Pilot, multicentric, open-label, single-arm, phase I-II clinical trial to evaluate the safety and efficacy of a novel Umbilical Cord Blood Transplantation (UCBT) platform, that consists of a UCBT of the 80 fraction, followed by a Donor Lymphocyte Infusion (DLI) of the 20 fraction (between 60 and 90 days after transplantation).

Multicenter, open-label, single-arm, phase I-II pilot study in which a minimum of 20 patients will enter the study with the primary objective to assess the safety and secondary objective to assess efficacy in relation to immune reconstitution followed by a new platform of treatment consisting of initial cord blood unit 80 fraction transplantation, followed by a prophylactic donor lymphocyte infusion (DLI) of the fraction 20 of the cord blood unit. The second infusion will take place between 60 and 90 days after transplantation.

Inclusion Criteria:

At the time of transplantation:

• Patients under 60 years with proposal UCBT according to assistance protocol
• Diagnosis of high-risk acute leukemia with an indication of allogenic transplantation
• Frozen UCB bag split into two bags: one with the 80% of the product and another with the 20%
• Presence of at least 1.2E9 total nucleated cells and> 1E5 CD34 / kg and> 6E6 CD34 + in fraction 80%
• 4/6 or better compatibility taking Human Leukocyte Antigen (HLA) HLA-A, HLA-B by antigenic resolution and DRB1 by allelic resolution
• The patient (or legal representative if required) has signed the informed consent

At the time of DLI:

• Documented cord blood engraftment
• The patient has had no Graft Versus Host Disease (GVHD) during the first 60 days post-transplantation or, if present, receives less than 10 milligrams of prednisone at the time of the DLI or <0.2 mg / kg / day of prednisone for pediatric patients (<16 years).
• The patient has less than 200 CD4 + cells per microliter on peripheral blood at 60 days (± 7 days) post-transplantation
• The patient (or legal representative if required) has signed the informed consent

Exclusion Criteria:

At the time of transplantation:

• Simultaneous participation in another clinical trial or treatment with other research phase product within 30 days prior to inclusion in the study.
• Pregnant women or those who intend to become pregnant within 12 months after the signing of the informed consent or not taking proper contraceptive measures according to investigator criteria.
• Breastfeeding women
• Other pathologies or circumstances that may compromise the patient's participation in the study according to the criteria of the investigator.

At the time of DLI:

• Grade III-IV GVHD after allogeneic UCB
• Prednisone treatment (> 10 mg total per day in adults or> 0.2 mg / kg / day prednisone for pediatric patients)