The promise of novel treatments for severe chronic neutropenia.

INTRODUCTION: Severe chronic neutropenia, i.e. absolute neutrophil count (ANC) less than 0.5 × 109 /L, is a serious health problem because it predisposes patients to recurrent bacterial infections. Management radically changed with the discovery that granulocyte colony-stimulating factor (G-CSF) could be used to effectively treat most patients; therapy required regular subcutaneous injections. In the early days of G-CSF therapy, there were concerns that it might somehow overstimulate the bone marrow and cause myelodysplasia (MDS) or acute myeloid leukemia (AML). Detailed research records from the Severe Chronic Neutropenia International Registry (SCNIR) indicate that this is a relatively low risk event. The research records suggest that certain patient groups are primarily at risk. Presently, allogeneic hematopoietic stem cell therapy serves as an alternate form of therapy.

AREAS COVERED: Due to these concerns and the desire for an easy-to-take oral alternative, several new treatments are under investigation. These treatments include neutrophil elastase inhibitors, SGLT-2 inhibitors, mavorixafor - an oral CXCR4 inhibitor, gene therapy and gene editing.

EXPERT OPINION: All of these alternatives to G-CSF are promising. The risks, relative benefits and costs are yet to be determined.