Axitinib, an investigational selective inhibitor of vascular endothelial growth factor (VEGF) receptors 1, 2, and 3, significantly extended progression-free survival (PFS) compared with sorafenib (Nexavar) in patients with previously treated metastatic renal cell carcinoma (mRCC).
Progression-free survival was significantly longer in patients assigned to axitinib compared with sorafenib regardless of whether sunitinib (Sutent) or cytokines were used as first-line therapy, said first author Brian I. Rini, MD, who presented the results at the American Society of Clinical Oncology annual meeting in Chicago.
In previous phase II trials, the antitumor efficacy of axitinib was demonstrated in cytokine-refractory renal cell carcinoma (time to progression: 15.7 months) and sorafenib-refractory RCC (PFS: 7.4 months). However, the standard of care for patients with metastatic RCC resistant to initial therapy is not well-defined, as no randomized trials had compared targeted therapies prior to the one presented here, said Dr. Rini, associate professor of medicine at the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University and staff in solid tumor oncology at the Cleveland Clinic Taussig Cancer Institute.
Preclinical evidence had suggested that inhibiting all three VEGF receptor signaling pathways is more efficient at disrupting tumor growth, and the data from this study support the hypothesis that more potent biochemical targeting of the VEGF receptor improves the clinical outcome in metastatic RCC, he said.
The trial included 723 patients (median age: 61 years; 72% men, 76% Caucasian) with clear cell metastatic RCC who had measureable disease (per Response Evaluation Criteria in Solid Tumors criteria) and who had progressed despite prior therapy with either sunitinib (54%), cytokines (35%), bevacizumab (Avastin, 8%), or temsirolimus-based regimens (Torisel, 3%). An Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 was required for study entry. Patients were randomized to axitinib at a starting dosage of 5 mg twice daily, or sorafenib, 400 mg twice daily. Patients in the axitinib group had their dosage titrated to 7 mg, then to 10 mg as tolerated.