Immutep Announces Positive Update on IMP761, a First-in-Class LAG-3 Agonist Antibody for Autoimmune Diseases, from Phase I Study

Rhea-AI Summary

Immutep (NASDAQ: IMMP / ASX: IMM) reported a positive Phase I update for IMP761, a first-in-class LAG-3 agonist antibody for autoimmune diseases.

The single-ascending dose portion completed 2.5 mg/kg and 7 mg/kg cohorts with a favourable safety profile and no treatment-related adverse reactions beyond mild intensity. Dose-dependent immunosuppression was observed with significant, durable inhibition of three T-cell-mediated intradermal reactions at days 2, 9 and 23. The company said a PK/PD relationship was established between 1 and 7 mg/kg.

The trial will continue as planned and additional updates, including a possible presentation at a major medical conference, are anticipated in 1H CY2026.

Positive

• Completed single-ascending doses at 2.5 mg/kg and 7 mg/kg
• Dose-dependent immunosuppression with inhibition at days 2, 9, 23
• Established PK/PD relationship between 1 and 7 mg/kg
• No treatment-related adverse reactions beyond mild intensity

Negative

• Data from healthy participants, not autoimmune patients
• Results limited to single-ascending dose; multiple-dose effects unknown

Key Figures

IMP761 dose level 2.5 mg/kg Single-ascending dose Phase I in healthy participants

IMP761 dose level 7 mg/kg Single-ascending dose Phase I in healthy participants

Participants per dose group 8 participants Phase I pharmacokinetic/pharmacodynamic assessment between 1 and 7 mg/kg

Assessment days Days 2, 9 and 23 Follow-up for T-cell-mediated intradermal reactions after single IMP761 dose

Net loss FY2025 A$61.4 million Fiscal year ended June 30, 2025 (Form 20-F)

Net loss FY2024 A$42.7 million Fiscal year ended June 30, 2024 (Form 20-F)

Upfront payment USD 20 million Eftilagimod alfa licensing deal with Dr. Reddy’s on Dec 8, 2025

Milestone potential USD 349.5 million Regulatory and commercial milestones from Dr. Reddy’s collaboration

Market Reality Check

$2.95 Last Close

Volume Volume 359,456 is well below 20-day average 1,779,138 with relative volume at 0.2 before this update. low

Technical Shares traded above 200-day MA of 1.81, sitting 25.49% below the 52-week high and 99.24% above the 52-week low pre-news.

Peers on Argus 1 Up

Pre-update, IMMP showed a small gain of 0.38% while peers were mixed (e.g., ACIU +2.02%, EDIT -1.27%, HUMA -1.6%). Only NMRA appeared in momentum scans, up 5.71% without news, suggesting this IMMP catalyst is stock-specific rather than a broad biotech move.

Historical Context

Date	Event	Sentiment	Move	Catalyst
Dec 16	Phase III progress	Positive	+2.0%	Update on TACTI-004 Phase III enrolment, sites and upcoming futility analysis.
Dec 08	Licensing deal	Positive	+26.1%	Exclusive efti collaboration with Dr. Reddy’s including upfront and milestone payments.
Dec 02	Phase II breast data	Positive	-7.1%	AIPAC-003 Phase II breast cancer data and dose selection after FDA Project Optimus.
Nov 13	Sarcoma Phase II data	Positive	+2.8%	EFTISARC-NEO Phase II sarcoma results with significant tumor fibrosis and biomarker changes.
Nov 03	R&D tax incentive	Positive	-3.2%	Receipt of French R&D tax incentive cash inflow to support clinical development.

Pattern Detected

Recent news flow has been largely positive, with three clinical/partnership updates seeing positive next-day moves and two positive items sold off, indicating mixed follow-through on good news.

Recent Company History

Over the last few months, Immutep has reported multiple positive milestones across its LAG‑3 pipeline. Key updates include strong operational progress in the Phase III TACTI‑004/KEYNOTE‑F91 NSCLC trial on Dec 16, a lucrative global licensing deal for efti outside major markets on Dec 8, and several Phase II readouts in breast cancer and soft tissue sarcoma. A French R&D tax incentive on Nov 3 added non-dilutive funding. Today’s IMP761 Phase I data extends this sequence into autoimmune diseases.

Market Pulse Summary

This announcement reported favorable Phase I data for IMP761, showing dose-dependent immunosuppressive effects and a mild safety profile at up to 7 mg/kg, extending Immutep’s LAG‑3 pipeline beyond oncology into autoimmune disease. In recent months the company also advanced efti through multiple Phase II readouts and a Phase III program, while recording a net loss of A$61.4 million in FY2025. Investors may watch for 1H CY2026 updates and broader pipeline progress.

Key Terms

lag-3 medical

"IMP761, a first-in-class LAG-3 agonist antibody for autoimmune diseases."

