RATIONALE: Monoclonal antibodies, such as rituximab, can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells. Interleukin-12 may kill cancer cells by stopping blood flow to the tumor and by stimulating a person's white blood cells to kill cancer cells. Combining rituximab with interleukin-12 may kill more cancer cells.

PURPOSE: This randomized phase II trial is comparing how well giving rituximab together with two different schedules of interleukin-12 works in treating patients with B-cell non-Hodgkin's lymphoma.

OBJECTIVES:

• Compare the objective response in patients with B-cell non-Hodgkin's lymphoma treated with rituximab and 2 different schedules of interleukin-12*. (Arm II closed to accrual as of 11/13/03.)
• Compare the toxic effects of these regimens in these patients.
• Determine the objective response rate in patients with mantle cell lymphoma treated with these regimens.
• Determine the overall and progression-free survival of patients treated with these regimens.
• Compare the quality of life of patients treated with these regimens. NOTE: *Interleukin-12 will no longer be available after 6/30/05.

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to histology (mantle cell lymphoma vs other [closed to accrual as of 3/10/04]) and International Prognostic Factor Index (low and low-intermediate risk [closed to accrual as of 3/10/04] vs high-intermediate and high risk). Patients are randomized to 1 of 2 treatment arms. (Arm II closed to accrual as of 11/14/03.)

• Arm I: Patients receive rituximab IV on days 1, 8, 15, and 22. Patients receive interleukin-12* subcutaneously (SC) twice weekly beginning on day 2 and continuing until disease progression.
• Arm II (closed to accrual as of 11/14/03): Patients receive rituximab as in arm I. Patients are evaluated at week 12. Patients with stable or progressive disease receive interleukin-12* SC twice weekly until disease progression or for 24 weeks. Patients with a complete or partial response after rituximab are monitored until disease progression and then begin interleukin-12 SC twice weekly until further disease progression.

NOTE: *Interleukin-12 will no longer be available after 06/30/05. Patients proceed to follow-up as outlined below.

Quality of life is assessed at baseline and at 3 and 6 months.

Patients are followed every 3 months for 1 year and then every 6 months for up to 4 years.

PROJECTED ACCRUAL: A total of 90 patients (45 per treatment arm [arm II closed to accrual as of 11/14/03]) will be accrued for this study within 3 years.

• Biological: recombinant interleukin-12
• Biological: rituximab

DISEASE CHARACTERISTICS:

• Histologically confirmed CD20-positive B-cell non-Hodgkin's lymphoma

• Previously treated low-grade lymphoma considered incurable with standard therapy

  • Grade I or II follicular lymphoma*
  • Lymphoplasmacytic lymphoma*
  • Small lymphocytic lymphoma*
  • Nodal marginal zone lymphoma*
  • Extranodal marginal zone lymphoma of MALT type*
  • Splenic marginal zone lymphoma* NOTE: *Closed to accrual as of 3/10/04
• Previously treated mantle cell lymphoma allowed

• Meets one of the following criteria for measurable disease:

  • Bidimensional diameter at least 1.5 cm by 1.5 cm on physical exam
  • At least 2 cm in one dimension by CT scan, MRI, or plain radiograph imaging
  • Palpable spleen at least 5 cm below the left costal margin
• No CNS involvement by lymphoma NOTE: 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:

• ECOG 0-1

Life expectancy:

• At least 12 weeks

Hematopoietic:

• Absolute neutrophil count ≥ 1,500/mm^3
• Platelet count ≥ 75,000/mm^3
• Hemoglobin ≥ 8 g/dL

Hepatic:

• Bilirubin ≤ 3 times upper limit of normal (ULN)
• AST and ALT ≤ 3 times ULN
• Alkaline phosphatase ≤ 3 times ULN

Renal:

• Creatinine ≤ 2 times ULN

Cardiovascular:

• No New York Heart Association class III or IV heart disease
• No history of angina

Other:

• No uncontrolled peptic ulcer disease
• No uncontrolled infection
• No other active malignancy
• No autoimmune-related phenomena (e.g., antinuclear antibody less than 2 times ULN, rheumatoid factor less than 2 times ULN, and negative direct Coombs)
• HIV negative
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Prior stem cell transplantation allowed
• More than 12 months since prior rituximab
• No prior interleukin-12
• No other concurrent immunotherapy

Chemotherapy:

• Recovered from prior chemotherapy
• No concurrent chemotherapy

Endocrine therapy:

• No concurrent steroid therapy

Radiotherapy:

• No concurrent radiotherapy

Surgery:

• Not specified

Other:

• Any number of prior therapies allowed