Administration of alemtuzumab and G ‐ CSF to adults with relapsed or refractory acute lymphoblastic leukemia: results of a phase II study

The outlook for adults with refractory and relapsed acute lymphocytic leukemia ( ALL ) is poor. CD 52 is expressed in most patients with ALL . Alemtuzumab is an anti‐ CD 52 humanized monoclonal antibody. This phase II study assessed the efficacy of alemtuzumab combined with granulocyte‐colony stimulating factor (G‐ CSF ) to boost antibody‐dependent cell cytotoxicity mediated by neutrophils. Twelve patients with relapsed ( n  = 11) or refractory ( n  = 1) ALL , including four relapses postallogeneic stem cell transplantation, were treated and monitored between October 2006 and January 2011. Patients received 1 wk of alemtuzumab every other day at increasing doses of 3, 10, and 30 mg to test tolerance and 30 mg three times a week for 12–18 infusions. If in complete remission ( CR ), patients received maintenance therapy for 1 wk, every 2 months. G‐ CSF was administered at 5 μg/kg per day during alemtuzumab administration. The primary endpoint was disappearance of blast cells on a marrow aspirate. CD 52 was expressed in all patients. Four patients reached CR . In one additional patient, clearance of blast cells was observed in peripheral blood but not in the marrow. The most frequent adverse events during course 1 of treatment were fever and chills ( n  = 3), skin rash ( n  = 3), and bronchospasm ( n  = 2). Tumor lysis syndrome was observed at treatment initiation in one patient who reached CR . All patients progressed within a few months and all but one died. The surviving patient is still alive after relapse and a second allogeneic stem cell transplantation. This study shows that in relapse/refractory ALL , alemtuzumab with G‐ CSF can produce good responses of short duration.