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KRAS Mutations and Primary Resistance of Lung Adenocarcinomas to Gefitinib or Erlotinib

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      Abstract

      Background

      Somatic mutations in the gene for the epidermal growth factor receptor (EGFR) are found in adenocarcinomas of the lung and are associated with sensitivity to the kinase inhibitors gefitinib (Iressa) and erlotinib (Tarceva). Lung adenocarcinomas also harbor activating mutations in the downstream GTPase, KRAS, and mutations in EGFR and KRAS appear to be mutually exclusive.

      Methods and Findings

      We sought to determine whether mutations in KRAS could be used to further enhance prediction of response to gefitinib or erlotinib. We screened 60 lung adenocarcinomas defined as sensitive or refractory to gefitinib or erlotinib for mutations in EGFR and KRAS. We show that mutations in KRAS are associated with a lack of sensitivity to either drug.

      Conclusion

      Our results suggest that treatment decisions regarding use of these kinase inhibitors might be improved by determining the mutational status of both EGFR and KRAS.

      Abstract

      Mutational analysis of the KRAS gene in lung cancer patients treated with two different kinase inhibitors suggests that tumors with KRAS mutations do not respond to these drugs

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      Most cited references 15

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      New guidelines to evaluate the response to treatment in solid tumors. European Organization for Research and Treatment of Cancer, National Cancer Institute of the United States, National Cancer Institute of Canada.

      Anticancer cytotoxic agents go through a process by which their antitumor activity-on the basis of the amount of tumor shrinkage they could generate-has been investigated. In the late 1970s, the International Union Against Cancer and the World Health Organization introduced specific criteria for the codification of tumor response evaluation. In 1994, several organizations involved in clinical research combined forces to tackle the review of these criteria on the basis of the experience and knowledge acquired since then. After several years of intensive discussions, a new set of guidelines is ready that will supersede the former criteria. In parallel to this initiative, one of the participating groups developed a model by which response rates could be derived from unidimensional measurement of tumor lesions instead of the usual bidimensional approach. This new concept has been largely validated by the Response Evaluation Criteria in Solid Tumors Group and integrated into the present guidelines. This special article also provides some philosophic background to clarify the various purposes of response evaluation. It proposes a model by which a combined assessment of all existing lesions, characterized by target lesions (to be measured) and nontarget lesions, is used to extrapolate an overall response to treatment. Methods of assessing tumor lesions are better codified, briefly within the guidelines and in more detail in Appendix I. All other aspects of response evaluation have been discussed, reviewed, and amended whenever appropriate.
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        Activating mutations in the epidermal growth factor receptor underlying responsiveness of non-small-cell lung cancer to gefitinib.

        Most patients with non-small-cell lung cancer have no response to the tyrosine kinase inhibitor gefitinib, which targets the epidermal growth factor receptor (EGFR). However, about 10 percent of patients have a rapid and often dramatic clinical response. The molecular mechanisms underlying sensitivity to gefitinib are unknown. We searched for mutations in the EGFR gene in primary tumors from patients with non-small-cell lung cancer who had a response to gefitinib, those who did not have a response, and those who had not been exposed to gefitinib. The functional consequences of identified mutations were evaluated after the mutant proteins were expressed in cultured cells. Somatic mutations were identified in the tyrosine kinase domain of the EGFR gene in eight of nine patients with gefitinib-responsive lung cancer, as compared with none of the seven patients with no response (P<0.001). Mutations were either small, in-frame deletions or amino acid substitutions clustered around the ATP-binding pocket of the tyrosine kinase domain. Similar mutations were detected in tumors from 2 of 25 patients with primary non-small-cell lung cancer who had not been exposed to gefitinib (8 percent). All mutations were heterozygous, and identical mutations were observed in multiple patients, suggesting an additive specific gain of function. In vitro, EGFR mutants demonstrated enhanced tyrosine kinase activity in response to epidermal growth factor and increased sensitivity to inhibition by gefitinib. A subgroup of patients with non-small-cell lung cancer have specific mutations in the EGFR gene, which correlate with clinical responsiveness to the tyrosine kinase inhibitor gefitinib. These mutations lead to increased growth factor signaling and confer susceptibility to the inhibitor. Screening for such mutations in lung cancers may identify patients who will have a response to gefitinib. Copyright 2004 Massachusetts Medical Society
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          EGFR mutations in lung cancer: correlation with clinical response to gefitinib therapy.

          Receptor tyrosine kinase genes were sequenced in non-small cell lung cancer (NSCLC) and matched normal tissue. Somatic mutations of the epidermal growth factor receptor gene EGFR were found in 15of 58 unselected tumors from Japan and 1 of 61 from the United States. Treatment with the EGFR kinase inhibitor gefitinib (Iressa) causes tumor regression in some patients with NSCLC, more frequently in Japan. EGFR mutations were found in additional lung cancer samples from U.S. patients who responded to gefitinib therapy and in a lung adenocarcinoma cell line that was hypersensitive to growth inhibition by gefitinib, but not in gefitinib-insensitive tumors or cell lines. These results suggest that EGFR mutations may predict sensitivity to gefitinib.
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            Author and article information

            Affiliations
            1simpleProgram in Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center New York, New YorkUnited States of America
            2simpleDepartment of Medicine, Memorial Sloan-Kettering Cancer Center New York, New YorkUnited States of America
            3simpleDepartment of Pathology, Memorial Sloan-Kettering Cancer Center New York, New YorkUnited States of America
            4simpleDepartment of Radiology, Memorial Sloan-Kettering Cancer Center New York, New YorkUnited States of America
            simpleMD Anderson Cancer Center United States of America
            Author notes

            Competing Interests: VAM has received research funding from Genentech (co-developer of erlotinib). He has received honoraria from AstraZeneca (maker of gefitinib) for consultancy. MGK has received research funding from AstraZeneca and research funding and consulting fees from Genentech and has represented AstraZeneca before the US Food and Drug Administration. WP, VAM, MFZ, and HEV, represented by the Sloan-Kettering Institute for Cancer Research, filed on June 1, 2004, a provisional patent application entitled “Use of mutations in EGFR kinase as an indicator of therapeutic efficacy of erlotinib in the treatment of NSCLC,” serial number 60/576,275. HEV is Co-founder and Chair of the Board of Directors of the Public Library of Science.

            Author Contributions: WP and HEV designed the study. QP and ML designed and performed more sensitive methods to detect EGFR mutations. WP, TYW, GJR, VAM, MFZ, MGK, and RTH acquired and analyzed the data. WP, TYW, and HEV contributed to writing the paper.

            *To whom correspondence should be addressed. E-mail: paow@ 123456mskcc.org
            Contributors
            Role: Academic Editor
            Journal
            PLoS Med
            pmed
            PLoS Medicine
            Public Library of Science (San Francisco, USA )
            1549-1277
            1549-1676
            January 2005
            25 January 2005
            : 2
            : 1
            545207
            15696205
            10.1371/journal.pmed.0020017
            (Academic Editor)
            Copyright: © 2005 Pao et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
            Categories
            Research Article
            Genetics/Genomics/Gene Therapy
            Oncology
            Oncology
            Cancer: Lung
            Genetics

            Medicine

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