ALaCART-B: Acute Leukemia and Chimeric Antigen Receptor-T Cell Therapy for B-lymphoblastic Leukemia.

This trial is testing CAR T-cell therapy — a treatment where a patient's own immune cells are modified in a lab to hunt and destroy cancer cells — for children and young adults with B-cell acute lymphoblastic leukemia (B-ALL) that has come back or failed to respond to standard treatment. **You may be eligible if...** - You have relapsed, treatment-resistant, or hard-to-treat B-cell leukemia - Your cancer expresses the CD19 surface protein - Your heart and lung function meet minimum requirements - Your kidneys and liver are functioning adequately - You have a Karnofsky or Lansky performance score of at least 50 **You may NOT be eligible if...** - You are pregnant or breastfeeding - You have a genetic syndrome associated with bone marrow failure (e.g., Fanconi anemia) - You have active or recently uncontrolled hepatitis B, C, or HIV - You have severe graft-versus-host disease from a prior transplant - Your leukemia has already relapsed after another CAR T-cell treatment - You have a prior cancer (except certain cured skin or cervical cancers) Talk to your doctor to see if this trial is right for you.