Immutep’s First-in-Human Autoimmune Drug Clears Safety Bar With Phase I Win
Immutep hits pivotal Phase I milestone as IMP761 data turns heads at EULAR 2026
Immutep Limited (ASX: IMM) presented first-in-human clinical data for IMP761 at the European Alliance of Associations for Rheumatology (EULAR) Congress in London on 4 June 2026, marking a significant public debut for the company’s lead autoimmune candidate. The Phase I study met its primary endpoint in the single ascending dose portion, confirming favourable safety and tolerability in healthy volunteers. IMP761 is described as a first-in-class LAG-3 agonist antibody and remains the only LAG-3 agonist currently in clinical development.
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What the Phase I data actually showed
Primary endpoint met with clean safety profile
The study is a randomised, placebo-controlled, double-blind first-in-human trial (NCT06637865) conducted by the Centre for Human Drug Research (CHDR) in Leiden, the Netherlands. IMP761 was reported as safe and very well tolerated across all dose levels tested, ranging from 0.9 mg/kg to 7 mg/kg.
Pharmacokinetic data from single ascending doses indicates that IMP761 may support once per 4-week dosing, a clinically convenient dosing interval that could ease administration in future indication development programmes.
Statistically significant pharmacodynamic activity
To assess IMP761’s pharmacological activity early in development, the study employed CHDR’s keyhole limpet haemocyanin (KLH) challenge model. KLH is a validated human immune response model that uses a foreign protein to trigger a controlled, measurable immune reaction in healthy volunteers, allowing researchers to evaluate how a drug modulates immune activity before progressing to patient populations.
The key efficacy signals observed across cohorts were:
- Reduction of local inflammatory responses versus placebo
- Attenuated T-cell activity across dose cohorts
- At 7 mg/kg, a statistically significant improvement in skin blood perfusion versus placebo (p = 0.029)
The placebo-controlled, double-blinded design strengthens the credibility of these findings, reducing the potential for bias in interpreting the pharmacodynamic results.
Dr. Frédéric Triebel, Chief Scientific Officer, Immutep
“I am very excited about this first clinical evaluation of IMP761. IMP761 is designed to selectively target overactive T cells linked to chronic inflammation and is now showing clear immunosuppressive effects at dose levels above 0.9 mg/kg in this placebo controlled Phase I study.”
Understanding LAG-3 agonism — why this mechanism matters for autoimmune disease
LAG-3 (Lymphocyte Activation Gene-3) is a receptor found on the surface of T cells, the white blood cells that direct the body’s immune response. In healthy individuals, LAG-3 helps regulate immune activity. In autoimmune disease, T cells become overactive and mistakenly attack the body’s own tissues.
There are two fundamentally different ways to target LAG-3, and the distinction matters considerably for investors evaluating Immutep’s pipeline:
| Feature | LAG-3 Antagonist | LAG-3 Agonist (IMP761) | Disease Target |
|---|---|---|---|
| Immune action | Releases the brakes on the immune system | Applies the brakes on overactive immune cells | Autoimmune diseases |
| Effect on T cells | Activates / disinhibits T cells | Suppresses overactive T cells | T-cell driven inflammation |
| Clinical use case | Oncology (boost immune attack on tumours) | Autoimmunity (dampen pathological immune response) | Rheumatoid arthritis, others |
| Immutep asset | Eftilagimod alpha (cancer pipeline) | IMP761 | Autoimmune pipeline |
IMP761’s design targets activated T cells specifically at sites of inflammation, aiming to reduce pathological immune responses while preserving broader systemic immune function. This selectivity differentiates it from conventional immunosuppressants, which typically dampen the entire immune system and carry broader side effect profiles.
Preclinical data supporting IMP761’s mechanism have been published in the Journal of Immunology, with additional supporting data in oligoarticular juvenile idiopathic arthritis published in Pediatric Research, providing independent scientific validation of the approach. As the only LAG-3 agonist currently in clinical development, IMP761 holds a potential first-mover position in what could become a distinct therapeutic class.
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What comes next — and why investors should watch H2 CY2026
The company has confirmed that additional trial updates are expected in H2 CY2026, representing a near-term catalyst for investors monitoring the programme’s progress. The data presented at EULAR support further evaluation of IMP761 in a Phase II setting, with the CSO specifically citing rheumatoid arthritis and other T-cell driven conditions as potential target indications.
CEO Marc Voigt also pointed to broader commercial optionality in his commentary on the results:
Marc Voigt, Chief Executive Officer, Immutep
“These first-in-human results are a pivotal milestone for Immutep and for the broader field of LAG-3 biology in autoimmunity… the program supports further clinical evaluation and potential strategic collaboration.”
The reference to “potential strategic collaboration” signals that business development discussions around IMP761 may be a component of the company’s near-term planning.
Key items for investors to monitor include:
- Phase II design and indication selection announcements
- Additional Phase I cohort data from the multiple ascending dose portion of the study
- Any partnership or licensing discussions tied to IMP761
- Further congress presentations — the EULAR poster is available on Immutep’s website
Immutep’s broader platform spans both oncology and autoimmune disease, with its LAG-3 expertise deployed across two distinct therapeutic strategies. The IMP761 results add clinical weight to the autoimmune arm of that dual pipeline, at a stage where verifiable human data carry considerably more weight than preclinical evidence alone.
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