Clofarabine/cyclophosphamide for debulking before stem cell transplantation

Allogeneic haematopoietic stem cell transplantation (HSCT) is the only curative rescue therapy for patients (pts) with chemotherapy-refractory acute leukaemia. Disease control prior to HSCT is essential for long-term disease-free survival after HSCT.

We have retrospectively analysed the outcome of 20 pts aged 21-64 years with refractory leukaemia (acute myeloid leukaemia, n = 16; acute lymphatic leukaemia, n = 4) who received debulking therapy with clofarabine (10 mg/m², days 1-4) and cyclophosphamide (200 mg/m², days 1-4; ClofCy) prior to HSCT.

Clofarabine/cyclophosphamide (1-4 cycles) was well tolerated and resulted in a substantial reduction of leukaemic cells in all pts. HSCT was performed in 15 of 20 pts. After HSCT (myeloablative, n = 9; dose-reduced, n = 6), all pts showed engraftment and full donor chimerism (related donors, n = 4 or unrelated donors, n = 11) and all pts achieved complete haematologic remission (CR). The median survival after HSCT is 531 days (range: 48-1462 days), and six pts are still alive after a median of 1245 days. Seven pts died after they had relapsed between days +152 and +1496. One patient died from acute graft-versus-host disease (day +48) and one from systemic fungal infection (day +87).

Clofarabine/cyclophosphamide is a novel effective treatment approach for pts with chemotherapy-refractory acute leukaemia prior to HSCT. Whether this novel debulking protocol leads to improved long-term outcome in pts with refractory leukaemias remains to be determined in forthcoming clinical studies.