AbolerIS Pharma Announces Publication in Molecular Therapy Cell Press Journal of New Preclinical Results Supporting Mechanism of Action of ABO21009, a First-in-Class Anti-CD45RC Antibody, Currently in Phase 1
-Results highlight the potential to transform treatment of autoimmune diseases, organ transplant rejection and GVHD-
GOSSELIES, Belgium and NANTES, France, Nov. 12, 2025 /PRNewswire/ -- AbolerIS Pharma ("AbolerIS"), a clinical-stage biopharmaceutical company committed to improving the lives of people suffering from autoimmune diseases, today announced the publication of new preclinical findings describing the mechanism of action of its first-in-class therapeutic antibody, ABO21009, a humanized monoclonal antibody targeting CD45RC, a novel immune cell surface protein implicated in pathogenic T and B cell activity. The study, conducted in collaboration with Nantes Université, INSERM, and the Center for Research in Transplantation and Translational Immunology, was published in Molecular Therapy, a Cell press journal, and provides the first detailed description of how anti-CD45RC antibodies selectively deplete disease-driving immune cells while sparing T regulatory cells.
"We are pleased to be recognized by Molecular Therapy for our groundbreaking work targeting CD45RC. These results define the mechanism of action of a new class of immunotherapies that modulate the immune system with unprecedented selectivity," said Carole Guillonneau, Ph.D., Head of Research of AbolerIS Pharma. "By targeting CD45RC, ABO21009 can eliminate the drivers of autoimmune disease while sparing protective regulatory cells—a profile that could fundamentally reshape the way we treat chronic immune-mediated inflammatory disorders."
Key preclinical findings published:
- Selective immune modulation — The study demonstrates that anti-CD45RC monoclonal antibodies, including AbolerIS's clinical candidate ABO21009, selectively induce apoptosis and antibody-dependent cellular phagocytosis (ADCP) in pathogenic CD45RChigh T and B cells without activating cytokine release, and without depleting T regulatory (Treg) and memory cells.
- Novel mechanism of action — Unlike conventional T or B cell–depleting therapies, ABO21009 acts through a dual mechanism—direct apoptosis and macrophage-mediated phagocytosis—without triggering antibody-dependent cellular cytotoxicity (ADCC) or complement activation, minimizing the risk of cytokine release syndrome.
- In vivo proof-of-concept — In humanized mouse models of acute graft-versus-host disease (aGvHD), ABO21009 showed a dose-dependent depletion of pathogenic immune cells with prevention of disease progression, establishing a minimal effective dose and confirming selective immune modulation.
- Favorable safety profile — Single-cell transcriptomics confirmed that ABO21009 spares beneficial immune cell subsets and does not elicit inflammatory cytokine responses, underscoring its potential for durable disease control with improved tolerability compared to broad immunosuppressants.
The publication can be found online here:
Current immunotherapies often suppress the immune system broadly, leading to toxicity and increased infection risk. ABO21009 introduces a novel therapeutic paradigm: precise depletion of pathogenic immune cells while preserving immune balance and long-term tolerance. This approach may offer a higher rate of durable remission in patients with autoimmune diseases.
"These findings validate CD45RC as a powerful new target for immune modulation," said Dr. Ann Meulemans, Ph.D., CEO of AbolerIS. "Our preclinical data position ABO21009 as a transformational first-in-class candidate that could redefine treatment for autoimmune and inflammatory diseases."
In March 2025, AbolerIS began dosing of healthy volunteers under an authorized Clinical Trial Application (CTA) for a first-in-human Phase 1 study of ABO21009. Dr. Ronald van Brempt, MD, CMO of AbolerIS, mentions that a milestone has been reached. "Building on the highly encouraging safety and PK/PD results of the healthy volunteer part of the study, we can now start dosing the first patients suffering from Rheumatoid Arthritis (RA). Pending clinical proof-of-concept in RA, the Company intends to broaden its development into other autoimmune diseases."
About ABO21009
ABO21009 is the Company's lead monoclonal antibody program stemming from its novel immunomodulatory approach to treating autoimmune and inflammatory diseases. ABO21009 is effective through a multi-pronged mechanism of action, selectively depleting CD45RChigh cells that are actively sustaining the autoimmune response in Rheumatoid Arthritis and other autoimmune diseases. These CD45RChigh cells are present in the T-, B-, NK-, and pDC-cell compartments of the adaptive immune system. By selectively depleting these effector cells, the driving culprits of the autoimmune disease are taken out of the immune cell population.
ABO21009 also spares regulatory T cells, which can unleash their full potential and suppress ongoing and future autoimmune activity in the adaptive immune system: previous experimental work uncovered this switch to a deep immunosuppressive phenotype in both CD4+ and CD8+ T regulatory cells, enabling long term tolerance. Treatment with ABO21009 may induce more frequent and long-lasting remissions in RA and other autoimmune diseases, with improved patient reported outcomes on both safety and efficacy sides in comparison to currently available therapeutic options.
About AbolerIS Pharma
AbolerIS Pharma is a clinical-stage biopharmaceutical company committed to improving the lives of patients suffering from autoimmune and inflammatory diseases. The Company is advancing potentially best-in-class and first-in-class immunomodulatory antibodies that target CD45RC, a key regulator of the immune system. AbolerIS' lead program, ABO21009, is designed to demonstrate broad efficacy in multiple autoimmune and inflammatory disorders with large unmet medical needs including rheumatoid arthritis (RA), inflammatory bowel disease (IBD), and organ transplantation.
At AbolerIS, we envision a future where patients can enjoy long-term remission and improved quality of life through therapies that are effective and safe. The Company is based in Gosselies, Belgium and Nantes, France, and is backed by a syndicate of experienced investors, which includes Criteria Bio Ventures, Invested Tech, Sound Bioventures, Newton Biocapital, WE, Sambrinvest, SFPIM and Sham Innovation Santé.
For more information, please visit www.aboleris-pharma.com or follow us on LinkedIn to learn more about our transformative approach to immunotherapies.
Company Contact
Dr. Ann Meulemans, CEO Aboleris
+32479900357
[email protected]
Media & Investor Contact
Amy Conrad
Juniper Point
[email protected]
SOURCE AbolerIS Pharma
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