S0801 Iodine I 131 Tositumomab, Rituximab, and Combination Chemotherapy in Previously Untreated Stage II, Stage III, or Stage IV Follicular Non-Hodgkin Lymphoma

OBJECTIVES:

- To evaluate the response rate in patients with previously untreated stage II-IV
follicular non-Hodgkin lymphoma treated with rituximab, cyclophosphamide, doxorubicin
hydrochloride, vincristine sulfate, and prednisone (R-CHOP) in combination with iodine I
131 tositumomab.

- To evaluate the toxicity of this regimen in these patients.

- To estimate the 3-year progression-free survival rate in patients treated with this
regimen.

- To estimate the 5-year progression-free and overall survival rate in patients treated
with this regimen.

- To assess the safety profile of this regimen in these patients.

OUTLINE: This is a multicenter study.

- Induction therapy: Patients receive R-CHOP* comprising rituximab IV, cyclophosphamide
IV, doxorubicin hydrochloride IV, and vincristine sulfate IV on day 1 and oral
prednisone once daily on days 1-5. Treatment repeats every 21 days for up to 6 courses
in the absence of disease progression or unacceptable toxicity. Patients with at least
stable disease then proceed to consolidation therapy.

NOTE: *Patients receive R-CHOP in courses 1-4 and CHOP alone in courses 5 and 6.

- Consolidation therapy: Within 12 weeks after completion of induction therapy, patients
receive tositumomab IV over 1 hour followed by a dosimetric dose of iodine I 131
tositumomab IV over 20 minutes. Patients then undergo whole body gamma camera scans over
a 1-week period to determine the rate of total body clearance of radioactivity and the
therapeutic dose of iodine I 131 tositumomab. Within 7-14 days after the dosimetric
dose, patients receive tositumomab IV over 1 hour followed by a therapeutic dose of
iodine I 131 tositumomab IV over 20 minutes. Patients with at least stable disease then
proceed to maintenance therapy.

- Maintenance therapy: Beginning approximately 1 year after study entry and no more than
28 days after restaging, patients receive rituximab IV every 3 months for up to 4 years
(16 courses) in the absence of disease progression or unacceptable toxicity.

After completion of maintenance therapy, patients are followed annually for up to 7 years.
Patients who do not complete maintenance therapy are followed every 6 months for 2 years and
then annually for up to 7 years.

DISEASE CHARACTERISTICS:

- Histologically confirmed* grade 1, 2, or 3 follicular B-cell non-Hodgkin lymphoma
meeting the following criteria:

- Bulky stage II or stage III or IV disease

- Diffuse large cell component must be < 25% of the biopsy

- Confirmed cluster of differentiation antigen 20 (CD20) antigen-positive disease
NOTE: *Needle aspiration or cytology are not considered adequate for pathology
review

- Patient must have unilateral or bilateral bone marrow aspirate and biopsy performed
within 42 days

- Positive biopsy performed > 42 days but < 6 months allowed

- Previously untreated disease

- Bidimensionally measurable disease

- No clinical evidence of central nervous system (CNS) involvement by lymphoma

PATIENT CHARACTERISTICS:

- Zubrod performance status 0-2

- Cardiac ejection fraction ≥ 45% by multigated acquisition scan (MUGA) or ECHO

- No significant cardiac abnormalities

- No known HIV positivity

- No requirement for continuous supplemental oxygen therapy

- No other malignancy within the past 5 years except adequately treated basal cell or
squamous cell skin cancer, carcinoma in situ of the cervix, or adequately treated
stage I or II cancer from which the patient is currently in complete remission

- Not pregnant or nursing

- Fertile patients must use effective contraception during and for 12 months after
completion of maintenance therapy

PRIOR CONCURRENT THERAPY:

- No prior chemotherapy, radiotherapy, or antibody therapy for lymphoma

- No prior solid organ transplantation