FDA Approves New Immunotherapy to Improve Stem Cell Transplant Success in Blood Cancer Patients

On June 30, 2026, the U.S. Food and Drug Administration (FDA) approved a groundbreaking new cell therapy called Tregzi (T cells-vldq), developed by Orca Bio. This therapy is designed for adults with blood cancers (like leukemia or myelodysplastic syndrome) who are undergoing a stem cell transplant from a matched donor. 

Tregzi aims to help rebuild the immune system safely while dramatically lowering the risk of long-term complications known as chronic graft-versus-host disease (cGVHD).

What is Tregzi and how does it work?

Tregzi is a personalized, three-part immunotherapy that is planned to change the standard stem cell transplant. Normally, people who undergo a stem cell transplant receive donor cells that can sometimes affect healthy tissues, causing a serious condition called graft-versus-host disease. 

Tregzi addresses this risk by sorting and balancing the donor's cells into three specific groups before giving them to the patient: 

• Blood-forming stem cells (HSPCs)
• Protective regulatory T cells (Tregs) that control the immune response
• Conventional T cells (Tcons) that eliminate infections and remaining cancer cells. 

By infusing these cells in a precise, timed order over a few days, Tregzi helps the patient grow a healthy new immune system while actively stopping the donor cells from attacking the patient's body.

The clinical trial behind the approval

The FDA based its approval on excellent results from the Precision-T clinical trial. This study compared patients who received Tregzi against patients who received a traditional, unmodified stem cell transplant.

The trial measured chronic graft-versus-host disease-free survival, which tracks how long a patient can live after a transplant without developing moderate-to-severe chronic complications.

• Patients who received traditional transplants had a median complication-free survival of just 7.3 months. In contrast, the median for the Tregzi group was not even reached during the study, meaning a vast majority of patients did not have any complications throughout the follow-up period.
• Only 12.6% of patients treated with Tregzi developed moderate-to-severe chronic graft-versus-host disease within the first year, compared to 44% of patients in the standard treatment group.
• 100% of patients treated with Tregzi successfully grew a safe level of infection-fighting white blood cells (neutrophils) within 28 days of their infusion.

Because Tregzi completely resets the immune system, it requires close monitoring 

The treatment can cause strong immune reactions and lowers blood cell counts temporarily, which can increase the risk of illness.

Most common side effects from Tregzi include:

• Mouth sores (mucositis) and stomach issues (diarrhea, nausea, vomiting, abdominal pain)
• Skin rashes
• Bacterial, viral, and fungal infections
• Swelling (edema) and bleeding (hemorrhage)

The prescribing information for Tregzi includes standard warnings regarding the risks of graft failure, severe immune reactions, and secondary conditions. Because of its ability to fill a major unmet medical need, the FDA fast-tracked this application through its Priority Review and Orphan Drug programs.

VISIT THE COMPLETE ASCT GUIDE 

 For more details on the data that led to this approval, view the official clinical trial registry for the Precision-T Study (NCT05316701).

Sources:

• FDA approves allogeneic regulatory T cell-based immunotherapy with HSPC and T cells-vldq for use in matched donor hematopoietic stem cell transplantation for adults with hematologic malignancies
• Orca Bio
• Precision-T: A Study of Orca-T in Recipients Undergoing Allogeneic Transplantation for Hematologic Malignancies
• FDA Approves Immunotherapy to Reduce Chronic GVHD in Patients Undergoing Stem Cell Transplant