A Phase II Study of Campath-1H in Children With Relapsed or Refractory Acute Lymphoblastic Leukemia: A Children's Oncology Group Report

Background. Despite the increasing Cure rates for children with acute lymphoblastic leukemia (ALL), patients who relapse continue to have poor prognosis. The Children's Oncology Group (COG) conducted a limited institution Phase II trial of Campath-1H, a monoclonal antibody that targets CD52 on leukemic cells, in children with relapsed or refractory ALL. Methods. From October 2005 to December 2006, 13 eligible patients were enrolled on the COG phase II study of Campath-1H (ADVL0222). Campath-1H was initially administered as an intravenous infusion over 2hr, five times per week for I week, then three times per week for three additional weeks. Patients with stable disease or better on day 29 could continue on to combination therapy with Campath-1H, methotrexate, and 6-mercaptopurine for two additional cycles. Results. One of 13 patients enrolled had a complete response to Campath-1H and 4 had stable disease. Dose limiting toxicity occurred in two out of nine fully evaluable patients (Grade IV pain and Grade III allergic reaction/hypersensitivity). No patients received combination therapy. Serum Campath-1H concentrations appeared to be somewhat lower in children with ALL compared with adult patients with chronic lymphocytic leukemia. Conclusion. Although a single complete response was observed, activity of single agent Campath-1H appears limited. Our study does not support future single agent evaluation of Campath-1H in children with relapsed ALL. Pediatr Blood Cancer 2009;53:978-983. (C) 2009 Wiley-Liss, Inc.