Mesoblast Limited (ASX:MSB; Nasdaq:MESO), global leader in allogeneic cellular medicines for inflammatory diseases, announced today that the US Food and Drug Administration (FDA) has issued a Complete Response Letter to its Biologics License Application (BLA) for remestemcel-L for the treatment of pediatric steroid-refractory acute graft versus host disease (SR-aGVHD). While the Oncologic Drugs Advisory Committee (ODAC)1 of the FDA voted 9:1 that the available data support the efficacy of remestemcel-L in pediatric patients with SR-aGVHD, the FDA recommended that Mesoblast conduct at least one additional randomized, controlled study in adults and/or children to provide further evidence of the effectiveness of remestemcel-L for SR-aGVHD. As there are currently no approved treatments for this life-threatening condition in children under 12, Mesoblast will urgently request a Type A meeting with the FDA, expected within 30 days, to discuss a potential accelerated approval with a post-approval condition for an additional study.

Joanne Kurtzberg, MD, Jerome Harris Distinguished Professor of Pediatrics, Director, Pediatric Blood and Marrow Transplant Program, and Co-Director, Stem Cell Transplant Laboratory Duke University Medical Center, said: “The Phase 3 trial results showed that remestemcel-L provides a meaningful treatment for children with SR-aGVHD who have a very dismal prognosis. I look forward to having this much-needed therapy available to our patients.”

Mesoblast is currently conducting a randomized, controlled Phase 3 trial evaluating remestemcel-L in up to 300 ventilator-dependent adults with moderate to severe acute respiratory distress syndrome (ARDS) due to COVID-19. A second interim analysis by the trial’s independent Data Safety Monitoring Board is expected in early November, with completion of patient enrollment expected in December. COVID-19 ARDS is an inflammatory disease with a similar profile of damaging inflammatory cytokines as is seen in children with SR-aGVHD, and is the primary cause of death in COVID-19 infection. The trial’s primary endpoint is reduction of all-cause mortality within 30 days of randomization.

The FDA also identified a need for further scientific rationale to demonstrate the relationship of potency measurements to the product’s biologic activity. Assays measuring the potency of remestemcel-L will continue to be refined to provide further scientific rationale for its use in severe inflammatory diseases with high mortality risk, such as SR-aGVHD and COVID-19 ARDS.

Mesoblast Chief Executive Dr Silviu Itescu stated: “We are working tirelessly to bring remestemcel-L to patients with life threatening inflammatory conditions, including SR-aGVHD and COVID-19 ARDS.”