Immutep Limited (IMMP) shared encouraging results Monday from its Phase I study of IMP761, an experimental antibody that could represent a new approach to treating autoimmune diseases. The placebo-controlled, double-blind trial is testing the first-in-class LAG-3 agonist antibody in healthy participants, and so far, the data looks promising.
The single-ascending dose portion of the trial successfully completed testing at the 2.5 mg/kg and 7 mg/kg dose levels, with IMP761 continuing to show positive safety and efficacy results. Participants tolerated the treatment well, with no adverse reactions beyond mild intensity.
Long-Lasting Effects From a Single Dose
What's particularly interesting here is the durability of the effect. IMP761 demonstrated dose-dependent immunosuppressive activity, with significant and long-lasting inhibition of T-cell-mediated intradermal reactions to a strong foreign antigen measured at day 2, day 9, and day 23 after administration.
Dr. Frédéric Triebel, Chief Scientific Officer of Immutep, highlighted the significance: "We are excited to see IMP761 having a long-term immunosuppressive effect after a single injection...Encouragingly, our clinical progress with IMP761 has corresponded with increased external interest in this program."
Targeting a Multi-Billion Dollar Opportunity
The LAG-3 immune checkpoint (lymphocyte-activation gene-3) has emerged as a promising therapeutic target for various autoimmune diseases, including rheumatoid arthritis, Type 1 diabetes, and multiple sclerosis. IMP761 is the first LAG-3 agonist antibody developed to potentially treat these large and increasingly prevalent disorders, each representing multi-billion dollar markets.
How IMP761 Works Differently
The mechanism here is elegant. By enhancing the "brake" function of LAG-3 to silence dysregulated self-antigen-specific memory T cells, IMP761 is designed to target the root cause of autoimmune diseases and restore immune system balance rather than just suppressing symptoms.
LAG-3 expression on activated T cells shows high specificity for disease sites, particularly in regions characterized by chronic inflammation. This distinct characteristic suggests IMP761 may enable a more targeted therapeutic approach with fewer adverse effects compared to existing treatments that broadly suppress the immune system.
The company said the trial will continue as planned, with additional updates anticipated in the first half of 2026.
Immutep shares climbed 6.84% to $2.81 at the time of publication on Monday.
