Two new studies published in Nature suggest that resistance to targeted cancer therapies "may be almost inevitable" if they aren't used in combination, reports MedPage Today's Michael Smith. Johns Hopkins Kimmel Cancer Center's Luis Diaz and his colleagues developed a mathematical model based on genetic testing of colorectal cancer patients suggesting that resistance may exist before treatment has even begun, Smith says. Alberto Bardelli's group at the Institute for Cancer Research and Treatment in Turin, Italy, not only found evidence of "preexisting resistance," Smith adds, but also that resistance is largely a problem when a patient is treated with a single targeted therapeutic. The solution, according to both groups, would be to use the drugs in combination.
"These resistance mutations develop by chance as cancer cells divide so that tumors always contain thousands of resistance cells," Diaz said in a statement. Co-author Bert Vogelstein adds that "long-term remissions of advanced cancers will be nearly impossible with single targeted agents."