The U.S. Food and Drug Administration (FDA) has approved a groundbreaking cell-based therapy, offering renewed hope to children suffering from a severe post-transplant complication: steroid-refractory acute graft-versus-host disease (SR-aGVHD). The approved product, Ryoncil (remestemcel‑L‑rknd), is an allogeneic therapy derived from mesenchymal stromal cells (MSCs) taken from donor bone marrow. This marks the first FDA approval for a mesenchymal stromal cell therapy in the United States—a significant milestone in regenerative and immune-modulating medicine.
Understanding GvHD and its treatment challenges
Graft-versus-host disease (GvHD) is a potentially fatal complication that may arise after an allogeneic stem cell transplant. In this condition, donor immune cells attack the recipient’s tissues, often affecting the skin, gastrointestinal tract, and liver. When GvHD becomes acute and unresponsive to steroids, therapeutic options become extremely limited—especially in pediatric cases. That’s why the approval of Ryoncil represents a critical advancement in the treatment landscape for these young patients.
How Ryoncil works: a novel cell therapy approach
Ryoncil consists of mesenchymal stromal cells (MSCs) derived from the bone marrow of healthy donors. These cells possess immunomodulatory properties and the ability to support tissue repair. Delivered intravenously, the MSCs migrate to inflamed areas and reduce the immune response that drives GvHD. The FDA’s approval is based on a multicenter, single-arm clinical trial involving 54 pediatric patients with steroid-refractory acute GvHD. After 28 days of treatment, 70% of the participants showed a positive response, including 30% who achieved complete remission.
Safety profile, clinical guidance, and future potential
During clinical evaluation, the most commonly reported side effects included fever, infections, hypertension, abdominal pain, and edema. The FDA advises clinicians to closely monitor for infusion-related reactions such as dyspnea, tachypnea, hypotension, or cyanosis, and to halt treatment if these occur. Ryoncil received Orphan Drug, Fast Track, and Priority Review designations from the FDA—highlighting its high medical value. Beyond its immediate clinical use, this approval also sets a precedent for the broader development of allogeneic cell therapies for various immune-related conditions.
