Mesoblast Gets Good FDA Feedback on its Stem Cell Therapy for Back Pain, Rexlemestrocel-L, Progressing Towards BLA

Key findings

• Mesoblast received FDA feedback on its stem cell therapy for chronic discogenic low back pain.
• The company says the FDA viewed Phase 3 pain outcomes as favoring rexlemestrocel-L, and that 12-month pain reduction could support efficacy.
• The product may be labeled with opioid-reduction. 

Mesoblast had a Type B meeting with the FDA to hear feedback on its off-the-shelf bone marrow-derived mesenchymal stem cell therapy for chronic discogenic low back pain (CLBP). The meeting was about its plans to apply for a Biologics License Application (BLA) for rexlemestrocel-L.

They went through the data from rexlemestrocel’s first Phase 3 RCT to review pain reduction and how this may relate to decreased or even eliminated opioid use for up to three years from a single administration. 

Rexlemestrocel-L previously received Regenerative Medicine Advanced Therapy (RMAT) designation for this indication. 

What the FDA feedback covered
The MSB-DR003 trial enrolled 404 patients, including 168 taking opioids at baseline. Patients were treated with an intradiscal injection of either saline or rexlemestrocel-L + hyaluronic acid (HA), and the stem cell group reportedly had 3x as many patients able to cease all opioid use by 36 months(p=0.008).

Now, Mesoblast is seeking FDA approval based on these results, and, according to their account, the FDA acknowledged that the effects on pain intensity favored the rexlemestrocel-L arm, which could support product efficacy. 

Separately, discogenic back pain accounts for approximately 50% of prescription opioid usage in the US, and Mesoblast is hoping to reduce that. Reportedly, the FDA stated that robust opioid reduction results from at least one adequate and well-controlled trial could be included in the Clinical Studies section of product labeling.

Second Phase 3
Mesoblast’s second randomized controlled Phase 3 trial, MSB-DR004, is recruiting across 40 U.S. sites, is over 50% enrolled, and is expected to complete its 300-patient target in the coming three months. 

Mesoblast describes rexlemestrocel-L as a second-generation, STRO3-immunoselected, and “industrially manufactured” stromal cell product candidate, injected with hyaluronic acid (HA) into the lumbar disc. The trial is enrolling patients with chronic low back pain due to inflammatory degenerative disc disease (DDD) of less than five years duration.

The primary endpoint is a 12-month pain reduction, which Mesoblast says was met in the first Phase 3, and they’ll also measure quality of life and functional improvements. 

Company snapshot
Mesoblast develops allogeneic cellular medicines for inflammatory conditions using a mesenchymal lineage cell therapy platform. The company’s product, Ryoncil (remestemcel-L-rknd), is the only FDA-approved mesenchymal stem cell therapy, and it’s indicated for steroid-refractory acute graft-versus-host disease (SR-aGvHD) in pediatric patients 2 months and older.

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