NEW YORK and MELBOURNE, July 13-14, 2026
Mesoblast Limited announced that it has achieved its target of treating at least 300 patients in the pivotal MSB-DR004 Phase 3 randomized controlled trial evaluating rexlemestrocel-L for chronic low back pain (CLBP) associated with degenerative disc disease (DDD). The study is designed to confirm the durable pain reduction observed in the earlier Phase 3 MSB-DR003 trial following a single intra-discal injection of the allogeneic stromal cell therapy. The company is simultaneously advancing commercial manufacturing while preparing for potential regulatory submission after topline data become available in mid-2027.
Phase 3 Trial Designed to Confirm Durable Pain Relief
The pivotal placebo-controlled Phase 3 study is evaluating a single intra-discal injection of rexlemestrocel-L combined with hyaluronic acid in patients suffering from inflammatory degenerative disc disease lasting less than five years. The primary endpoint measures reduction in low back pain after 12 months, while secondary endpoints assess improvements in physical function, quality of life, and discontinuation of pain medications, including opioids. Mesoblast noted that the trial has been designed in agreement with the U.S. Food and Drug Administration (FDA), with the primary endpoint based on the successful outcome achieved in its previous Phase 3 study.
Commercial Manufacturing Advances Alongside Clinical Development
Mesoblast stated that reaching the enrollment target ensures the trial is appropriately powered to evaluate efficacy while enabling parallel commercial manufacturing activities. According to the company, this approach is intended to support rapid regulatory filing following completion of the study. Rexlemestrocel-L has already received Regenerative Medicine Advanced Therapy (RMAT) designation from the FDA for chronic low back pain caused by degenerative disc disease, providing eligibility for priority review once a Biologics License Application (BLA) is submitted.
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Cell Therapy Targets Significant Unmet Need in Chronic Back Pain
Chronic low back pain associated with degenerative disc disease affects more than 7 million people in the United States and remains a major cause of disability and long-term opioid use. Mesoblast believes rexlemestrocel-L has the potential to provide durable pain relief through a single administration while improving function and reducing dependence on opioid medications. With commercial manufacturing underway, regulatory support through RMAT designation, and topline Phase 3 data expected in mid-2027, the company continues advancing rexlemestrocel-L toward potential approval as a novel regenerative treatment for chronic low back pain.
Source: Mesoblast press release
