Chemoimmuno-Therapy with Fludarabine, Cyclophosphamide and Alemtuzumab in Patients with Relapsed/Refractory CLL: Interim Analysis of the CLL2L Trial of the German CLL Study Group

Introduction: Purine nucleoside combination therapy has become the standard treatment approach in B-CLL. In order to enhance efficacy, various combinations with monoclonal antibodies are under investigation. As alemtuzumab has proven to be the most effective antibody in CLL treatment, we developed a multicenter phase II trial combining fludarabine, cyclophosphamide and alemtuzumab in a 4-weekly schedule

Methods: Fludarabine 25mg/m² iv, cyclophosphamide 200mg/m2 iv and alemtuzumab 30 mg sc were given on days 1 – 3 and repeated on day 29 for up to six cycles. A 2-day escalation of alemtuzumab was administered prior to the first cycle. Minimal residual disease (MRD) was measured by 4-color flow cytometry. Antiinfective prophylaxis consisted of TMP-SMZ DS twice daily 3d/wk and valacyclovir during and at least two months after completion of treatment. CMV antigen in blood was tested in 14-days intervals.

Results: A total of 55 patients of a planned sample size of 61 patients were included in this phase-II study so far, of which 24 patients are evaluable for response and safety analysis. Median age is 63 (range 47–78) years with a medium number of 1 prior regimen; 19/24 patients completed at least four cycles with a median number of 5 cycles. Pretreatment consisted of fludarabine (8/24), fludarabine and cyclophosphamide (13/24) or rituximab combinations (3/24). Thrombocytopenia and neutropenia were the most serious side effects and detailed data will be presented. 3 CMV-reactivations, 1 Herpes-zoster-reactivation and 12 fever of unknown origin have been reported. The overall response rate was 83% with 9 CR(6 CRu) (38%), 9 PR (46%), 3 SD and 1 PD, response was independent of FISH status. A correlation of response with prior treatment was observed, with 100% ORR for fludarabine pre-treatment versus only 77% for those patients pretreated with fludarabine and cyclophosphamide. Updated data of 30 patients and MRD data will be presented.

Conclusions: The concomitant application of fludarabine, cyclophosphamide and alemtuzumab appears as a safe and effective approach for patients with relapsed CLL.