Zhang AW, Morjaria S, Kaltsas A, et al. - Cancer patients are widely administered recombinant human granulocyte colony-stimulating factor (G-CSF, filgrastim), a cytokine that induces proliferation and differentiation of mature granulocytes, to counteract neutropenia, lowering susceptibility to infection. Researchers aimed at determining the clinical impact of neutropenia and G-CSF use in cancer patients with COVID-19. In this observational cohort study, 379 actively treated cancer patients with COVID-19 were assessed. In the setting of active COVID-19 infection, an increased number of hospitalizations were observed in correlation with outpatient receipt of G-CSF and increased need for high levels of oxygen supplementation and death were recorded in correlation with inpatient receipt of G-CSF. Patients exhibiting a high response to G-CSF, based on their absolute neutrophil count increase post-G-CSF administration, predominantly displayed this effect. Based on findings, researchers recommend considering the potential risks vs benefits of G-CSF administration in neutropenic cancer patients with COVID-19, since G-CSF administration may result in worsening clinical and respiratory status.