Mesoblast to begin pivotal adult aGvHD trial with BMT CTN

Mesoblast Limited today announced a collaboration with the BMT CTN to initiate a pivotal trial for Ryoncil® (remestemcel-L-rknd) as part of a first-line regimen in adults with severe acute graft versus host disease (aGvHD) refractory to corticosteroids (SR-aGvHD). This trial aims to address the high mortality and non-responsiveness observed in adult patients who fail existing therapies. The BMT CTN represents U.S. centers responsible for approximately 80% of all U.S. allogeneic BMTs.

The trial protocol will be submitted to the FDA, with enrollment expected to begin in the first quarter of 2026, following discussions with the FDA regarding the patient population and treatment timing. Adult patients with severe SR-aGvHD will be randomized to receive ruxolitinib alone or combined with Ryoncil® after corticosteroid refractoriness.

This initiative expands the availability of Ryoncil®, currently FDA-approved for pediatric SR-aGvHD, to an adult market opportunity estimated to be 3-4 times larger. Mesoblast's Expanded Access program in patients aged 12 and older with SR-aGvHD who failed ruxolitinib or other second-line agents demonstrated 76% survival at Day 100, contrasting with survival rates of 20-30% for adults failing ruxolitinib in two studies that supported FDA approval.