Immutep Reports Positive Phase I Results for IMP761 in Autoimmune Disease

Immutep has reported encouraging first-in-human Phase I results for IMP761, its lead autoimmune candidate and the only LAG-3 agonist currently in clinical development. Findings presented at the European Alliance of Associations for Rheumatology (EULAR) Congress 2026 in London showed favorable safety, tolerability, and statistically significant pharmacodynamic activity in healthy volunteers, providing the first clinical validation of LAG-3 agonism in autoimmune disease.

The data mark an important milestone for the company’s autoimmune portfolio and support further development of IMP761 in T-cell-driven inflammatory disorders.

Novel LAG-3 Agonism in Autoimmune Disease

IMP761 is a first-in-class LAG-3 agonist antibody that suppresses activated T cells involved in chronic inflammation. By selectively dampening pathological immune responses, the therapy could offer a targeted alternative to broad immunosuppressive approaches commonly used in autoimmune diseases.

Many autoimmune disorders, including rheumatoid arthritis and juvenile idiopathic arthritis, are driven by dysregulated T-cell activity. Through activation of the LAG-3 checkpoint pathway, IMP761 may help restore immune balance while preserving broader immune function.

Phase I Data Validate Safety and Biological Activity

The ongoing randomized, placebo-controlled, double-blind Phase I study (NCT06637865) is being conducted at the Centre for Human Drug Research (CHDR) in the Netherlands. Investigators are evaluating IMP761 in healthy volunteers using CHDR’s validated keyhole limpet hemocyanin (KLH) challenge model, which provides an established method for assessing immune responses and pharmacological activity early in clinical development.

The single ascending dose portion of the study met its primary endpoint, demonstrating favorable safety and tolerability across all evaluated dose levels ranging from 0.9 mg/kg to 7 mg/kg.

IMP761 reduced local inflammatory responses and dampened T-cell activity across evaluated dose cohorts, providing early evidence of biological activity in humans. The strongest effect was observed at the 7 mg/kg dose, where IMP761 produced a statistically significant attenuation of KLH-induced skin blood perfusion changes compared with placebo (p=0.029).

Pharmacokinetic findings also supported a once-every-four-weeks dosing schedule, which could offer a convenient administration approach in future studies.

Collectively, the findings provide early proof-of-mechanism for IMP761 and support its potential use across multiple autoimmune diseases driven by T-cell-mediated inflammation.

Clinical Significance

Chief Scientific Officer Dr. Frédéric Triebel said the study demonstrated clear immunosuppressive activity at doses above 0.9 mg/kg, validating IMP761’s biological activity in a controlled clinical setting. He noted that the therapy could have broad applicability across autoimmune diseases characterized by excessive T-cell activation.

Dr. Matthijs Moerland, Research Director at CHDR and Principal Investigator of the study, said the results support continued clinical development and highlight the potential of targeted immunomodulatory therapies to restore immune balance without broadly compromising immune function.

Path Forward

Immutep plans to provide additional updates from the Phase I program during the second half of 2026. The favorable safety, pharmacodynamic, and pharmacokinetic findings support advancement into Phase II studies and further evaluation of IMP761 across autoimmune diseases driven by T-cell-mediated inflammation.

Reference

Immutep | LAG-3 Immunotherapy for Cancer & Autoimmune Disease