by Dr. C.H. Weaver M.D. updated 2/2019
According to results recently presented at the 38th Annual Meeting of the American Society of Clinical Oncology, the monoclonal antibody rhuMab-VEGF (bevacizumab) appears to delay cancer progression in some patients with metastatic renal cell cancer.
The kidneys are a pair of bean shaped organs located on each side of the spine. The kidneys filter the 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 cancer is an uncommon form of cancer that is most often characterized by the presence of cancer cells in the lining of the filtration tubules of the kidney. Metastatic renal cell cancer is cancer that has spread to distant sites in the body. Approximately 31,000 new cases of renal cell cancer are diagnosed every year in the United States. Currently, the only approved agent for the treatment of renal cell carcinoma in the United States is Proleukin® (Interleukin-2).
Vascular endothelial growth factor (VEGF) is a small protein that promotes angiogenesis. Angiogenesis is the formation of new blood vessels and is a process that is essential for the growth and spread of cancer. Cancer cells need oxygen and nutrients provided by blood in order to grow. The blood vessels formed by angiogenesis supply these necessary nutrients, stimulating cancer cells to replicate and spread. VEGF binds to existing vessels and stimulates them to branch out, ultimately allowing the cancer cells to spread. Many cancer cells have high levels of VEGF and are thought to produce an overabundance of the proteins.
RhuMab-VEGF is a monoclonal antibody, or protein made in the laboratory, that selectively binds to VEGF. This renders VEGF unable to bind to its receptor on existing vessels and thus halts angiogenesis mediated through this mechanism.
Recently, researchers from the National Cancer Institute conducted a clinical trial to evaluate rhuMab-VEGF in the treatment of metastatic renal cell cancer. In this trial, 37 patients were treated with high doses of rhuMab-VEGF, 35 patients were treated with low doses of rhuMab-VEGF and 38 patients received a placebo (inactive substitute). Patients on placebo were allowed to “cross over” and receive rhuMab-VEGF if their cancer progressed. An interim analysis revealed that time to cancer progression was significantly longer in patients treated with high-dose rhuMab-VEGF than placebo, meeting criteria to close the trial earlier than planned. Time to cancer progression was approximately five months in patients treated with high-dose rhuMab-VEGF, over three months in patients treated with low-dose rhuMab-VEGF and only less than two months in patients who received placebo. The most significant side effects were hypertension and measurable protein in the urine. Longer follow-up is needed to determine survival benefits.
These results indicate that rhuMab-VEGF may delay cancer progression in patients with metastatic renal cell cancer and is generally well tolerated. There are now over 20 clinical trials underway to evaluate rhuMab-VEGF in various cancers. Patients with metastatic renal cell cancer may wish to speak with their physician about the risks and benefits of participating in a clinical trial further evaluating rhuMab-VEGF or other promising therapies.
Reference: Yang J, Haworth L, Steinberg S, et al. A randomized double-blind placebo-controlled trial of bevacizumab (anti-VEGF antibody) demonstrating a prolongation in time to progression in patients with metastatic renal cancer. Proceedings from the 38th annual meeting of the American Society of Clinical Oncology. 2002;21:Abstract 15.