Race, Ethnicity and Donor Type Continue to Affect Survival After Donor Stem Cell Transplant

A study led by Roswell Park Comprehensive Cancer Center reveals that a patient’s race and ethnicity, as well as how closely matched they are to their stem cell donor, can all significantly affect clinical outcomes for those who undergo stem cell transplant as treatment for cancer — despite the introduction of a new standard-of-care drug regimen shown to lower the risk of graft-versus-host disease, a potentially fatal side effect. Study results are expected to lay the groundwork for improved selection of stem cell donors.

The findings relate to allogeneic hematopoietic stem cell transplant (HCT), in which patients receive stem cells drawn from a consenting donor’s blood as part of their treatment for some cancers, including many forms of leukemia and lymphoma.

“The biggest takeaway of our analysis is that for patients undergoing allogeneic stem cell transplant, the patient’s race, ethnicity and age should be a strong consideration in identifying their stem cell donor,” explains first and presenting author Megan Herr, PhD, Associate Member and Associate Professor of Oncology in Roswell Park’s Transplant and Cellular Therapy Program, who will share the findings today during the 67th annual meeting of the American Society of Hematology (ASH) in Orlando, Florida. Theresa Hahn, PhD, Professor of Oncology in Roswell Park’s Department of Cancer Prevention and Control, is senior author.

“There is no one-size-fits-all model to guide stem cell donor selection — we have to keep building on the start we've made here in applying insights from big data to chart patterns in which patients have the best outcomes following which types of transplant,” adds Dr. Herr.

The research marks the first evaluation of race- and ethnicity-related disparities in overall survival since the standard of care changed to include administration of the chemotherapy drug cyclophosphamide (PTCy) after an allogeneic transplant, which involves donor-provided stem cells. In the pre-PTCy era, Hispanic and non-Hispanic Black HCT patients had higher mortality rates than non-Hispanic white patients and were less likely to use an unrelated stem cell donor.

Cyclophosphamide has dramatically reduced the risk of graft-versus-host disease (GVHD) — which occurs when donor cells attack the patient’s body. Research led nationally by study co-author Shernan Holtan, MD, Chief of Blood and Marrow Transplantation at Roswell Park, paved the way for expanded use of cyclophosphamide, a shift that also made stem cell transplants increasingly available to minority patients.

But this latest study shows that disparities in overall survival persist between racial and ethnic groups, and donor type plays a key role. Analyzing data from the Center for International Blood and Marrow Transplant Research (CIBMTR) for more than 4,000 patients who received cyclophosphamide after undergoing allogeneic transplant between 2013 and 2018, investigators looked at three main racial/ethnic groups — Hispanic, non-Hispanic Black and non-Hispanic white — and compared overall survival rates. They also factored in the type of transplant according to donor type: haploidentical — a “half-matched” donor, typically a family member — or a matched unrelated donor (MUD), matched related donor (MRD) or mismatched unrelated donor (MMUD).

Among patients with a matched related donor or mismatched unrelated donor, the data showed no difference in overall survival between the three racial/ethnic groups. For the other types of transplants, the data revealed:

• Among patients who are non-Hispanic and white, those with a matched unrelated donor had higher overall survival than those with other donor types.
• Among non-Hispanic Black patients, those with haploidentical, matched related or mismatched unrelated donors had higher survival rates than those with matched unrelated donors.
• Among Hispanics, those with haploidentical or matched related donors had higher overall survival than those with other donor types.

In the U.S. alone, an estimated 8,000 patients undergo allogeneic hematopoietic stem cell transplant every year, mostly to treat such hematologic cancers as leukemia, lymphoma or multiple myeloma.

ASH 2025 presentation details

Megan Herr, PhD, is first/presenting author, with senior author Theresa Hahn, PhD, on oral abstract 8885, Overall survival after post-transplant cyclophosphamide (PTCy) peripheral blood hematopoietic cell transplantation (HCT) differs by race, ethnicity, and donor

• Monday, Dec. 8, 3:15-3:30 p.m. EST in room W414C