BL22 Immunotoxin in Treating Patients Previously Treated With Cladribine for Hairy Cell Leukemia

DISEASE CHARACTERISTICS: Histologically confirmed hairy cell leukemia CD22-positive disease by fluorescence-activated cell sorting with anti-CD22 antibody Meets at least 1 of the following indications for treatment: Absolute neutrophil count less than 1,000/mm^3 Hemoglobin less than 10 g/dL Platelet count less than 100,000/mm^3 Absolute lymphocyte count greater than 20,000/mm^3 Symptomatic splenomegaly Meets 1 of the following response criteria: No response Complete response (CR) or partial response (PR) less than 2 years in duration after the last course of prior cladribine CR or PR less than 4 years in duration after a second or later course of prior cladribine PATIENT CHARACTERISTICS: Age 18 and over Performance status ECOG 0-2 Life expectancy Not specified Hematopoietic See Disease Characteristics Hepatic AST and ALT no greater than 2.5 times upper limit of normal (ULN) Bilirubin no greater than 2.2 mg/dL Albumin at least 3.0 g/dL Renal Creatinine no greater than 1.4 mg/dL OR Creatinine clearance at least 50 mL/min Cardiovascular No symptomatic congestive heart failure No unstable angina pectoris No cardiac arrhythmia Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No serum that neutralizes more than 75% of the activity of 1 µg/mL of BL22 immunotoxin using a bioassay No ongoing or active infection No psychiatric illness or social situation that would preclude study compliance No other concurrent uncontrolled illness that would preclude study participation Understand and give informed consent PRIOR CONCURRENT THERAPY: Biologic therapy No prior BL22 immunotoxin More than 12 weeks since prior monoclonal antibody therapy Chemotherapy See Disease Characteristics More than 4 weeks since prior systemic cytotoxic chemotherapy Endocrine therapy More than 4 weeks since prior systemic steroids (except stable doses of prednisone no greater than 20 mg/day) Radiotherapy Not specified Surgery Not specified Other No other concurrent investigational agents