There’s a new frontier in treating autoimmune diseases. Today’s treatments tamp down the friendly fire but don’t fix what’s causing it. Now in dozens of studies, scientists are testing ways to reprogram patients’ out-of-whack immune systems, including with a cancer treatment called CAR-T therapy. The new approaches are highly experimental and largely restricted to patients out of other options. But early results are raising hope as some people with lupus and other hard-to-treat illnesses have gone into drug-free remission.