Results of Multicentre Phase IV Study of Rituximab in Combination with CHOP Chemotherapy in Patients with Previously Untreated Non-Hodgkin’s Lymphoma.

Purpose: Rituximab is a chimeric anti-CD20 monoclonal antibody that was the first antibody approved by the FDA in the United States of America and SDA in China for the treatment of B-cell non-Hodgkin’s Lymphoma (NHL). It has shown significant efficacy and good tolerability in refractory and relapsed NHL. We have conducted a multicenter phase IV trial to evaluate the efficacy and safety of rituximab combined with standard CHOP chemotherapy in patients with newly diagnosed B-NHL.

Methods: Patients with newly diagnosed, histologically proven CD20-positive NHL were eligible for the study. All patients received 4–6 infusions of rituximab (375mg/m² per dose) in combination with CHOP chemotherapy, either concurrently (rituximab administered on the first day of each 21-day CHOP cycle) or sequentially (4–6 once-weekly infusions of rituximab followed by six 21-day cycles of CHOP). Each CHOP cycle consisted of cyclophosphamide 750 mg/m², doxorubicin 50mg/m², and vincristine 1.4mg/m² (maximum 2.0mg/dose) given intravenously on day 1, and prednisone 100mg/day orally on days 1-5. Tumor responses were assessed at the end of treatment.

Results: A total of 347 patients were recruited between February 2002 and December 2003. Of these 235 (68%) were male and 94 (27%) aged >60. The main lymphoma subtypes were diffuse large B-cell 196 (56%), follicular 41(12%), small lymphocytic/chronic lymphocytic leukemia 13(4%) and MALT 11(3%). Ann Arbor staging was as follows: stage I, 52 (15%); stage II, 80 (23%); stage III, 90(26%); stage IV, 105(30%); twenty patients (6%) could not be assessed. Of the 347 patients enrolled, 314 were evaluable for response. An objective response was observed in 94% of evaluable patients with a complete response (CR) in 56%, stable disease in 3.8% and progressive disease in 2.5%. The complete response rate was 63% for patients receiving 6 cycles of rituximab and 54% for those receiving four cycles of rituximab. No difference in response rate was observed between the sequential and concurrent groups. The most common adverse events were leucopenia in 122 patients (35%), nausea and vomiting 66 (19%), fever 39 (11%), rash 15 (4%) and asthma 4 (1%).

Conclusion: The combination of rituximab and CHOP chemotherapy is an effective and well-tolerated treatment for patients with newly-diagnosed CD20-positive NHL. The safety and efficacy achieved in this study suggests that more than four doses of rituximab may be required for optimal efficacy.