LOS ANGELES - In what’s being called a major advance in organ transplants, doctors say they have developed a technique that could free many patients from having to take anti-rejection drugs for the rest of their lives. The treatment involved weakening the patient’s immune system, then giving the recipient bone marrow from the person who donated the organ. In one experiment, four of five kidney recipients were off immune-suppressing medicines up to five years later."There’s reason to hope these patients will be off drugs for the rest of their lives,” said Dr. David Sachs of Massachusetts General Hospital in Boston, who led the research published in Thursday’s New England Journal of Medicine.