04:25 AM EST, 11/21/2025 (MT Newswires) -- Mesoblast (MESO) said late Thursday it will collaborate with the US National Institutes of Health-funded Blood and Marrow Transplant Clinical Trials Network on a trial of Ryoncil as part of first-line regimen in adults with severe acute graft versus host disease refractory to corticosteroids.

The development comes amid a high rate of non-responsiveness to therapies in adults with the disease who fail corticosteroids, and the high mortality in such patients, the company said.

To give such patients the best chance of survival, they will be randomized in the trial as early as possible after corticosteroid refractoriness to receive ruxolitinib alone or combined with Ryoncil.

Mesoblast said the trial protocol will be provided to US Food and Drug Administration to begin enrollment in Q1.

Graft versus host disease is a complication that might occur after an allogeneic transplant.