Tregzi

Tregzi (Orca-T) is a cell therapy used for a matched-donor stem cell transplant in adults with blood cancers (hematological malignancies), with the goal of rebuilding the blood and immune system and lowering the risk of moderate to severe chronic graft-versus-host disease (chronic GVHD).

Tregzi is given as a series of three infusions over two to three days in a hospital.

After a donor stem cell transplant, one common and serious complication is chronic graft-versus-host disease, which happens when the donor's immune cells attack the recipient's healthy tissue. Tregzi is designed to lower the risk of this complication while helping rebuild the blood and immune system, a process called hematopoietic and immunologic reconstitution.

Tregzi is made from living cells collected from a matched donor; the cells are separated into three cell types and given as three separate infusions. The first infusion is hematopoietic stem and progenitor cells (HSPCs), which rebuild the blood and immune system. The second is highly purified regulatory T cells (Tregs), which lower the risk of GVHD. The third is conventional T cells (Tcons), which speed immune recovery and provide a cancer-fighting effect known as graft-versus-leukemia (GVL)

Tregzi, clinically known as Orca-T, is the first and only precision-engineered cell therapy approved by the U.S. Food and Drug Administration (FDA) for use in allogeneic (donor) stem cell transplant. Its full generic name is allogeneic regulatory T cell immunotherapy with HSPC and T cells-vldq. It is manufactured individually for each patient.

Tregzi received its initial FDA approval on June 30, 2026.

Tregzi is FDA-approved for adults with hematological malignancies (blood cancers). It is indicated for use in matched-donor hematopoietic stem cell transplantation with a myeloablative preparative (conditioning) regimen, to help rebuild the blood and immune system and to improve chronic graft-versus-host-disease-free survival.

The blood cancers studied in the approval trial included acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), high-risk myelodysplastic syndrome (MDS), and mixed-phenotype acute leukemia (MPAL).

Tregzi is given only after a matched donor has been identified and after the patient has received an appropriate myeloablative conditioning regimen to prepare the body for transplant.

Tregzi is collected from the mobilized peripheral blood of a donor whose tissue type closely matches the patient (an 8/8 HLA-matched related or unrelated donor). It is given after conditioning treatment and works through its three separate cell components.

Tregzi works by:

Rebuilding blood counts and immune function. The hematopoietic stem and progenitor cells (HSPCs) travel to the bone marrow, engraft, and develop into all types of mature blood cells, restoring the blood and immune system.

Lowering the risk of GVHD. The highly purified regulatory T cells (Tregs) are given first to help control graft-versus-host disease. In laboratory studies, Tregs suppressed the activation and multiplication of conventional T cells and supported immune recovery without reducing the cancer-fighting effect of the transplant.

Speeding immune recovery and fighting cancer. The conventional T cells (Tcons) are given about two days later to accelerate immune reconstitution. This helps the body fight infection (graft-versus-infection) and target remaining cancer cells (graft-versus-leukemia).

Together, these effects help rebuild a healthy blood and immune system while improving survival free of chronic GVHD.

Tregzi is given by a transplant care team through a vein (intravenous infusion), usually through a central venous catheter. It is for intravenous use only. Patients do not administer Tregzi themselves.

Before infusion, patients receive an appropriate myeloablative conditioning regimen to prepare the body for transplant, along with premedication (such as diphenhydramine and/or acetaminophen) about 30 minutes before the infusions. Corticosteroids are strongly discouraged as premedication. The care team verifies the patient's identity against the patient-specific labels before each infusion.

Tregzi is given across two treatment days:

On day 0, the HSPC infusion is given first (Step 1), followed immediately by the Treg infusion (Step 2).

On day 2 or day 3, the Tcon infusion is given (Step 3) after it is thawed and diluted with the provided Tcon diluent.

The care team does not use a leukodepleting filter and infuses each component at a controlled rate. Starting the day after the Tcon infusion, patients receive a single-agent calcineurin inhibitor to help prevent GVHD.

Tregzi can cause serious and sometimes life-threatening complications. The care team will monitor patients closely before, during, and after treatment.

Graft failure has occurred after Tregzi. Recipients are screened for antidonor antibodies that may prevent engraftment, and blood counts are monitored closely for signs of recovery.

