Mesoblast enrolls 300th patient in Phase 3 back pain trial of rexlemestrocel-L

Mesoblast Limited announced on July 13 and 14, 2026 that it has reached its target of enrolling at least 300 patients in the MSB-DR004 pivotal Phase 3 trial of rexlemestrocel-L for chronic low back pain linked to degenerative disc disease.¹ The study is designed to confirm the lasting pain relief from a single injection into the disc that was observed in the company's earlier MSB-DR003 trial.¹

CEO Silviu Itescu said, completing enrollment in the placebo-controlled trial ensures it is well powered for success, and that commercial manufacturing is proceeding in parallel so the company can file for approval as soon as possible after results are read out.¹

The trial is measuring pain reduction at the 12-month mark, comparing rexlemestrocel-L against sham treatment, and looking at secondary measures such as functional improvement, quality of life, and whether patients are able to stop using pain medications, including opioids.¹ The FDA had previously signed off on this 300-patient trial's design and agreed that the 12-month pain reduction endpoint could support approval.¹ That endpoint was met in Mesoblast's first Phase 3 trial.¹

Rexlemestrocel-L holds Regenerative Medicine Advanced Therapy designation from the FDA for this indication, making it eligible for priority review once a Biologics License Application is filed.¹

Top-line results are expected in mid-2027, once the last enrolled patient completes 12 months of follow-up.¹ The company noted the condition affects more than 7 million people in the U.S.¹ and said it views the indication as a potential blockbuster with peak annual revenue exceeding $10 billion even at single-digit market penetration.¹