The FDA Rejects New Drug for SR-aGVHD, Shocking Scientists and Patients

As reported in BioSpace, the FDA shocked Mesoblast executives, a stem-cell research company, when this October, they rejected the Biologics License Application (BLA) for the drug Ryoncil, meant to treat pediatric steroid-refractory acute graft-versus-host disease (SR-aGVHD). The disease is incredibly lethal with up to a 90% mortality rate in severe cases, and no current treatment options for young patients are available.

Pediatric Steroid-Refractory Acute Graft Versus Host Disease

Pediatric steroid-refractory acute graft-versus-host disease (SR-aGVHD) is a rare disorder in which the immune system from transplanted material attacks the host body following a stem cell transplant. The disease manifests in half of patients that receive an allogeneic bone marrow transplant, which are often used to treat blood cancers. The acute manifestation occurs within six months of the transplant. Symptoms include cramps, abdominal pain, nausea, vomiting, diarrhea, jaundice, rashes, itching, and redness. In the most serious types of aGVHD, there is a 90% mortality rate, with no current treatment options for patients under age 12.

Ryoncil in Trials

The drug has already been in the process of view, which is part of the surprise at the rejection. In just August, theFDA’s Oncologic Drugs Advisory Committee (ODAC) took a vote and recommended the drug at 9 to 1.
Ryoncil is created out of stem cells that derive from an unrelated person’s bone marrow, a novel type of treatment. The stem cells are then dosed to patients through scheduled intravenous infusions. They suspect this is responsible for the delay, as the FDA has never approved any similar stem cell treatments. While they did not pass the study, the FDA’s letter recommended that Mesoblast run another randomized control trial in order to gather further data on the impact of the treatment.


Recently, the company has had their attention focused on fixing the prime medical catastrophe of the century so far: COVID-19. The inflammatory cytokines that are the primary cause of death in COVID-19 patients share a similar mechanism to SR-aGVHD. A drug to treat ventilator-dependent adults who had COVID-19 is currently in a Phase III trial, to treat them for severe acute respiratory distress syndrome (ARDS).
The CEO of the drug’s developer Mesoblast, Silviu Itescu, said to the Sydney Morning Herald that this should push back their scheduling, “somewhere in the order of three to five months. It would have been great if they had simply taken the advice of their panel and given immediate unrestricted approval. Short of that, this is the way these things evolve.”

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