Rituximab (anti-CD20 monoclonal antibody) as single first-line therapy for patients with follicular lymphoma with a low tumor burden: clinical and molecular evaluation.

The clinical activity of rituximab, a chimeric monoclonal antibody which binds to the CD20 antigen, was evaluated as a single first-line therapy for patients with follicular non-Hodgkin lymphoma (NHL). Fifty patients with follicular CD20(+) NHL and a low tumor burden were analyzed for clinical and molecular responses. They received 4 weekly infusions of rituximab at a dose of 375 mg/m(2). The response rate a month after treatment (day 50) was 36 of 49 (73%), with 10 patients in complete remission, 3 patients in complete remission/unconfirmed, and 23 patients in partial remission. Ten patients had stable disease, and the disease progressed in 3 patients. One of 13 (8%) patients in complete remission, 9 of 23 (39%) patients in partial remission, and 5 of 10 (50%) patients with stable disease exhibited disease progression during the first year. Within the study population, 32 patients were initially informative for polymerase chain reaction (PCR) data on bcl-2-J(H) rearrangement. On day 50, 17 of 30 patients (57%) were negative for bcl-2-J(H) rearrangement in peripheral blood, and 9 of 29 (31%) were negative in bone marrow; a significant association was observed between molecular and clinical responses (P <.0001). At month 12, 16 of 26 patients (62%) were PCR negative in peripheral blood. These results indicate that early molecular responses can be sustained for up to 12 months and that this response is highly correlated with progression-free survival. Rituximab has a high clinical activity and a low toxicity and induces a high complete molecular response rate in patients with follicular lymphoma and a low tumor burden.

European phase II study of rituximab (chimeric anti-CD20 monoclonal antibody) for patients with newly diagnosed mantle-cell lymphoma and previously treated mantle-cell lymphoma, immunocytoma, and small B-cell lymphocytic lymphoma.

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.