INCLUSION CRITERIA:

DISEASE CHARACTERISTICS:

• Confirmed diagnosis of hairy cell leukemia
• Measurable disease

At least one of the following indications for treatment:

• Neutropenia (ANC <1000 cells/µL)
• Anemia (Hgb <10g/dL)
• Thrombocytopenia (Plt <100,000/µL)
• An absolute lymphocyte count of >20,000 cells/µL, or
• Symptomatic splenomegaly
• Patient’s must have had at least 2 prior systemic therapies. There must have been at least 2 prior courses of purine analog, or 1 if the response to this course lasted <2 years, or if the patient had unacceptable toxicity to purine analog.

PATIENT CHARACTERISTICS:

Performance status • ECOG 0-2

Life expectancy

• Life expectancy of greater than 6 months, as assessed by the principal investigator

Other

• Patients with other cancers who meet eligibility criteria and have had less than 5 years of disease free survival will be considered on a case-by-case basis
• Ability to understand and sign informed consent
• Female and male patients agree to use an approved method of contraception during the study

EXCLUSION CRITERIA:

• Documented and ongoing central nervous system involvement with their malignant disease (history of CNS involvement is not an exclusion criterion)
• History of bone marrow transplant
• Pregnant or breast-feeding females
• Patients whose plasma contains either a significant level of antibody to CAT-8015 as measured by ELISA, or antibody that neutralizes the binding of CAT-8015 to CD22 as measured by a competition ELISA.
• HIV positive serology (due to increased risk of severe infection and unknown interaction of CAT-8015 with antiretroviral drugs)
• Hepatitis B surface antigen positive
• Uncontrolled, symptomatic, intercurrent illness including but not limited to: infections requiring systemic antibiotics, congestive heart failure, unstable angina pectoris, cardiac arrhythmia, psychiatric illness, or social situations that would limit compliance with study requirements

Hepatic function: serum transaminases (either ALT or AST) or bilirubin:

• ≥ Grade 2, unless bilirubin is due to Gilbert’s disease

Renal function: serum creatinine clearance ≤60mL/min as estimated by Cockroft-Gault formula

Hematologic function:

• The ANC <1000/cmm, or platelet count <50,000/cmm, if these cytopenias are not judged by the investigator to be due to underlying disease (i.e. potentially reversible with anti-neoplastic therapy)
• Baseline coagulopathy > grade 3 unless due to anticoagulant therapy
• A patient will not be excluded because of pancytopenia ≥ Grade 3, or erythropoietin dependence, if it is due to disease, based on the results of bone marrow studies

Pulmonary function:

• Patients with < 50% of predicted forced expiratory volume (FEV1) or <50% of predicted diffusing capacity for carbon monoxide (DLCO), corrected for hemoglobin concentration and alveolar volume. Note: Patients with no prior history of pulmonary illness are not required to have PFTs. FEV1 will be assessed following bronchodilator therapy.

Recent prior therapy:

• Cytotoxic chemotherapy (except stable doses of prednisone), whole body electron beam radiation therapy, interferon, retinoids or other systemic therapy, or investigational therapy of the malignancy for 3 weeks prior to entry into the trial
• Less than or equal to < 3 months prior monoclonal antibody therapy (i.e. rituximab)
• Patients who have received or are receiving radiation therapy less than 3 weeks prior to study entry will be not be excluded providing the volume of bone marrow treated is less than 10% and also the patient has measurable disease outside the radiation port
• Any history of pseudomonas-exotoxin (PE) immunotoxin administration