A Phase I/II study indicates that activated regulatory T cells from healthy donors can safely help prevent severe graft-versus-host disease after stem cell transplants.

Researchers have completed a Phase I/II clinical trial of a new cell therapy, ATreg, designed to prevent graft-versus-host disease (GvHD) following allogeneic stem cell transplants. The study, involving 10 patients, demonstrated that the therapy is safe, well-tolerated, and can be produced from healthy donor blood within 24 hours. The findings were published in the journal Transplantation and Cellular Therapy.

Addressing Transplant Complications

Allogeneic stem cell transplantation is a curative treatment for blood cancer, but it carries a high risk of acute graft-versus-host disease, where immune cells from the graft attack the patient's tissues. While natural regulatory T cells can act as immune system 'brakes' to prevent this, traditional methods require labor-intensive isolation and weeks of laboratory cultivation from a genetically compatible donor.

The ATreg Approach

Developed by ActiTrexx in Mainz, the ATreg process uses regulatory T cells harvested from unrelated, healthy blood donors. These cells are stimulated with a patented activator for 16 hours, bypassing the need for long-term cell expansion. Because the cells do not need to be genetically matched to the patient, they can be produced and administered on demand.

Study Results and Future Outlook

In the 'ATreg-001' study, 10 patients across four German sites received the therapy approximately 10 days after their transplant. During a 100-day observation period, no patients developed severe grade 3–4 GvHD, and no transplant-related mortality occurred. ActiTrexx plans to conduct a randomized, controlled follow-up study to further evaluate the therapy's efficacy compared to standard prophylaxis.