What Is Efbemalenograstim Alfa? Definition and What Research Reports

Definition

Efbemalenograstim alfa is a long-acting recombinant human granulocyte colony-stimulating factor (rhG-CSF) engineered as an Fc fusion protein, studied in clinical development under the code F-627, and described in the review literature as a once-per-cycle supportive-care biologic intended to reduce the risk of infection manifested by febrile neutropenia in adults receiving myelosuppressive anticancer therapy (PMID 37368138). In plain terms, it is a laboratory-made version of a natural signalling protein that prompts the bone marrow to produce neutrophils — a type of white blood cell — with a structural modification designed to keep it circulating longer than short-acting forms. This page is for educational purposes only and is not medical advice; consult a licensed physician for any question about a medical condition or treatment.

What Class of Molecule Is It?

Efbemalenograstim alfa belongs to the colony-stimulating factor class of recombinant protein therapeutics. Native human G-CSF is a signalling glycoprotein of roughly 175 amino acids that acts on progenitor cells in the bone marrow. Efbemalenograstim alfa is substantially larger: trial reports describe it explicitly as an Fc fusion protein, meaning the G-CSF portion is joined to the crystallisable fragment (Fc) region of an immunoglobulin, a common half-life-extension strategy in biologic engineering (PMID 41066031).

That distinction matters for anyone reading peptide literature. Short synthetic peptides are typically chain lengths of a few dozen residues or fewer and are often made by solid-phase synthesis. Efbemalenograstim alfa is a recombinant fusion protein produced by biotechnology manufacturing, not a synthetic peptide, and it is regulated as a biologic rather than as a research chemical. It is frequently encountered in peptide and protein-therapeutic reference lists because G-CSF sits at the boundary between "peptide hormone" and "protein drug" terminology.

Where the Name Comes From

The name follows international non-proprietary naming conventions. The -stim stem marks colony-stimulating factors (the same stem appears in filgrastim, lenograstim and pegfilgrastim), while the alfa designator distinguishes a particular recombinant glycosylation variant. The prefix efbemaleno- is the assigned distinguishing element. The literature also uses the development code F-627 interchangeably, particularly in earlier trial reports (PMID 39272058).

How the Term Is Used in Research

In published research the term appears in three main contexts:

• Oncology supportive care. Trials evaluated once-per-cycle administration for prophylaxis of chemotherapy-induced neutropenia in patients with breast cancer receiving myelotoxic regimens (PMID 39272058).
• Comparative biologics research. Studies used pegfilgrastim, another long-acting G-CSF, as the active comparator when assessing neutrophil support (PMID 38194162).
• Protein-engineering and pharmacokinetics literature. A phase I study characterised the pharmacokinetics, pharmacodynamics, safety and tolerability of the molecule in healthy Chinese participants in an open-label, single-centre design (PMID 41015990).

What the Published Literature Reports

The clinical evidence base runs from first-in-human pharmacology through randomised phase III work and pooled analyses. A phase I study reported on pharmacokinetics, pharmacodynamics, safety and tolerability of the long-acting rhG-CSF in healthy volunteers (PMID 41015990). At the phase II stage, researchers reported in a randomised, multicentre, open-label trial that efbemalenograstim alfa was not inferior to pegfilgrastim in providing neutrophil support in women with breast cancer undergoing myelotoxic chemotherapy (PMID 38194162), and a separate phase II randomised open-label trial examined the Fc fusion protein for reducing the risk of chemotherapy-induced neutropenia (PMID 41066031).

At the phase III stage, the study programme included a trial assessing the agent for reducing the risk of febrile neutropenia following chemotherapy (PMID 38103088) and a randomised, multicentre trial of once-per-cycle administration for prophylaxis of chemotherapy-induced neutropenia in patients with breast cancer (PMID 39272058). Two subsequent systematic reviews with meta-analysis pooled randomised controlled trial data on the safety and efficacy of efbemalenograstim alfa in chemotherapy-induced neutropenia (PMID 42153908, PMID 42400926).

