Approved Afucosylated Antibody Therapeutics: Engineering, Mechanism, and Uses

The removal of core fucose from the Fc N-glycan of IgG1 monoclonal antibodies is a well-validated strategy to enhance effector functions, specifically antibody-dependent cellular cytotoxicity (ADCC) via improved binding to FcγRIIIa on natural killer (NK) cells. The intentional engineering of afucosylated antibodies, primarily through FUT8 gene knockout in CHO cell lines, has now translated into multiple regulatory approvals. These approvals confirm the clinical and commercial viability of glycoengineering technologies and provide case studies in optimizing Fc effector function for therapeutic outcomes.

This article summarizes the four monoclonal antibodies approved by at least one regulatory agency in the world, including the U.S. Food and Drug Administration (FDA), that are afucosylated through defined glycoengineering platforms.

1. Mogamulizumab (Poteligeo)

Target: CCR4
Indication: Mycosis fungoides (MF), Sézary syndrome (SS)
First Approval: Japan (2012)
Sponsor: Kyowa Kirin
Antibody Type: Humanized IgG1, afucosylated

Glycoengineering Strategy

Mogamulizumab is engineered using FUT8-knockout CHO cells. This eliminates the addition of core fucose to the Fc N-glycan, leading to enhanced ADCC by increasing the antibody’s affinity for FcγRIIIa on NK cells.

Clinical Rationale

CCR4 is an established therapeutic target in cutaneous T-cell lymphomas. The CCR4 receptor is highly expressed on malignant T cells in nearly all patients with Mycosis Fungoides and Sézary Syndrome, independent of disease stage or extent of skin and blood involvement. Mogamulizumab is a nonchemotherapeutic biologic therapy that selectively depletes CCR4+ T cells via enhanced ADCC. This mechanism enables targeted elimination of malignant cells while avoiding direct cytotoxic chemotherapy. The afucosylated Fc region is critical for maximizing NK cell–mediated cytotoxicity and therapeutic activity in this patient population.

2. Benralizumab (Fasenra)

Target: Interleukin-5 receptor alpha (IL-5Rα)
Indication: Severe eosinophilic asthma
First Approval: FDA (2017)
Sponsor: AstraZeneca
Antibody Type: Humanized IgG1, afucosylated

Glycoengineering Strategy

Benralizumab is also produced using FUT8-deficient CHO cells to generate an afucosylated Fc. This enhances its ability to mediate ADCC against IL-5Rα–expressing eosinophils and basophils.

Clinical Rationale

Eosinophils are key effector cells in the pathophysiology of eosinophilic asthma. Their activation, driven by upstream cytokines such as IL-5, IL-13, IL-25, and alarmins (e.g., TSLP, IL-33), leads to the release of cytotoxic granules, inflammatory mediators, and promotion of airway inflammation, mucus hypersecretion, and hyperreactivity. Elevated eosinophil counts are associated with an increased risk of asthma exacerbations and are implicated in both allergic and non-allergic eosinophilic inflammation.

Benralizumab is a humanized IgG1 monoclonal antibody that binds specifically to IL-5 receptor alpha (IL-5Rα) on eosinophils. Through afucosylation, it exhibits enhanced ADCC by increasing affinity to FcγRIIIa on NK cells, facilitating rapid and direct eosinophil depletion. While the mechanism of action in asthma is not definitively established, this receptor-targeted depletion of eosinophils is proposed to underlie its clinical effects in patients with severe eosinophilic asthma.

3. Inebilizumab (Uplizna)

Target: CD19
Indication: Neuromyelitis optica spectrum disorder (NMOSD)
First Approval: FDA (2020)
Sponsor: Horizon Therapeutics
Antibody Type: Humanized IgG1, afucosylated

Glycoengineering Strategy

Inebilizumab is expressed in a FUT8−/− CHO cell line, ensuring high levels of afucosylation. This improves FcγRIIIa engagement and ADCC efficiency, leading to the depletion of a broader B-cell population than CD20-targeted therapies.

Clinical Rationale

Immunoglobulin G4–related disease (IgG4-RD) is a chronic, immune-mediated condition characterized by infiltration of tissues with plasmablasts and plasma cells, leading to tumor-like inflammatory masses, organ enlargement, and fibrosis in multiple organs, including the pancreas, biliary tract, salivary glands, and lacrimal glands. The pathogenesis involves the expansion of CD19+ plasmablasts and plasma cells that secrete autoantibodies, cytokines, and chemokines, contributing to inflammation and progressive fibrotic tissue damage.

