A second gene mutation explains why some lung cancer tumors become resistant to treatment with new cancer drugs meant to disrupt a molecular target that helps tumors grow, two separate research teams report.Researchers from Beth Israel Deaconess Medical Center in Boston detail their findings in the Feb. 24 issue of The New England Journal of Medicine, and researchers from Memorial Sloan-Kettering Cancer Center in New York City outline their research in the Feb. 22 issue of PLoS Medicine.The Sloan-Kettering researchers reported on six patients who had received treatment with either Iressa (gefitinib) or Tarceva (erlotinib), both new cancer drugs. The Beth Israel team reported on one patient who stopped responding to Iressa. All patients had non-small cell lung cancer, which accounts for about 87 percent of all lung cancers, according to the American Cancer Society.Both drugs are relatively new to the market. Iressa was approved for use against lung cancer by the U.S. Food and Drug Administration in May 2003 and Tarceva was approved in November 2004.Researchers reported last year that another gene mutation in these patients predicts which cancers will initially respond to the drugs, said Dr. William Pao, a Sloan-Kettering researcher and co-author of the study in PloS Medicine.
