Organ transplants often fail because the body tries hard to oust the foreign tissue. Now, a Stanford scientist reports that an experimental drug halts an insidious form of organ rejection that until now has been impossible to treat. The study, conducted in monkeys. measured the effects of the drug rapamycin on "chronic" rejection. Rapamycin is the first drug to show promise as a treatment for advanced chronic rejection, said Randall Morris, MD, professor of cardiothoracic surgery at Stanford University School of Medicine and leader of the 14-member research team.