Graft-versus-host disease (GVHD) is a major complication of bone marrow transplant, a potentially curative treatment for patients with blood-borne cancers such as leukemia and lymphoma. Inhibiting Sirt-1 in a mouse model helped control GVHD without making tumor relapse more likely, report researchers. The inhibitor has already been proven safe in humans but would need further testing in patients with blood-borne cancers.