FDA Approves Orca Bio's Donor-Derived Regulatory T Cell Therapy Tregzi for Matched-Donor Transplant in Blood Cancers

Prophylaxis dropped from two drugs to one

Precision-T randomized patients to Tregzi with single-agent tacrolimus or to a conventional allogeneic transplant with tacrolimus and methotrexate. The primary endpoint counted death from any cause or the first onset of moderate or severe chronic GVHD within two years of day 0. After accounting for death as a competing risk, the FDA reported that 12.6% of Tregzi recipients developed serious chronic GVHD within one year against 44% of conventional transplant recipients, a hazard ratio of 0.19 by the company's account. GVHD-free and relapse-free survival came to 63% and 31%. Grade 3 or 4 acute GVHD at day +180 stood at 6% and 10% (HR 0.37; p=0.044). Results were published in Blood in December 2025.

A graft sorted into three components

Every dose is made for a named recipient from the mobilized peripheral blood of that recipient's matched donor, sorted into three components before infusion. Stem and progenitor cells rebuild the marrow, the purified Treg fraction suppresses alloreactivity, and the conventional T cells speed immune reconstitution and preserve graft-versus-leukemia activity. Robert Negrin, M.D., professor of medicine in blood and marrow transplantation at Stanford Medicine, whose laboratory work on Treg biology underlies the product, put the result this way.

Developing this concept from early foundational research in our labs based upon the fundamental biology of regulatory T cells, to it now receiving the first FDA approval for a therapy that utilizes highly purified Tregs, is a defining moment for the transplant community. The peer-reviewed findings demonstrated this precision-engineered cell therapy delivered improved GVHD-free survival alongside less toxicity, including fewer serious infections and lower non-relapse mortality.

Miguel-Angel Perales, M.D., chief of the adult bone marrow transplant service at Memorial Sloan Kettering Cancer Center, said the field's long-standing challenge has been "preserving the vital graft-versus-leukemia effect while minimizing the risk of GVHD and infection." Orca Bio discloses that Perales has financial interests related to the company.

What the label asks of the transplant team

Recipients are to be screened for antidonor antibodies that may prevent engraftment and monitored for laboratory evidence of hematopoietic recovery. Graft failure has occurred after administration, though none was seen during the study period. Patients get antipyretics and histamine antagonists before infusion, because the product contains DMSO, human serum albumin, dextran and murine protein, any of which can trigger anaphylaxis, and reactions may not peak until hours after the infusion ends. Serial blood monitoring for EBV DNA may be warranted in patients with persistent cytopenias, given the risk of post-transplantation lymphoproliferative disorder, and Orca Bio reports no case of PTLD in a treated patient so far.

Why This Matters to the APO|APE Reader

The approval came on June 30, six days ahead of the July 6 target action date the FDA set in April after classifying an updated chemistry, manufacturing and controls submission as a major amendment and adding three months to the review. Two weeks before that decision, Orca Bio opened East Coast manufacturing capacity in Princeton, New Jersey, to work alongside its Sacramento plants and shorten vein-to-vein time, with the Princeton lines starting on clinical supply and moving to commercial production once validated. A dose assembled per patient from one donor collection ties each transplant to a scheduled apheresis, a shipping window and a release test, which is a coordination problem the service has not had to solve for a conventional graft. Orca is privately held and has published neither a price for Tregzi nor a list of treating centers.