Yttrium Y 90 Ibritumomab Tiuxetan and Rituximab in Treating Patients With Previously Untreated Marginal Zone Lymphoma

This phase II study will assess the clinical response rate to Ibritumomab Tiuxetan in
patients with untreated nodal, splenic and non-gastric extranodal MZL as well as in
antibiotic resistant patients with mucosa-associated lymphoid tissue (MALT) gastric
lymphoma.

Inclusion Criteria:

- ≥ 18 years old with previously untreated, histologically confirmed Marginal Zone
Lymphoma (non-gastric extranodal MZL, splenic MZL and nodal MZL) or gastric MZL that
did not respond to antibiotic therapy given up to 6 months prior to enrollment, but
not less than 2 months)

- Measurable and evaluable disease

- All stages are eligible

- Eastern Cooperative Oncology Group (ECOG) performance status score of 0, 1, or 2
(Appendix B)

- Willing and able to provide written informed consent

- Women of childbearing potential must have a negative pregnancy test at study entry
and must agree to use effective contraception while on treatment and for 6 months
after treatment

- Life expectancy of at least 6 months

Exclusion Criteria:

- Prior chemotherapy, radiation therapy, immunotherapy, systemic corticosteroids, or
systemic biologic anticancer therapy before beginning study treatment.

- ≥ 25% lymphoma bone marrow involvement

- Platelet count < 100,000 cells/mm³

- Neutrophil count < 1,500 cells/mm³

- Known history of HIV infection

- Pregnant or lactating (pregnancy test is required for all female patients of
childbearing potential)

- Woman of childbearing potential or sexually active man unwilling to use adequate
contraceptive protection.

- Physical or mental condition that makes patient unable to complete specified
follow-up assessments