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 2 hr, five times per week for 1 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.