To Observe the CD7-targeted CAR-T Therapy in the Treatment of MRD Positive T-ALL/LBL Post Allo-HSCT

This trial is testing a CAR-T cell therapy targeting a protein called CD7 in patients with T-cell leukemia or lymphoma who have had a stem cell transplant but whose cancer is still detectable at a very low level (called minimal residual disease, or MRD-positive). **You may be eligible if...** - You are 3 years old or older - You have T-cell leukemia or lymphoma (T-ALL or LBL) that has relapsed or is not responding to treatment after a stem cell transplant - Your bone marrow shows less than 5% abnormal cells, but leukemia is still detected by sensitive flow cytometry testing - Your cancer cells test positive for a protein called CD7 - Your organ function (liver, kidneys) meets required levels **You may NOT be eligible if...** - You have a history of epilepsy, stroke, paralysis, dementia, or other significant brain/nerve conditions - You have an uncontrolled active infection - You have active hepatitis B, hepatitis C, HIV, or active CMV infection - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.