A Clinical Study to Evaluate the Safety, Tolerability, and Preliminary Efficacy of B019 Injection in Subjects With Relapsed or Refractory B-cell Acute Lymphoblastic Leukemia.

This study is testing B019 — a bispecific CAR T-cell therapy that simultaneously targets two proteins (CD19 and CD22) found on B-cell leukaemia cells — in patients with B-cell acute lymphoblastic leukaemia (B-ALL) that has relapsed or stopped responding to treatment. **You may be eligible if...** - You (or your guardian) are willing to participate and consent - You have been confirmed to have relapsed or refractory B-cell acute lymphoblastic leukaemia - Your leukaemia cells express CD19 and/or CD22 markers - Your liver, kidney, lung, and heart function meet acceptable levels - Your expected survival is more than 3 months - You are willing to use effective contraception for 1 year after the infusion **You may NOT be eligible if...** - Your leukaemia has spread into the brain or spinal fluid (active CNS involvement) - You have active severe infections - Your organ function is too impaired for the treatment Talk to your doctor to see if this trial is right for you.