Background: The objective of this study was to independently evaluate the objective response rate of sorafenib and sorafenib plus low-dose interferon-alfa 2b (IFN) as frontline therapy in patients with metastatic renal cell carcinoma (mRCC).
Methods: Untreated patients with clear cell mRCC were randomized to receive sorafenib 400 mg orally twice daily or sorafenib 400 mg orally twice daily plus subcutaneous IFN 0.5 million U (MU) twice daily. Primary endpoints included the objective response rate (ORR) and safety. Secondary endpoints included progression-free survival (PFS) and overall survival (OS). Exploratory endpoints included the predictive value of tumor tissue biomarkers.
Results: Eighty patients were enrolled. The median follow-up was 19.7 months (range, 0-34.2 months). The ORR was 30% (95% confidence interval [CI], 16.6%-46.5%) in the sorafenib arm and 25% (95% CI, 12.7%-41.2%) in the combination arm. The median PFS was 7.39 months in the sorafenib-alone arm (95% CI, 5.52-9.20 months) and 7.56 months in the sorafenib plus IFN arm (95% CI, 5.19-11.07 months). The median OS was 27.04 months in the combination arm (95% CI, from 22.31 to not attained) and was not reached in the sorafenib arm. Toxicities were comparable in both arms. In a multivariate model, increased phosphorylated protein kinase B (pAKT) levels were associated with poorer PFS (hazard ratio, 1.04; 95% CI, 1.00-1.08; P = .0411) and OS (hazard ratio, 1.15; 95% CI, 1.02-1.29; P = .0173).
Conclusions: The addition of low-dose IFN to sorafenib resulted in efficacy outcomes that were comparable to those achieved with sorafenib monotherapy. The current results indicated that pAKT levels may predict for clinical outcome, but further mechanistic study is required.
Copyright 2010 American Cancer Society.