In short
FOXP3-T4 is an investigational gene therapy being studied for IPEX syndrome, a rare primary immunodeficiency caused by mutations in the FOXP3 gene. One Phase 1 clinical trial is currently authorised in the EU, planning to enroll 5 patients. The trial will assess the safety and efficacy of FOXP3-T4 given by intravenous infusion, alone or combined with low-dose IL-2.
Key points
- FOXP3-T4 is an investigational gene therapy for IPEX syndrome, a rare immune disorder.
- The single authorised trial is a Phase 1 study with a planned enrollment of 5 patients.
- FOXP3-T4 consists of gene-modified regulatory T cells given by intravenous infusion.
- The trial will test FOXP3-T4 alone or combined with low-dose IL-2.
- The primary endpoint is safety and efficacy up to 24 months after infusion.
What is FOXP3-T4?
FOXP3-T4 is an investigational gene therapy being developed for the treatment of IPEX syndrome. It consists of CD4+ regulatory T cells (Treg cells) that have been genetically modified using a lentiviral vector carrying the FOXP3 gene. The full name of the product is LV-FOXP3-LNGFR lentiviral vector gene-modified induced CD4+ Treg cells. FOXP3-T4 is not yet an authorised medicine; it is still in the clinical trial stage.
How does FOXP3-T4 work?
IPEX syndrome is a primary immunodeficiency caused by mutations in the FOXP3 gene, which encodes a transcription factor that is essential for maintaining immunological tolerance by thymus-derived regulatory T cells. In IPEX syndrome, the lack of functional FOXP3 means the body's regulatory T cells cannot properly control the immune system, leading to autoimmune complications. FOXP3-T4 aims to restore this function by providing patients with Treg cells that have been genetically modified to carry a working copy of the FOXP3 gene.
Which conditions is FOXP3-T4 studied for?
- IPEX syndrome — a rare primary immunodeficiency caused by mutations in the FOXP3 gene, leading to severe autoimmune complications affecting multiple organs.
The authorised trial accepts patients with IPEX syndrome confirmed by molecular diagnosis, who have either active autoimmune complications or are controlled under immunosuppressive therapy.
How is FOXP3-T4 given?
FOXP3-T4 is given by intravenous infusion. In the trial, it is administered either alone or in combination with low doses of IL-2 (interleukin-2), which is given as a subcutaneous injection under the name ILT-101. IL-2 is a protein that supports the survival and function of regulatory T cells.
What do the clinical trials show?
One clinical trial of FOXP3-T4 is registered in the EU Clinical Trials Information System. The trial, named THERIPEX, is a Phase 1 study with a planned enrollment of 5 patients. It is currently authorised, meaning it has received regulatory approval to begin.
The primary objective of the trial is to assess the initial safety and efficacy of treatment with FOXP3-T4 alone or combined with low-dose IL-2. The primary endpoint is safety and efficacy up to 24 months following intravenous infusion. Because the trial is in Phase 1, the main focus is on establishing that the treatment is safe and tolerable in patients, while also gathering early information on whether it may be effective.
No results from this trial are available yet, as the study has only recently been authorised.