Limited efficacy of a therapeutic anti-CD40 monoclonal antibody to inhibit activated CD4 T cell autoimmunity in vitro
Chelsea Gootjes, Jaap Jan Zwaginga, Tatjana Nikolic, Bart O. Roep
Abstract
Iscalimab is a nondepleting anti-CD40 monoclonal antibody, expected to suppress immune responses by blocking the costimulation by antigen-presenting cells through CD40-CD40L ligation. This therapeutic antibody indeed inhibited proliferation of B lymphocytes and TNF production by dendritic cells and is being tested in clinical trials to treat B cell mediated autoimmune diseases.
Introduction
Monoclonal antibodies are successfully used as immune therapy in different inflammatory diseases. There are more than 160 approved monoclonal antibodies used to treat tumors, organ transplantation, infectious diseases, and autoimmune diseases [1]. These include monoclonal antibodies against cytokines (e.g., anti-TNF; adalimumab, infliximab) or CD3 (e.g., teplizumab, otelixizumab), depleting monoclonal antibodies against CD20 (e.g., rituximab) and monoclonal antibodies interfering in cell-cell interactions (e.g., anti-CD25; daclizumab, anti-PD-1; nivolumab or pembrolizumab, and anti-CTLA4; ipilimumab).
Materials and method
2.1. Generation of monocyte-derived dendritic cells for antigen presentation
Buffy coat preparations from healthy adult peripheral blood were purchased from Sanquin (Sanquin Bloedvorziening, Amsterdam, The Netherlands), released for research under informed consent. Human peripheral blood mononuclear cells (PBMCs) were isolated from these buffy coats with Ficoll density gradient centrifugation.
Results
3.1. Anti-CD40 antibody binds to dendritic cells, monocytes and B cells but not to T cells
First, we analyzed whether the iscalimab biosimilar binds to T cells, using flow cytometry analysis. Dendritic cells, monocytes and B cells showed a strong and specific binding of the monoclonal antibody whereas, as expected, no binding was observed when incubated with T cells (Fig 1).
Discussion
Iscalimab, a CD40 antagonist, has been tested in clinical trials as a treatment for B cell and autoantibody mediated autoimmune diseases such as myasthenia gravis, primary Sjogren’s syndrome and SLE with limited clinical benefit, while a clinical trial in T1D was stopped [21–23]. In vitro studies have shown an effect of iscalimab on B cell proliferation and cytokine production by DCs, but antagonistic effects for T cell responses have not been reported so far.
Acknowledgments
We thank A.M. Joosten and L. van den Broeke for technical assistance.
Citation: Gootjes C, Zwaginga JJ, Nikolic T, Roep BO (2026) Limited efficacy of a therapeutic anti-CD40 monoclonal antibody to inhibit activated CD4 T cell autoimmunity in vitro. PLoS One 21(6): e0351131. https://doi.org/10.1371/journal.pone.0351131
Editor: Srinivasa Reddy Bonam, Indian Institute of Chemical Technology, INDIA
Received: December 18, 2025; Accepted: May 21, 2026; Published: June 12, 2026
Copyright: © 2026 Gootjes et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: The raw data supporting the conclusions of this article have been uploaded as supporting information.
Funding: The authors are supported by Stichting DON. BOR is supported by the European Research Council (ERC-AdG 101200304). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