Graft-versus-host disease (GVHD), including life-threatening and fatal cases, has occurred with Tregzi. Patients are given a single-agent calcineurin inhibitor as prophylaxis to lower the risk of GVHD, and are monitored and treated if GVHD develops.

Infusion reactions, including serious allergic reactions such as anaphylaxis, may occur because of DMSO, human serum albumin, dextran, or murine (mouse) protein in Tregzi. Patients receive premedication and are monitored during and after the infusion. If a reaction occurs, the infusion is paused and supportive care is given.

Secondary cancers and cancers of donor origin may occur and can appear years after transplant, including post-transplant lymphoproliferative disorder (PTLD). Patients are monitored over time.

Transmission of infectious agents may occur because Tregzi is made from human donor blood and animal-derived materials. Risks include viruses such as HIV, hepatitis B and C, and others, even when donors are screened. Patients are monitored and tested for infections and treated as needed.

Tregzi has no contraindications and does not carry a boxed warning.

Tell your healthcare provider about your full medical history and all medicines and supplements you take before treatment with Tregzi. Because Tregzi is given as part of a stem cell transplant, your care team will also review your donor match, your conditioning regimen, and your overall readiness for transplant.

Pregnancy

There are no data on the use of Tregzi in pregnant women, and it is not known whether Tregzi can harm an unborn baby. Tregzi should be used during pregnancy only if the potential benefit justifies the potential risk. Females who can become pregnant should have a pregnancy test before starting the conditioning regimen. There is not enough information to recommend how long to use contraception after Tregzi, so follow the guidance in the prescribing information for the conditioning (myeloablative) regimen. Report any pregnancy after Tregzi to Orca Bio at 1-877-411-6722.

Breastfeeding

It is not known whether Tregzi passes into breast milk or how it may affect a breastfed baby or milk production. Talk with your healthcare provider about the best way to feed your baby, weighing the benefits of breastfeeding against your need for treatment.

Common Tregzi side effects

The most common Tregzi side effects were mouth and throat soreness (mucositis), diarrhea, rash, viral infections, infections with an unspecified cause, abdominal pain, vomiting, nausea, bacterial infections, bleeding (hemorrhage), acute graft-versus-host disease (acute GVHD), swelling (edema), and fungal infections, which occurred in 20% or more of patients.

The most common severe (Grade 3 to 4) laboratory abnormalities were decreases in white blood cells (leukocytes, and the lymphocyte and neutrophil subtypes), platelets (which help blood clot), and hemoglobin (which carries oxygen in red blood cells), all occurring in 20% or more of patients.

Serious Tregzi side effects

Tregzi can cause serious side effects. In the approval trial, serious adverse reactions within the first 100 days occurred in about 28% of patients treated with Tregzi. These included bacterial infections (14%), fever (pyrexia, 5%), a liver blood-flow problem (veno-occlusive liver disease, 3%), and viral infections (3%). Fatal adverse reactions occurred in about 3% of patients.

Serious side effects that may occur with Tregzi include:

Graft failure, which can be life-threatening. This is when the transplanted cells fail to establish and rebuild blood counts.

Graft-versus-host disease (GVHD), including acute and chronic forms that can be life-threatening or fatal. In GVHD, the donor cells attack the patient's own tissues. Acute GVHD can cause a raised rash, digestive symptoms, and elevated bilirubin. Chronic GVHD can cause skin rash, mouth sores, dry eyes, liver inflammation, scarring of the skin and joints, and lung damage.

Infusion reactions, including serious allergic reactions (hypersensitivity) such as anaphylaxis. These can begin within minutes of starting the infusion and may keep intensifying for several hours after it finishes.

Secondary cancers and cancers of donor origin, which may develop years after transplant. This includes post-transplant lymphoproliferative disorder (PTLD), a lymphoma-like condition that is usually fatal if not treated. No patient treated with Tregzi has developed PTLD.

Transmission of infectious agents, because Tregzi is made from human donor blood and animal-derived materials. There is a risk of passing on serious infections even when donors are screened and tested.

The care team will monitor closely for these problems and treat them if they occur. Patients should report any signs of GVHD (such as rash, joint pain, diarrhea, or yellowing of the eyes) or any signs of an infusion reaction (such as fever, chills, flushing, tiredness, shortness of breath, or dizziness) right away.

