Randomized phase II trial of the multi-kinase inhibitor sorafenib versus interferon (IFN) in treatment-naïve patients with metastatic renal cell carcinoma (mRCC)

4501 Background: Sorafenib, an oral multi-kinase inhibitor that targets tumor growth and vascularization, significantly prolonged PFS in a Phase III trial with previously treated mRCC patients. This randomized Phase II trial investigated the efficacy and tolerability of sorafenib compared with IFN in first-line therapy of patients with clear-cell RCC. Methods: Untreated patients with mRCC were stratified by MSKCC prognostic score and randomized to receive continuous oral sorafenib 400 mg bid or IFN 9 million units tiw, with an option of dose escalation (600 mg bid sorafenib) or crossover from IFN to sorafenib upon disease progression. The study assessed PFS at 99 events as primary objective, best response (RECIST), overall survival, health-related quality of life, and adverse events (AEs). Results: Baseline characteristics of 188 patients (sorafenib n=97; IFN n = 91) were: median age 62.0 years; MSKCC score: 57% low, 41% intermediate, 1% high; prior nephrectomy: 82%; ECOG 0:1, 55.3%:44.7%. As of January 6, 2006, PFS events have been reported for 64 (34%) patients. Preliminary data showed drug-related AEs of any severity (sorafenib vs IFN) in 50.5% vs 51.6% of patients (≥grade 3: 8.2% vs 11.0%), including diarrhea (24.7% vs 5.5%), fatigue (14.4% vs 20.9%), fever (2.1% vs 18.7%), hypertension (13.4% vs 0%), nausea (5.2% vs 13.2%), flu-like syndrome (1.0% vs 6.6%), hand-foot skin reaction (6.2% vs 0%), and rash/desquamation (4.1% vs 0%). Drug-related metabolic/laboratory abnormalities at grade 3 (no grade 4) comprised hypophosphatemia (21.7% vs. 0%), lipase elevation (5.6% vs. 11.1%), anemia (0% vs. 5.3%) and hypoalbuminemia (0% vs. 3.6%). Five patients receiving IFN withdrew from treatment due to AEs, whereas only one patient withdrew from sorafenib. Conclusions: Sorafenib was generally well tolerated in RCC patients in the first-line setting, with relatively infrequent drug-related AEs ≥grade 3. Full PFS data will be presented at the meeting. [Table: see text]