PTCy Levels the Playing Field for Unrelated Donor Hematopoietic Cell Transplants


Jeff Auletta, MD, discusses findings from a study evaluationg posttransplant cyclophosphamide in unmatched stem cell transplants.

A study presented by Jeff Auletta, MD, at the 2024 Transplantation and Cellular Therapy Tandem Meetings investigated the impact of a specific medication, posttransplant cyclophosphamide (PTCy), on transplant outcomes for patients with blood cancers who receive unrelated donor (URD) hematopoietic cell transplants (HCT).

Traditionally, perfectly matched donors (8/8 HLA match) were preferred due to lower complication rates. However, finding such a match can be difficult, especially for patients of diverse ancestry.

The study found that using PTCy-based therapy eliminated the previously observed difference in survival rates between patients receiving a perfectly matched (8/8) or 1-antigen mismatched (7/8) URD HCT. This suggests that PTCy allows for successful transplants with slightly mismatched donors, potentially increasing access to HCT for a wider group of patients.

Furthermore, PTCy-based therapy seemed to be more effective than the previously used calcineurin inhibitor based therapy, regardless of the donor match. This was demonstrated by lower rates of complications like graft-vs-host disease and improved survival rates.

While a perfectly matched donor (8/8 URD) with PTCy remains the preferred option, the study suggests that 7/8 URD HCT with PTCy is a viable alternative for patients lacking a perfectly matched donor. This finding allows for increased access to HCT, particularly for patients with diverse backgrounds, potentially improving overall outcomes for patients with blood cancers.

Here Auletta, senior vice president of health equity at the National Marrow Donor Program and chief scientific officer at the Center for International Blood and Marrow Transplant Research, discuses findings and implications from the study.


0:05 | We found that overall survival was the same between 8 out of 8t and 7 out of 8 unrelated donor transplants. We found that using calcineurin inhibitor-based GVHD prophylaxis that there was an outcome disparity in overall survival between 8 out of 8 and 7 out of 8 unrelated donor transplants. However, using post-transplant cyclophosphamide, we found that the overall survival was similar between 8 out of 8 and 7 out of 8 unrelated donor transplants. In addition, we found that graft-vs-host disease-free, relapse-free survival was similar between 8 out of 8 and 7 out of 8 unrelated donor transplants when using calcineurin inhibitor-based GVHD prophylaxis.

0:39 | However, when using post-transplant cyclophosphamide-based GVHD prophylaxis, graft-vs-host disease-free, relapse free survival was the same between 8 out of 8 and 7 out of 8 unrelated donor transplants and higher than unrelated donor transplants receiving calcineurin inhibitor-based GVHD prophylaxis.

0:59 | There are 3 takeaways of the study. The first is always refer a patient with a transplant disease indication. This study looked at acute leukemia and myelodysplasia, and typically, community physicians don't often see those. So transplant centers are definitely ways to go in terms of early referral. The second thing is ethnically diverse patients deserve equal outcomes, and so this study enables ethnically diverse patients to receive life-saving therapy like a stem cell transplant. And the last is the use of post-transplant cyclophosphamide has clearly been a major advantage to the field and has taken the field in another direction in terms of using alternative donor transplants, specifically enabling more ethnically diverse patients to receive stem cell transplant.

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