Extended Rituximab for patients with WM
DFCI Protocol 99-253, a multicenter Phase II clinical trial chaired by Dr. Treon was closed to accrual after 29 patients were enrolled (2 more than the intended target of 27 patients). Patients on this study received extended (i.e. 8 courses) of rituximab. Among the first 22 evaluable patients, an overall response rate of 73% was observed, and 14% of patients attained stable disease. Importantly, the response duration estimated at over 20 months compares favorably to those reported by us (Treon et al, J. Immunotherapy 2001) and others using standard dose rituximab wherein response durations have ranged from 6-9 months. Notably in this study, significant improvements in hematological function were observed in patients receiving extended rituximab. Pre-rituximab therapy, 35% of patients were anemic and 28% were thrombocytopenic which decreased to 5% and 9%, respectively following therapy. Interestingly, response to extended dose rituximab was correlated with pre-therapy IgM levels, but not BM tumor cell burden. Eighteen of 20 patients (90%) with an IgM level of <6,000 mg/dL responded, whereas only 1/6 (16%) patients with an IgM level of >6,000 mg/dL responded. The reason for this finding remains under active investigation. The results of these studies were presented at the 2002 American Society of Clinical Oncology and American Society of Hematology meetings.