Long-term follow-up of a phase I/II trial of radioimmunotherapy (RIT) with yttrium 90 (90Y) ibritumomab tiuxetan for CD20+ B-cell non-Hodgkin's lymphoma (NHL)

Abstract

6574 Background: Updated time to disease progression (TTP) and duration of response (DR) are reported for responders from a multicenter phase I/II dose-escalation trial of 90Y ibritumomab tiuxetan (Zevalin®) in 51 patients (pts) with relapsed or refractory CD20+ B-cell NHL. Methods: 5 pts were treated at a dose of 0.2 mCi/kg, 15 at 0.3 mCi/kg, and 30 at 0.4 mCi/kg; 1 pt was not treated. Maximum tolerated dose (MTD) was 0.4 mCi/kg for pts with baseline platelets (plts) ≥ 150,000/μL (0.3 mCi/kg for plts 100,000–149,000/μL). Maximum dose for all pts was 32 mCi. Median age was 60 years (yrs) (range, 24–82). Median time from diagnosis to treatment was 3.8 yrs (range, 0.7–33.1). Median number of prior chemotherapy regimens was 2 (range, 1–7); 47 pts (92%) had received an anthracycline. 10 pts (20%) were resistant to prior chemotherapy. At study entry, 59% of pts had ≥ 1 tumor mass ≥ 5 cm; 43% had bone marrow involvement. Results: TTP and DR in responders were updated, response rates (RR) reported at all dose le...