Single-agent rituximab as first-line and maintenance treatment for patients with chronic lymphocytic leukemia or small lymphocytic lymphoma: a phase II trial of the Minnie Pearl Cancer Research Network.

PURPOSE: To assess the efficacy and toxicity of first-line single-agent rituximab, followed by re-treatment with rituximab at 6-month intervals, in previously untreated patients with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL). PATIENTS AND METHODS: Forty-four previously untreated patients with CLL/SLL received rituximab 375 mg/m2 weekly for 4 consecutive weeks. All patients were required to have one or more indications for treatment. Patients with objective response or stable disease continued to receive identical 4-week rituximab courses at 6-month intervals, for a total of four courses.
RESULTS: The objective response rate after the first course of rituximab was 51% (4% complete responses). Twenty-eight patients received one or more additional courses of rituximab. At present, the overall response rate is 58%, with 9% complete responses. After a median follow-up of 20 months, the median progression-free survival (PFS) time was 18.6 months, and the 1- and 2-year PFS rates were 62% and 49%, respectively. Treatment was well tolerated, with only two episodes of grade 3 to 4 infusion-related toxicity. No cumulative toxicity or opportunistic infections occurred.
CONCLUSION: Single-agent rituximab, used at a standard dose and schedule, is active in the first-line treatment of patients with CLL/SLL, producing substantially higher response rates than previously reported in relapsed or refractory patients (51% v 13%, respectively). Re-treatment with rituximab at 6-month intervals is well tolerated. The PFS time of 18.6 months in patients with CLL/SLL seems shorter than the 36- to 40-month median PFSs previously reported with first-line plus maintenance rituximab in patients with follicular lymphoma. Additional follow-up is required to fully assess the impact of this treatment strategy.