Filgrastim biosimilar(Dong-A Pharmaceutical Co., Ltd.)

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.

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.

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.

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.

In clinical practice, granulocyte colony-stimulating factor (G-CSF) is often used to lower infection risk and avoid poor outcomes from chemotherapy dose reduction or delay. Efbemalenograstim alfa (also known as F-627) is a non-pegylated but long-acting (once-per-cycle) recombinant human granulocyte colony-stimulating factor (rhG-CSF) compared with pegfilgrastim. This study was designed to obtain pharmacokinetic (PK)/pharmacodynamic (PD), safety, and tolerability data for F-627 in healthy Chinese participants.

This was a single-center, open-label phase I clinical study involving 24 healthy Chinese volunteers (sex ratio = 1:1). All the participants were administered a single subcutaneous injection of 20 mg F-627 into the abdomen.

In this study, 15 (62.5%) participants reported 28 treatment-related adverse events. PK/PD data showed that after a single 20 mg subcutaneous (SC) F-627 abdominal injection in healthy Chinese participants, serum concentrations peaked at 36 h post dose, while the absolute neutrophil count (ANC) peaked at 96 h. After peaking, F-627 serum levels decreased rapidly to low concentrations by 120 h, while ANC declined gradually to near baseline by day 15. Similar trends in serum concentration and ANC kinetics were seen between sex.

This phase I study showed that 20 mg F-627 was well tolerated and exhibited a favorable safety profile in a healthy Chinese population. The PK and PD data correlated well and were consistent across sex.

This trial was registered at the Chinese Clinical Trial Registry (chictr.org.cn) on 10 September 2024 (registration ID: ChiCTR2400089548).