Friday, December 12, 2025
NIH clinical trial shows promise for people with treatment-limited, life-threatening disorder.
A clinical trial at the National Institutes of Health (NIH) has shown that an experimental treatment for patients with severe aplastic anemia resulted in a 94% survival rate without complications following transplantation. The treatment, which deploys an expanded umbilical cord blood approach known as omidubicel, was recently approved by the U.S. Food and Drug Administration for use against severe aplastic anemia for patients without options to receive donor hematopoietic stem cell (HSC) transplantation.
Nearly all (94%) of patients had rapid neutrophil engraftment, meaning that their white blood cell count had recovered, at median of eight days, dramatically faster than standard umbilical cord transplants. By 100 days post-transplant, most patients had experienced sustained cord engraftment, which means that the transplanted donor stem cells were established in the patient’s bone marrow and able to produce healthy new blood cells long term.
“The results of this ongoing study are extremely encouraging and indicate a significant advancement in the treatment options for patients with a high unmet medical need. Patients in the study were high-risk but had significantly better than expected outcomes,” said Richard Childs, M.D., assistant U.S. Surgeon General, NIH study lead, and scientific director of NIH’s National Heart, Lung, and Blood Institute.
Severe aplastic anemia causes bone marrow to stop producing adequate blood cells, which leads to infections, bleeding, and ongoing dependence on blood transfusions. If left untreated, the disease can be fatal. Conventional treatment typically involves immunosuppressive therapy and/or HSC transplantation. However, while immunosuppressive therapy can help prolong survival, not all patients respond to it, and many relapse. Lack of a tissue-matched sibling or related donor match remains a major barrier to successful HSC transplantation. In the absence of a donor, patients can undergo umbilical cord blood transplantation, but such transplants often contain low stem-cell numbers, prolonging the time to immune recovery and substantially increasing the risk of infection and rejection of the transplant.
Omidubicel stem cell therapy involves taking limited numbers of donated umbilical cord blood stem cells, and culturing them in a lab, where they multiply and are enhanced with a form of vitamin B3, known as nicotinamide, which provides a larger, more effective stem cell dose for restoring the patient’s blood and immune system.
The clinical trial enrolled 18 patients (aged 4-60 years) with severe aplastic anemia who were unresponsive to standard immunosuppressive therapy and without an available donor.
Results from two additional study participants have yet to be analyzed. Publication of the complete trial findings are expected next year.
The promising trial results prompted the U.S. Food and Drug Administration to approve the novel transplantation approach for refractory severe aplastic anemia. The therapy’s brand name is Omisirge by Gamida Cell Ltd., Israel.
“The approval of a therapy for patients who were lacking therapeutic options is a prime example of how NIH advances patient care and helps shape the future of medicine through the development of new therapeutics,” said Childs.
The trial is ongoing. For more information, visit clincialtrials.gov and search for identifier NCT03173937.
About the National Heart, Lung, and Blood Institute (NHLBI): NHLBI is the global leader in conducting and supporting research in heart, lung, and blood diseases and sleep disorders that advances scientific knowledge, improves public health, and saves lives. For more information, visit https://www.nhlbi.nih.gov.
About the National Institutes of Health (NIH): NIH, the nation’s medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.
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