Stem cells can be extracted from a donor’s blood. Recently, researchers have identified a groundbreaking treatment that significantly broadens the range of individuals who can serve as effective stem cell donors.
Key Points to Note:
- Historical Limitation: Previously, patients requiring bone marrow or stem cell transplants needed a donor with a perfect 100-percent match. This stringent requirement often posed challenges in finding suitable donors, especially for those with rare genetic profiles.
- Innovative Use of an Old Drug: A repurposed chemotherapy drug has revolutionized the transplant process by allowing successful transplants from partially matched donors. This advancement not only increases the pool of potential donors but also enhances the feasibility of life-saving transplants.
- Impact on Minority Communities: The new technique is poised to significantly improve access to stem cell transplants for minority populations, who have historically faced greater difficulties in finding fully matched donors. By easing the match requirements, this development can lead to more equitable healthcare outcomes.
Innovative Stem Cell Transplant Approach Enhances Outcomes for Blood Cancer Patients
For individuals battling blood cancers like leukemia, lymphoma, and multiple myeloma, finding a stem cell donor who is a perfect match can be a life-or-death challenge. Despite a national registry boasting over 40 million potential donors, exact matches are often elusive, especially for those from underrepresented racial and ethnic groups. However, a groundbreaking method utilizing an older chemotherapy drug, cyclophosphamide, is revolutionizing stem cell transplants. Researchers have discovered that administering cyclophosphamide several days post-transplant allows patients receiving stem cells from unrelated, partially matched donors to achieve survival rates akin to those with perfectly matched donors. This significant advancement is highlighted in the interim results of the ACCESS trial, set to be presented at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago on May 31.
Expanding Access to Lifesaving Therapy
“This innovative approach can greatly expand patient access to safe and effective stem cell transplant, regardless of matching degree with the donor,” says Monzr M. Al Malki, MD, a hematologist and oncologist and the director of the Unrelated Donor BMT program at City of Hope, a renowned cancer research and treatment organization. This development is particularly thrilling as it opens the door for more patients to receive potentially life-saving treatments, Dr. Al Malki emphasizes.
Challenges in Finding Compatible Donors
Finding a compatible stem cell donor is often fraught with challenges, especially for Black, Hispanic, and Latino patients. Compatibility hinges on human leukocyte antigens (HLAs), a set of protein markers on blood cells, explains David Miklos, MD, a professor of medicine and the chief of the Stanford BMT and Cell Therapy Program at Stanford Medicine, one of the medical sites participating in the trial. Historically, the best matches come from close relatives, typically siblings, but even then, the odds are limited—only a 25% chance for a full match and 50% for a partial match. Consequently, many patients are left without suitable donors.
While approximately 80% of white patients find a match through the National Bone Marrow Registry, the numbers drop significantly for other groups: fewer than 30% of Black individuals and less than half of Latino and Hispanic people find a match. The need for an exact match has been critical because any deviation increases the risk of graft failure and graft-versus-host disease, where the transplanted cells attack the recipient’s body, potentially causing severe or fatal complications, Dr. Miklos explains.
Cyclophosphamide: A Game-Changer in Stem Cell Transplants
About a decade ago, researchers began using cyclophosphamide to eradicate parts of the immune system that would otherwise reject the transplant. This breakthrough led to improved outcomes for fully matched donors and paved the way for successful transplants with partially matched donors. More recently, studies have explored the efficacy of cyclophosphamide in transplants from partially matched, unrelated donors. A study published in June 2021 showed high survival rates among 80 patients receiving bone marrow transplants from such donors.
Promising Results in Peripheral Blood Stem Cell Transplants
The current study investigates the use of cyclophosphamide in peripheral blood stem cell transplants, where healthy stem cells are harvested from a donor’s bloodstream and then infused into the patient. This method has largely replaced bone marrow transplants because it is easier and safer; donors are spared the need for anesthesia, notes Dr. Al Malki.
Researchers analyzed data from 70 adults, with an average age of 65, all suffering from advanced blood cancers. Participants underwent a “reduced-intensity” conditioning regimen to suppress their immune system before transplantation, followed by the infusion of stem cells from unrelated, partially matched donors. The results were promising, with a 79% overall survival rate at one year, comparable to fully matched donor outcomes.
One of the primary risks of transplantation is graft-versus-host disease. However, the study found that 51% of participants were free from this disease and had not relapsed one year post-transplant, aligning with rates seen in fully matched donor transplants, Dr. Al Malki reports.
Transformative Impact on Donor Availability
Historically, the scarcity of matched, related sibling donors and the significant variability in unrelated donor availability have been major barriers, especially for patients of diverse ethnic backgrounds, explains Steven M. Devine, MD, chief medical officer of the National Marrow Donor Program (NMDP) and Be The Match. “These findings advance our ability to offer more options to patients without a fully matched donor, many of whom are ethnically diverse and have been underserved in receiving potentially lifesaving cell therapy,” Dr. Devine asserts.
These results are a crucial step towards addressing existing disparities, agrees Dr. Miklos. “In the past, we could not bring some patients forward to receive this lifesaving therapy because they didn’t have a compatible donor, but with the new approach of using post-transplant cyclophosphamide, all patients have donors now,” he says.
Future Implications and Broader Access
The success of this new approach holds significant implications for the future of stem cell transplants. By making it possible for patients to receive transplants from partially matched, unrelated donors, this method could drastically reduce the waiting time for suitable donors and increase the overall accessibility of stem cell therapy. This is particularly important for ethnically diverse populations who have historically faced challenges in finding matching donors.
Dr. Al Malki and his colleagues are optimistic about the potential of this approach to transform the landscape of stem cell transplants. “We are hopeful that this technique will become a standard part of stem cell transplant protocols, providing more patients with the opportunity to receive the treatment they need,” he says.
Hence, the innovative use of cyclophosphamide in stem cell transplants represents a significant advancement in the treatment of blood cancers. By expanding the pool of potential donors and improving survival rates, this approach offers new hope to many patients, particularly those from underrepresented racial and ethnic groups. The findings from the ACCESS trial underscore the potential for broader access to lifesaving therapies, paving the way for a more equitable and effective healthcare system.
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