The FDA has approved Tregzi, a precision-engineered cell therapy from Orca Bio, as the first regulatory T-cell (Treg) based treatment for adults undergoing allogeneic stem cell transplants for blood cancers. Trial data showed it more than doubled one-year survival free of chronic graft-versus-host disease compared with standard transplants.
Table of Contents
- What Happened
- How Tregzi Works
- What the Data Show
- Why This Matters
- Conclusion
What Happened
On June 30, 2026, the FDA approved Tregzi (allogeneic regulatory T cell immunotherapy with HSPC and T cells-vldq), developed by Orca Bio and previously known as Orca-T. It is indicated for use in matched-donor hematopoietic stem cell transplantation with a myeloablative preparative regimen, for hematopoietic and immunologic reconstitution and to improve chronic graft-versus-host disease (GVHD)-free survival in adults with hematologic malignancies. The approval makes Tregzi the first FDA-cleared therapy built on highly purified regulatory T cells, and only the second cell therapy ever approved specifically in the GVHD setting, following Mesoblast’s Ryoncil.
Tregzi received Orphan Drug and Regenerative Medicine Advanced Therapy (RMAT) designations ahead of filing, along with Priority Review. The FDA’s target action date was extended from April to July 2026 after the agency requested additional manufacturing information.
How Tregzi Works
Tregzi reformulates a standard allogeneic stem cell transplant rather than replacing it outright. Instead of infusing an unmodified mix of stem and immune cells from a matched donor, it separates the donor material into components: hematopoietic stem and progenitor cells to rebuild the patient’s blood and immune system, highly purified regulatory T cells to suppress the immune attack that causes GVHD, and a follow-up dose of conventional T cells to help clear residual cancer cells. The goal is to preserve the beneficial graft-versus-leukemia effect of a transplant while reducing the collateral immune damage that has long made GVHD one of the field’s most difficult trade-offs.
What the Data Show
Approval was based on the Phase 3 PRECISION-T trial, a randomized, open-label study of 187 adults with blood cancers, including acute leukemia and myelodysplastic syndrome, across 19 transplant centers. Patients received either Tregzi with single-agent tacrolimus, or a standard transplant with a combination of tacrolimus and methotrexate.
At one year, 78.0% of Tregzi recipients achieved chronic GVHD-free survival, compared with 38.4% in the standard transplant group. After accounting for death as a competing risk, serious chronic GVHD developed in 12.6% of Tregzi patients versus 44.0% of controls. Safety data also favored Tregzi: Grade 3 or 4 acute GVHD at day 180 occurred in 6% of Tregzi recipients versus 10% with standard transplant, alongside fewer serious infections.