⁹⁰y-Ibritumomab Tiuxetan Treatment for Relapsed and/or Refractory B-Cell Non- Hodgkin’S Lymphoma. Multi-Institutional Argentinian Study. An Update

Background: 90Y-ibritumomab tiuxetan (Zevamab®; ZEV; Bayer-Schering Pharma- Argentina) has been approved for the treatment of relapsed, refractory and transformed (high grade) follicular lymphomas.

Methods: Between Sep. 2005 and Feb. 2008, 45 patients (pts) [22 F & 23 M; median age 62 yrs (45–83)] with refractory/relapsed lymphoma were enrolled.

Diagnoses: 37 follicular lymphoma (FL), 5 were mantle cell lymphoma (ML) and 3 transformed lymphoma (TL); 18 pts had bulky disease, 8 had bone marrow involvement and 21 had stage III–IV disease. Median time from diagnosis was 5 yrs (0.5– 29). Twenty two pts had received 1–2 previous treatments, and 23 pts had received 3–5 previous treatments including 5 pts with autologous bone marrow transplantation. All had previously received anti-CD20 monoclonal antibody therapy. Six pts received previous radiotherapy. ZEV was administered at 0.3 or 0.4 mCi, based on initial platelet count. Seven days before, and the same day of the ZEV administration, pts received standard rituximab 250 mg/m2. In 3 pt, ZEV was part of the conditioning regimen of autologous bone marrow transplantation.

Results: Forty pts were evaluable for response: 34 (86%) pts responded – 19 CR (48%), 15 PR (38%). Overall survival and PFS for the entire group at 18 months was 63% and 37% respectively, with a median follow-up of 12 months (1–29 months). Of the 45 patients, 5 pts (11%) had died before third month and response was not assessed, 6 pts (13%) did not respond, 3 (7%) died with response from other causes, 14 pts (31%) responded and subsequently relapsed. Finally 17 pts (38%) continue to be in response, 9 (20%) lasting more than twelve months (long lasting responders). Slight differences in duration of response and survival were observed between FL vs ML and TL favouring FL (RR 2.047). Forty six per cent of pts required filgrastim for neutropenia, 24% required platelet transfusions, 22% had neutropenia plus fever and were admitted for complicated pancytopenia, and 20% required red blood cells transfusion. Two patient died 30 & 40 days after treatment with hypoplastic bone marrow complicated with sepsis in the post autologous bone marrow transplantation period. Four pts with previous bone marrow transplantation required filgrastim, transfusions and 2/3 had febrile neutropenia.

Conclusion: Our experience with ZEV in relapsed and refractory FL shows 48 % CR. Even heavily treated pts that had previous bone marrow transplantation were able to receive ZEV, although they required extra support. Our experience supports the use of ZEV in relapsed and refractory lymphomas even after autologous bone marrow transplantation.