Jeffrey Miller, MD, Professor of Medicine at the University of Minnesota and Deputy Director of the Masonic Cancer Clinic in Minneapolis, commented on the haploidentical hematopoietic stem cell transplantation studies presented at the American Society of Hematology meeting for The ASCO Post

“The problem with haploidentical transplants is doing them safely, without the occurrence of lethal [graft-vs-host disease],” he said, estimating the risk is about 70% under the conventional approach.

“This is why most transplant centers have not adapted haploid transplants. Most look for adult unrelated donors, and with this there is a problem with [unequal] access,” he said.

Safer Procedure

“T-cell alpha/beta depletion presumes that the [graft-vs-host disease]–causing cells are T-cell receptor alpha/beta–positive, so if we eliminate them we can do the transplant more safely, without the use of post-transplant immune-suppressive drugs,” Dr. Miller explained. “You leave the NK and gamma/delta–positive cells.”

His center was the first in the United States to try this approach, mirroring the experience described by the Italian investigators at the American Society of Hematology meeting. He said the first patient engrafted quickly and is doing well. “Anecdotally, the results are very promising. We believe in this enough to get this program up and running,” he reported.

“This approach has things in common with the Hopkins approach, which gives post-transplant cyclophosphamide to blunt or knock down the [graft-vs-host disease]–reactive T-cells in a way that seems relatively safe. But high-dose [cyclophosphamide] blunts NK cells, so we personally favor alpha/beta depletion, which will allow immune reactivity to occur, perhaps somewhat better,” Dr. Miller continued.

“The limiting factor in doing haploid transplant is [graft-vs-host disease], and both of these approaches are intended to blunt this. Both can also be used in older patients,” he said. ■

Disclosure: Dr. Miller reported no potential conflicts of interest.