Non-significant impact of proteinuria on renal function in Japanese patients with metastatic renal cell carcinoma treated with axitinib

Background To investigate the impact of proteinuria on the renal function of patients with metastatic renal cell carcinoma (mRCC) who received axitinib, a tyrosine kinase inhibitor specifically targeting vascular endothelial growth factor receptors. Methods This study included 65 consecutive Japanese patients who were diagnosed with mRCC and were subsequently treated with axitinib for at least 12 weeks. The association between the changes in the estimated glomerular filtration rate (eGFR) and proteinuria in these 65 patients was retrospectively assessed. Results Of the 65 patients, 41 (63.1 %) were judged to be positive for proteinuria. There were no significant differences between the eGFR value before the introduction of axitinib and that at the last clinic visit in either group with or without proteinuria. Furthermore, no significant correlation was noted between the changes in eGFR and the urine protein to creatinine ratio in the group positive for proteinuria, and there was no significant effect of the duration of treatment with axitinib on the changes in eGFR in the proteinuria group. Of several factors examined, univariate analysis identified age, eGFR prior to the introduction of axitinib, and timing of axitinib introduction, but not the presence of proteinuria, as predictors of a decrease in eGFR of >10 %; however, only age appeared to be independently associated with a decrease in eGFR of >10 %. Conclusions These findings suggest that treatment with axitinib may not have a significant adverse impact on the renal function in patients with mRCC, irrespective of the presence of proteinuria.