Journal of Clinical Oncology Publishes Study Finding No Discernable Difference in Overall Survival or GVHD-free-Relapse Free Survival for Mismatched Unrelated Adult Donors Versus Matched Unrelated Donors

Blood stem cell transplant using novel treatment modality improves outcomes and reduces risk of life-threatening graft-versus-host disease, NMDP and CIBMTR research shows

Results show nearly three-fold increased likelihood of identifying a suitable donor for blood cancer patients from ethnically diverse backgrounds

Research results from NMDP℠ and CIBMTR® (Center for International Blood and Marrow Transplant Research®)—published today in the peer-reviewed Journal of Clinical Oncology—found no discernable difference in overall survival (OS) among patients with blood cancer receiving blood stem cell transplant when investigators used an unrelated donor matched at 7/8 human leukocyte antigen (HLA) markers, compared to a fully matched 8/8 unrelated donor when using a post-transplant cyclophosphamide-based (PTCy) graft-versus-host disease (GVHD) prevention strategy. Conducted by CIBMTR—a research collaboration between the Medical College of Wisconsin® and NMDP—the observational study also showed no discernable differences in GVHD-free, relapse-free survival (GRFS) for adults with blood cancers who had a 7/8 or an 8/8 unrelated donor transplant when using PTCy.

The study, “Post-Transplant Cyclophosphamide–Based Graft-Versus-Host Disease Prophylaxis Attenuates Disparity in Outcomes Between Use of Matched or Mismatched Unrelated Donors,” evaluated 10,025 adult patients at 153 U.S. transplant centers who underwent initial unrelated donor blood stem cell transplant for acute leukemia or myelodysplastic syndromes from 2017–2021 and reported outcomes to CIBMTR. The most clinically significant outcome observed showed that when compared to 8/8 unrelated donor transplant using PTCy, 7/8 unrelated donor transplant with PTCy had similar OS (hazard ratio [HR], 0.96 [95% Confidence Interval, 0.823-1.11]; P = .60) and similar GRFS (HR, 0.90 [0.79-1.02]; P = .1).

Previously established methods to prevent GVHD involved use of immunosuppressants called calcineurin inhibitors, yet outcomes were traditionally worse with mismatched donors. In this study, when compared to 8/8 unrelated donor transplant using traditional calcineurin-inhibitor GVHD prevention methods, OS was improved after 8/8 PTCy transplant (HR, 0.88 [0.80-0.96]; P = .004) and similar with 7/8 PTCy transplant (HR, 0.92 [95% CI, 0.80 to 1.05]; P = .2062). GRFS was improved after 8/8 (HR, 0.61 [0.57-0.66]; P < .0001) or 7/8 PTCy transplant (HR, 0.68 [0.60-0.76]; P < .0001).

Investigators showed adoption of novel treatment modality PTCy can eliminate disparities in survival, greatly reduce GVHD risk, and expand safe and effective transplant access to people for whom a matched unrelated donor is unavailable, which disproportionally impacts patients who are racially and ethnically diverse.

“These data confirm we are at the forefront of transplant practice change. As our global population becomes more diverse and geographically disparate, patients facing blood cancer are increasingly looking for a safe and effective method to increase their survival and longevity,” Brian Shaffer, MD, co-first author; bone marrow transplant specialist & cellular therapist, Memorial Sloan Kettering Cancer Center, said. “Achieving recognition from one the most prestigious, peer-reviewed medical publications demonstrates the credibility of these data and builds the evidential case for using mismatched unrelated donors to expand access to blood stem cell therapy for all patients.”

In the U.S., patients with blood cancers from Asian/Pacific Islander backgrounds currently have a 47% chance of finding a fully matched, 8/8 unrelated donor on the NMDP Registry℠ of potential volunteer donors. However, those odds increase to 92% when searching for a 7/8 match or greater. African American and Black patients’ chances jump from 29% with an 8/8 match, to as high as 84% with a 7/8 match—while patients with Latino / Hispanic or non-Hispanic White ancestry improve their odds from 48% (8/8) to 90% (7/8) and 79% (8/8) to 99% (7/8), respectively.¹

“This novel approach transforms the landscape for physicians, researchers, patients and families, expanding the definition of a ‘suitable donor,’” said Steven Devine, MD, chief medical officer, NMDP and senior scientific director, CIBMTR. “Not only does achieving significantly greater outcomes give patients another chance at life, it breaks down the barriers to transplant for all patients, regardless of their ancestry.”

These results are part of NMDP’s ongoing research commitment to expand access to cell therapy to all patients and close the donor availability gap. NMDP’s network of transplant centers, many of which participate in CIBMTR trials, are collaborating to bring new research to light that is challenging previously established blood stem cell transplantation science. NMDP’s Donor for All initiative includes several research efforts, including this published study, that aim to establish a new, safe and effective approach for using mismatched unrelated donor transplants in the U.S. and abroad.

Operational data from NMDP-facilitated transplants show 60% year-over-year growth in mismatched unrelated donor transplant—the majority of which are from unrelated donors matched at 7/8 HLA markers, indicating how the U.S. medical community is seeking other safe and effective, evidence-based methods to prolong patients’ ability to survive and thrive.²

“This is scientific evidence showing we are addressing an unmet need,” Dr. Devine added.

CIBMTR presented findings from this study at the American Society for Transplantation and Cellular Therapy’s scientific congress, Tandem 2024, in February 2024.

About CIBMTR®

CIBMTR® (Center for International Blood and Marrow Transplant Research®) is a nonprofit research collaboration between NMDP℠, in Minneapolis, and the Medical College of Wisconsin, in Milwaukee. CIBMTR collaborates with the global scientific community to increase survival and enrich quality of life for patients. CIBMTR facilitates critical observational and interventional research through scientific and statistical expertise, a large network of centers, and a unique database of long-term clinical data for more than 675,000 people who have received hematopoietic cell transplantation and other cellular therapies. Learn more at cibmtr.org.

About NMDP℠

At NMDP℠, we believe each of us holds the key to curing blood cancers and disorders. As a global nonprofit leader in cell therapy, NMDP creates essential connections between researchers and supporters to inspire action and accelerate innovation to find life-saving cures. With the help of blood stem cell donors from the world’s most diverse registry and our extensive network of transplant partners, physicians and caregivers, we’re expanding access to treatment so that every patient can receive their life-saving cell therapy. NMDP. Find cures. Save lives. Learn more at nmdp.org.

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