Mesoblast Receives FDA IND Clearance to Directly Proceed to Registrational Trial for Ryoncil in Duchenne Muscular Dystrophy

Mesoblast Limited (Nasdaq: MESO; ASX: MSB) said the U.S. Food and Drug Administration (FDA) has granted Investigational New Drug (IND) clearance to proceed directly with a registrational clinical trial evaluating Ryoncil® (remestemcel-L-rknd) in Duchenne muscular dystrophy (DMD). The company said DMD affects approximately 15,000 children in the United States.

Registrational trial design

Mesoblast said the trial will randomize 76 patients aged 5 to 9 years to receive either Ryoncil® or placebo, in addition to standard of care.

• Ryoncil® dosing: 7 infusions of 2 x 10⁶ cells/kg over 9 months
• Primary endpoint: time-to-stand at nine months, described by the company as a validated FDA endpoint for approval

The company said it is collaborating with Parent Project Muscular Dystrophy (PPMD) to support patient identification and trial awareness through community engagement.

Rationale and development pathway

Mesoblast said the registrational trial is based on Ryoncil’s proven safety in children, evidence of efficacy in DMD preclinical models, and an FDA-approved manufacturing process. The company said it is leveraging Ryoncil’s anti-inflammatory mechanism of action, aiming to reduce the inflammatory cascade associated with DMD, preserve muscle function, and slow disease progression.

“We are very pleased to have received clearance to proceed directly to a registrational study for DMD based on our preclinical data in DMD animal models and our extensive safety data in children with SR-aGvHD, which suggests that we may have a unique approach to help with this devastating disease in children,” said Silviu Itescu, Chief Executive of Mesoblast.

Duchenne muscular dystrophy: disease background

Mesoblast described DMD as a X-linked genetic disorder characterized by progressive muscle degeneration affecting skeletal, respiratory, and cardiac muscles. The company said DMD is caused by the absence of functional dystrophin, a key structural protein in muscle cells.

The company said DMD affects approximately 15,000 individuals in the United States and primarily impacts boys. It said deterioration of muscle leads to loss of ambulation, respiratory failure and cardiomyopathy, ultimately leading to death by the third decade.

Mesoblast said chronic inflammation of skeletal and heart muscle remains a major underlying cause of progressive weakness in DMD. It noted that corticosteroid use has improved survival but that effects plateau and long-term use has serious side effects.

About Ryoncil and Mesoblast

Mesoblast said Ryoncil® is the first FDA-approved mesenchymal stromal cell (MSC) therapy. The company said Ryoncil is the only product approved for children under age 12 with steroid-refractory acute graft-versus-host disease (SR-aGvHD).

Mesoblast described itself as a developer of allogeneic (off-the-shelf) cellular medicines for severe and life-threatening inflammatory conditions. It said its therapies are designed to respond to severe inflammation by releasing anti-inflammatory factors that counter and modulate multiple effector arms of the immune system, reducing damaging inflammatory processes.

The company said it is developing additional cell therapies for distinct indications based on its remestemcel-L and rexlemestrocel-L allogeneic stromal cell technology platforms, including SR-aGvHD in adults and biologic-resistant inflammatory bowel disease for Ryoncil, and heart failure and chronic low back pain for rexlemestrocel-L. Mesoblast said it has commercial partnerships in Japan, Europe and China.

Company and intellectual property

Mesoblast said it has a global intellectual property portfolio with over 1,000 granted patents or patent applications covering mesenchymal stromal cell compositions of matter, manufacturing methods and indications, with protection extending through at least 2044 in major markets.

The company said its proprietary manufacturing processes produce industrial-scale, cryopreserved, off-the-shelf cellular medicines with defined pharmaceutical release criteria.

Mesoblast said it has locations in Australia, the United States and Singapore, and is listed on the Australian Securities Exchange (MSB) and on the Nasdaq (MESO).