Study Map

Adverse Events: What Studies Report

Tolerability was a stated endpoint across the development programme rather than an afterthought. The phase I report in healthy participants covered safety and tolerability alongside pharmacokinetic and pharmacodynamic measures (PMID 41015990). Two independent systematic reviews with meta-analysis specifically examined pooled safety as well as efficacy outcomes from randomised controlled trials of efbemalenograstim alfa in chemotherapy-induced neutropenia (PMID 42153908, PMID 42400926). Readers who want event-level detail — which adverse events occurred, at what frequency, and how they compared with the pegfilgrastim comparator arm — should read those pooled analyses and the individual phase II and phase III reports directly, since summary tables in the primary papers carry the specifics that a glossary entry cannot reproduce (PMID 38194162, PMID 38103088).

Regulatory Context

Efbemalenograstim alfa is a prescription biologic, not a research-use-only compound. The Drugs "First Approval" review documented its approval in 2023 for reducing the incidence of infection manifested by febrile neutropenia in adults with non-myeloid malignancies receiving myelosuppressive anticancer drugs (PMID 37368138). Because it is an approved biologic administered in a supervised oncology setting, decisions about its use sit entirely with treating clinicians; nothing on this page constitutes guidance about use.

Terms Often Seen Alongside It

• G-CSF / rhG-CSF — granulocyte colony-stimulating factor; the native signalling protein and its recombinant human forms.
• Fc fusion — an engineering approach in which a therapeutic protein is linked to an antibody Fc region, described in the trial literature for this molecule (PMID 41066031).
• Pegfilgrastim — the long-acting G-CSF used as the active comparator in randomised trials of efbemalenograstim alfa (PMID 38194162).
• Chemotherapy-induced neutropenia / febrile neutropenia — the clinical outcomes that the phase III programme was designed to address (PMID 38103088).
• F-627 — the development code used interchangeably with the non-proprietary name in earlier reports (PMID 39272058).

Summary of the Entry

Efbemalenograstim alfa is best understood as a half-life-extended recombinant G-CSF built on an Fc fusion scaffold and developed for once-per-cycle supportive care during myelosuppressive chemotherapy (PMID 37368138). Its evidence base spans first-in-human pharmacology, randomised phase II comparisons against pegfilgrastim, phase III neutropenia-prophylaxis trials and two pooled meta-analyses (PMID 41015990, PMID 38194162, PMID 39272058, PMID 42153908).

References

• Efbemalenograstim Alfa: First Approval (Drugs, 2023)
• Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability of Efbemalenograstim Alfa (F-627), a Novel Long-Acting rhG-CSF, in Healthy Chinese Participants: An Open-Label, Single-Center Phase I Study (Clinical Drug Investigation, 2025)
• Efbemalenograstim Alfa, an Fc Fusion Protein, Long-Acting Granulocyte Colony-Stimulating Factor for Reducing the Risk of Chemotherapy-Induced Neutropenia: Results of a Phase II Randomized, Multicenter, Open-Label Trial (Clinical Drug Investigation, 2025)
• Efbemalenograstim alfa not inferior to pegfilgrastim in providing neutrophil support in women with breast cancer undergoing myelotoxic chemotherapy: results of a phase 2 randomized, multicenter, open-label trial (Supportive Care in Cancer, 2024)
• Efbemalenograstim alfa, an Fc fusion protein, long-acting granulocyte-colony stimulating factor for reducing the risk of febrile neutropenia following chemotherapy: results of a phase III trial (Supportive Care in Cancer, 2023)
• A randomized, multicenter phase III study of once-per-cycle administration of efbemalenograstim alfa (F-627), a novel long-acting rhG-CSF, for prophylaxis of chemotherapy-induced neutropenia in patients with breast cancer (BMC Cancer, 2024)
• Safety and efficacy of efbemalenograstim alfa for chemotherapy-induced neutropenia: A systematic review and meta-analysis of randomized controlled trials (Journal of Oncology Pharmacy Practice, 2026)
• Safety and efficacy of Efbemalenograstim alfa for patients at risk for chemotherapy-induced neutropenia: A systematic review and meta-analysis (Pharmacology, 2026)