A phase II trial 90y-ibritumomab tiuxetan in combination with reduced intensity regimen of fludarabine (flu) and melphalan (mel) followed by allo-HCT in patients with refractory B-cell lymphoma.

6545 Background: RIC allo-HCT has reduced transplant-related mortality (TRM) in patients with relapsed NHL. However, relapses do occur despite potential graft vs. lymphoma (GVL) effect. We hypothesized that adding Zevalin to Flu/Mel may improve disease control and reduce relapse post allo-HCT. Methods: Patients received In- Zevalin on day -21 followed by 90Y- Zevalin 0.4mCi/kg on day -14, flu 25 mg/m2 daily on days -9 to -5 and mel 140 mg/m2 on day -4. Rituximab (R) level was measured on Day -22 and -15 and if the level was ≥ 10 μg/ml, R was not given prior to In-Zevalin or 90Y- Zevalin to enhance biodistribution. Tacrolimus and sirolimus was used for GVHD prophylaxis. Between 10/2007 and 11/2011, 31 were treated. Median age 55 (range 27-67), median regimen =3 (range 2-8). Median time from diagnosis to HCT was 20 mo (range 5-105). Histology: DLBCL (including transformed lymphoma)=14 (45%), MCL=7 (23%), FL=5 (16%) and SLL/CLL=5 (16%). Disease status at HCT: 1CR=7, Relapse=9, ≥2CR=5, primary refractory =10....