Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically proven newly diagnosed or relapsed non-Hodgkin's
lymphoma (NHL) of 1 of the following types: Low grade (diffuse small lymphocytic/marginal
zone, grade I follicular small cleaved cell, or grade II follicular mixed cell) OR Mantle
cell OR Histologically proven newly diagnosed or relapsed stage III or IV chronic
lymphocytic leukemia (CLL) or prolymphocytic leukemia (PLL) At least 1 measurable disease
parameter Enlarged spleen extending at least 2 cm below the costal margin constitutes
measurable disease provided that no explanation other than lymphomatous involvement is
likely Enlarged liver extending at least 5 cm below the costal margin constitutes
measurable disease Not allowable as sole indication for therapy: Isolated splenomegaly OR
Isolated hepatomegaly No central nervous system (CNS) metastases or carcinomatous
meningitis A new classification scheme for adult non-Hodgkin's lymphoma has been adopted
by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former
terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol
uses the former terminology.

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Eastern Cooperative Oncology
Group (ECOG) 0-2 Life expectancy: At least 12 weeks Hematopoietic: NHL: Granulocyte count
greater than 1,500/mm^3 Hemoglobin at least 9.0 g/dL Platelet count greater than
100,000/mm^3 CLL or PLL: Granulocyte count greater than 500/mm^3 Hemoglobin greater than
7.0 g/dL Platelet count greater than 50,000/mm^3 Hepatic: Bilirubin no greater than 1.5
mg/dL SGOT no greater than 3 times upper limit of normal (ULN) (no greater than 5 times
ULN if liver tumor present) No Gilbert's disease Renal: Creatinine no greater than 2.0
mg/dL OR Creatinine clearance at least 60 mL/min Calcium less than 12.0 mg/dL (corrected)
Cardiovascular: No myocardial infarction or atrial fibrillation within the past 6 months
No congestive heart failure requiring therapy Other: No active or uncontrolled infection
HIV negative No psychiatric disorder that would preclude informed consent or compliance No
other malignancy within the past 5 years except basal cell or squamous cell skin cancer or
carcinoma in situ of the cervix Not pregnant or nursing Negative pregnancy test Fertile
patients must use effective contraception No history of seizures No uncontrolled diabetes
mellitus, defined as random blood glucose at least 200 mg/dL No other severe concurrent
disease that would increase risk

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior
irinotecan or any other topoisomerase I inhibitor (e.g., topotecan) Endocrine therapy: Not
specified Radiotherapy: Not specified Surgery: Not specified Other: No concurrent
phenytoin, phenobarbital, or other antiepileptic prophylaxis