Bone metastases affect prognosis but not effectiveness of third-line targeted therapies in patients with metastatic renal cell carcinoma

Introduction: Treatment of metastatic renal cell carcinoma (mRCC) has improved with the use of targeted therapies, but bone metastases continue to be negative prognostic factor. Methods: Patients with mRCC treated with everolimus (EV) or sorafenib (SO) after two previous lines of targeted therapies were included in the analysis. Overall survival (OS) and progression-free survival (PFS) were assessed based on the presence of bone metastases and type of therapy; they were also adjusted based on prognostic criteria. Results: Of the 233 patients with mRCC, 76 had bone metastases. Of the 233 patients, EV and SO were administered in 143 and 90 patients, respectively. Median OS was 10.4 months in patients with BMs and 17.4 months in patients without bone metastases (p = 0.002). EV decreased the risk of death by 1 8% compared to SO (adjusted hazard ratio [HR] 0.82, 95% confidence interval [CI] 0.74-0.91; p < 0.001), with comparable effects in patients with or without bone metastases. In the same manner, EV decreased the risk of progression by 12% compared to SO (adjusted HR 0.88, 95% CI 0.82-0.96; p = 0.002), but this difference was not significant in patients without bone metastases. The major limitations of the study are its retrospective nature, the heterogeneity of the methods to detect bone metastases, and the lack of data about patients treated with bisphosphonates. Conclusions: The relative benefit of targeted therapies in mRCC is not affected by the presence of bone metastases, but patients without bone metastases have longer response to therapy and overall survival.