Mesoblast gets FDA nod for new potency assay to release Ryoncil batches

Mesoblast Limited said on September 24, 2026 (September 23 in Melbourne) that the FDA approved a new potency assay for releasing and monitoring the stability of commercial batches of its cell therapy Ryoncil (remestemcel-L-rknd). The assay, called the T-cell Proliferation Inhibition BioAssay, or TIBA, will be used to release and monitor stability for all new commercial lots of the FDA-approved mesenchymal stromal cell product.¹

According to Mesoblast, the TIBA assay is designed to be sensitive enough to catch potency shifts that might occur as manufacturing processes change or as production moves to new facilities.¹ It will be used together with the product's existing potency assays, which measure IL-2Rα inhibition and Cell Adhesion and Proliferation (CAP), as part of the release requirements under Ryoncil's Biologics License.¹ The company said the combination of these assays is meant to ensure that Ryoncil remains consistent, potent, and clinically effective.¹

Mesoblast described Ryoncil as the first industrially manufactured allogeneic MSC product approved by the FDA for any indication, and the only MSC product approved for patients with steroid-refractory acute graft versus host disease aged 2 months or older.¹ The company also said it has been working closely with the FDA since Ryoncil's approval to align on manufacturing advances and new quality-control assays.¹

Beyond its approved use in pediatric steroid-refractory acute graft versus host disease, Mesoblast said Ryoncil is being developed for additional inflammatory conditions, including the adult form of steroid-refractory acute graft versus host disease and biologic-resistant inflammatory bowel disease.¹ Separately, the company said its rexlemestrocel-L platform is being developed for heart failure and chronic low back pain.¹ Mesoblast noted it has established commercial partnerships in Japan, Europe and China.¹