The addition of the targeted agent Avastin® (bevacizumab) to reduced doses of the immune-stimulating agent interferon appears to improve progression-free survival among patients with advanced kidney cancer while reducing side effects caused by full doses of interferon. These results were recently published in the Annals of Oncology.
The kidneys are each filled with tiny tubules that clean and filter the blood; this process removes waste and makes urine. Renal cell cancer (RCC) is a malignancy involving these tubules of the kidney. Metastatic RCC refers to cancer that has spread from the kidney to distant sites in the body. Metastatic RCC was historically treated with interferon (IFN) alfa, an agent that stimulates the immune system to help fight the cancer.
Avastin is a type of therapy known as a monoclonal antibody, which specifically targets the vascular endothelial growth factor (VEGF) receptor. The VEGF is responsible for establishing blood vessels that support the cancerous tissues. Drugs that interfere with VEGF can slow or stop the growth of cancer cells. In addition, drugs that interfere with VEGF may improve the delivery of chemotherapy and radiation therapy to cancer cells by normalizing blood supply. Avastin continues to be evaluated in clinical trials with different combinations of agents for the treatment of various cancers.
Researchers affiliated with a multicenter international trial recently conducted a Phase III clinical trial (phase prior to FDA review) that compared Avastin plus interferon with interferon alone in 649 patients with metastatic RCC who had not received prior therapies. The results of this trial were previously published in the Lancet; however, the researchers recently conducted an analysis of a subset of patients whose dose of interferon had been reduced due to side effects of the agent. The data from the subset analysis included 131 patients treated with Avastin and reduced-dose interferon and 97 patients treated with reduced-dose interferon alone.
Overall, patients treated with reduced-dose interferon plus Avastin had nearly equivalent progression-free survival rates as those treated with full-dose interferon plus Avastin.
At one year event-free survival (survival without progression or recurrences) was slightly higher among the group of patients treated with reduced-doses of interferon plus Avastin compared with those treated with full-dose interferon plus Avastin.
The researchers stated, “[This] subgroup analysis suggests that the dose of IFN can be reduced to manage side-effects while maintaining efficacy in patients with [metastatic] RCC receiving [Avastin plus] IFN.” Patients diagnosed with metastatic RCC may wish to speak with their physician regarding their individual risks and benefits of participating in a clinical trial further evaluating Avastin and reduced doses of IFN or other promising therapeutic approaches. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (www.cancer.gov) and www.eCancerTrials.com.
Reference: Melichar B, Koralewski P, Ravaud A, et al. First-line bevacizumab combined with reduced dose interferon alfa 2a is active in patients with metastatic renal cell carcinoma. Annals of Oncology. 2008;19: 1470-1476.