Mesoblast (ASX:MSB) has taken a significant step closer to regulatory approval for its investigational cell therapy, rexlemestrocel-L, after the U.S. Food and Drug Administration (FDA) acknowledged that clinical trial data demonstrate meaningful and sustained reductions in chronic low back pain, with the potential to reduce accompanying opioid use.
The feedback follows a Type B meeting with the FDA reviewing results from Mesoblast’s first randomised, placebo-controlled Phase 3 trial in patients with chronic discogenic low back pain. In that study, the agency agreed that reductions in pain intensity through 12 months favoured rexlemestrocel-L over placebo and that these outcomes could support a finding of product efficacy in a future Biologics License Application.
Importantly, the FDA also indicated that evidence showing reduced or eliminated opioid use could be included in product labelling, provided it is supported by at least one adequate and well-controlled trial. For Mesoblast, this represents a potentially meaningful differentiation in a therapeutic area closely linked to the U.S. opioid crisis.
Rexlemestrocel-L is being developed as a single, intra-discal injection for patients with chronic low back pain caused by inflammatory degenerative disc disease. In the completed Phase 3 study, pain reduction was accompanied by long-term opioid outcomes. Among patients taking opioids at baseline, those treated with rexlemestrocel-L were more than three times as likely to discontinue opioid use entirely over a 36-month follow-up period compared with placebo-treated patients.
A second confirmatory Phase 3 trial is now underway across approximately 40 U.S. sites. The study is more than halfway enrolled and is expected to reach its 300-patient target in the coming months. The FDA has already agreed that the trial’s primary endpoint, pain reduction at 12 months, would be considered approvable, a milestone that was successfully achieved in the earlier study.
Chronic low back pain remains one of the leading causes of disability in the United States and accounts for roughly half of all prescription opioid use. Against this backdrop, the FDA’s recent guidance encouraging development of non-opioid treatments for chronic pain has heightened interest in alternatives that can deliver durable pain relief without long-term reliance on opioids.
Mesoblast Chief Executive Silviu Itescu said the therapy has the potential to address both dimensions of the problem. He noted that rexlemestrocel-L could provide a new option for managing chronic inflammatory back pain while also supporting broader public health goals around opioid reduction and cessation.