Brain tumors with a particular gene composition are more responsive to a specific class of drugs, researchers are reporting.This knowledge should allow doctors to tailor therapies more appropriately to individual patients, and also open the door to devising new therapies for tumors that have different genetic make-ups. The specific tumors in question are glioblastomas, a difficult-to-treat, aggressive form of cancer with a low survival rate. “A subset of patients are more likely to respond, and by understanding why other subsets are failing, we can begin to think about customizing combinations of therapies to help treat those” patients, said Dr. Paul Mischel, senior author of the study that appears in the Nov. 10 issue of the New England Journal of Medicine.