This is not a complete list of side effects, and others may occur. Call your healthcare provider for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Tregzi (Orcra-T) was studied in the Precision-T trial (NCT05316701), a randomized, open-label, multicenter Phase 3 study of 187 adults with blood cancers, including acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), high-risk myelodysplastic syndrome (MDS), and mixed-phenotype acute leukemia (MPAL). The median age was 44 years (range 19 to 65 years). Patients received either Tregzi plus single-agent tacrolimus or a conventional (unmanipulated) allogeneic stem cell transplant plus tacrolimus and methotrexate, both after a myeloablative conditioning regimen.

In the Precision-T trial, an estimated 78.0% of patients treated with Tregzi were alive and free of moderate to severe chronic graft-versus-host disease (chronic GVHD) at 12 months, compared with 38.4% of those who received a conventional transplant (hazard ratio 0.26; p less than 0.00001). This was the trial's main measure, called chronic GVHD-free survival.

Other results at 12 months included:

Moderate to severe chronic GVHD (cumulative incidence): 12.6% with Tregzi compared with 44.0% with conventional transplant (hazard ratio 0.19; p equals 0.00002).

Severe acute GVHD (Grade 3 or higher): 6% with Tregzi compared with 15% with conventional transplant.

Non-relapse mortality (death not caused by the cancer returning): 3.4% with Tregzi compared with 11.7% with conventional transplant.

Deaths on study from any cause: 7.5% with Tregzi compared with 16.0% with conventional transplant.

Relapse on study: 16.1% with Tregzi compared with 10.6% with conventional transplant.

Blood count recovery was strong. All patients treated with Tregzi reached a neutrophil count of 500/mm3 within 28 days of infusion, and about 60% had confirmed neutrophil recovery (counts above 500/mm3 on three consecutive days) within 28 days. Among patients with available data, all showed donor engraftment (myeloid-lineage donor chimerism above 95%) by day 28 after transplant.

A single dose of Tregzi is prepared individually for each patient and supplied as four separate infusion bags. The target cell doses are based on the patient's body weight:

HSPCs: at least 1.0 x 10^6 viable cells per kilogram, given by IV once on day 0.

Tregs: 1.3 x 10^6 to 3.5 x 10^6 viable cells per kilogram, given by IV once on day 0 immediately after the HSPCs.

Tcons: 1.3 x 10^6 to 6.9 x 10^6 viable cells per kilogram, given by IV once on day 2 to day 3.

Tcon diluent: used to dilute the Tcons before infusion (it is not infused on its own).

Exact patient-specific dose information is provided in the Certificate of Analysis (COA) that accompanies each dose.

Tregzi is shipped directly to the treatment center in two transport containers and is handled only by the care team:

The HSPC and Treg infusion bags are shipped and stored refrigerated at 2°C to 8°C (36°F to 46°F) and must not be frozen.

The Tcon infusion bag is shipped and stored frozen in the vapor phase of liquid nitrogen at below -125°C (below -193°F) and is thawed and diluted just before infusion.

The Tcon diluent is shipped and stored at ambient room temperature.

Each Tregzi dose is patient-specific and intended for a single patient. Staff match the patient's identity to the labels on each bag and carton, and follow universal precautions and local biosafety guidelines because Tregzi contains human blood cells.

Active components: purified hematopoietic stem and progenitor cells (HSPCs), regulatory T cells (Tregs), and conventional T cells (Tcons), collected from a matched donor.

Inactive ingredients (excipients): multiple electrolytes injection (MEI) and human serum albumin (HSA) in all components. The Tcon component also contains dimethyl sulfoxide (DMSO) and hetastarch, which are used for cryopreservation.

Tregzi is made by Orca Biosystems Inc. (Orca Bio), a commercial-stage biotechnology company based in Menlo Park, California, that develops high-precision cell therapies for blood cancers and autoimmune diseases.

Healthcare providers and patients can refer to the full Tregzi Prescribing Information for more detailed information on indications and usage, dosage and administration, warnings and precautions, adverse reactions, clinical pharmacology, and clinical studies. The Prescribing Information is sometimes called the package insert or the FDA label. This page is not a complete source of information about Tregzi and does not take the place of talking with your healthcare provider about your treatment.