Key Outcomes From FDA Type A Meeting and Mesoblast Next Steps to Achieve RYONCIL Approval

NEW YORK, Sept. 21, 2023 (GLOBE NEWSWIRE) -- Mesoblast Limited (Nasdaq:MESO; ASX:MSB), global leader in allogeneic cellular medicines for inflammatory diseases, today provided an update on the path to approval for its lead-product candidate remestemcel-L in the treatment of pediatric and adult steroid-refractory acute graft versus host disease (SR-aGVHD), following a Type A meeting held with the United States Food and Drug Administration (FDA). FDA clarified that the key remaining issue for pediatric approval is providing further evidence that the potency assay will assure the consistent efficacy of commercial product.

The key outcomes of the meeting and Mesoblast next steps are:

• Mesoblast summarised the large body of existing clinical data with the improved RYONCIL product version of remestemcel-L, manufactured after 2008 using the current process inspected by FDA, for potential approval in children.
• Mesoblast presented clinical data indicating that RYONCIL was associated with much higher survival of children with SR-aGVHD in the Expanded Access Protocol (EAP) compared with the earlier Prochymal version manufactured before 2008.
• Mesoblast presented consistently high survival in patients treated in RYONCIL, in children with SR-aGVHD in the EAP between 2008-2015, in the Phase 3 trial MSB-GVHD001 between 2015-2018, and in the Emergency Investigational New Drug (EIND) protocol from 2015-2023.
• FDA noted that the lack of a suitable potency assay for the RYONCIL product used during the Phase 3 trial MSB-GVHD001 for the pediatric acute GVHD indication has prevented the trial from being considered an adequate study for the purpose of demonstrating substantial evidence of effectiveness required for a marketing approval.
• Mesoblast intends to generate in the coming months new potency assay data for RYONCIL showing that the product used during pediatric Phase 3 trial MSB-GVHD001 was standardized as to its identity, strength, quality, purity, and dosage form to give significance to the results of the investigation as described in the Code of Federal Regulations for adequate and well-controlled studies (21 CFR 314.126), and that commercial batches made for the pediatric indication will meet the same standard.
• Mesoblast believes these additional data will provide a link between the RYONCIL product that was used in the Phase 3 trial MSB-GVHD001 for the pediatric indication to the RYONCIL product which will be used in a future trial for the adult indication.
• To address the adult indication, Mesoblast proposed an externally controlled single-arm registration trial design in adults and children over age 12 with SR-aGVHD who have failed both steroids and a second line agent, such as ruxolitinib, to be underpinned by a suitable potency assay.
• Mesoblast intends to perform this trial in partnership with world-leading investigators at the Blood and Marrow Clinical Trials Network (BM CTN), a body responsible for approximately 80% of all US transplants, with the costs expected to be covered by previously announced reductions in operational spend.
• FDA indicated its willingness to consider Mesoblast’s proposed registrational trial design in adults, subject to agreement on the suitability of the potency assay for the product to be used in adults.