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.