Inebilizumab (Uplizna) is a humanized, glycoengineered IgG1 monoclonal antibody that binds to CD19, a marker expressed throughout most stages of B-cell maturation, including on plasmablasts and some plasma cellsm, unlike CD20, which is lost at later stages. By targeting CD19+ cells, inebilizumab promotes antibody-dependent cellular cytolysis, resulting in the depletion of disease-driving B-cell subsets and a subsequent reduction in autoantibody production and proinflammatory signaling. Although the precise mechanism in IgG4-RD has not been definitively established, inebilizumab is the first approved therapy for this indication and represents a targeted approach to modulating pathogenic B-cell activity in IgG4-RD.

4. Belantamab Mafodotin (Blenrep)

Target: B-cell maturation antigen (BCMA)
Indication: Relapsed or refractory multiple myeloma
First Approval: FDA (2020) (withdrawn in 2022 from US market, but remains a key regulatory precedent)
Sponsor: GlaxoSmithKline
Antibody Type: Humanized IgG1, afucosylated antibody-drug conjugate (ADC)

Glycoengineering Strategy

The antibody portion of belantamab mafodotin is afucosylated using FUT8−/− CHO cells to enhance FcγRIIIa binding and ADCC. Although the main mechanism is cytotoxic payload delivery (monomethyl auristatin F), afucosylation is intended to contribute additional immune effector functionality.

Clinical Rationale

Belantamab mafodotin-blmf (Blenrep) is an antibody-drug conjugate (ADC) targeting B-cell maturation antigen (BCMA), a receptor universally expressed on malignant plasma cells in multiple myeloma. BCMA is implicated in cell survival and proliferation, making it a validated therapeutic target. Blenrep consists of an afucosylated humanized IgG1 monoclonal antibody specific for BCMA, conjugated via a non-cleavable maleimidocaproyl (mc) linker to monomethyl auristatin F (MMAF), a cytotoxic agent that disrupts microtubule polymerization. Upon binding to BCMA, the ADC is internalized, and MMAF is released intracellularly, inducing apoptotic cell death. In addition to direct cytotoxicity, the afucosylated antibody enhances FcγRIIIa binding, promoting antibody-dependent cellular cytotoxicity (ADCC) and facilitating immune-mediated clearance of tumor cells. This dual mechanism supports the therapeutic activity of belantamab mafodotin in relapsed or refractory multiple myeloma.

Afucosylated Antibody Production at Biointron

Biointron offers a rapid, high-quality afucosylated antibody production platform designed to support therapeutic antibody research and development. Using an engineered mammalian cell system, CHOK1BN-Fut8KO, Biointron provides afucosylated antibodies within 2-4 weeks, with verified fucose knockout and high reproducibility in expression quantity and quality.

CHOK1BN-Fut8KO Expression Platform

Biointron’s afucosylated antibody expression is based on a Fut8-knockout CHOK1BN host cell line. FUT8 is the enzyme responsible for adding core fucose to the N-glycan on Asn297 of the Fc region. Its removal enhances ADCC via increased FcγRIIIa affinity. The engineered CHOK1BN-Fut8KO line maintains productivity comparable to its fucosylated counterpart while reliably producing afucosylated antibodies.

This cell line is suitable for:

• Recombinant antibodies

• Bispecific formats

• Antibody-drug conjugates (ADCs)

• Custom Fc-engineered antibodies

Production Features and Quality Control

Biointron’s platform integrates high-throughput expression and quality monitoring:

• Timeline: 2-4 weeks, depending on complexity

• Purity: >95% (SDS-PAGE)

• Endotoxin: <1 EU/mg

• QC: SDS-PAGE, SEC-HPLC, and endotoxin testing by default; LC-MS and FcγRIIIa binding assays available upon request

• Formats: IgG, Fab, scFv, bispecific antibodies 

Summary of Approved Afucosylated Antibodies

Afucosylated antibodies now form a distinct regulatory and technological class of monoclonal therapeutics. For biotech companies and CROs working in antibody discovery and development, the ability to engineer, express, and characterize afucosylated antibodies is a strategic differentiator in the current therapeutic landscape.

References:

1. The Antibody Society. Therapeutic monoclonal antibodies approved or in regulatory review. (date accessed); www.antibodysociety.org/antibody-therapeutics-product-data

2. Kyowa Kirin. (2023). POTELIGEO® (mogamulizumab-kpkc). Poteligeohcp.com. https://www.poteligeohcp.com/

3. AstraZeneca. (2019). FASENRA® (benralizumab) for Severe Eosinophilic Asthma | For HCPs. Fasenrahcp.com. https://www.fasenrahcp.com/

4. Amgen. (2017). UPLIZNA® (inebilizumab-cdon). Upliznahcp.com. https://www.upliznahcp.com/

5. International Myeloma Foundation. (2021). BLENREP (belantamab mafodotin-blmf). International Myeloma Foundation. https://www.myeloma.org/blenrep-belantamab-mafodotin-blmf