G-CSF in feline medicine: From molecular mechanisms to clinical applications.

BACKGROUND

Granulocyte colony-stimulating factor (G-CSF) is a crucial hematopoietic growth factor essential for granulopoiesis, inflammation, and immune responses in humans and animals. Although widely used in human medicine for neutropenia and transplantation support, its applications in feline medicine, encompassing neutropenia, infection management, and transplantation, remain underexplored, with limited comprehensive reviews. A significant limitation of recombinant human G-CSF (rhG-CSF) treatment in cats is the risk of developing neutralizing antibodies, which can target G-CSF and potentially reduce its efficacy. Developing feline-specific or long-acting variants offers potential solutions.

METHODS

A comprehensive literature search was performed using PubMed and other databases up to August 1, 2025. Search terms included "G-CSF", "granulocyte colony-stimulating factor", "feline", and "cat". Studies reporting the clinical use of G-CSF in cats were included.

RESULTS

rhG-CSF administration elevated neutrophil and lymphocyte counts but could induce transient neutropenia and immunogenicity. In contrast, recombinant feline G-CSF (rfG-CSF) demonstrated improved bioactivity and did not generate anti-drug antibodies in small-scale studies with follow-up periods extending beyond one year. Novel long-acting variants, including PEGylated rfG-CSF (PEG-rfG-CSF) and a fusion protein, exhibited prolonged half-life and enhanced efficacy compared to standard forms.

CONCLUSION

rfG-CSF represents a promising therapeutic alternative to rhG-CSF for managing neutropenia in cats, primarily due to its lack of immunogenicity. Future development efforts should focus on optimizing these long-acting formulations and maximizing bioactivity to facilitate widespread clinical adoption and commercialization in veterinary medicine.