The study will test the effectiveness (rate of complete remissions, total remission rate and duration of remission) and toxicity of the combined immuno/chemotherapy with subcutaneous cladribine (LITAK®) plus anti-CD20* antibody rituximab in patients requiring treatment for relapsed hairy cell leukaemia or hairy cell leukaemia variant independent of any previous therapy.

CD20* = cluster of differentiation antigen 20

The trial is a prospective, multi-centre, open Phase II study on patients with hairy cell leukaemia variant or with relapsed hairy cell leukaemia.

Inclusion Criteria:

• Patients with histologically verified hairy cell leukaemia (HCL) Hairy cell leukaemia variant (HCLv) or
• Relapse of hairy cell leukaemia after therapy with cladribine or pentostatin
• Need for treatment is indicated (see 4.3 below)
• Age at least 18 years
• General state of health according to WHO 0-2
• Written declaration of consent by the patient
• Current histology, which should not be older than 6 months, is necessary

Exclusion Criteria:

• Patients, who do not fulfil the above-mentioned inclusion criteria.
• Patients with severe functional limitations of the heart according to New York Heart Association III / IV, of the lung according to WHO degree III / IV, the liver (bilirubin > 2mg/dl, alkaline phosphatase, raised GOT and GPT (glutamate- pyruvate transaminase) values more than twice normal), diseases of the central nervous system, including psychoses. Creatinine > 2 mg/dl, or creatinine clearance < 50 mg/min
• Patients with proven HIV infections
• Patients with active hepatitis
• Patients with other florid infections
• Patients with anamnesis / diagnosis of another malignant disease (other than nonmelanoma associated skin tumours or stage 0 in situ carcinoma of the cervix)
• Pregnant or lactating women