Could abatacept fuel greater use of mismatched, unrelated donors?
One downside of using an HLA-mismatched donor is the potential risk of developing aGVHD, Doris M. Ponce, MD, a hematologic oncologist with Memorial Sloan Kettering Cancer Center in New York, who was not involved with the research, said in an interview.
Dr. Doris M. Ponce
Potential risk factors for aGVHD include “having a female multiparous donor, HLA-mismatched donor, unrelated donor, donor and recipient age (>40 years), [peripheral blood stem cell] stem cell graft, recipient [cytomegalovirus] serostatus (recipient/donor), myeloablative conditioning, [total body irradiation]–based conditioning, [and] gut microbiome dysbiosis,” Dr. Ponce explained.
Abatacept’s approval may have particular relevance for people of color. “It’s been understood for a long time that the likelihood of finding an 8/8 well-matched, volunteer unrelated donor varies by race or ethnicity,” Steven Devine, MD, a board-certified oncologist who is chief medical officer of Be The Match and associate scientific director at CIBMTR, said in an interview.
Mr. Spellman noted that, of the more than 35 million donors on worldwide registries accessible through the National Marrow Donor Program’s Be The Match Registry, “the match rates differ quite substantially by race and ethnicity.” Approximately 29% of African Americans find a full match on the registry, compared with 81% of Whites, 49% of Hispanics, and 47% Asian/Pacific Islanders.
“Being able to utilize a 7/8 match in a safe, effective manner using abatacept, which abatacept has been approved for, does increase those match rates quite substantially,” he explained. Among African Americans, this means the match rate increases to 84%, among Hispanics and Asian/Pacific Islanders to approximately 90%, and among Whites to about 98%.
That kind of improvement in the match rate is “the equivalent of adding more than more than 10 million ethnically diverse donors to the registry in 1 day,” Dr. Devine said. “The availability of abatacept could really level the playing field for patients in need of a lifesaving transplant.”
Further study of abatacept
With abatacept, “I think the results are really encouraging, and I think that further studies [are needed] to better define how the drug would work and whether it can later prevent chronic graft versus host disease,” Dr. Devine said. He said the ABA3 trial has been designed around this question, with the hypothesis that extending abatacept to an eight-dose regimen may help with chronic GVHD.
Although the FDA’s approval of abatacept was recent, Mr. Spellman said, Be The Match has seen early indications that mismatched donors in the registry are being used, which may point to an increased utilization of abatacept. “Through October to December of 2021, there was a pretty substantial increase in the use of mismatched, unrelated donors in that time frame.”
Dr. Steven Devine
Dr. Devine noted that he is seeing a lot of interest in using abatacept. “I think people are still learning how best to incorporate it into their standard of care right now.”
Meanwhile, Memorial Sloan Kettering Cancer Center is already planning to use abatacept, Dr. Ponce noted. “We have abatacept in our formulary for adult and children, and are planning on using it for patients receiving an unmodified graft from a [matched unrelated donor] or 1-allele [mismatched unrelated donor] using CNI and MTX-based GVHD prophylaxis.”
Dr. Devine and Mr. Spellman are employees of Be The Match and CIBMTR, which provided the registry control group for the ABA2 trial. Dr. Devine also reported that he has been a scientific advisory board member for Bristol-Myers Squibb. Dr. Ponce reports no relevant conflicts of interest.