Inclusion Criteria:

- histologically or immunologically confirmed chronic B-cell leukemia

- refractory (i.e. no response or progression during initial chemotherapy) or relapsed
situation after first-line treatment regimen

- disease stage II-IV according to Rai or B/C according to Binet staging system,
respectively

- Eastern Cooperative Oncology Group (ECOG) performance status of 3 or better

- negative pregnancy test/ adequate method of contraception

Exclusion Criteria:

- T-CLL, PLL (prolymphocytic leukemia)

- presence of Richter's transformation

- first-line treatment containing either fludarabine or bendamustine

- acute infections or distinctly reduced organ function precluding the application of
chemotherapy, as for pulmonary, heart, liver (total bilirubin > 5mg/dl), renal system
(creatinine > 2 mg/dl), or metabolic disorders

- secondary malignancy (except for curative treated basal cell carcinoma or cervical
cancer)