Researchers have found that allogeneic stem cell transplantation from a haploidentical relative may significantly increase the rate of success in Hispanic patients with acute lymphoblastic leukemia (ALL), according to a recent study published by Ashouri et al in Leukemia Research.
Background
In patients with ALL—which originates in the bone marrow—allogeneic stem cell transplantation may be necessary for survival. Prior to receiving transplantation, potential recipients are required to find a donor with a matching human leukocyte antigen tissue type. When white blood cells find foreign cells with an unfamiliar human leukocyte antigen type, they trigger an attack response. To ensure that a patient’s immune system accepts the new bone marrow stem cells, physicians aim to find a donor with the closest possible match for the patient.
Because human leukocyte antigen tissue type is inherited, patients initially look for potential donors among their immediate family members. Unrelated matched donors may be available through the National Marrow Donor Program, which manages the largest registry of potential bone marrow donors. Despite the size of the registry, certain ethnic backgrounds may have more difficulties finding a match as a result of underrepresentation. White patients have a 79% chance of finding a match through the registry; Hispanic patients may face challenges finding an identically matched donor within their family or through the national bone marrow donor registry. These patients often find a matching relative or a matching bone marrow donor in 30% and 48% of cases, respectively.
Hispanic patients have a higher incidence of ALL compared with White patients and often present with higher-risk disease characteristics that are associated with poorer outcomes and require complex care, making the identification of a bone marrow donor more crucial.
Study Methods and Results
In the recent study, the researchers retrospectively assessed the 2-year outcomes of 88 patients with B-cell ALL who underwent allogeneic stem cell transplantation. They noted that bone marrow donors included fully matched sibling donors, fully matched unrelated donors identified through the national donor registry, and half-matched donors from the patients’ families.
Parents and children of patients with ALL were guaranteed half matches, and siblings were capable of being half matches 50% of the time—which was twice as likely as finding a fully matched sibling (25%).The patients who received allogeneic stem cell transplantation using bone marrow from a half-identical relative were about 70% more likely to avoid relapse compared with those who received a transplant using bone marrow from a fully identical relative. Compared with those who received a transplant using bone marrow from an identically matched registered donor, half-identical relative transplant recipients were more than twice as likely to avoid relapse and graft-vs-host disease.
The researchers revealed that allogeneic stem cell transplantation using bone marrow from half-identical family members has been performed more frequently because of the challenges in finding a fully matched donor and treatment advances that help the body accept the new cells despite not having a fully matched human leukocyte antigen type.
Conclusions
The researchers hope the results of their study will inspire larger clinical trials to further investigate the findings and provide insights into why allogeneic stem cell transplantation from half-identical relatives could result in more positive outcomes, particularly among patients with high-risk subtypes of ALL.
“These results suggest that Hispanic patients may benefit more from receiving [allogeneic stem cell transplantation] from a half-matched parent, child, or sibling, rather than a full match from the national donor registry. This creates opportunities for patients to receive a life-saving procedure that may otherwise be out of reach,” highlighted senior study author George Yaghmour, MD, Associate Professor of Clinical Medicine at the Keck School of Medicine as well as Associate Director of Transplant and Cellular Therapy and a hematologist at the Norris Comprehensive Cancer Center at the University of Southern California. “These findings are a strong basis to continue researching the clinical benefits of haploidentical bone marrow donation, particularly among patient groups with historically limited access to fully matched donors. Future studies can potentially address health disparities while optimizing outcomes and ultimately provide more hope for all patients facing this difficult diagnosis,” he concluded.
Disclosure: For full disclosures of the study authors, visit sciencedirect.com.
