FDA Approves Tregzi: Donor Treg-Cell Therapy Nearly Doubles Chronic GVHD-Free Survival After Stem Cell Transplant

On June 30, 2026, the FDA approved Tregzi, a donor-derived regulatory T-cell (Treg) immunotherapy from Orca Bio, for adults with blood cancers who are undergoing allogeneic hematopoietic stem cell transplantation from a closely matched donor. In the pivotal PRECISION-T trial, Tregzi more than doubled the rate of chronic graft-versus-host-disease-free survival at one year compared with a standard transplant, while sharply cutting rates of severe chronic GVHD. This article explains what chronic GVHD is, how Tregzi works, what the trial data show, and what the approval does and does not change for patients facing transplant.

A New Option for a Long-Feared Transplant Complication

For patients with blood cancers like acute myeloid leukemia, acute lymphoblastic leukemia, and myelodysplastic syndrome, an allogeneic stem cell transplant from a donor can be curative — but it comes with a well-known trade-off. The same donor immune cells that help eliminate residual cancer can also turn against the patient's own healthy tissue, causing chronic graft-versus-host disease (GVHD). For decades, oncologists have had only broad immunosuppressive drugs to manage that risk, often trading one set of complications for another. Tregzi represents a genuinely different approach: rather than suppressing the immune system after the fact, it engineers the composition of the transplant itself. The FDA's approval makes Tregzi the first regulatory T-cell-based cellular immunotherapy cleared for this purpose — a meaningful first in a field that has had few new prevention tools for chronic GVHD in years.

What Chronic GVHD Is, and Why Preventing It Matters

Graft-versus-host disease occurs when immune cells from a donor's transplanted tissue recognize the recipient's body as foreign and attack it. According to a clinical overview hosted on the National Institutes of Health's NCBI Bookshelf (StatPearls), acute GVHD typically appears within the first 100 days after transplant, while chronic GVHD develops later and can persist for years, often resembling autoimmune or connective-tissue disorders. It can affect the skin, eyes, mouth, gastrointestinal tract, lungs, and liver, and in more severe cases requires prolonged immunosuppressive treatment. That same review notes chronic GVHD is a leading cause of illness and death among long-term survivors of allogeneic transplant — which is exactly why a therapy that meaningfully reduces its incidence is significant news for this patient population.

How Tregzi Works

Tregzi is manufactured from a healthy, closely matched (8/8 HLA-matched) donor's mobilized peripheral blood and combines three purified cell populations: hematopoietic stem and progenitor cells (which rebuild the blood and immune system), donor regulatory T cells (Tregs, which help dampen harmful immune attacks on the patient's tissue), and a calibrated dose of conventional T cells (which support engraftment and residual anti-cancer activity). The idea is to preserve the beneficial, cancer-fighting effects of the transplant while specifically boosting the regulatory signal that keeps the donor immune system from attacking healthy tissue.

The PRECISION-T Trial Results

The approval rests on PRECISION-T, a randomized, multi-center phase 3 trial that enrolled 187 adults with blood cancers, comparing Tregzi to a standard allogeneic transplant. At one year, 78% of patients who received Tregzi were alive and free of chronic GVHD, compared with 38.4% in the standard-transplant group — roughly double the rate. Severe chronic GVHD within the first year occurred in just 12.6% of Tregzi recipients, versus 44% of those who received a standard transplant. Secondary results reported by the company and independent trade coverage, including one-year overall survival (94% vs. 83%) and non-relapse mortality (roughly 3% vs. 13%), point in a consistently favorable direction, though these were not the FDA's primary basis for approval and warrant continued follow-up as more data accumulate.

Safety Profile and What the FDA Flagged

No treatment is risk-free. Infections were the most common adverse effect reported with Tregzi, consistent with the fact that any allogeneic transplant — with or without this product — involves a period of intensive immune reconstitution. Importantly, the FDA noted no severe infusion reactions and no cases of graft failure in the study. Still, patients receiving Tregzi require the same close post-transplant monitoring — for infection, organ function, and disease relapse — that any allogeneic transplant recipient needs.

Availability, Cost, and What Comes Next

Orca Bio has priced Tregzi at a wholesale acquisition cost of roughly $428,000, reflecting the complexity of manufacturing a personalized, donor-matched cellular product — a cost patients and families should discuss with their transplant center and insurer well before treatment. Because Tregzi must be manufactured from a specific matched donor's cells, it will initially be available only through transplant centers equipped to coordinate that process, not as an off-the-shelf product.

What This Approval Does — and Doesn't — Mean

Tregzi is indicated to improve chronic GVHD-free survival in the transplant setting — it is not a treatment for the underlying blood cancer itself, and it does not replace the transplant or the chemotherapy conditioning that precedes it. It's also specific to patients receiving an 8/8 HLA-matched donor transplant, so it isn't yet an option for every transplant candidate, including many who rely on mismatched or haploidentical donors. And while the PRECISION-T results are strong, they come from one randomized trial; longer-term follow-up and broader real-world use will further clarify Tregzi's place in transplant care.

Bottom Line

Tregzi is a legitimate, FDA-approved advance for a complication that has long haunted allogeneic stem cell transplant survivors, and the PRECISION-T data — roughly doubling chronic GVHD-free survival and cutting severe chronic GVHD by more than half — are genuinely encouraging. If you or a family member are facing an allogeneic transplant for a blood cancer, this is a therapy worth raising directly with your transplant team: ask whether you're a candidate for an 8/8 HLA-matched donor graft, how Tregzi would be incorporated into your specific conditioning and transplant plan, what the realistic infection and monitoring requirements would look like in your case, and how your insurance and transplant center would handle the cost. This approval changes what's possible for GVHD prevention — it doesn't change the need for a careful, individualized conversation with your own care team.