Rituximab plus chlorambucil as first-line treatment for chronic lymphocytic leukemia: Final analysis of an open-label phase II study.

PURPOSE: Most patients with chronic lymphocytic leukemia (CLL) are elderly and/or have comorbidities that may make them ineligible for fludarabine-based treatment. For this population, chlorambucil monotherapy is an appropriate therapeutic option; however, response rates with chlorambucil are low, and more effective treatments are needed. This trial was designed to assess how the addition of rituximab to chlorambucil (R-chlorambucil) would affect safety and efficacy in patients with CLL. PATIENTS AND METHODS: Patients with first-line CLL were treated with rituximab (375 mg/m(2) on day 1, cycle one, and 500 mg/m(2) thereafter) plus chlorambucil (10 mg/m(2)/d all cycles; day 1 through 7) for six 28-day cycles. For patients not achieving complete response (CR), six additional cycles of chlorambucil alone could be administered. The primary end point of the study was safety. RESULTS: A total of 100 patients were treated with R-chlorambucil, with a median follow-up of 30 months. Median age of patients was 70 years (range, 43 to 86 years), with patients having a median of seven comorbidities. Hematologic toxicities accounted for most grade 3/4 adverse events reported, with neutropenia and lymphopenia both occurring in 41% of patients and leukopenia in 23%. Overall response rates were 84%, with CR achieved in 10% of patients. Median progression-free survival was 23.5 months; median overall survival was not reached. CONCLUSION: These results compare favorably with previously published results for chlorambucil monotherapy, suggesting that the addition of rituximab to chlorambucil may improve efficacy with no unexpected adverse events. R-chlorambucil may improve outcome for patients who are ineligible for fludarabine-based treatments.

A randomized phase II trial of fludarabine, cyclophosphamide and mitoxantrone (FCM) with or without rituximab in previously treated chronic lymphocytic leukaemia.

Combination fludarabine (F), cyclophosphamide (C) and rituximab (R) is the standard front-line therapy in chronic lymphocytic leukaemia (CLL), but appropriate treatment of relapsed/refractory CLL is less clear. Combined FC and mitoxantrone (M) has been reported to be effective in a single arm study, and rituximab when added to chemotherapy in CLL is synergistic. A randomized, two-stage, Phase II trial of FCM and FCM-R was conducted in relapsed CLL. The primary endpoint was response rate 2 months after therapy, assessed according to the 2008 International Workshop CLL criteria. In addition, minimal residual disease (MRD) in the marrow was studied 2 months after therapy, with MRD negativity defined as <0·01% CLL cells. Fifty-two patients were entered, 26 in each arm. The overall response rates to FCM and FCM-R were 58% and 65% respectively. Combined complete response (CR) and CR with incomplete marrow recovery [CR(i)] was 15% (95% confidence interval [CI]:4-35%) for FCM and 42% (95%CI:23-63%) for FCM-R, with eight patients achieving MRD negativity (3 FCM; 5 FCM-R). The toxicity of both regimens was acceptable. In conclusion, the addition of rituximab to FCM improves the response rates in relapsed CLL, resulting in more complete remissions and without additional safety concerns. Efficacy and safety should be fully tested in a randomized Phase III trial.

Minimal residual disease assessment in chronic lymphocytic leukaemia.

The concept of minimal residual disease (MRD) eradication in chronic lymphocytic leukaemia (CLL) is a relatively new one, as conventional therapy with alkylating agents is relatively ineffective and responding patients almost always have a significant tumour burden remaining at the end of treatment. However, a variety of novel therapies is now yielding higher response rates, and responses of better quality are now routinely achieved. This progress in therapy has been paralleled by an improvement in laboratory assays, allowing detection of CLL cells to levels as low as ten CLL cells in a million leukocytes. In this chapter we briefly review the existing methods for MRD assessment, the clinical relevance of MRD eradication in CLL, and the therapies available to attain this endpoint.