According to results recently presented at the 2005 Chemotherapy Foundation Symposium, the oral agent sunitinib malate (SU11248), still in clinical trials, appears to be a promising new agent for the treatment of advanced renal cell carcinoma.
The kidneys are a pair of bean-shaped organs located on each side of the spine that filter blood and eliminate waste in the urine through a complex system of filtration tubules. All of the blood in the body passes through the kidneys approximately 20 times an hour.
Renal cell carcinoma (RCC) is an uncommon form of cancer that is most often characterized by the presence of cancer cells in the lining of the kidney’s filtration tubules. Cancer that has spread outside the kidney to several and/or distant sites in the body is referred to as metastatic RCC.
Treatments for metastatic RCC include palliative (non-curative) surgery, radiation therapy, and immune stimulating agents such as Proleukin® (interleukin-2). In an effort to improve the poor prognosis (median survival is roughly 10 months) for patients with metastatic RCC, researchers continue to explore new treatment options. Clinical trials of targeted therapies (therapies that target a specific component of a cancer cell) are producing promising results.
The vascular endothelial growth factor (VEGF) and platelet-derived growth factor rectors (PDGFR) are two components in the body involved in cellular growth and replication. Often, cancerous cells have altered pathways that include these components; therefore, therapeutic agents that are targeted against the VEGF and PDGFR often reduce or prevent the uncontrolled replication of cancer cells.
Sunitinib malate is an oral agent that is targeted against both VEGF and PDGFR. It has demonstrated anticancer activity in early clinical trials, which prompted further evaluation of its activity in the treatment of advanced RCC.
Two phase II clinical trials were conducted by researchers from several medical institutions in the U.S. to evaluate sunitinib in the treatment of metastatic RCC. Both trials included patients with metastatic RCC who had received prior therapy with immune-stimulating agents. Trial 1 included 63 patients enrolled in 2003, and Trial 2 included 106 patients enrolled in 2004. In both trials, sunitinib demonstrated promising results:
- Partial or complete shrinkage of cancer occurred in 40% of patients in Trial 1 and 44% of patients in Trial 2.
- Stable disease lasting for at least 3 months was achieved in 27% of patients in Trial 1 and 23% of patients in Trial 2.
- Median time to cancer progression was 8.7 months in Trial 1 and 8.1 months in Trial 2.
- Median overall survival was 16.4 months in Trial 1 and has not yet been reached in Trial 2.
- Treatment was well tolerated, with the majority of side effects being mild.
- Patients with good performance status (ability to maintain daily activities) and those with higher hemoglobin levels had an improved progression-free survival.
The researchers concluded that sunitinib demonstrated impressive anticancer activity in patients with metastatic RCC who had received prior therapy. Furthermore, this agent is well tolerated. Trials evaluating sunitinib as initial therapy for RCC are currently ongoing. Patients diagnosed with RCC may wish to speak with their physician regarding their individual risks and benefits of participating in a clinical trial further evaluating sunitinib or other promising therapeutic agents.
Reference: George D, Motzer R, Rini B, et al. Sunitinib malate (SU11248) Shows Antitumor Activity in Patients with Metastatic Renal Cell Carcinoma: Updated Results from Phase II Trials. Proceedings from the 2005 annual Chemotherapy Foundation Symposium. New York, NY. Abstract #18.
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