Strong Fcγ Receptor Binding in Antibody Therapeutics Linked to Anaphylaxis Risk
Researchers from Chiba University and Tokyo University of Science have identified a potential mechanism linking the binding affinity of antibody therapeutics to Fcγ receptors on immune cells with the development of antidrug antibodies (ADAs) and severe allergic reactions such as anaphylaxis.
The study, published on March 4, 2026, in the Journal for ImmunoTherapy of Cancer, suggests that antibody drugs with stronger Fcγ receptor binding are more likely to trigger an immune response, leading to increased ADA production and potentially anaphylaxis.
Understanding Antibody Therapeutics
Antibody therapeutics are laboratory-made proteins designed to mimic natural antibodies, widely utilized in treating various diseases, including cancer. Despite their therapeutic benefits, the body can sometimes develop antidrug antibodies (ADAs) against these treatments. The production of ADAs can lead to severe allergic reactions, including anaphylaxis, a condition whose precise underlying mechanisms have not been fully understood.
Key Research Findings
The research team, including Professor Hiroto Hatakeyama and Dr. Ruiheng Tang from Chiba University, and Dr. Kyohei Higashi from Tokyo University of Science, investigated the interaction between antibody therapeutics and Fcγ receptors on immune cells.
Their findings indicate that antibody drugs with a stronger binding affinity to Fcγ receptors are more frequently identified as foreign by the immune system, which contributes to increased ADA production.
Experimental EvidenceExperiments were conducted using tumor-bearing mice to evaluate two programmed death-ligand 1 (PD-L1) targeting antibodies:
- 10F.9G2: This antibody demonstrated strong Fcγ receptor binding. Its administration resulted in rapid and fatal anaphylaxis in all tested mice, accompanied by a significant increase in ADA levels.
- MIH6: In contrast, this PD-L1 targeting antibody exhibited a lower Fcγ receptor binding affinity. It did not induce anaphylaxis and showed minimal ADA production.
To further validate these observations, modified versions of 10F.9G2 were engineered with reduced Fcγ receptor binding. These modified antibodies did not trigger anaphylaxis and were associated with low ADA production, reinforcing the role of strong Fcγ receptor interactions in the immune response.
Proposed Mechanism and Clinical Correlation
The study proposes that tumor-associated myeloid cells may play a role in this process. These cells could capture antibodies that exhibit strong Fcγ receptor binding, subsequently leading to immune activation and promoting ADA production.
"Blocking Fcγ receptors was observed to significantly reduce this antibody capture by immune cells, which resulted in lower ADA levels and improved survival rates in the mouse models."
Further analysis of clinical data from the Food and Drug Administration Adverse Events Reporting System database supported these findings. Antibody drugs with stronger Fcγ receptor binding or higher antibody-dependent cellular cytotoxicity activity were more frequently associated with reported cases of anaphylaxis.
Implications for Therapy Development
This research provides insights into how antibody therapeutics may be linked to anaphylaxis, highlighting a potential connection between Fcγ receptor binding, ADA production, and immune reactions.
While the study was conducted using a tumor model, the findings are expected to contribute to a better understanding of the causes of anaphylaxis in clinical settings and to guide the development of safer antibody therapies.