Phase II trial of rituximab and short duration chemotherapy followed by ⁹⁰Y-ibritumomab tiuxetan as first-line treatment for patients with follicular lymphoma: A Minnie Pearl Cancer Research Network phase II trial

Abstract

6519 Background: First-line treatment with combination chemotherapy + rituximab improves molecular complete remission (CR) rates and lengthens remission duration in patients (pts) with follicular NHL. In a previous phase II trial, we demonstrated a high CR rate with short course chemotherapy + rituximab (CHOP-R or CVP-R). In an attempt to further improve the CR rate, we added 90Y-ibritumomab tiuxetan (Zevalin) after CHOP-R. Methods: Previously untreated pts with follicular lymphoma (grades 1–3) and stages II-IV were eligible. Additional entry criteria: ECOG PS 0–2; adequate organ function; no CNS involvement; no HIV infection; informed consent. Pts with cardiac ejection fraction < 45% received CVP instead of CHOP. All pts first received 4-weeks of rituximab (375mg/m2 weekly x 4), then 3 courses of CHOP-R (standard doses). After complete restaging, responding pts with bone marrow involvement < 25% received 90Y-ibritumomab tiuxetan 5 weeks after the last dose of CHOP-R. Final restaging was performed 12 weeks after 90Y-ibritumomab tiuxetan. Results: 33 of 40 pts have been accrued, with median follow-up of 10 months. Pt characteristics: median age, 56 years; stage IV, 54%; M/F = 16/17. Prior to 90Y-ibritumomab tiuxetan, 27 of 28 pts (96%) had objective response (9 CR). All pts completing CHOP-R were eligible for 90Y-ibritumomab tiuxetan. 22 pts have completed therapy and been restaged: 19 pts (86%) are in CR, with 3 PR's. 10 pts with PR converted to CR after 90Y-ibritumomab tiuxetan. No unexpected toxicity was seen during CHOP-R therapy. Hematologic toxicity following 90Y-ibritumomab tiuxetan: gr 4 neutropenia 18%; gr 4 thrombocytopenia 0; RBC transfusion 5%; platelet transfusion 18%; neutropenia/fever 5%; GI bleed 5%. 90Y-ibritumomab tiuxetan caused no grade 3/4 nonhematologic toxicities. Conclusions: First-line CHOP-R followed by 90Y-ibritumomab tiuxetan is highly active and well tolerated in pts with follicular NHL. Further follow-up is necessary to determine progression-free and overall survival, and to monitor for late toxicity. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Genentech Brogen IDEC