June 30, 2026 - FDA Approves New Treatment That Uses Donor Immune Cells to Prevent Serious Complications in Blood Cancer Patients

The U.S. Food and Drug Administration today 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). It represents a novel approach to allogeneic hematopoietic stem cell transplantation in some adult patients with high-risk blood cancers. It addresses an important unmet need in transplantation, where curing the cancer is often only part of the challenge; avoiding chronic GVHD is equally important for long-term outcomes.

Tregzi uses stem cells and immune cells collected from blood of a closely matched donor to help the body fight cancer while reducing the risk of a serious complication called chronic GVHD - a condition that can occur when transplanted donor blood cells attack the patient's body. Patients receive this treatment after undergoing chemotherapy to prepare their bodies for a bone marrow or stem cell transplant.

"For patients with blood cancers who need stem cell transplantation, chronic graft-versus-host disease has long been one of the most feared and difficult-to-prevent complications," said Karim Mikhail, B.Pharm., M.S., Acting Director of the Center for Biologics Evaluation and Research (CBER). "Today's approval offers a genuine new approach that can help reconstitute the immune system while substantially reducing that risk and reflects the promise of what cellular therapy can deliver for patients."

Tregzi is a donor-derived cellular immunotherapy composed of three cell components: purified hematopoietic stem and progenitor cells (HSPCs), Treg cells, and conventional T (Tcon) cells, each derived from the mobilized peripheral blood of an 8/8 HLA-matched related or unrelated donor. Treg cells are a type of immune cell that help regulate immune responses and maintain immune tolerance. Tregzi is designed to reduce the risk of chronic GVHD during reconstitution of the patient's blood-forming and immune systems.

The safety and effectiveness of Tregzi were established through PRECISION-T, a clinical trial in which 187 adult patients with blood cancers, including acute leukemia and myelodysplastic syndrome, were randomly assigned to receive either Tregzi or a standard stem cell transplant. The primary endpoint was chronic GVHD-free survival, defined as the time from HSCT to the earliest occurrence of either death from any cause or the first onset of moderate or severe cGVHD, within two years after day 0. Patients who received Tregzi achieved significantly higher rates of chronic GVHD-free survival. At one year, 78% of patients who received Tregzi achieved this outcome, compared to 38.4% of patients who received a standard transplant. After accounting for death as a competing risk, 12.6% of patients who received Tregzi developed serious chronic GVHD within one year, compared with 44% of patients who received a standard transplant. The highly persuasive and internally consistent results from this randomized controlled trial denote clinical benefit in the indicated population. The FDA reviewed the results of this trial and determined that the benefits of Tregzi outweigh its risks.

The side effects observed with Tregzi were generally consistent with those expected in patients undergoing stem cell transplantation - most commonly, infections. No patient had a severe reaction during the infusion of Tregzi, and no cases of graft failure were observed within the study period. Patients and health care professionals should review the full prescribing information for complete safety information.

The application was granted Orphan Drug and Regenerative Medicine Advanced Therapy designations.

The FDA granted approval of Tregzi to Orca Biosystems, Inc.

###