Hypofractionated radiotherapy with concomitant sunitinib - is there a radiosensitizing effect?

We present a case of a patient with metastatic renal cell cancer (RCC) treated with hypofractionated radiotherapy while being treated with sunitinib. He received a single dose of 8 Gy of external beam radiation to a metastatic mass of several centimeters diameter in the right lateral ribs, followed by a second identical dose. Clinically, the patient achieved a nearly complete disappearance of the mass. We discuss the possible synergy between tyrosine kinase receptor inhibitors (TKRIs) and radiotherapy and the importance of dose fractionation.