The experimental drug, called PTK/ZK, is paired with what is considered the best chemotherapy combination available for advanced colorectal cancer, so study volunteers will receive the highest standard of care.
All volunteers enrolled in the studies will get chemotherapy; half will also receive PTK/ZK, while half will be given a placebo. Researchers hope that PTK/ZK will cut off the blood supply that allows tumors to grow and spread, said Dr. J. Randolph Hecht, a Jonsson Cancer Center researcher and national lead investigator for the studies.
A tumor cannot grow bigger than a pinhead unless it establishes an independent blood supply through a process called angiogenesis. Researchers theorize that by stopping or cutting off this new blood supply, they can starve and hopefully kill the cancer. PTK/ZK, an angiogenesis inhibitor, is designed to block the cellular receptors for VEGF, or vascular endothelial growth factor, which signals blood vessels to grow.
"It's a little like satellite television," Hecht said. "The signal, VEGF, is picked up by the receptor, which is like a satellite dish. If you're a blood vessel, this signal tells you to grow. What we hope PTK/ZK does is block the receptor from working, sort of like snipping the wires in the satellite dish. We're hoping this drug keeps the cancer from growing, makes it more sensitive to the chemotherapy we're giving and maybe even makes the tumor shrink by itself."
The studies are open at UCLA's Jonsson Cancer Center in Westwood, as well as at UCLA oncology practices in Santa Monica, Pasadena and Santa Clarita.
One of the clinical trials, called CONFIRM 1 (Colorectal Oral Novel Therapy for the Inhibition of Angiogenesis and Retarding Metastases), studies the angiogenesis inhibitor as a first-line therapy in patients with newly diagnosed colorectal cancer that has spread to other organs. The study will compare the time it takes for tumors to worsen and overall survival rates among two groups of patients. One group will receive a daily dose of PTK/ZK combined with the chemotherapy agents 5-fluorouracil, leucovorin and oxaliplatin, and the other group will be treated with the chemotherapy drugs alone.
The other study, CONFIRM 2, is for advanced colorectal cancer patients who have already undergone treatment with the chemotherapy combination of 5-fluorouracil, leucovorin and irinotecan but whose cancer has progressed. The study will look at the potential survival benefit of PTK/ZK combined with the chemotherapy agents 5-flurouracil, leucovorin and oxaliplatin, as compared to the chemotherapy drugs alone.
PTK/ZK is a member of one of the newest classes of cancer drugs in development, those that target specific molecules in cells. The idea behind these targeted therapies is to attack what goes awry in cancer cells and spare the healthy cells as much as possible.
"Cancers can't make their own blood vessels. To grow larger and spread, they need to trick the body into growing these new vessels," Hecht said. "These vessels make an attractive target for therapy because an adult rarely needs to grow blood vessels unless they're healing a wound. So blocking new blood vessel growth as a way to treat cancer has the potential for relatively few side effects."
Advanced colorectal cancer is usually fatal, Hecht said, so it is vital that oncologists find new and better ways to treat the disease. Colorectal cancer will strike about 150,000 Americans this year alone and kill more than 58,000 people. It is the second leading cause of cancer deaths in the United States, after lung cancer.
"The treatments we have now for advanced colorectal cancer prolong life, but unfortunately, they are not a cure," Hecht said. "We need to look for improved methods of treatment, and angiogenesis inhibitors have been promising."
The two studies are being conducted at multiple sites across the country, Hecht said. Researchers are seeking 1,090 patients for CONFIRM 1 and 830 patients for CONFIRM 2, according to Novartis Oncology and Schering AG, sponsors of the study.
Also contact: Mary Hardin, mhardin@mednet.ucla.edu 310-206-3769
For more information on the studies at UCLA's Jonsson Cancer Center and its affiliated locations, call the clinical trials hotline at 888-798-0719.
UCLA's Jonsson Comprehensive Cancer Center is composed of more than 240 cancer researchers and clinicians engaged in cancer research, prevention, detection, control and education. The center, one of the nation's largest comprehensive cancer centers, is dedicated to promoting cancer research and applying the results to clinical situations.
In 2003, the Jonsson Cancer Center was named the best cancer center in the western United States by U.S. News & World Report, a ranking it has held for four consecutive years.
For more information on the Jonsson Cancer Center, visit the Web site at www.cancer.mednet.ucla.edu.