Genetic variation-Lung cancer drugs work better in the Japanese than in the Americans
Jun 3, 2007 - 3:30:28 AM
, Reviewed by: Dr. Sanjukta Acharya
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âNobody else in the world has ever done this, with a common arm looking at genetic differences among ethnic groups,â Gandara says.
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Key Points of this article
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A study last year showed that lung cancer drugs worked better in the Japanese vs. the Americans.
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Patients with variations in the CYP3A4 gene took longer for their lung cancer to progress.
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Variation in another gene , ERCC2, appeared to interfere with how well patients responded to treatment.
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By University of Michigan Health System,
[RxPG] Last year, a groundbreaking international project found that a group of Japanese patients with advanced non-small cell lung cancer survived longer âand had a higher rate of side effects â than U.S. patients with the same diagnosis,.when both groups were given two well-known drugs for the disease.
Now, a follow-up study suggests the reasons appear to lie in subtle variations in certain genes that govern how the body metabolizes chemotherapy drugs. David Gandara, M.D., a University of California, Davis researcher who led the recent Southwest Oncology Group study, presented the results Saturday, June 2, at the American Society of Clinical Oncology annual meeting.
The discovery that Japanese and U.S. patients, matched in age, gender and other respects, had differences in key metabolism-related genes is the latest result from a seven-year collaboration between the Southwest Oncology Group and two clinical trials groups in Japan. Gandara, who leads lung cancer trial efforts for the Southwest Oncology Group, is director of clinical research at the University of California, Davis, Cancer Center. The Southwest Oncology Group (SWOG) is the largest federally funded U.S. cancer trials network.
The recent SWOG study breaks new ground by exploring the possible role of ethnic patterns in the emerging science of pharmacogenomics, which promises to tailor drug regimens to a patientâs genetic profile. âNobody else in the world has ever done this, with a common arm looking at genetic differences among ethnic groups,â Gandara says.
Researchers looked at DNA from 156 patients who received the chemotherapy drugs paclitaxel and carboplatin in a SWOG clinical trial and one conducted by the Japan Multicenter Trial Organization. In the trials, half the Japanese patients survived one year, while slightly more than one-third of U.S. patients did. The Japanese patients as a group survived longer despite the fact that a significant number of them had to be given a lower dose of paclitaxel and for a shorter time than the U.S. patients because of toxicity. The U.S. group was predominantly Caucasian; 2 percent were Asian-Americans.
To find clues to the differences, the scientists examined six genes in DNA samples from the patients. They found differences in four. In patients with certain variations in the CYP3A4 gene, it took 2.75 times longer for their lung cancer to progress than in patients without the variations. A variation in another gene, ERCC2, appeared to interfere with how well patients responded to treatment.
The differences in outcomes corresponded with the patientsâ genetic makeup, rather than their ethnicity per se, since. some individuals in each group possessed genetic variations not typical of their group. Thus, the study suggests therapies in the future need to be tailored to each individual based on analysis of his or her genetic makeup, not simply ethnicity.
The relatively small number of patients makes the results of the study far from conclusive: Gandara calls the study âhypothesis-generating.â Next, he and other SWOG scientists are seeking funding to learn what genes may explain why Japanese and U.S. patients respond differently to EGFR inhibitors such as erlotinib, a relatively new targeted therapy that is another important class of drugs for lung cancer.
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About Dr. Sanjukta Acharya
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This news story has been reviewed by Dr. Sanjukta Acharya before its publication on RxPG News website. Dr. Sanjukta Acharya, MBBS is the chief editor for RxPG News website. She oversees all the medical news submissions and manages the medicine section of the website. She has a special interest in diabetes and endocrinology.
RxPG News is committed to promotion and implementation of Evidence Based Medical Journalism in all channels of mass media including internet.
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Additional information about the news article
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Institutions involved in the study include the Southwest Oncology Group (in addition to Gandara, members John Crowley, James Moon, Stephen K. Williamson, M.D., and Philip. C. Mack); the University of California, Davis, Cancer Center; the Japan Multinational Trial Organization; the University of Kansas, and the University of North Carolina.
The Southwest Oncology Group (www.swog.org) is the largest cancer clinical trials cooperative group in the United States. Funded by research grants from the National Cancer Institute, part of the National Institutes of Health, the group conducts clinical trials to prevent and treat cancer in adults, and to improve the quality of life for cancer survivors. The group's network of more than 5,000 physician-researchers practice at nearly 550 institutions, including 16 National Cancer Institute-designated cancer centers. Headquartered in Ann Arbor, Mich. (734-998-7130), the group has an operations office in San Antonio, Texas. and a statistical center in Seattle, Wash.
The University of California, Davis, Cancer Center, is the nation's 61st National Cancer Institute center. Its research program unites more than 275 scientists from more than a dozen disciplines on three campuses: the University of California, Davis, the UC Davis Medical Center in Sacramento, and Lawrence Livermore National Laboratory in Livermore, Calif.
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