Orca-T Approval is “Important Advance” for Graft Engineering in Transplant

CancerNetwork^® spoke with Wendy Stock, MD, about the FDA approval of allogeneic regulatory T cell–containing immunotherapy with hematopoietic stem and progenitor cell (HSPC) and T cells-vldq (Tregzi; Orca-T) on June 30, 2026, for use in matched donor hematopoietic stem cell transplantation with a myeloablative regimen in adults with hematologic malignancies.¹ The approval was supported by the phase 3 Precision-T trial (NCT05316701), in which 187 patients with acute leukemias or myelodysplastic syndrome (MDS) were randomly assigned to Orca-T or a conventional allograft. The 1-year chronic graft-versus-host disease (GVHD)–free survival rate was 78% with Orca-T vs 38.4% with the conventional allograft.²

Stock discussed what the approval validated about engineering the allograft itself and how Orca-T is positioned relative to the standard GVHD prophylaxis backbone of post-transplant cyclophosphamide (PTCy). She also highlighted what the data from the Precision-T trial mean for referring clinicians and patients going forward.

Stock is the Anjuli Seth Nayak Professor of Medicine, cochair of the Leukemia Committee for the National Cancer Institute–supported Alliance for Clinical Trials in Oncology, and coleader of the Clinical and Experimental Therapeutics Research Program at the University of Chicago Medicine Comprehensive Cancer Center.

CancerNetwork: Orca-T was recently approved. What does this approval validate conceptually, and does it change how clinicians should think about the allograft itself, as a drug that can be engineered rather than just infused?

Stock: It does give us some validation of many years of work that has been ongoing to try to manipulate the graft in order to improve outcomes for patients undergoing allogeneic transplant, where the big risks are relapse and GVHD, which sometimes go hand in hand because of the complications that occur after allogeneic transplant: the need for more immunosuppression, and then the increased risk of relapse.

I do think this is an important advance along with other things that have been progressing in the world of allogeneic transplant [like] other manipulations that do not always have to do with graft engineering. This shows and validates that graft engineering is possible in a successful manner to improve outcomes for patients undergoing allogeneic transplant.

The standard of care for GVHD prophylaxis has shifted heavily toward PTCy cyclophosphamide in recent years. How do you position Orca-T against a PTCy backbone? Is this a replacement, a competitor for specific patients, or a different philosophy of graft engineering altogether?

It is a different concept in the sense that…PTCy is not graft engineering per se, in terms of ex vivo engineering. Yes, it could be a competitor to Orca-T. That is not known, and that is one of the key questions that needs to be answered prospectively in terms of whether or not these 2 approaches are comparable, or whether one is better than the other.

Orca-T was tested in a different population, a very specific population. These were all HLA [human leukocyte antigen]–matched recipient and donor pairs, and it was done in the myeloablative setting. The Orca-T study does not include mismatched donors and does not include reduced-intensity conditioning. It is a very specific subset that has been shown in a randomized trial to be more effective than not manipulating the graft, but it was not compared with PTCy. That is a huge question in many ways, including potentially toxicity, which we do not fully know about. We do know there are differences in toxicity with PTCy vs non-PTCy approaches, but what we do not know is the improvement in GVHD-free survival when these 2 approaches are compared head-to-head in a similar population of patients.

One of the big issues, of course, is an economic one, and it is something I have thought about. PTCy is not particularly expensive, at least financially, to the patient. It can be costly, it increases the number of days of hospitalization, and it has some toxicity associated with it. It has clearly been shown to be a huge advance, improving the number of donors available for our patients, and that is something the Orca-T trial has not yet shown in any way. These are HLA-matched donors, both related and unrelated, so it is a different population, and it is an important question to answer prospectively. That kind of study should be coming. The other difference is that this was a myeloablative regimen, not a reduced-intensity conditioning regimen, so the PTCy comparisons are not always fully comparable. You can never fully compare different populations or different studies, so this does need to be studied prospectively.

The Precision-T trial spanned acute myeloid leukemia, acute lymphoblastic leukemia, high-risk MDS, and mixed-phenotype acute leukemia. Do you expect the benefit with Orca-T to be uniform across those diseases, or are there malignancies where reducing GVHD matters more?

I do not think we know the answer. This is a good-sized trial, but when you divide it into all these different subsets, it is hard to say that one population benefited more than another. We tend to know that myeloid malignancies benefit a lot from a graft-vs-leukemia effect, but all populations [experience] GVHD, and it can depend on the preparative regimen, which differed across populations on this trial [because] different preparative regimens were allowed on the Orca-T trial.

