Combination Veltuzumab and Fractionated 90Y- Epratuzumab Radioimmunotherapy in Follicular Lymphoma

The treatment regimen consists of 2 elements. The first element is represented by one courses of veltuzumab (4 weekly injections of 200 mg/m2). 90Y-epratuzumab will be given as 2 injections at escalating doses 1 week apart and administered starting one week following the 4th veltuzumab injection. After confirming eligibility and undergoing baseline assessments, the treatment starts with an imaging study using 111In-epratuzumab (5-mCi 111In-DOTA-epratuzumab co-infused with a total of 1.5 mg/kg unlabeled epratuzumab). Blood samples (\~7 samples, 5 mL each) for pharmacokinetic analysis will be collected over 5-7 days, and patients will be imaged on 4 separate occasions (e.g., the day of injection (Day 0), Day 1, Day 3, 4, or 5, and day 6 or 7). The patient will then initiate veltuzumab treatments starting 7 days after the 111In-epratuzumab injection. Veltuzumab is given in 4 weekly doses, each 200 mg/m2. A single blood sample will be taken before each veltuzumab dose to assess residual veltuzumab concentrations in the serum, and then at 1 h later to determine peak values. Patients will receive unlabeled, unconjugated epratuzumab (1.5 mg/kg) that will be infused over \~30 minutes. Patients will also receive 111In-epratuzumab immediately following the unlabeled epratuzumab. Blood samples will be collected at the same intervals as after the first 111In-epratuzumab. Only 2 imaging sessions will be required, on Day 1 and then again on day 6 or 7 (these days should match those obtained after the first 111In-epratuzumab injection). The 90Y-epratuzumab treatment will begin one week after the 4th veltuzumab injection. Patients will receive unlabeled, unconjugated epratuzumab (1.5 mg/kg) that will be infused over \~30 minutes. All patients will then receive a 90Y-epratuzumab dose. Dose will be escalated by patient cohort starting at 2x15 mCi/m2 and, at 2x 20 mCi/m2, and 2x 25 mCi/m2.. Blood samples will be collected at the same intervals as after each 111In-epratuzumab.Patients will also receive 111In-epratuzumab immediately following the unlabeled epratuzumab and immediately before the 90Y-epratuzumab injection. Blood samples will be collected at the same intervals as after the first 111In-epratuzumab. Only 2 imaging sessions will be required, on Day 1 and then again on day 6 or 7 (these days should match those obtained after the first 111In-epratuzumab injection). The second 90Y-epratuzumab treatment will be given at the same dose, 1 week after the first 90Y-epratuzumab dose. CBC will be checked prior to administration of this second dose to ensure blood counts continue to meet criteria for treatment as specified in inclusion criteria. Blood samples will again be collected over the same period as the first injection, but no imaging studies are required. Patients are closely monitored during all infusions, and then at intervals over a 12-weeks post-treatment evaluation period, with evaluation procedures including vital signs, physical examination, CT (chest, abdomen, pelvis, other regions of involvement), CBC, serum chemistries, serum immunoglobulins, urinalysis, peripheral blood B-cell levels (immunophenotyping based on CD19), and serum samples for HAHA (veltuzumab and epratuzumab ELISA to be analyzed by Immunomedics). Follow-up evaluations then continue every 3 months for up to 5 years or until progression occurs or until resolution of treatment-related toxicity.