Inclusion Criteria:

- Diagnosis of acute lymphoblastic leukemia (pro B, pre B, c-ALL or T-ALL), proved by
morphology and immunophenotyping

- Age > 55 yrs (no upper age limit)

- Written informed consent

Exclusion Criteria:

- Severe leukemia associated complications, not controllable before therapy onset e.g.

- life threatening infections as sepsis, pneumonia, hypoxia, shock, life threatening
bleeding)

- Severe comorbidity e.g.

- decompensated renal failure if not caused by leukemia with Creatinine > 2x ULN

- heart failure (NYHA II/IV), instable Angina, significant coronary stenosis

- hepatic insufficiency e.g. liver cirrhosis or chronic active hepatitis with bilirubin
> 1,5 x ULN and/or ASA, ALA, AP > 2,5 ULN

- decompensated metabolic disturbances (e.g. not controllable diabetes)

- severe obstructive or restrictive pulmonary disease with hypoxaemia

- Severe psychiatric illness or other circumstances which may compromise cooperation of
the patient

- Active second neoplasia

- HIV infection

- Severely reduced general condition

- Cytostatic pre-treatment of ALL

- Chemotherapy treatment of any other malignancy during the last 5 years

- Participation in other clinical trials interfering with the study therapy