Mesoblast presented new clinical data at the American Society for Transplantation and Cellular Therapy (ASTCT) and Center for International Blood & Marrow Transplant Research (CIBMTR) Tandem Meetings held February 4‑7 in Salt Lake City, with the announcement released on March 3, 2026.
The data showed that Ryoncil achieved a 76 % day‑100 survival rate in adult patients with steroid‑refractory acute graft‑versus‑host disease (SR‑aGvHD), matching the 76 % rate observed in pediatric patients. The figures come from the expanded access (EIND) program, where adults who had failed ruxolitinib or other second‑line agents were treated with Ryoncil.
The presentation also highlighted the benefit of early treatment: patients who received Ryoncil as a second‑line therapy had a 2 % pre‑completion mortality rate, compared with 15 % for those who received it as a third‑line therapy, underscoring the importance of initiating therapy sooner.
Dr. Silviu Itescu emphasized that the results support positioning Ryoncil as the earliest treatment option for severe SR‑aGvHD after steroid resistance.
The data reinforce Mesoblast’s commercial momentum for Ryoncil and support the company’s plan to enroll adults in a pivotal registration trial this quarter. The adult SR‑aGvHD market is estimated to be three times larger than the pediatric indication, offering a significant growth opportunity.
Investors reacted to the announcement with a mixed response. While the survival data were encouraging, the market noted concerns about the size of the adult trial and the competitive landscape, leading to a modest decline in the company’s valuation on February 11, when the data were first disclosed.
Ryoncil is the first FDA‑approved mesenchymal stromal cell therapy, approved for children aged 2 months and older with SR‑aGvHD. Since its commercial launch in March 2025, Mesoblast has onboarded 45 U.S. transplant centers and secured payer coverage for over 260 million U.S. lives. The company is collaborating with the NIH‑funded Bone Marrow Transplant Clinical Trials Network for the adult trial.
The adult trial, slated to begin in Q1 2026, will evaluate Ryoncil against standard of care in a randomized, controlled design. A successful trial could unlock a larger market and strengthen payer coverage, potentially accelerating adoption across transplant centers.
Mesoblast’s presentation of robust day‑100 survival data and its strategy to expand Ryoncil into the adult SR‑aGvHD market position the company to capitalize on a growing therapeutic need while navigating a competitive landscape.
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