This study is for kids, teens, and young adults with a type of blood cancer called B-ALL (B-acute lymphoblastic leukemia). It looks at a new way to help them get ready for a special treatment called a bone marrow transplant (HCT) without using a radiation method called Total Body Irradiation (TBI). Doctors will use a test called NGS-MRD (next generation sequencing minimal residual disease) to see if there's a high or low chance of the cancer coming back. This test checks for tiny bits of cancer in the bone marrow before the transplant. If the test shows no cancer (NGS-MRD negative), the patient may use the new method without TBI. If cancer is found (NGS-MRD positive), they'll follow regular treatment plans. The study will check how well patients do over 2 years. It lasts for 3 years and includes different tests on blood and bone marrow samples at several times before and after the transplant.

• The study lasts 3 years with several follow-up tests.
• Participants who test NGS-MRD negative may receive non-TBI treatment.
• Compensation details are not specified in the study.