NASHVILLE, Tennessee—A pilot study of rituximab(Drug information on rituximab) (Rituxan) as first-line therapy for small lymphocytic lymphoma (SLL) or chronic lymphocytic leukemia (CLL) found an overall response rate of 56%, according to John Hainsworth, MD, director of clinical research at the Sarah Cannon Cancer Center in Nashville, Tennessee. Dr. Hainsworth discussed this work in a poster session at the 43rd Annual Meeting of the American Society of Hematology.
Although patients with SLL/CLL have CD20 expression on malignant lymphocytes, response rates with standard rituximab courses in refractory patients are only about 15%, compared to 60% in patients who have follicular non-Hodgkin’s lymphoma (NHL), Dr. Hainsworth reported.
"In a previous clinical trial performed in a multicenter, community-based setting, we treated 62 patients with indolent NHL (follicular and SLL histologies included) with first-line single-agent rituximab using a standard-dose 4-week schedule. Patients with initial response or stable disease received maintenance courses of rituximab at 6-month intervals. This produced responses in 15 of 24 patients with SLL (73%), with a median progression-free survival of 31 months. This was similar to results in patients with follicular NHL. We have therefore expanded our experience, and have now treated a total of 68 previously untreated patients with either SLL (37 patients) or CLL (31 patients) with single-agent rituximab," Dr. Hainsworth said.
Study Design
Rituximab was given at 375 mg/m² weekly by slow intravenous infusion for 4 weeks. Patients who had objective response or stable disease at the 6-week evaluation continued maintenance courses of rituximab, using a standard 4-week schedule, every 6 months, for a maximum of four courses. The study enrolled treatment-naive patients with stage III or IV SLL or CLL. Median age was 66 years (range: 48-89), 13 patients (23%) had B symptoms, and 19 patients (28%) had white blood counts above 50,000/µL.
Evaluation
At the first 6-week evaluation, 33 of 66 evaluable patients (50%) had objective responses (3% complete response rate), and 32 additional patients (48%) had stable disease. Complete responses continued to appear during the maintenance period (see Table 1). Current responses included complete remissions in 8% and partial remissions in 48%, for a response rate of 56%.
