Purpose: Mantle-cell lymphoma (MCL), immunocytoma (IMC), and small B-cell lymphocytic lymphoma (SLL) are B-cell malignancies that express CD20 and are incurable with standard therapy. A multicenter phase II study was conducted to assess the toxicity and the overall response rates (RR) and complete response (CR) rates to rituximab (chimeric anti-CD20 monoclonal antibody).
Patients and methods: Between January 1997 and January 1998, 131 patients with newly diagnosed MCL (MCL1; n = 34) and previously treated MCL (MCL2; n = 40), IMC (n = 28), and SLL (n = 29) received rituximab 375 mg/m(2)/wk for 4 weeks via intravenous infusion. Restaging studies were performed 1 and 2 months after treatment. An analysis of the duration of response was conducted in December 1998.
Results: Eleven patients were unassessable, including one who died of splenic rupture after the first infusion. The RR among the 120 assessable patients was 30% (36 of 120 patients). The RR by histology was as follows: MCL1, 38%; MCL2, 37%; IMC, 28%; and SLL, 14%. Ten patients, all with MCL, achieved CR. The median duration of response in MCL was 1.2 years. Immediate side effects were common and usually responded to adjustments in the infusion rate. There were 31 episodes of infection after treatment; most cases were mild. Cardiac arrhythmia and ophthalmologic side effects occurred in 10 and nine patients, respectively, including one case of severe loss of visual acuity.
Conclusion: Single-agent rituximab has moderate activity in MCL and IMC but only limited activity in SLL. The duration of response in MCL was similar to that previously reported in follicular lymphoma. Its use in combination with cytotoxic chemotherapy to increase the CR rate is warranted in MCL and IMC.