Bone marrow suppression (anemia, neutropenia, thrombocytopenia) is the most commonly occurring side effect of chlorambucil.
Homozygous mutations in the HAX1 gene are associated with Kostmann disease, i.e. the "classical," autosomal recessive form of severe congenital neutropenia (SCN3).
In collaboration with Amgen, recombinant G-CSF (Neupogen) was developed and in 1987 the first clinical studies were begun at Memorial Sloan-Kettering in cancer patients and pediatric patients with a genetic form of neutropenia.