A protein found on certain immune cells that acts like a brake, helping control how aggressively the immune system attacks threats such as cancer. Drugs that block or modify LAG-3 can release that brake, potentially enabling stronger anti‑cancer responses; because such treatments can change patient outcomes and open new markets, LAG-3-related data, approvals, or setbacks often have big effects on a biotech or pharmaceutical company’s valuation.

agonist antibody medical

"IMP761, a first-in-class LAG-3 agonist antibody for autoimmune diseases."

An agonist antibody is a laboratory-made protein that binds to a specific cell surface receptor and activates it, mimicking the effect of a natural signaling molecule. For investors, these drugs matter because they can stimulate desired biological pathways (for example, boosting an immune response) and therefore represent potential therapeutic value; their ability to trigger activity rather than block it affects clinical use, development risk, and market opportunity.

immune checkpoint medical

"The LAG-3 (lymphocyte-activation gene-3) immune checkpoint has been identified..."

Immune checkpoints are molecules on immune cells that act like brakes, helping prevent the immune system from attacking healthy tissue. Drugs that block or modulate these checkpoints can release those brakes to boost the body’s ability to fight cancer or infections, but they can also increase the risk of immune side effects. Investors watch progress on checkpoint-targeting therapies because clinical trial results, approvals, and safety profiles strongly influence a drug’s commercial potential and company value.

pharmacokinetic/pharmacodynamic medical

"A solid pharmacokinetic/pharmacodynamic relationship has now been established..."

Pharmacokinetic/pharmacodynamic (PK/PD) describes two linked ideas: pharmacokinetics is how a drug moves through the body (how fast it’s absorbed, spread, broken down and eliminated) and pharmacodynamics is how the drug affects the body (the relationship between dose and response). Investors care because strong, predictable PK/PD data reduce uncertainty about effective dosing, safety and likelihood of regulatory approval—similar to knowing a car’s fuel efficiency and braking before buying, which lowers the risk of a costly surprise.

intradermal medical

"inhibition of the three T-cell-mediated intradermal reactions to a strong foreign antigen..."

Intradermal means delivering a drug or vaccine into the middle layer of the skin rather than into muscle or under the skin. Investors care because this delivery route can change how much of a product is needed, how fast it works, and what safety or regulatory testing is required—similar to placing a small patch inside the layers of a cake to get a different effect than spreading it on top.

AI-generated analysis. Not financial advice.

• Single-ascending dose portion of study has successfully completed 2.5 and 7 mg / kg levels
  
  
• Dose dependent immunosuppressive effect against a strong foreign antigen observed with continued favourable safety profile
  
  
• Substantial reduction in T cell activity highlights the potential efficacy of IMP761 in treating autoimmune diseases
  
  
• Given encouraging efficacy and safety, the trial will continue as planned and further updates are anticipated in 1H CY2026 including presentation of data at a major medical conference
  
  

 SYDNEY, AUSTRALIA, Dec. 22, 2025 (GLOBE NEWSWIRE) -- Immutep Limited (ASX: IMM; NASDAQ: IMMP) (“Immutep” or “the Company”), a late-stage immunotherapy company targeting cancer and autoimmune diseases, today announces a positive update from the placebo-controlled, double-blind first-in-human Phase I study in healthy participants evaluating IMP761, a first-in-class LAG-3 agonist antibody for autoimmune diseases.

The single-ascending dose escalation portion of the trial has successfully completed the 2.5 and 7 mg / kg dosing levels of IMP761 with continued positive safety and efficacy data. IMP761 was tolerated well with no treatment-related adverse reactions beyond mild intensity. Additionally, evidence of dose dependent immunosuppressive effects with IMP761 was observed with significant, long-lasting inhibition of the three T-cell-mediated intradermal reactions to a strong foreign antigen at day 2, 9 and 23.

Dr. Frédéric Triebel, CSO of Immutep, said: “We are excited to see IMP761 having a long-term immunosuppressive effect after a single injection. A solid pharmacokinetic/pharmacodynamic relationship has now been established between 1 and 7 mg/kg with eight participants per group to cover the variability of the responses. This novel immunotherapy’s significant level of immune suppression combined with its favourable safety provide proof-of-concept data in its potential to silence the dysregulated T cells at the epicenter of many autoimmune diseases. Encouragingly, our clinical progress with IMP761 has corresponded with increased external interest in this program.”

The LAG-3 (lymphocyte-activation gene-3) immune checkpoint has been identified as a promising therapeutic target for many autoimmune diseases, including rheumatoid arthritis, Type 1 diabetes, and multiple sclerosis.^1-3 IMP761 is the first LAG-3 agonist antibody developed to potentially treat these large, increasingly prevalent disorders, each of which represent multi-billion dollar markets.

