Rituximab and Denileukin Diftitox in Treating Patients With Previously Untreated Stage III or Stage IV Follicular B-Cell Non-Hodgkin's Lymphoma

OBJECTIVES:

Primary

- Determine the response rate (complete response [CR], unconfirmed CR, and partial
response) in patients with previously untreated stage III or IV follicular B-cell
non-Hodgkin's lymphoma treated with rituximab and denileukin diftitox.

- Assess the overall survival, time-to-progression, duration of response, and time-to-new
therapy in patients treated with this regimen.

Secondary

- Determine whether this regimen depletes or inhibits the function of regulatory T cells
in these patients.

OUTLINE: This is a multicenter study.

Patients receive rituximab IV on days 1, 8, 15, and 22. Patients also receive denileukin
diftitox IV over 15-60 minutes on days 1-5. Treatment with denileukin diftitox repeats every
21 days for up to 4 courses in the absence of disease progression or unacceptable toxicity.

Blood is collected at baseline; on day 1 of courses 2-4; and 1 and 4 months after completion
of study treatment for research studies. Research studies include analysis of peripheral
blood lymphocyte subsets expressing CD3, CD4, CD8, CD19, CD25, and CD26 by flow cytometry;
quantitation of CD4+, CD25+ regulatory T cells by flow cytometry; tumor-specific
γ-interferon-secreting T cells by enzyme-linked immunospot assay; tumor-specific cytotoxic
T-lymphocyte activity; and immune activation by enzyme-linked immunosorbent assay.

After completion of study treatment, patients are followed periodically for up to 5 years
after registration.

PROJECTED ACCRUAL: A total of 53 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

- Pathologically confirmed follicular B-cell non-Hodgkin's lymphoma (NHL)

- Stage III or IV disease

- Grade 1 or 2 disease

- Previously untreated disease

- Measurable disease, defined as ≥ 1 unidimensionally measurable lesion ≥ 20 mm by
conventional techniques

- Clearly defined bidimensional diameter ≥ 2 x 2 cm on physical examination OR >
2.0 cm in 1 of the dimensions by CT scan, MRI, or plain radiograph imaging

- Splenic enlargement may be used as a measurable parameter if the spleen is
palpable ≥ 3 cm below the left costal margin

- Circulating tumor cells < 5,000/mm³

- Must have paraffin-embedded tissue blocks/slides available

- No CNS lymphoma

PATIENT CHARACTERISTICS:

- ECOG performance status 0-2

- Life expectancy ≥ 1 year

- WBC ≥ 3,400/mm³

- Platelet count ≥ 100,000/mm³

- Hemoglobin ≥ 10.0 g/dL

- Bilirubin ≤ 1.5 times upper limit of normal (ULN)

- Alkaline phosphatase ≤ 3 times ULN

- AST ≤ 3 times ULN

- Creatinine ≤ 1.5 times ULN

- Albumin ≥ 3 g/dL

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception during and for 1 year after
completion of study therapy

- No HIV infection

- No other active malignancies

- No active uncontrolled infection

- No known hypersensitivity to denileukin diftitox or any of its components, including
diphtheria toxin, aldesleukin, or excipients

PRIOR CONCURRENT THERAPY:

- No prior chemotherapy, immunotherapy, vaccines, or radiotherapy for NHL