The answer is unknown, and I cannot speak to the strength of the benefit in one population vs another. Overall, it was very significant, and the data seemed to suggest it was effective across all populations, but the numbers in each subset are small and not able to be statistically differentiated.

This is a manufactured, time-sensitive cell product layered onto an already complex transplant workflow. What does adoption realistically require on an operational level, and would treatment be concentrated at large academic centers initially?

In general, allogeneic transplant is done at larger centers. It is such a complex operation with so many regulatory pieces. The actual shipment of the cells does not seem that complicated: the donor cells are collected in advance, shipped to the company, and returned as separate cell populations. Yes, this will be done mostly at larger transplant centers, but most centers that do transplant probably could do this. They can do the apheresis, and the shipment and quality control of the cells is all part of a transplant program; those programs that have the infrastructure and do enough allogeneic transplants should have FACT accreditation and should be able to manage this. That said, if a center is small and does not do very many allogeneic transplants per year, this might stress their system a little because the cells have to be collected in advance and shipped out, and then the center has to be prepared to receive them back.

I am not the person working in the cell-processing lab, so I cannot speak to that piece directly, but centers are very used to doing apheresis and to freezing and sending off a whole product; that is something many centers do not currently do. Still, they should be able to do that in general.

For the referring community oncologist or hematologist, what should change, and how and when should they think about sending a patient for transplant now that a lower-GVHD option exists? Does this move the conversation earlier?

This conversation should always happen earlier. Patients need to be referred for transplant regardless of Orca-T; I do not think this necessarily shifts the timing of the conversation, but one of the big struggles many centers and patients face is that patients are not referred quickly enough or are not made aware enough of the option of transplant. They need to be referred early to have the best option for transplant in first remission, which is the optimal time to do it.

I do not think patients will necessarily be referred earlier because of Orca-T but hearing that GVHD risk is lower may inspire more of that conversation. In general, that is a long transplant discussion with the experts in transplantation, and patients need to be referred earlier and made more aware of the option of transplant.

Looking ahead, with products like this, could they become the default for matched donor transplant, or will this be a specialized option for select patients and centers? What determines which way it goes?

First, this is the beginning of this investigation, so it will not be the last cellular product where regulatory T cells are selected; there is the option for selecting specific subsets, or additional subsets, in the future. This is just the beginning, but it is an important proof of concept. It will potentially allow, just as PTCy has allowed, higher-risk populations to move forward with the knowledge that it is possible to undergo transplant safely, and that outcomes are likely to be better in terms of GVHD and some of the other outcomes that looked promising in this trial, [albeit] a randomized trial without huge numbers of patients and still without long-term follow-up.

This is a very important beginning. It inspires the field of transplant graft engineering to look more carefully at other options that might improve things even more, but I do not think it will be the only one. It will become one of many important options considered when we discuss transplant with patients, to assure them that we now have methods that can truly reduce the risk of severe chronic GVHD, which is a terrible long-term complication of transplant. The results of this trial were very significant in decreasing that risk, as PTCy has also done.

That brings us back to the earlier question: is it important to compare the 2 options? Yes. Is it important to consider other, more sophisticated methods that may allow for even more specific graft engineering? Absolutely. These are things the field is now open to.

What do you hope others take away from this conversation, as well as the approval overall?

The most important point is that the primary end point was achieved, which was very statistically significant GVHD-free survival in patients who received Orca-T, the regulatory T cells infused. There were hints of other potentially good outcomes as well from this trial: fewer infections, quicker time to engraftment, and potentially even less acute GVHD. But that all needs to be followed up on in subsequent studies with longer follow-up because perhaps relapse-free survival and overall survival will also be better. That has not yet been shown, but perhaps it will be.

The big takeaway is that over the last 10 years, we have incredibly exciting, still-to-be-tweaked methods for improving outcomes for patients undergoing transplant, which is such an important procedure for curing or [achieving] long-term survival for patients with acute leukemias and high-risk myelodysplastic syndromes. This is a big advance, and it needs to be studied further, including comparisons with other major improvements in the world of transplant, such as PTCy.

Of course, I do not know what the cost of this product is, but it is going to be expensive. It will increase costs, and that is another question that can be answered in a prospective trial comparing [Orca-T vs PTCy] in a similar population.

References

1. 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. News release. FDA. June 30, 2026. Accessed July 8, 2026. https://tinyurl.com/38s3wznr
2. Meyer EH, Salhotra A, Gandhi AP, et al. Orca-T vs allogeneic hematopoietic stem cell transplantation (Precision-T): a multicenter, randomized phase 3 trial. Blood. 2026;147(11):1168-1177. doi:10.1182/blood.2025031313