Demethylating Agents Combined With Venetoclax for High-risk T-cell Lymphoblastic Lymphoma/Leukemia Post-Transplant Relapse Prevention

This study tests whether giving a combination of DNA-demethylating drugs plus venetoclax (a targeted cancer drug) after a bone marrow transplant can prevent relapse in people who were treated for high-risk T-cell lymphoma or leukemia (T-LBL/ALL). **You may be eligible if...** - You are 14–55 years old - You have undergone an allogeneic bone marrow/stem cell transplant for T-cell lymphoblastic lymphoma or leukemia - You have at least one high-risk feature (such as older age at diagnosis, high white blood cell count, or specific genetic mutations) - Your blood counts are in the required range - You are in remission (no signs of disease returning) **You may NOT be eligible if...** - Your cancer came back before or was never in complete remission before the transplant - You are allergic to venetoclax or demethylating drugs - You have active graft-versus-host disease (a complication after transplants) at grade 2 or higher - You have poor organ function (kidneys, liver) - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.