According to results from a recent clinical trial, the multi-targeted agent SI11248 is effective in the treatment of gastrointestinal stromal tumors (GIST) that have stopped responding to the biologic agent Gleevec® (imatinib mesylate).
Gastrointestinal stromal tumors are very aggressive cancers that occur in the gastrointestinal (GI) tract. They differ from the more common types of cancers found in the GI tract in that they originate from different cells. The most common types of cancers in the digestive system originate from glandular cells that line the GI tract. Gastrointestinal stromal tumors are thought to originate in cells found within the wall of the GI tract, called the interstitial cells of Cajal. These cells are thought to be involved in transmitting signals to the GI tract to aid in the movement in food or liquid. Treatment for GIST is very different than treatment for gastric or colorectal cancer, as GIST tends to not respond well to chemotherapy. One commonly used agent for the treatment of GIST is Gleevec®. However, once GIST stops responding to Gleevec®, effective treatment options are limited and researchers are evaluating novel therapeutic approaches for this group of patients.
SU11248 is an oral agent that is still in clinical trials. It produces anti-cancer effects through several targeted mechanisms that include anti-angiogenesis, as well as direct killing of the cancer cell. Cancer cells need blood and nutrients to grow and survive and have complex biologic mechanisms through which networks of arteries and capillaries are produced that deliver the necessary nutrients. This process is called angiogenesis. Several newer agents are being evaluated in clinical trials that target the angiogenesis process in an attempt to “cut off” the nutrient supply to the cancer cells, resulting in the prevention of their growth or spread.
A recent clinical trial was conducted to evaluate SU11248 in the treatment of GIST. The trial included patients who had stopped responding to Gleevec®. Patients were treated with either SU11248 or placebo (inactive substitute). At 7 months following treatment, the effectiveness of SU11248 was significantly superior to placebo and the trial was ended early so that patients initially treated with placebo could begin treatment with SU11248. Further analysis of data will provide more definitive results.
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Patients with GIST that has stopped responding to Gleevec® may wish to speak with their physician regarding the risks and benefits of participating in a clinical trial further evaluating SU11248 or other novel therapeutic approaches. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (cancer.gov) and cancerconsultants.com. Personalized clinical trial searches are also performed on behalf of patients at cancerconsultants.com.
Reference: Pfizer. Pfizer Cancer Drug Demonstrates Early Efficacy and Safety; Placebo Patients to Switch Immediately to Drug Therapy. Available at: http://www.pfizer.com/are/investors_releases/2005pr/mn_2005_0208.cfm. Accessed February 2005.