Recent studies of a new anticancer drug show continued response for patients with late-stage kidney cancer. Robert Motzer, MD, attending physician at Memorial Sloan-Kettering Cancer Center (MSKCC), reported a response rate of 40 percent in patients with metastatic (advanced) renal cell (kidney) cancer who received SU11248 in second-line therapy. Findings from two consecutive, Phase II multicenter trials of 169 patients were presented today at the annual meeting of the American Society for Clinical Oncology (ASCO).
"Continuing with our study of SU11248 treatment for renal cell cancer, first reported at last year's annual ASCO meeting, we found a partial response rate for 40 percent of patients, with 6 of the 25 patients having a continuous response for greater than 12 months," said Dr. Motzer, principal investigator of the trials. "In the second trial, both partial and complete responses have been observed, indicating that SU11248 is a very active agent in the treatment of a disease for which standard treatment provides only a 15 percent response rate."
In the first trial, 63 patients with metastatic renal cell carcinoma, whose cancer had failed to respond to standard therapy, received SU11248. Twenty-five of them (40 percent) showed a partial response to the drug; in 21 patients (33 percent), the disease stabilized. Of the 25 patients who achieved a partial response, the median duration of partial response was 10 plus months. Eight of the patients remain progression-free, including two whose tumors became operable as a result of the treatment. The median time to progression was 8.7 months; the median survival was 16 months; six patients remain on therapy.
In a second trial, 106 patients have been treated and were assessed for a response. Of the 106 patients, 41 (39 percent) had tumor shrinkage greater than 30 percent, including one patient whose cancer is in complete remission. The drug was generally well-tolerated, with patients experiencing mild- to-moderate side effects that include fatigue, nausea, diarrhea, and stomatitis (mouth inflammation).
According to American Cancer Society estimates, kidney cancer will be diagnosed in approximately 36,160 people this year; 22,490 will be men. The disease will be responsible for about 12,660 deaths, almost two-thirds of them men. Standard treatment for metastatic kidney cancer is interleukin-2 and interferon-alpha. These agents have a response rate of 15 percent and cause significant side effects for virtually all treated patients.
The orally administered agent SU11248 is a multi targeted tyrosine kinase inhibitor, which works by simultaneously blocking two growth factor receptors, a vascular endothelial growth factor receptor, and a platelet-derived growth factor receptor. By targeting multiple receptors, SU11248 cuts off the blood supply to the tumor and destroys cellular reproduction.
Physicians in the SU11248 Study Group from Memorial Sloan-Kettering, the University of California, San Francisco, Massachusetts General Hospital, the University of Michigan Hospital, the Fox Chase Cancer Center, the University of Wisconsin, the Cleveland Clinic Foundation, and Duke University participated in the multicenter study led by Dr. Motzer. The study was sponsored by Pfizer Pharmaceuticals.