Successful treatment with sorafenib for sunitinib-refractory metastatic papillary renal cell carcinoma: Potential impact of Raf overexpression on predicting the efficacy of sorafenib

Introduction The prognosis of type 2 papillary renal cell carcinoma is often poor. We herein report a case of papillary renal cell carcinoma with liver metastasis that was successfully treated with sorafenib as a second-line therapy. Case presentation An 82-year-old man who had undergone radical nephrectomy 5 years previously experienced biopsy-proven liver metastasis. He received sunitinib as a first-line treatment; the dose was initially 12.5 mg/day and was escalated to 25 mg/day, but it was discontinued due to several adverse events. We then switched to sorafenib as a second-line treatment, which resulted in a partial response (51% reduction in tumor size); the patient showed no recurrence 5 months after the initiation of sorafenib treatment. An immunohistochemical analysis revealed the overexpression of Raf in both the primary and metastatic tumors. Conclusion As sorafenib blocks Raf signaling, the expression of Raf may serve as a useful predictor of the efficacy of sorafenib.