Mesenchymal Stem Cell (MSC) Therapy: FDA Approves Ryoncil 

Ryoncil has been approved for the treatment of steroid-refractory acute graft-versus-host disease (SR-aGVHD), a life-threatening condition that may result from blood stem cell transplantation performed to replace recipient’s defective stem cells in certain types of blood cancers, blood disorders or immune system disorders. This makes Ryoncil the first FDA-approved MSC (Mesenchymal Stem Cell) therapy. Ryoncil contains MSCs isolated from the bone marrow of healthy adult human donors which can differentiate into multiple other types of cells. Intravenous infusions of mesenchymal stromal cells (MSCs) provide survival benefits.  

On 18 December 2024, FDA approved Ryoncil (remestemcel-L-rknd), an allogeneic (donor) bone marrow-derived mesenchymal stromal cell (MSC) therapy for the treatment of steroid-refractory acute graft-versus-host disease (SR-aGVHD) in paediatric patients 2 months of age and older. This makes Ryoncil the first FDA-approved MSC (Mesenchymal Stem Cell) therapy.  

Ryoncil contains MSCs isolated from the bone marrow of healthy adult human donors which can differentiate into multiple other types of cells.  

Steroid-refractory acute graft-versus-host disease (SR-aGVHD) is a serious and life-threatening condition that can have significant, wide-ranging health consequences, including damage to multiple organs, reduced quality of life and risk of death in affected patients. This can occur as a complication of allogeneic hematopoietic (blood) stem cell transplantation (allo-HSCT).   

In allo-HSCT, a patient receives hematopoietic stem cells from a healthy donor to replace their own stem cells and form new blood cells, a procedure often done as part of treatment for certain types of blood cancers, blood disorders or immune system disorders. 

Approval of Ryoncil follows evaluation of its safety and effectiveness in a multicentre, single-arm study involving 54 paediatric participants with SR-aGVHD who had undergone allo-HSCT. The participants received a total of eight intravenous infusions of Ryoncil twice weekly for four consecutive weeks. The assessment of effectiveness was based primarily on the rate and duration of response to treatment 28 days after initiating Ryoncil. 

In another trial for SR-aGVHD after allo-HSCT, it was found that a combination of MSCs and basiliximab (a monoclonal antibody used to prevent transplant rejection) leads to a much better complete response (CR) rate than basiliximab alone.

It has been observed in clinical trials that IV infusions of mesenchymal stromal cells (MSCs) provide survival benefits. 

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References:  

1. FDA News Release – FDA Approves First Mesenchymal Stromal Cell Therapy to Treat Steroid-refractory Acute Graft-versus-host Disease. Posted 18 December 2024. Available at https://www.fda.gov/news-events/press-announcements/fda-approves-first-mesenchymal-stromal-cell-therapy-treat-steroid-refractory-acute-graft-versus-host  

2. Fu, H., Sun, X., Lin, R. et al. Mesenchymal stromal cells plus basiliximab improve the response of steroid-refractory acute graft-versus-host disease as a second-line therapy: a multicentre, randomized, controlled trial. BMC Med 22, 85 (2024). https://doi.org/10.1186/s12916-024-03275-5 

3. Kelly, K., Bloor, A.J.C., Griffin, J.E. et al. Two-year safety outcomes of iPS cell-derived mesenchymal stromal cells in acute steroid-resistant graft-versus-host disease. Nat Med 30, 1556–1558 (2024). https://doi.org/10.1038/s41591-024-02990-z 

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