Safety and Efficacy of OC-1 Therapy in Patients With R/R T-ALL/LL

Inclusion Criteria: 1. Children older than 2 years or adults, male and female in both groups. 2. Patients CD1a antigen blast expression ≥20% at inclusion, either immunophenotypically (flow cytometry) or histologically confirmed. 3. R/R CD1a-positive T-ALL/LL patients, including morphologic or MRD-detectable (≥1x10-4) bone marrow and/or extramedullary relapses after 2 therapy lines: 1. Relapse after allogeneic haematopoietic stem cell transplantation (allo-HSCT) 2. Primary refractoriness, defined as either morphologic persistence or detectable MRD (≥1x10-4) after two standard therapy lines, making the patient not candidate for allo-HSCT. 3. Refractory first relapse. 4. Second or further relapse. 4. Patient without reproductive capacity or else, commitment to the use of a highly effective method of contraception during the study. Exclusion Criteria: 1. Limiting organ dysfunction, such as uncontrolled cardiac (e.g., depressed left ventricular ejection fraction (LVEF), \<45%), pulmonary, liver, renal or CNS dysfunction. 2. Allo-HSCT within a timeframe \<3 months, or requiring continued immunosuppressive treatment for graft versus host disease (GvHD). 3. Uncontrolled epilepsy or underlying central nervous system (CNS) severe disease. 4. Active bacterial, fungal or viral infection not controlled by adequate treatment. 5. Known HIV, active hepatitis B (HBV), or hepatitis C virus (HCV) infection. 6. Women who are pregnant (positive urine/blood pregnancy test) or lactating.