Study Evaluating the Safety and the Efficacy of Human T Lymphoid Progenitor (HTLP) Injection to Accelerate Immune Reconstitution After Umbilical Cord Blood (UCB) Transplantation in Adult Patients With Hematologic Malignancies (HTLP-ONCO)

This study is testing an innovative approach to speed up immune system recovery after umbilical cord blood stem cell transplants in adults with blood cancers. Researchers are injecting human T lymphoid progenitor cells (HTLPs) — early immune cells — to help rebuild immunity faster after transplant. **You may be eligible if...** - You are between 18 and 65 years old - You have a blood cancer (such as leukemia or lymphoma) that requires an allogeneic stem cell transplant - You do not have a fully matched related or unrelated donor available - Two suitable umbilical cord blood units are available for your transplant **You may NOT be eligible if...** - You have a matched related or unrelated donor available - You are over 65 years old - You have serious organ dysfunction or uncontrolled infection - You are pregnant Talk to your doctor to see if this trial is right for you.