The study, called EMERGE, evaluated 122 breast cancer patients who had failed at least three rounds of treatment and whose tumors expressed the GPNMB protein in at least 5% of their cells.

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One example: The gene that makes the Epogen protein is expressed in only a few scattered tissues and is hard to detect by conventional gene-finding methods, which discover genes not by looking at DNA but by examining the RNA messengers that ferry genetic code between the DNA itself and the cellular machinery that make proteins.

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These latch on to a protein that is expressed often in cancer cell but not in normal ones.

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All three drugs target the epidermal growth factor receptor (EGFR), a protein that is over-expressed in cancer cells.

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