FDA Approves First Mesenchymal Stromal Cell Therapy for Steroid-Refractory Acute Graft-Versus-Host Disease

The U.S. Food and Drug Administration approved Ryoncil (remestemcel-L-rknd), an allogeneic (donor) bone marrow-derived mesenchymal stromal cell (MSC) therapy indicated for the treatment of steroid-refractory acute graft-versus-host disease (SR-aGVHD) in pediatric patients 2 months of age and older.

Ryoncil is the first FDA-approved MSC therapy. It contains MSCs, which are a type of cell that can have various roles in the body and can differentiate into multiple other types of cells. These MSCs are isolated from the bone marrow of healthy adult human donors.

“Today’s decision marks an important milestone in the use of innovative cell-based therapies to treat life-threatening diseases with devastating impacts on patients, including children,” said Peter Marks, M.D., Ph.D., director of the FDA’s Center for Biologics Evaluation and Research (CBER). “This first mesenchymal stromal cell therapy approval demonstrates the FDA’s commitment to supporting the development of safe and effective products that could improve the quality of life for patients with symptoms that are unresponsive to other therapies.”

Steroid-refractory acute graft-versus-host disease is a serious and life-threatening condition that 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.

“Steroid-refractory acute graft-versus-host disease can have significant, wide-ranging health consequences, including damage to multiple organs, reduced quality of life and risk of death in affected patients,” said Nicole Verdun, M.D., director of the Office of Therapeutic Products in CBER. “The FDA remains dedicated to helping address the urgent unmet needs of individuals with debilitating and deadly diseases, and today’s approval is an important step in that effort.”

The safety and effectiveness of Ryoncil were evaluated in a multicenter, single-arm study in 54 pediatric study participants with SR-aGVHD after undergoing allo-HSCT. Study participants received intravenous infusion of Ryoncil twice weekly for four consecutive weeks, for a total of eight infusions. Each study participant’s condition at baseline was analyzed using the International Blood and Marrow Transplantation Registry Severity Index Criteria (IBMTR) to evaluate which organs have been affected and the overall severity of the disease.

Ryoncil’s effectiveness was based primarily on the rate and duration of response to treatment 28 days after initiating Ryoncil. Study participants who had a partial or mixed response to treatment-meaning that there was improved condition in one organ with either no change (partial) or worsening condition (mixed) in another organ-received additional infusions once weekly for an additional four weeks. Sixteen study participants (30%) had a complete response to treatment 28 days after receiving Ryoncil, while 22 study participants (41%) had a partial response.

Infusion of Ryoncil should be monitored by the treating physician, and the infusion should be discontinued if there is any evidence of a reaction which may include dyspnea (shortness of breath), hypotension (low blood pressure), fever, tachypnea (rapid breathing), cyanosis (blue discoloration of skin, lips or nails) and hypoxia (low oxygen in the blood).

The most common adverse reactions in study participants who received Ryoncil were infections, fever, hemorrhage, edema, abdominal pain and hypertension. Complications such as hypersensitivity and acute infusion reactions, transmission of infectious disease or agents and ectopic tissue formation may occur following treatment with Ryoncil.

Ryoncil is contraindicated in patients with known hypersensitivity to dimethyl sulfoxide or porcine and bovine proteins. Patients should be premedicated with corticosteroids and antihistamines prior to infusion and monitored for hypersensitivity reactions during treatment with Ryoncil.

The application received Orphan Drug, Fast Track and Priority Review designations by the FDA.

The FDA granted approval of Ryoncil to Mesoblast, Inc.