Preliminary Results of a Phase I/II Study of Weekly or Twice Weekly Bortezomib in Combination with Rituximab, in Patients with Follicular Lymphoma, Mantle Cell Lymphoma and Waldenström’s Macroglobulinaemia.

Introduction: Rituximab (R) is an integral component of therapy for B-cell lymphoid malignancies; bortezomib (Btz) has shown provocative single agent activity in Follicular Lymphoma (FL), Mantle Cell Lymphoma (MCL) and Waldenström’s Macroglobulinaemia (WM), providing the rationale for investigating the combination.

Patients+Methods: Forty-five adult patients (pts.) (30 men, 15 women) with histologically confirmed recurrent CD20+ve FL, MCL or WM, median age 60 years (range 45-79), FL: 17, MCL: 18, WM: 10, stage III/IV 40 (93%), bone marrow (BM) infiltration 32 (73%), elevated LDH 22 (49%), performance status ≥1 22 (49%), were enrolled in a randomised trial comparing 2 schedules of Brz+R: Arm A (twice weekly) Btz: 1.3mg/m² (on days 1, 4, 8, 11 of a 21-day cycle) and R: 375mg/m² (on day 1) for 8 cycles, or Arm B (weekly) Btz: 1.6mg/m² (on days 1, 8, 15, 22 of a 35-day cycle) and R: 375mg/m² (on days 1, 8, 15, 22 of cycles 1 and 4) for 6 cycles (23 arm A, 22 arm B). The median number of previous treatments was 2 (range 1-7). Seventeen pts. had received a R-containing regimen, with response lasting >6 months, and 8 high-dose treatment. Response was evaluated using the IWR criteria (Cheson et al,

Results: Ability to deliver the therapy, toxicity and efficacy were equivalent in both arms. The median number of cycles given in arm A was 4 and 5 in arm B. Haematological toxicity (grade≥3: anaemia 0%, neutropenia 25%, thrombocytopenia 22%) was significantly influenced by the high percentage of pts. with BM infiltration and concomitant cytopenia on entry to the trial. The most common non-haematological adverse events were fatigue (76%), nausea (56%), diarrhoea (56%), lethargy (46%). Neurotoxicity occurred in 19 pts. (46%) (10 pts. grade 1, 7 pts. grade 2, 2 pts. grade 3). Btz dose was reduced in 7 pts.; 5 doses were omitted because of neuro or haematological toxicity. In 16 pts., treatment was delayed by 1-14 days and in 24 pts. treatment was stopped prematurely. The reasons for stopping treatment were: treatment-related toxicity 11 pts., progressive disease 9 pts., patient’s preference 3 pts., myocardial infarction 1 pt. One pt. was excluded having been found ineligible post randomisation. Thirty-nine pts. (21 arm A, 18 arm B) are evaluable for response so far, one having only received 1 cycle of therapy, which had to be discontinued because of excessive toxicity. 15/32 were in remission (CR, CRu, PR) at the completion of therapy, 7/7 at “mid-therapy” assessment, and 5 have yet to be evaluated. Thus the overall response rate (RR) presently is 22/39 (56%) (CR, CRu, PR), FL 44%, MCL 46%, WM 90%.

Conclusions:

1. The combination was active in pts. with recurrent NHL especially WM (RR 90%), despite multiple previous treatments,

2. The weekly schedule is preferable being more convenient, as efficacious and no more toxic.

Further investigation is warranted, despite not insignificant therapy compromising toxicity.