FDA Approves Tregzi (Orca-T) as First Regulatory T Cell-Based Immunotherapy for Blood Cancer Transplant Complications
On June 30, 2026, the U.S. Food and Drug Administration (FDA) approved Tregzi (hematopoietic stem and progenitor cell and T cells-vldq; clinically known as Orca-T), developed by Orca Biosystems (Orca Bio). This milestone marks the first-ever regulatory T (Treg) cell-based immunotherapy approved by the FDA.
Tregzi is indicated for improving chronic graft-versus-host disease (GVHD)-free survival in adult patients with hematological malignancies undergoing matched-donor allogeneic hematopoietic stem cell transplantation (allo-HSCT). It represents a major advancement in stem cell transplant medicine, where preventing the transplanted donor cells from attacking the recipient's body (chronic GVHD) is a critical determinant of long-term survival and quality of life.
The Science and Efficacy
Tregzi is a donor-derived, precision-engineered cellular immunotherapy composed of three distinct cell components:
- Purified hematopoietic stem and progenitor cells (HSPCs)
- Purified regulatory T (Treg) cells, which maintain immune tolerance and regulate immune response
- Conventional T (Tcon) cells
All components are derived from the mobilized peripheral blood of an 8/8 HLA-matched related or unrelated donor.
The approval is supported by highly persuasive data from the randomized, controlled Phase 3 PRECISION-T trial (187 patients), which demonstrated a profound reduction in chronic GVHD:
- GVHD-Free Survival: At one year, 78% of patients treated with Tregzi achieved chronic GVHD-free survival, compared to 38.4% of patients receiving a standard stem cell transplant.
- Severe Chronic GVHD Rate: Only 12.6% of patients in the Tregzi cohort developed moderate-to-severe chronic GVHD within one year, compared to 44% in the standard transplant control group (after accounting for death as a competing risk).
- Safety: Side effects were consistent with standard allo-HSCT conditioning (predominantly infections). No severe infusion reactions or graft failures were observed.
"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. 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." — Karim Mikhail, B.Pharm., M.S., Acting Director of the FDA's Center for Biologics Evaluation and Research (CBER)