Safety and Efficacy of Radio-immunotherapy (RIT) for Patients With Relapse or Refractory Acute Lymphoblastic Leukaemia (ALL) B CD22+

Inclusion Criteria: * Age 18-70 years * B-ALL (OMS) with \>=20% of blasts in bone marrow * CD22+ expression \>=70% of the blast population * All previously treated ALL patients who have experienced relapse or treatment failure * At least 15 days since previous treatment * Performance status 0 - 2 * Creatinine clearance \>= 50 ml/min (Cockroft formula). * Serum bilirubin \<= 30 mmol/l * Written informed consent Exclusion Criteria: * T-ALL * Meningeal involvement * CD22 expression on tumor cells or \< 70% * HIV positive * Active Hepatitis B or C * Active infection within 7 days of starting treatment * Left ventricular ejection fraction \< 50%. * Contra-indication to 90Y-DOTA-hLL2 * Previous or concurrent second malignancy except for adequately treated basal cell carcinoma of the skin, curatively treated in situ carcinoma of the cervix, curatively treated solid cancer, with no evidence of disease for at least 5 years * Any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule * Participation at the same time in another study in which investigational drugs are used * Absence of written informed consent