Long-term safety of treatment with recombinant human granulocyte colony-stimulating factor (r-metHuG-CSF) in patients with severe congenital neutropenias

Summary . Congenital neutropenias include a heterogenous group of diseases characterized by a decrease in circulating neutrophils. In phase I/II/III studies in patients with severe congenital and cyclic neutropenia, treatment with recombinant human granulocyte colony-stimulating factor (r-metHuG-CSF) resulted in a rise in the absolute neutrophil counts (ANC) and a reduction in infections. We report the effects of long-term safety of subcutaneous r-metHuG-CSF administration in 54 patients (congenital n = 44, cyclic n = 10) treated for 4–6 years. A sustained ANC response was seen in 40/44 severe congenital neutropenia patients and 10/10 cyclic neutropenia patients. Two patients required an increase of > 25% in dose to maintain a clinical response; one patient became refractory to therapy. A significant decrease in the incidence of severe infections and the need for intravenous antibiotics was noted. Significant adverse events noted which may or may not be related to therapy included: osteopenia ( n = 15), splenomegaly ( n = 12), hypersplenism ( n = 1), vasculitis ( n = 2), glomerulonephritis ( n = 1), BM fibrosis ( n = 2), MDS/leukaemia ( n = 3), and transient inverted chromosome 5q with excess blasts ( n = 1). R-metHuG-CSF has been well tolerated in the majority of patients and resulted in a longterm improvement in their clinical status.