Preliminary Results of a Phase I/II Trial of BBR-2778 (Pixantrone) in Combination with Fludarabine, Dexamethasone, and Rituximab (FPD-R) in the Treatment of Patients with Relapsed/Refractory Indolent Non-Hodgkin’s Lymphoma (NHL).

Background: Fludarabine-mitoxantrone-dexamethasone-rituximab (FND-R) is a combination chemotherapy with significant activity in untreated and relapsed indolent B-cell lymphoma patients (pts). Pixantrone is a novel aza-anthracenedione that has no delayed cardiotoxicity in animal models and has single agent activity in NHL. We conducted an outpatient phase I/II trial, to define the recommended dose (RD) of pixantrone when substituting for mitoxantrone in the FND-R regimen, and the safety and efficacy of this regimen in pts with relapsed or refractory indolent NHL.

Methods: Pts received pixantrone with fludarabine (25mg/m²/day, days 1–3), dexamethasone (20mg/day, days 1–5), and rituximab (375mg/m²/day on day 1) in a 28 day regimen (FPD-R). Based on previous single agent clinical studies, the starting dose of pixantrone was defined as 80mg/m². The RD was established to be 120mg/m² and the protocol was amended to treat patients in the phase II part.

Results: 9 pts (6 males) with a median age of 65 years (range 41–78) were included in the dose-finding part of the study. Following the protocol amendment, 23 pts (11 males) of WHO performance status 0–1, median age 61 (range 32–78) have been enrolled in the currently ongoing phase II part. Pathology included SLL/CLL, follicular grade I, follicular grade II, MALT, marginal cell, and other indolent B-cell lymphomas. All pts had received a prior anthracycline-containing regimen (median number 1, range 1–4). The study regimen was well tolerated; median number of courses received was 5 (range 2–8). Grade 4 toxicities were neutropenia in 10 pts, leukopenia in 5 pts, and thrombocytopenia in 1 pt. No clinically significant cardiac events or decreases in LVEF ≥20% were noted. However 4 pts went below 50% LVEF including 1 pt who was below 50% at baseline. Non-hematologic adverse events were primarily grade 1 or 2 in severity. Response rate was 75% for the 20 pts evaluable for response, with 11 (55%) complete remission [7 confirmed (CR), 4 unconfirmed (CRu)], and 4 (20%) partial remission (PR). Two responders went onto bone marrow transplant (BMT): one had a CRu and one a PR. A third patient was pending BMT after CR. At a median follow-up of 345 days, the median duration of response has not been reached, as only two pts have progressed: the first progression occurred at 113 days, and the second pt progressed at 699 days. The remaining pts are still in remission.

Conclusions: The RD of pixantrone in the FPD-R regimen is 120mg/m². The primary toxicity is hematologic. The regimen can be given on an outpatient basis, is associated with major responses, and is very well tolerated in relapsed and refractory indolent NHL pts.