A Study of Fixed Dose Radioimmunotherapy (Zevalin, Yttrium-90 Ibritumomab Tiuxetan) for Patients With Incomplete Response to Chemotherapy Prior to Autologous Stem Cell Transplant for Multiple Myeloma

Patients with multiple myeloma measurable disease following stem cell mobilization with
institution standard high dose cyclophosphamide and peripheral blood stem cell collection
are candidates for participation on this trial. 90Y Zevalin targets CD20 expressed on the
surface of mature B-cells and is FDA approved for relapsed/refractory low grade lymphoma.
This is a single arm, phase II safety and efficacy study of 90-Y Zevalin in multiple
myeloma. Subjects will receive cold antibody (Rituximab 100mg/m2) followed by 5 mCi test
dose of 111-In Zevalin on transplant day -21. Gamma camera images are obtained 48 to 72
hours after 111-In Zevalin to document appropriate / expected distribution of radiotracer.
On transplant day -14, subjects will receive another cold antibody dose followed by 90Y
Zevalin 0.4 mg/kg (max 32 mCi) as single dose. Subjects are admitted for transplant on day
-3 and proceed with institution standard high dose melphalan (200mg/m2) on day -2. Subjects
are followed for safety for 6 weeks after transplant.

Inclusion Criteria:

- Meet established criteria for the diagnosis of multiple myeloma

- Durie-Salmon stage II or III disease

- Measurable disease in the serum and/or urine

- Scheduled to receive high dose chemotherapy and autologous stem cell transplant for
multiple myeloma

- Individuals who have previously undergone autologous stem cell transplant are
eligible for this study provided more than 6 months have elapsed from the prior
transplant.

- Minimum stem cell dose of 4x106 CD34+ MNC / kg stored for autologous stem cell
rescue.

- Adequate hematologic reserve as evidenced by ANC ≥ 1500/mm3 and platelets ≥
100,000/mm3.

- Serum direct bilirubin ≤ 2.0 mg/dl and transaminases ≤ 3x institution upper limit of
normal.

- Serum creatinine ≤ 2 mg/dl with creatinine clearance ≥ 60 ml/min (either calculated
or measured).

Exclusion Criteria:

- Stage I or smoldering myeloma, isolated plasmacytoma, or benign monoclonal gammopathy

- Non-secretory multiple myeloma

- Pregnant or lactating women

- Males and females who do not agree to practice approved methods of birth control for
the duration of the study

- Presence of active infection

- Receipt of previous radiation therapy to critical organs exceeding any of the
following limits: kidney 500 cGy, liver 1000 cGy, lungs 500 cGy