Inclusion Criteria:

•Patients must have a histologically-confirmed diagnosis of B-cell CLL/PLL/SLL; lymphoplasmacytic
• immunocytoma; follicle center, follicular, grade I; or follicle center, follicular, grade II NHLs or one of these B-cell lymphomas which has transformed to a more aggressive histology (37).
•Patients must have evidence that their tumor tissue expresses the CD20 antigen. Immunoperoxidase stains of paraffin-embedded tissue showing positive reactivity with L26 antibody or immunoperoxidase stains of frozen tissue showing positive reactivity with Anti B1 Antibody (>50% of tumor cells are positive) or evidence of CD20 positivity by flow cytometry (>50% of tumor cells are positive) are acceptable evidence of CD20 positivity. Testing of tumor tissue from any time in the course of the patient’s disease is acceptable.
•Patients must have received 1 or 2 prior chemotherapy regimens and have progressed following their last regimen. Patients who have received >2 prior chemotherapy regimens are excluded. Prior therapy with radiation, immunosuppressants, or steroids are not counted as chemotherapy regimens.
•Patients must have a performance status of at least 60% on the Karnofsky Scale (see Appendix B) and an anticipated survival of at least 3 months.
•Patients must have an absolute granulocyte count >1,500 x 109/l and a platelet count >100,000 x 109/l within 14 days of study entry. These blood counts must be sustained without support of hematopoietic cytokines or transfusion of blood products.
•Patients must have adequate renal function (defined as serum creatinine <1.5 upper limit of normal) and hepatic function (defined as total bilirubin <1.5 upper limit of normal and hepatic transaminases [AST + ALT] <5 x upper limit of normal) within 14 days of study entry.
•Patients must have bi-dimensionally measurable disease. At least one lesion must be >/=2cm x 2 cm (by CT scan).
•Patients must be at least 18 years of age.
•Patients must give written informed consent and sign an EC-approved informed consent form prior to study entry.


Exclusion Criteria:

•Patients with more than an average of 25% of the intratrabecular marrow space involved by lymphoma in bone marrow biopsy specimens as assessed microscopically within 42 days of study entry. Bilateral posterior iliac crest core biopsies are required if the percentage of intratrabecular space involved exceeds 10% on a unilateral biopsy. The mean of bilateral biopsies must be no more than 25%. The procedure for bilateral bone marrow biopsy analysis of marrow involvement is included in Appendix C.
•Patients who have received cytotoxic chemotherapy, radiation therapy, or cytokine treatment within 4 weeks prior to study entry (6 weeks for nitrosourea compounds) or who exhibit persistent clinical evidence of toxicity. The use of systemic steroids must be discontinued one week prior to study entry.
•Patients with prior hematopoietic stem cell transplant following high-dose chemotherapy or chemo/radiotherapy.
•Patients with active obstructive hydronephrosis.
•Patients with evidence of active infection requiring IV antibiotics at the time of study entry.
•Patients with New York Heart Association class III or IV heart disease (see Appendix D) or other serious illness that would preclude evaluation.
•Patients with prior malignancy other than lymphoma, except for adequately-treated skin cancer, in situ cervical cancer, or other cancer for which the patient has been disease-free for 5 years. Patients who have been disease-free of another cancer for greater than 5 years must be carefully assessed at the time of study entry to rule out recurrent disease.
•Patients with known HIV infection.
•Patients with known brain or leptomeningeal metastases.
•Patients who are pregnant or breast-feeding. Patients of child-bearing potential must undergo a serum pregnancy test within 7 days prior to study entry and radiolabeled antibody is not to be administered until a negative result is obtained. Males and females must agree to use effective contraception for 6 months following treatment.
•Patients with previous allergic reactions to iodine. This does not include reacting to IV iodine-containing contrast materials.
•Patients who were previously given any monoclonal or polyclonal antibodies of any non-human species for either diagnostic or therapeutic purposes. This includes engineered chimeric and humanized antibodies.
•Patients who previously received radioimmunotherapy.
•Patients with progressive disease within 1 year of irradiation arising in a field that has been previously irradiated with >3500 cGy.
•Patients who are concurrently receiving either approved or non-approved (through another protocol) anti-cancer drugs or biologics.
•Patients who have received more than 2 prior chemotherapy regimens. Prior therapy with radiation, immunosuppressants, or steroids are not counted as chemotherapy regimens.