CYTOKINE TREATMENT OF SEVERE CHRONIC NEUTROPENIA

Severe neutropenia (absolute neutrophil count < 500 eells/mm(3)) is as sociated with life-threatening infections. Therapeutic regimens used t o ameliorate severe neutropenia have been of limited benefit. The newl y discovered cytokines acting primarily on granulocytic differentiatio n are an important new therapeutic modality in inherited and acquired neutropenic disorders. Very encouraging results in early phase I-II tr ials in neutropenic patients led to the implementation of a phase III randomized multi-center trial to investigate the efficacy and safety o f G-CSF in these disorders. Of 120 patients with severe neutropenia en tered on the phase III study, 108 experienced a complete response, 4 a partial response and 8 failed to respond. Response was associated wit h improvement in quality of life with reductions in infections and ant ibiotic usage. Reasons for non-response are currently be investigated. The long-term effects of cytokine administration to neutropenic patie nts is unknown. Osteopenia and secondary myelodysplasia or leukemia ar e beginning to be reported. For this reason only patients with severe neutropenia or those exhibiting serious infection should receive cytok ine therapy at this time.