CAR T CELL Therapy for Pediatric, Adolescent and Young Adult Patients With CD19-Positive Leukemia

This study is testing CAR T-cell therapy — a treatment where a patient's own immune cells are genetically engineered to attack cancer cells — for children, teenagers, and young adults with a type of leukemia (blood cancer) that carries a marker called CD19. **You may be eligible if...** - You are 21 years old or younger - You have CD19-positive leukemia that has come back, stopped responding to treatment, or relapsed after a bone marrow transplant - You are in at least your second relapse, or your first relapse if a bone marrow transplant is not a suitable option for you - You are in reasonably good physical condition (able to care for yourself with some assistance) **You may NOT be eligible if...** - You have a known primary immune deficiency - You have HIV infection - You have a severe active infection (bacterial, viral, or fungal) - You are pregnant or breastfeeding - You have had a severe allergic reaction to mouse-derived protein products Talk to your doctor to see if this trial is right for you.