ActiTrexx treats first patient with novel regulatory T cell therapy against Graft-versus-Host Disease

ActiTrexx treats first patient with novel regulatory T cell therapy against Graft-versus-Host Disease

• Phase Ib/II study with Actileucel, a novel cellular product based on activated regulatory T cells for prevention of Graft-versus-Host Disease (GvHD)
• Clinical study evaluates the safety and feasibility of Actileucel treatment as well as frequency and severity of GvHD
• Actileucel is the first regulatory T cell therapy from an unmatched third-party donor

Mainz, Germany, 19 March 2024 - ActiTrexx GmbH, a clinical-stage company focusing on the activation of regulatory T cells, has treated the first patient with Actileucel, its novel cell therapy for the prevention and treatment of Graft-versus-Host Disease (GvHD) in patients receiving an allogeneic haematopoietic stem cell transplant as treatment for haematological malignancies such as acute leukemia. Actileucel is generated by activating regulatory T cells isolated from an unmatched, third-party donor via a fast proprietary process with a vein-to-vein time of 24 hours.

GvHD is a severe and potentially life-threatening complication that can arise after an allogeneic haematopoietic stem cell transplantation and affects about 50 % of recipients. GvHD occurs when the stem cell donor’s T cells attack the patient’s tissues, leading to a range of symptoms that can affect the skin, gastrointestinal tract, and liver. Currently, immunosuppressants are used to treat GvHD, but they have limited effectiveness and come with severe side effects. Consequently, the 3-year mortality rate of GvHD patients remains high. Actileucel uses activated regulatory T cells from a second donor, who does not need to match the patient’s tissue markers, to control or prevent GvHD.

Prof. Dr. Andrea Tüttenberg, CEO of ActiTrexx, said: “GvHD can lead to life-long symptoms for the patient and is a major cause for the high mortality rate of blood stem cell transplantation. Our goal is to tamper the overshooting immune response with Actileucel, to reduce the risk and severity of GvHD, ultimately improving patient outcomes and quality of life. The treatment of the first patient with Actileucel marks a significant milestone in our mission to address this critical unmet need of patients undergoing bone marrow transplantation.”

Objective of the prospective open, single-arm non-randomized multicentric Phase Ib/II study is to evaluate safety and feasibility of Actileucel treatment. Ten patients who have recently received a blood stem cell transplantation as treatment for leukemia will receive a single treatment with Actileucel. Patients will be treated early after transplantation in three cohorts with increasing doses of Actileucel with a follow-up of six months. Primary endpoint is the safety and tolerability of the Actileucel treatment, while secondary endpoints include an assessment of the frequency and severity of GvHD in treated patients as well as of the feasibility of Actileucel manufacturing. The trial will run at two sites in Germany, the III. Medical Clinic of the University Medical Center Mainz and the University Hospital Carl Gustav Carus in Dresden.

“Allogeneic stem cell transplantation is able to cure patients with acute Leucemia – but half of them suffer from GvHD, need immunosuppressive medication with high infection rates and risk for lethal complications. Especially patients who did not respond to our immunosuppressive treatment are at risk. The main goal is to identify strategies to prevent patients from developing GvHD, so we are very hopeful and enthusiastic to conduct this clinical trial with Actileucel,” said Dr. Eva Wagner-Drouet, Principal Investigator and Head of the Center for Cellular Immunotherapy and Stem Cell Transplantation of the University Medical Center Mainz.

“Unlike the currently available treatments, we are targeting the root-cause of the overshooting immune reaction in GvHD by using regulatory T cells. Preclinical data demonstrated that Actileucel can significantly attenuate an already existing GvHD, and even largely prevent the development of the disease when given early after transplantation as a prophylactic treatment. In contrast to currently approved cell therapies, Actileucel offers a streamlined manufacturing process by using cells that can be taken from any healthy third-party donor," commented Dr. Helmut Jonuleit, CSO of ActiTrexx.

About GvHD
GvHD is a life-threatening side effect of allogeneic haematopietic stem cell transplantation. Donor lymphocytes react against tissue antigens in the recipient and cause severe organ and tissue damage, that often takes a chronic course. GvHD is primarily triggered by the donor's CD4⁺ T cells, whose activity is controlled by regulatory T cells. About 50% of patients develop the disease with a significantly increased mortality rate within 3 years after transplantation. Once developed, patients suffer from the often life-long symptoms.

About Actileucel
Actileucel is a cellular therapeutic agent that contains optimally activated regulatory T cells, the natural guardian cells of our immune system. Regulatory T cells modulate the activity of T cells and prevent unwanted inflammatory reactions. Actileucel suppresses the undesired activation of CD4⁺ T cells in the transplant, prevents the development of GvHD and promotes the development of a healthy immune system in the patient. The cellular therapeutic Actileucel is classified as an Advanced Therapy Medicinal Product (ATMP), produced in an automated process within 24 hours and ready for clinical use in patients.

About ActiTrexx
ActiTrexx is a clinical phase biotech company developing a platform of cellular and biologic therapies for overshooting T cell mediated autoimmune and autoinflammatory diseases with high medical unmet need. The first product candidate, Actileucel, is a cell therapy based on regulatory T cells that are activated in a proprietary ultrafast process, and is in clinical Phase Ib/II for the treatment of Graft-versus-Host Disease (GvHD) after blood stem cell transplantation. ActiTrexx GmbH was founded in 2020 as a spin-off from the University Medical Center Mainz and is backed by LBBW Venture Capital GmbH, High-Tech Gründerfonds (HTGF), Investitions- und Strukturbank Rheinland-Pfalz (ISB) and MediVentures GmbH. www.actitrexx.de