progressive mRCC. With high dose RT, complete response seems to be possible. Further evaluation should be based upon combination of RT with systemic therapy, rather than sequential RT regiments.