Branimir I. Sikic, MD, professor of medicine and program director of Stanford's General Clinical Research Center, is leading a study on the new treatment. He and his colleagues will present their preliminary results June 1 at the American Society of Clinical Oncology in Chicago.
Iressa was recently approved by the federal Food and Drug Administration for use in treating lung cancers that haven't responded to other forms of chemotherapy. It is one of a new class of drugs called epidermal growth factor receptor blockers, which work by blocking a protein found on the surface of many tumor types. This protein binds to a chemical found in the bloodstream that stimulates cells to divide. Iressa prevents that signal from being translated into the cell, slowing the cancer's growth.
The Stanford researchers knew that Iressa seemed to enhance chemotherapy in mice. With these results, they initially tested the drug along with FOLFOX in 15 people with colon cancer as part of a phase-I trial. Although the study was too small for definitive results, the early numbers looked promising: The tumors shrank in two out of three patients who had never received chemotherapy and in two out of nine patients whose previous chemotherapy had failed.
These results prompted a larger phase-II trial. The researchers will present the initial results from this trial at the upcoming meeting. In the initial 16 patients who had never before received chemotherapy, 75 percent of the tumors shrank with the combination of Iressa and FOLFOX compared to 38 percent with FOLFOX alone. In those whose previous chemotherapy had not been successful, 29 percent of the tumors shrank compared with 9 percent using FOLFOX alone.
"What these initial results show is that Iressa may be effective when added to a good chemotherapy like FOLFOX in treating these tumors," Sikic said. He is hoping to recruit additional patients for the continuation of the second phase of the trial of this new treatment, which has been dubbed IFOX.
Stanford researchers who participated in this work include Cheryl D. Cho, MD, senior clinical fellow in oncology; George Fisher, MD, PhD, assistant professor of medicine; Heather Wakelee, MD, postdoctoral fellow in oncology; Ranjana Advani, MD, clinical instructor in oncology; Bert Lum, PharmD, associate director of the cancer clinical trials office when the study was conducted; Robert Rouse, MD, professor of pathology; Erich Schwartz, MD, PhD, immunodiagnosis fellow; and research nurses Joanne Halsey and Charro Jambalos.
The study was sponsored by the National Cancer Institute; AstraZeneca, the pharmaceutical company that makes Iressa; and Sanofi-Synthelabo, the company that makes oxaliplatin, one of the agents in FOLFOX.
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