Mesoblast Completes 350-Patient Phase 3 Trial for Low Back Pain Therapy
Mesoblast has treated 350 patients in its pivotal Phase 3 trial for rexlemestrocel-L, targeting chronic low back pain linked to degenerative disc disease, setting the stage for top-line results in mid-2027.
- Phase 3 trial enrollment exceeds target with 350 patients treated
- Primary endpoint focuses on durable pain reduction at 12 months
- Secondary endpoints include function, quality of life, and opioid cessation
- Rexlemestrocel-L holds FDA RMAT designation for priority review
- Potential market opportunity exceeds US$10 billion in the US alone
Phase 3 Trial Surpasses Enrollment Expectations
Mesoblast Limited (ASX:MSB; Nasdaq:MESO) has reached a significant clinical milestone by completing patient treatment in its pivotal MSB-DR004 Phase 3 trial for rexlemestrocel-L, a cellular therapy aiming to alleviate chronic low back pain (CLBP) caused by degenerative disc disease (DDD). The trial enrolled 350 patients, exceeding the initial target of 300 due to strong investigator demand, with participants randomized to receive either the active intradiscal injection or a sham procedure.
Trial Design Targets Durable Pain Relief and Functional Gains
The primary endpoint will assess durable pain reduction at 12 months following a single injection, building on positive findings from the earlier MSB-DR003 trial. Secondary endpoints include improvements in patient function, quality of life, and importantly, cessation of pain medications including opioids; a critical consideration given that discogenic back pain accounts for roughly half of opioid prescriptions in the US.
Regulatory Pathway and Market Potential
Rexlemestrocel-L benefits from the FDA’s Regenerative Medicine Advanced Therapy (RMAT) designation, which facilitates priority review upon submission of the Biologics License Application (BLA). Mesoblast expects top-line data in mid-2027 after the last patient completes their 12-month follow-up. With over 7 million Americans affected by CLBP linked to DDD, the potential market opportunity for Mesoblast could exceed US$10 billion annually, even with modest market penetration.
Broader Company Pipeline and Intellectual Property Strength
Mesoblast is also advancing its FDA-approved Ryoncil® therapy for pediatric steroid-refractory acute graft-versus-host disease, which generated US$115 million in revenue in its first full year post-approval. The company’s extensive intellectual property portfolio, encompassing over 1,000 patents and applications, underpins its allogeneic mesenchymal stromal cell technology platform. This platform supports multiple indications beyond CLBP, including heart failure and inflammatory bowel disease, with commercial partnerships established across Japan, Europe, and China.
Bottom Line?
The completion of patient treatment in this expanded Phase 3 trial sets a clear path toward a pivotal data readout that could reshape treatment options for chronic low back pain.
Questions in the middle?
- Will rexlemestrocel-L demonstrate statistically significant pain relief and functional improvement at 12 months?
- How will the therapy’s impact on opioid cessation influence regulatory and payer acceptance?
- What competitive pressures might Mesoblast face in the emerging regenerative medicine market for CLBP?
