Experimental MS therapy reinforces ‘brakes’ on overactive T-cells
IMP761 is being tested in healthy adults as part of first-in-human Phase 1 study
- Experimental therapy IMP761 for multiple sclerosis shows favorable safety results
- Treatment suppresses overactive T-cells, reducing immune responses for weeks
- IMP761 reinforces the LAG-3 receptor, the natural 'brakes' on the immune system
Immutep’s experimental immunotherapy, IMP761, continues to demonstrate a favorable safety profile, along with sustained suppression of T-cell activity, immune cells that are overly active in multiple sclerosis (MS) and other autoimmune diseases.
These findings are based on data from healthy people enrolled in an ongoing first-in-human Phase 1 trial (NCT06637865), who received single doses of IMP761 at either 2.5 or 7 mg/kg.
The trial is being conducted at a single site in the Netherlands and is expected to enroll up to 79 healthy adults. Its main goal is to assess the safety, tolerability, and pharmacological properties of IMP761 when administered into a vein, or intravenously, at increasing dose levels, either as a single dose or multiple doses over time.
Earlier results from participants who received a single 0.9 mg/kg dose showed no treatment-related side effects, allowing the researchers to continue testing higher doses, with doses planned to reach up to 14 mg/kg.
“We are excited to see IMP761 having a long-term immunosuppressive effect after a single injection.” Frédéric Triebel, MD, PhD, Immutep’s CEO, said in a company press release. A solid relationship between the dose given and its effects in the body “has now been established between 1 and 7 mg/kg with eight participants per group to cover the variability of the responses,” Treibel said.
MS is an autoimmune disease wherein the immune system mistakenly attacks and damages healthy parts of the brain and spinal cord. Several types of immune cells are involved in this process, including T-cells.
What does IMP761 do in MS?
IMP761 is an antibody designed to activate the lymphocyte-activation gene-3 (LAG-3) receptor on the surface of activated T-cells. LAG-3 acts as a natural brake on the immune system, helping to prevent immune cells from mounting overly strong responses. By reinforcing the “brake” function of LAG-3, IMP761 should calm overactive T-cells and prevent them from attacking healthy tissues.
The Phase 1 study is assigning healthy adults to randomly receive either IMP761 or a placebo. Some participants are also given a small skin injection of keyhole limpet haemocyanin (KLH), a protein that triggers a temporary and predictable immune reaction. This lets researchers directly measure how effectively IMP761 can dampen immune responses.
Earlier findings from participants given the 0.9 mg/kg dose showed that the number of T-cells in the skin was reduced by about 80% 10 days after a second KLH injection, demonstrating that IMP761 can strongly reduce unwanted immune responses.
Newly shared results from participants who received the 2.5 and 7 mg/kg doses showed that IMP761 significantly reduced T-cell-driven skin immune reactions within two days of dosing, with immunosuppressive activity sustained for up to 23 days. IMP761 has continued to be well tolerated overall, with only mild treatment-related side effects reported.
“This novel immunotherapy’s significant level of immune suppression combined with its favorable 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,” Triebel said.
Additional updates from the study are anticipated in the first half of 2026, the company said.
About the Author
