The U.S. Food and Drug Administration (FDA) has approved Tregzi, the first regulatory T (Treg) cell-based immunotherapy for improving chronic graft-versus-host disease (GVHD)-free survival in adult patients with blood cancers undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). The approval marks a major milestone in transplantation medicine by introducing a novel cellular therapy that not only supports successful stem cell transplantation but also significantly reduces the risk of chronic GVHD, one of the most serious and challenging long-term complications experienced by transplant recipients.
Patients with high-risk blood cancers, including acute leukemia and myelodysplastic syndrome (MDS), often require allogeneic stem cell transplantation to replace diseased blood-forming cells with healthy donor stem cells. Although this procedure can be lifesaving, donor immune cells may attack the recipient's healthy tissues, leading to chronic GVHD, which can affect multiple organs and significantly reduce quality of life. Tregzi has been developed to address this critical unmet need by helping rebuild the patient's blood-forming and immune systems while promoting immune tolerance and reducing harmful immune responses.
Tregzi is a donor-derived cellular immunotherapy composed of three carefully purified cell populations collected from the mobilized peripheral blood of an 8/8 HLA-matched related or unrelated donor. These include hematopoietic stem and progenitor cells (HSPCs), regulatory T (Treg) cells, and conventional T (Tcon) cells. Regulatory T cells play a vital role in controlling immune responses and maintaining immune balance, allowing the immune system to recover after transplantation while minimizing the likelihood of donor immune cells attacking the recipient's body. Patients receive Tregzi following conditioning chemotherapy as part of their stem cell transplant procedure.
The FDA's approval was supported by findings from the randomized Phase 3 PRECISION-T clinical trial involving 187 adults with blood cancers. Participants were randomly assigned to receive either Tregzi or a standard allogeneic stem cell transplant. The study's primary endpoint was chronic GVHD-free survival, measured as the time from transplantation until death from any cause or the first occurrence of moderate or severe chronic GVHD within two years. The results demonstrated a substantial clinical benefit. At one year after transplantation, 78% of patients treated with Tregzi remained alive without moderate or severe chronic GVHD, compared with only 38.4% of patients receiving a standard transplant. Furthermore, after accounting for death as a competing risk, only 12.6% of patients receiving Tregzi developed serious chronic GVHD within one year, compared with 44% of patients treated with conventional transplantation. Based on these robust and internally consistent findings, the FDA concluded that the benefits of Tregzi outweigh its potential risks in the approved patient population.
The safety profile of Tregzi was generally consistent with that expected in patients undergoing stem cell transplantation. The most commonly reported adverse events were infections, which are frequently observed during immune recovery following transplantation. Importantly, no patients experienced severe infusion-related reactions, and no cases of graft failure were reported during the clinical trial, providing additional reassurance regarding the therapy's safety.
Commenting on the approval, Karim Mikhail, B.Pharm., M.S., Acting Director of the FDA's Center for Biologics Evaluation and Research (CBER), stated that chronic graft-versus-host disease has long been one of the most feared and difficult complications following stem cell transplantation. He noted that Tregzi represents a genuine new approach that helps restore the immune system while substantially lowering the risk of chronic GVHD, demonstrating the growing promise of advanced cellular therapies in improving outcomes for patients with blood cancers.
The approval of Tregzi marks a significant advancement in transplantation and immunotherapy, making it the first FDA-approved regulatory T-cell therapy for preventing chronic GVHD in adult patients undergoing allogeneic stem cell transplantation. By significantly improving chronic GVHD-free survival while maintaining an acceptable safety profile, Tregzi offers new hope for patients facing high-risk blood cancers and has the potential to improve both long-term survival and quality of life following transplantation.
