Regenerative medicine company Mesoblast (ASX: MSB) has been granted US Food and Drug Administration (FDA) approval for its Ryoncil therapy to treat children with steroid-refractory acute graft-versus-host disease (SR-aGvHD).

The off-the-shelf  drug derived from bone marrow has become the first mesenchymal stromal cell therapy on the US market to treat the condition, which can occur after a bone marrow or stem cell transplant and has both a poor prognosis and high mortality rate.

Ryoncil will be available from today as an intravenous infusion at US transplant centres and other treating hospitals.

Late-stage products

Mesoblast chief executive Dr Silviu Itescu welcomed the FDA’s decision.

“We are very pleased that the FDA has granted approval of Ryoncil and we are proud of our commitment to the GvHD community in bringing this important new treatment to children and families with no other acceptable options,” he said.

“We will continue to work closely with the regulator to obtain approval of our other late-stage products, including Revascor for cardiovascular disease and rexlemestrocel-L for inflammatory pain indications, as well as expanding the indications for Ryoncil in children and adults with inflammatory conditions.”

Bone marrow statistics

Research shows that approximately 10,000 US patients each year — 1,500 of them aged 18 years or under — undergo an allogeneic bone marrow transplant.

Approximately 50% of patients develop aGvHD after surgery and almost half of them do not respond to steroids, which are the recognised first-line treatment.

In a trial of children with SR-aGvHD, where 89% had high-severity Grade C or Grade D disease, 70% achieved an overall response by Day 28 of intravenous treatment with Ryoncil.

More than 85% of patients completed the full course without interruption.

Anti-inflammatory therapies

Dr Itescu said Ryoncil’s immunomodulatory effects create potential for the drug to treat other indications in diseases including SR-aGvHD in adults and biologic-resistant inflammatory bowel disease.

Therapies from the company’s proprietary mesenchymal lineage cell therapy technology platform respond to severe inflammation by releasing anti-inflammatory factors that counter and modulate multiple effector arms of the immune system.

This can result in a significant reduction of the damaging inflammatory process.

Nasdaq biotech listing

Mesoblast will make its debut on the Nasdaq Biotechnology Index on 23 December.

The index contains securities of Nasdaq-listed companies calculated under a modified capitalisation-weighted methodology, with index constituents selected each December.

Companies must meet eligibility requirements including minimum average daily trading volumes.