Rationale and protocol of SOAP: a phase II study to evaluate the efficacy of sorafenib as second-line treatment after pazopanib in patients with advanced renal cell carcinoma.

The introduction of agents targeting vascular endothelial grow factors has radically changed the approach to metastatic renal cell carcinoma; however, cure is not within definitive reach. In many cases, the tumor will progress several months after the start of first-line therapy and new lines of therapy are required. Pazopanib and sorafenib are two frequently used targeted agents, and no sound data are currently available for patients who relapsed after pazopanib. In this paper we illustrate the SOAP study, which was designed to evaluate the safety and efficacy of sorafenib in terms of progression free-survival in 44 patients treated in 10 Italian centers who had relapsed after first-line pazopanib. Standard treatment with sorafenib will be administered until disease progression or unacceptable toxicity. Secondary endpoints include the evaluation of overall survival, safety and quality of life. A subanalysis to evaluate toxicities as predictive factors has also been planned.