By enhancing the “brake” function of LAG-3 to silence dysregulated self-antigen-specific memory T cells, IMP761 is designed to target the cause of autoimmune diseases and restore balance to the immune system. LAG-3 expression on activated T cells demonstrates high specificity for disease sites, especially in regions characterised by chronic inflammation. This distinct characteristic of the LAG-3 immune checkpoint suggests IMP761 may enable a more targeted therapeutic approach with fewer adverse effects compared to other treatments.

Given the encouraging efficacy and safety to date, the trial will continue as planned and additional updates are anticipated in the first half of CY2026 including a potential presentation of data at a major medical conference in the field of autoimmune diseases.

About IMP761
IMP761, a first-in-class immunosuppressive lymphocyte-activation gene-3 (LAG-3) agonist antibody, has the potential to address the root cause of many autoimmune diseases by specifically silencing autoimmune memory T cells that accumulate at disease sites and restoring balance to the immune system. As published in the Journal of Immunology, encouraging pre-clinical in vivo and in vitro studies show IMP761 inhibits peptide-induced T cell proliferation, activation of human primary T cells, and an antigen-specific delayed-type hypersensitivity (DTH) reaction.⁴ Additional preclinical data in oligoarticular juvenile idiopathic arthritis (o-JIA) published in Pediatric Research details how IMP761 led to a decrease in a broad spectrum of effector cytokines.⁵ This study also shows children with o-JIA have a skewed LAG-3 metabolism and suggests they can benefit from agonistic LAG-3 activity.

About Immutep
Immutep is a late-stage biotechnology company developing novel immunotherapies for cancer and autoimmune disease. The Company is a pioneer in the understanding and advancement of therapeutics related to Lymphocyte Activation Gene-3 (LAG-3), and its diversified product portfolio harnesses LAG-3’s ability to stimulate or suppress the immune response. Immutep is dedicated to leveraging its expertise to bring innovative treatment options to patients in need and to maximise value for shareholders. For more information, please visit www.immutep.com.

<sub>1. Pedersen, J.M., Hansen, A.S., Skejø, C. et al. Lymphocyte activation gene 3 is increased and affects cytokine production in rheumatoid arthritis. Arthritis Res Ther 25, 97 (2023). https://doi.org/10.1186/s13075-023-03073-z
2. Jones BE, Maerz MD et al. Fewer LAG-3+ T Cells in Relapsing-Remitting Multiple Sclerosis and Type 1 Diabetes. J Immunol. 2022 Feb 1;208(3):594-602. doi: 10.4049/jimmunol.2100850. Epub 2022 Jan 12. PMID: 35022272; PMCID: PMC8820445.
3. Zhou X, Gu Y et al. From bench to bedside: targeting lymphocyte activation gene 3 as a therapeutic strategy for autoimmune diseases. Inflamm Res. 2023 Jun;72(6):1215-1235. doi: 10.1007/s00011-023-01742-y. Epub 2023 Jun 14. PMID: 37314518.
4. Mathieu Angin, Chrystelle Brignone, Frédéric Triebel; A LAG-3–Specific Agonist Antibody for the Treatment of T Cell–Induced Autoimmune Diseases. J Immunol 15 February 2020; 204 (4): 810–818. https://doi.org/10.4049/jimmunol.1900823
5. Sag, E., Demir, S., Aspari, M. et al. Juvenile idiopathic arthritis: lymphocyte activation gene-3 is a central immune receptor in children with oligoarticular subtypes. Pediatr Res 90, 744–751 (2021). https://doi.org/10.1038/s41390-021-01588-2</sub>

Australian Investors/Media:
Eleanor Pearson, Sodali & Co.
+61 2 9066 4071; eleanor.pearson@sodali.com

U.S. Investors/Media:
Chris Basta, VP, Investor Relations and Corporate Communications
+1 (631) 318 4000; chris.basta@immutep.com

FAQ

What did Immutep announce about IMP761 on December 22, 2025 (IMMP)?

Immutep announced positive Phase I results: completed 2.5 and 7 mg/kg cohorts with dose-dependent immunosuppression and favourable safety.

What safety findings were reported for IMP761 (IMMP) in the Phase I study?

IMP761 was well tolerated with no treatment-related adverse reactions beyond mild intensity reported.

How long did IMP761 immunosuppressive effects last in the Phase I trial (IMMP)?

Significant inhibition of T-cell reactions was observed at days 2, 9 and 23 after a single injection.

Which dosing levels of IMP761 (IMMP) completed in the single-ascending dose portion?

The single-ascending dose portion successfully completed the 2.5 mg/kg and 7 mg/kg cohorts.

When will Immutep provide the next IMP761 clinical update and could data be presented at a conference?

Additional updates are anticipated in 1H CY2026, including a potential presentation at a major autoimmune diseases conference.

Does the Phase I IMP761 data prove efficacy in autoimmune patients (IMMP)?

No; current data are from healthy participants and do not demonstrate efficacy in autoimmune patients.