Fludarabine plus cyclophosphamide and rituximab in Waldenstrom macroglobulinemia: An effective but myelosuppressive regimen to be offered to patients with advanced disease

BACKGROUND: The combination of fludarabine, cyclophosphamide, and rituximab (FCR) has produced promising results in chronic lymphocytic leukemia and other lymphoproliferative disorders. The authors report the final results from a multicenter, prospective study examining FCR in Waldenstrom macroglobulinemia (WM). METHODS: Forty-three patients with symptomatic WM that was untreated or pretreated with 1 line of chemotherapy received rituximab 375 mg/m(2) intravenously on day 1 and fludarabine 25 mg/m(2) and cyclophosphamide 250 mg/m(2) intravenously on days 2 through 4. FCR was repeated every 28 days for up to 6 courses. RESULTS: The overall response rate was 79%, and the major response rate of 74.4%, including 11.6% complete remissions (CRs) and 20.9% very good partial remissions. An amelioration of the quality of responses was observed during follow-up, leading to 18.6% of CRs. No differences in terms of responses were observed among previously treated or untreated patients. Among the clinical and laboratory features that were considered, only the β2-microglobulin level had a significant impact in terms of achieving a major response. The major toxicity reported was grade 3/4 neutropenia, which occurred in 45% of courses and was the main reason for treatment discontinuation. After the end of treatment, 19 patients (44%) had long-lasting episodes of neutropenia. Three patients developed myelodysplastic syndrome during follow-up. CONCLUSIONS: The FCR regimen was capable of neutralizing adverse prognostic factors and proved to be active in patients with WM, leading to rapid disease control and good-quality responses. Because myelosuppression was the main concern, further studies are warranted to optimize dosages and treatment duration.