Time to treatment response in patients with follicular lymphoma treated with bortezomib is longer compared with other histologic subtypes.

PURPOSE To determine the antitumor activity of the novel proteasome inhibitor bortezomib in patients with indolent non-Hodgkin's lymphoma. EXPERIMENTAL DESIGN Patients with follicular lymphoma (FL), marginal zone lymphoma, mantle cell lymphoma, small lymphocytic lymphoma/chronic lymphocytic leukemia, and Waldenstrom's macroglobulinemia were eligible for study. Bortezomib was given at a dose of 1.5 mg/m(2) as an i.v. push on days 1, 4, 8, and 11 of a 21-day cycle. Eligibility included the following: (a) no more than three prior therapies, (b) at least 1 month since prior chemotherapy, (c) measurable disease, and (d) an absolute neutrophil count of >1,000/microL and a platelet count >50,000/microL for the first dose of any cycle. RESULTS Seventy-seven patients were registered, of which 69 were assessable for response based on the completion of two cycles of therapy. Subtypes included FL (59.5%), mantle cell lymphoma (52%), small lymphocytic lymphoma/chronic lymphocytic leukemia (16.2%), marginal zone lymphoma (21.6%), and one Waldenstrom's macroglobulinemia. The median number of prior therapies was three. The most common grade 3 toxicity was lymphopenia (35%) and thrombocytopenia (31%). Twenty-five patients experienced grade <or=2 sensory neuropathy (32), and 8% experienced grade 3 neurosensory toxicity. The overall response rate was 45% (40% on an intention to treat) including 10 complete remissions. Of 18 patients with FL, 9 responded with 4 complete response. The median time to treatment response for FL was 12 weeks, whereas the median time to treatment response for other subtypes of non-Hodgkin's lymphoma was only 4 weeks. CONCLUSIONS These data suggest that bortezomib has significant single agent activity in patients with FL, and that longer durations of treatment may improve overall response.