Clofarabine in combination with pegylated asparaginase in the frontline treatment of childhood acute lymphoblastic leukaemia: a feasibility report from the CoALL 08-09 trial

Clofarabine was the latest new drug to be approved, in 2004, for relapsed or refractory acute lymphoblastic leukaemia (ALL). To investigate its value in the frontline treatment of ALL we applied clofarabine 5x40mg/m(2) in combination with pegylated asparaginase (PEG-ASP) 1x2500iu/m(2) in high risk ALL patients as a novel post-induction element in the German Co-operative Study Group for treatment of ALL (CoALL) trial 08-09. Newly diagnosed ALL patients, defined by a significant minimal residual disease (MRD) load at the end of induction (B-progenitor ALL at day 2910(-4) and T-ALL at day 4310(-3)) were eligible for this phase II trial. All other patients received the standard treatment consisting of high-dose cytarabine (HIDAC) 4x3g/m(2) in combination with Peg-ASP 2500iu/m(2). Forty-two patients (39 B-progenitor; 3 T-ALL) fulfilled the criteria, were stratified and received the clofarabine/PEG-ASP treatment resulting in 24/39 (61%) MRD-negative B-progenitor patients compared to 18/39 (46%) after HIDAC/PEG-ASP in CoALL 07-03. Overall, the toxicity profile of clofarabine/PEG-ASP was similar to HIDAC/PEG-ASP without unexpected severe side effects. Clofarabine combined with PEG-ASP is safe and effective in the frontline treatment of ALL. A prospective, randomized trial is warranted to evaluate the antileukaemic efficacy of clofarabine versus HIDAC combined with PEG-ASP.