[1] Massachusetts Gen Hosp, Boston, MA 02114 USA
[2] New York Presbyterian Hosp, Dept Pediat & med, Div Hematol, New York, NY USA
[3] Royal London Hosp, Dept Haematol, London E1 1BB, England
[4] Univ Groningen, Univ Med Ctr Groningen, NL-9713 AV Groningen, Netherlands
[5] Univ Florida, Baptist Canc Inst, Jacksonville, FL USA
[6] DeQuttro Community Canc Ctr, Manchester, CT USA
[7] Amgen Inc, Thousand Oaks, CA 91320 USA