Stem cell transplantation in patients with severe congenital neutropenia without evidence of leukemic transformation

Severe congenital neutropenia (CN) (Kostmann syndrome) is a hematologic dis order characterized by a maturation arrest of myelopoiesis at the promyeloc yte/myelocyte stage of development, This arrest results in severe neutropen ia leading to absolute neutrophil counts (ANC) below 0.2 x 10(9)/L associat ed with severe bacterial infections from early infancy. Data on over 300 pa tients with CN collected by the Severe Chronic Neutropenia International Re gistry (SCNIR) beginning in 1994 indicate that more than 90% of these patie nts respond to recombinant human granulocyte colony stimulating factor (r-H uG-CSF) treatment with an ANC greater than 1.0 x 10(9)/L. For patients who are refractory to r-HUG-CSF treatment and continue to have severe and often life-threatening bacterial infections, hematopoietic stem cell transplanta tion is the only currently available treatment. We report on a total of 11 patients with CN reported to the SCNIR who underwent transplantation for re asons other than malignant transformation between 1976 and 1998. Of these p atients, 8 were nonresponders or showed only partial response to r-HuG-CSF treatment with ongoing infections. Results from these patients suggest that transplantation of stem cells from an HLA-identical sibling is beneficial for patients refractory to r-HuG-CSF. (Blood. 2000;95:1195-1198) (C) 2000 b y The American Society of Hematology.