Background: Relative dose intensity (RDI) is a simple index for evaluation of the amount of drug administered per unit time. We retrospectively investigated the prognostic impact of RDI for patients with metastatic renal cell carcinoma (mRCC) treated with second-line targeted therapy.
Methods: We enrolled 168 patients with mRCC. We assessed RDI at 4 weeks after second-line targeted therapy induction.
Results: The median follow-up after second-line targeted therapy was 18.1 months. The median time-to-treatment-failure (TTF) and overall survival (OS) were 4.9 and 25.4 months, respectively. In the Kaplan-Meier analysis, the median OS of patients with second-line RDI < 0.7 was significantly shorter than those with RDI ≥ 0.7 (12.1 vs. 31.3 months; P = .030). In the subgroup analysis, second-line RDI was definitely prognostic in the poor-risk group of the International Metastatic Renal Cell Carcinoma Database Consortium criteria, showing second-line RDI was an independent predictor for both TTF (hazard ratio [HR], 3.6; 95% confidence interval [CI], 1.6-8.0; P = .002) and OS (HR, 3.1; 95% CI, 1.1-8.4; P = .026). Also, assessing the type of second-line regimen, the multivariate analysis showed that second-line RDI was an independent prognostic indicator of TTF (HR, 1.7; 95% CI, 1.0-2.9; P = .040) and OS (HR, 2.7; 95% CI, 1.3-5.7; P = .009) in patients treated with everolimus. In this group, the median TTF and OS of patients with RDI < 0.7 were 2.4 and 11.1 months, and those with RDI ≥ 0.7 were 5.3 and 25.9 months, respectively.
Conclusion: The results suggest that second-line RDI may be a prognostic predictor for patients with mRCC treated with second-line targeted therapy, particularly in both the International Metastatic Renal Cell Carcinoma Database Consortium poor-risk group and everolimus-treated group.
Keywords: Dose modification; IMDC; Outcome; RDI; Renal cell carcinoma; Second-line; Targeted therapy.
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