Background: No report has evaluated axitinib-induced proteinuria as a biomarker for predicting treatment efficacy and survival of patients with metastatic renal cell carcinoma (mRCC).
Methods: The subjects were patients with mRCC treated with axitinib at Kinki University Hospital from February 2008 to November 2014. Clinical records were retrospectively reviewed including baseline patient characteristics, time-dependent changes of urinary protein status, computed tomography scans of metastatic lesions, treatment duration with axitinib, and survival time.
Results: A total of 45 patients were evaluable. Median tumor shrinkage rates were 32.3 and 35.0 % in patients with urinary protein increases ≥+2 and <+2, respectively (p = 0.496). Objective response rates were also similar between the two groups. Median progression-free survival (PFS) times with axitinib were 13.5 months [95 % confidence interval (CI) 0.0-27.5] and 11.0 months (95 % CI 0.0-26.7) in patients with urinary protein increases ≥+2 and <+2, respectively (p = 0.975). The maximum tumor shrinkage rate with axitinib was significantly associated with PFS with axitinib as a result of multivariate analysis (p = 0.002). Median overall survival (OS) times were 39.8 months (95 % CI 12.7-67.0) and 25.4 months (95 % CI 11.2-39.6) in patients with axitinib-induced urinary protein increases ≥+2 and <+2, respectively (p = 0.250). The number of metastatic sites (p = 0.006), the MSKCC risk (p = 0.009), and the maximum tumor shrinkage rate with axitinib (p = 0.019) were significantly associated with OS as a result of multivariate analysis.
Conclusions: The degree of urinary protein increase during axitinib treatment was not associated with objective response, PFS, and OS in mRCC patients treated with axitinib.
Keywords: Axitinib; Biomarker; Prognostic factor; Proteinuria; Renal cell carcinoma; Tumor shrinkage.