Inclusion Criteria:

- Age >= 18 years

- B-ALL (OMs) with >= 20 % of blasts in bone marrow

- CD22+ expression >= 30% of the blast population

- Refractory B-ALL defined by treatment failure after 2 successive courses of induction
therapy or relapse < 6 months after first CR

- First relapse of B-ALL

- Second relapse or beyond

- Performance status 0-2

- Creatinine clearance >= 50 ml/min (Cockroft formula)

- Serum bilirubine <= 30 µmom/l

- Written informed consent

Exclusion Criteria:

- T-ALL

- Meningeal involvement

- CD22 expression on tumor cells or < 30%

- HIV positive

- Active Hepatitis B or C

- Left ventricular ejection fraction < 50% in patients <60 years

- Contra-indication to Epratuzumab

- 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