Mesoblast Hits Recruitment Target for Pivotal Low Back Pain Trial

Recruitment Milestone Advances Rexlemestrocel-L Development

Mesoblast Limited (ASX:MSB) has reached a critical milestone in its clinical program by completing patient recruitment for its pivotal Phase 3 trial of rexlemestrocel-L, targeting chronic low back pain (CLBP) associated with degenerative disc disease (DDD). The 300-patient, placebo-controlled study will assess the efficacy of a single intradiscal injection of the allogeneic stromal cell therapy, with top-line data anticipated by mid-2027. This achievement moves Mesoblast closer to potentially commercialising a non-opioid, disease-modifying treatment for a condition affecting over 7 million Americans.

The trial, designated MSB-DR004, is designed to confirm the promising findings from the earlier MSB-DR003 study, which demonstrated meaningful reductions in pain and opioid use sustained for up to three years following treatment. The primary endpoint focuses on pain reduction at 12 months, while secondary measures include improvements in function, quality of life, and cessation of pain medications, particularly opioids; a key focus given discogenic back pain accounts for roughly half of opioid prescriptions in the US.

Regulatory Pathway and Market Opportunity

Rexlemestrocel-L holds the FDA's Regenerative Medicine Advanced Therapy (RMAT) designation, a status that confers expedited regulatory pathways including rolling and priority review upon Biologics License Application (BLA) submission. Mesoblast plans to file for FDA approval in the third quarter of 2027, assuming positive trial outcomes. The RMAT designation underscores the FDA's recognition of the therapy's potential to address a significant unmet medical need.

The commercial stakes are high: CLBP due to DDD is a leading cause of disability and a major contributor to the opioid epidemic in the US. Mesoblast estimates peak annual revenues exceeding US$10 billion with modest market penetration. This aligns with the company's broader strategy to leverage its proprietary cell therapy platforms across inflammatory and degenerative conditions, building on the commercial progress of its FDA-approved Ryoncil product for graft-versus-host disease.

Manufacturing and Intellectual Property Strength

Mesoblast's industrial-scale manufacturing capabilities and extensive intellectual property portfolio, comprising over 1,000 patents and applications extending to 2044, position the company well for commercialisation. The company’s off-the-shelf, cryopreserved cell therapies are designed for broad accessibility, supporting global distribution plans. This manufacturing scale-up complements Mesoblast’s recent strategic moves, including its acquisition of CAR technology to enhance cell therapy precision, as detailed in its April updates.

Mesoblast’s ongoing clinical and commercial momentum is further evidenced by its recent FDA clearance to initiate a registrational trial of Ryoncil in Duchenne muscular dystrophy, highlighting the company’s expanding pipeline and regulatory engagement. The successful enrolment in the rexlemestrocel-L Phase 3 trial adds another layer of validation to Mesoblast’s development capabilities and market potential.