FDA Approves Orca-T (Tregzi), First Regulatory T Cell-Based Immunotherapy to Prevent Chronic GVHD

The FDA approved Tregzi (Orca-T) on June 30, 2026, as the first regulatory T cell-based immunotherapy designed to improve chronic graft-versus-host disease-free survival in adults with blood cancers undergoing allogeneic hematopoietic stem cell transplantation. In the randomized PRECISION-T trial, 78% of patients who received Tregzi were alive without chronic GVHD at one year compared with 38.4% of those who received a standard transplant.

Tregzi is a donor-derived cellular immunotherapy composed of purified hematopoietic stem and progenitor cells, regulatory T cells, and conventional T cells, collected from the blood of an 8/8 HLA-matched related or unrelated donor. Patients receive Tregzi after chemotherapy prepares their bodies for a bone marrow or stem cell transplant. The therapy is designed to lower the risk of chronic GVHD as the patient's blood-forming and immune systems recover. It is approved for adults with blood cancers such as acute myeloid leukemia, acute lymphoblastic leukemia, and myelodysplastic syndrome undergoing a matched donor stem cell transplant.

The FDA based its approval on results from the PRECISION-T trial, which enrolled 187 adults with blood cancers including acute leukemia and myelodysplastic syndrome. Participants were randomly assigned to receive Tregzi or a standard stem cell transplant. The trial measured chronic GVHD-free survival, defined as time from transplantation until death from any cause or first occurrence of moderate or severe chronic GVHD within two years. After accounting for death as a competing risk, 12.6% of Tregzi recipients developed serious chronic GVHD within one year versus 44% of standard-transplant patients. The FDA stated that the randomized controlled trial produced highly persuasive and internally consistent results demonstrating clinical benefit for the approved patient population and that benefits outweigh risks.

The most common side effects seen with Tregzi were infections, generally consistent with those expected in patients undergoing stem cell transplantation. No patients experienced severe infusion reactions and no cases of graft failure were reported during the study period. Orca-T was also linked to fewer infections after transplant. The application received Orphan Drug and Regenerative Medicine Advanced Therapy designations. The FDA granted approval of Tregzi to Orca Biosystems Inc.

The approval validates years of research into engineering the allograft itself, according to the Anjuli Seth Nayak Professor of Medicine at the University of Chicago Medicine Comprehensive Cancer Center. The expert said the approval represents an important advance and shows that graft engineering is possible in a successful manner to improve outcomes for patients undergoing allogeneic transplant, where the big risks are relapse and graft-versus-host disease. Results of the phase 3 Precision-T trial were published in Blood.

Exploratory analyses of the Precision-T trial presented at the 2026 Tandem Meetings showed earlier recovery and better health-related quality of life (HRQoL) with Orca-T compared with conventional alloHSCT. In the trial, 182 adult patients were randomly assigned to Orca-T plus tacrolimus prophylaxis (n=88) or peripheral blood stem cells plus tacrolimus/methotrexate (n=94). Orca-T was associated with superior chronic GVHD-free survival (hazard ratio, 0.26; P<0.00001) and significantly lower rates of moderate to severe chronic GVHD (P<0.001) at 1 year.

HRQoL, measured by FACT-BMT, was higher in the Orca-T group throughout the trial, with total scores exceeding baseline at day 100, while the standard-of-care group did not exceed baseline until day 365. The minimal clinical importance difference (MCID) was achieved by 40.9% of Orca-T patients at day 100 versus 22.3% in the standard arm (P<0.05), and by 52.4% versus 31.9% at day 730 (P<0.05). Hospitalization outcomes also favored Orca-T: adverse events led to hospitalization in 27.3% of Orca-T patients versus 45.7% of standard-care patients; rehospitalization-free survival at 18 months was 66.4% versus 33.8% (HR, 0.53; P=.0096); and mean hospitalization days were 30.6 versus 40.8.