Ryoncil (remestemcel-L-rknd) is an FDA-approved allogeneic bone marrow-derived mesenchymal stromal cell (MSC) therapy designed to treat steroid-refractory acute graft-versus-host disease (SR-aGvHD) in pediatric patients aged two months and older. It acts by reducing severe inflammation, with studies indicating high response rates and improved survival in children.[1] Ryoncil is the first FDA approved MSC therapy.
MSCs are highly valued in regenerative medicine for three primary mechanisms: immunomodulation, trophic effects, and homing and migration. “The therapeutic effects of MSCs can be mediated through the release of bioactive molecules, including growth factors, cytokines, and extracellular vesicles, which play crucial roles in modulating the local cellular environment, promoting tissue repair, angiogenesis, and cell survival, and exerting anti-inflammatory effects. MSCs can also interact with various immune cells, such as T cells, B cells, dendritic cells, and macrophages, modulating the immune response through both direct cell‒cell interactions and the release of immunoregulatory molecules.”[2]
Duchenne Muscular Dystrophy (DMD) is an X-linked genetic disorder characterized by progressive muscle degeneration affecting the skeletal, respiratory, and cardiac muscles. It is caused by the absence of functional dystrophin, a key structural protein in muscle cells. DMD affects approximately 15,000 individuals in the United States and primarily impacts boys.[3] It occurs in approximately one in 3,500 to 5,000 male births.[4] Over time, deterioration of the muscle leads to loss of ambulation, respiratory failure and cardiomyopathy leading to death by the third decade.
Currently available gene therapies that replace or increase the missing dystrophin protein are not a complete cure. Chronic inflammation of skeletal and heart muscle remains a major underlying cause of progressive weakness, leading to loss of ambulation, reliance on wheelchair assistance and death in DMD. Corticosteroid use has improved survival, but there are long-term side effects and the drug effectiveness plateaus. Leveraging Ryoncil’s anti-inflammatory properties, Mesoblast will conduct a clinical trial randomizing 76 patients aged five to nine years to either Ryoncil® (seven infusions of 2 x 106 cells/kg over nine months) or placebo, on top of standard of care. The trial’s primary endpoint will be time-to-stand at nine months, a validated FDA endpoint for approval.5
According to Mesoblast’s press release on April 7, 2026, “This study represents an important step forward in potentially addressing the inflammatory component of DMD, a major driver of disease progression,” said Aravindhan Veerapandiyan, MD, Director of the Comprehensive Neuromuscular Program at Arkansas Children’s Hospital, and Principal Investigator of the study. “By leveraging the anti-inflammatory effects of Ryoncil, we aim to intervene at a stage where muscle tissue may still be preserved, potentially altering the trajectory of the disease.”
Ryoncil is currently FDA approved for children under twelve with steroid-refractory acute graft-versus-host disease. The cost per infusion is $194K for a total treatment cost of $1.552M.
Ryoncil has been in the headlines recently with University of Michigan announcing their first case using Ryoncil in a pediatric patient who received allogeneic stem cell transplant for sickle cell disease and experienced graft versus host disease. He was the first patient to receive Ryoncil after FDA approval.[5]
Article by Kathy Clark, RN, BSN, CMCN, RIT, Vice President, Director of Managed Care. For more information about how the impact on your plan, please contact your Summit ReSources care specialist. The following sources were used as reference material for this article:
[1] https://www.fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/ryoncil
[2] Han X, Liao R, Li X, Zhang C, Huo S, Qin L, Xiong Y, He T, Xiao G, Zhang T. Mesenchymal stem cells in treating human diseases: molecular mechanisms and clinical studies. Signal Transduct Target Ther. 2025 Aug 22;10(1):262. doi: 10.1038/s41392-025-02313-9. PMID: 40841367; PMCID: PMC12371117.
[3],5 https://investorsmedia.mesoblast.com/static-files/385a9c65-9fa5-4160-9c54-7dcd8e4d88ca
[4] https://www.mda.org/disease/duchenne-muscular-dystrophy
[5] First U-M patient receives newly FDA-approved stem cell therapy for sickle cell anemia | Michigan Medicine