Have regulators (FDA, EMA) reviewed or approved Memoblast and what did they report?
Executive summary
The U.S. Food and Drug Administration reviewed and granted approval to Mesoblast’s remestemcel‑L, branded Ryoncil, for steroid‑refractory acute graft‑versus‑host disease (SR‑aGVHD) in pediatric patients on December 18, 2024 [1] [2]. The European Medicines Agency’s public records in the provided reporting do not show an EMA approval or authorization for remestemcel‑L; the European context cited in the sources refers to other, non‑Mesoblast MSC products such as Alofisel and regulatory differences between EMA and FDA [3] [4].
1. FDA: a full review that ended in approval after earlier rejections
The FDA’s formal review pathway for remestemcel‑L included advisory committee scrutiny, two prior complete response letters (CRLs) and iterative resubmissions before the December 2024 approval; FDA materials and Mesoblast statements confirm the agency signed off on Ryoncil as the first FDA‑approved mesenchymal stromal cell (MSC) therapy for pediatric SR‑aGVHD [1] [2] [5]. The sponsor’s BLA experienced earlier setbacks — an advisory committee and ODAC discussions in 2020 and subsequent CRLs in 2020 and 2023 — and Mesoblast engaged in multiple meetings with FDA review teams and resubmissions before acceptance and final approval [6] [7] [8].
2. What the FDA reported about the decision and the evidence
FDA statements and Mesoblast communications indicate the approval was supported primarily by a Phase III single‑arm, multicenter trial showing a 70% overall response at 28 days and a 30% complete response rate in pediatric patients, and the agency granted expedited designations including orphan, fast track and priority review [9] [2]. The FDA’s public information also included safety‑monitoring guidance — clinicians should watch for infusion‑related respiratory or circulatory signs and discontinue treatment if they occur — reflecting the regulator’s attention to acute infusion reactions [9].
3. EMA and the European regulatory backdrop: approvals of other MSC products, not remestemcel‑L
The provided reporting situates Mesoblast’s U.S. approval within a broader global picture in which EMA previously approved other MSC‑based products (for example, Alofisel for complex Crohn’s anal fistula in 2018) while the United States lagged until Ryoncil’s nod; but the sources do not document an EMA review or marketing authorization specifically for remestemcel‑L [3] [10]. The EMA had earlier requested additional data on Alofisel during its own review process, and sponsors have taken different regulatory routes in Europe versus the U.S., illustrating divergent expectations and evidentiary standards across agencies [3] [4].
4. Regulatory concerns that shaped the outcome — efficacy signal vs. trial design and potency assays
Regulators and advisory panels repeatedly flagged two themes during the review: reliance on a non‑randomized, single‑arm pivotal study and questions about validated potency assays for a donor‑derived cell therapy; those issues underpinned earlier CRLs and agency requests for additional data, even as advisory committees ultimately voted in favor at points during the process [6] [8]. The FDA’s eventual approval followed Mesoblast’s iterative efforts to address potency and manufacturing consistency and to provide longer‑term and supplementary clinical data, according to the ISCT statement and Mesoblast’s submissions [10] [6].
5. Sponsor reaction, market signals and what the reporting leaves unresolved
Mesoblast characterized the approval as a landmark and commercial launch activity followed, and market coverage noted sharp positive investor reactions to the FDA decision; press releases and company updates indicate ongoing engagement with FDA on label extensions and additional indications [11] [12] [13]. The reporting does not, however, include EMA correspondence about remestemcel‑L, post‑marketing commitments’ full details, nor independent long‑term effectiveness or real‑world safety data beyond what Mesoblast and the FDA summarized in approval materials — these gaps remain in the provided sources [1] [2].
Conclusion
In the documentation provided, the FDA completed a multi‑year, iterative review and approved Mesoblast’s remestemcel‑L (Ryoncil) for pediatric SR‑aGVHD on December 18, 2024, citing trial data and attaching safety monitoring guidance; the EMA’s recorded approvals in the sources concern other MSC products but do not indicate an EMA approval or final decision for remestemcel‑L in the material supplied [1] [2] [3]. Where the record is thin — notably on any parallel EMA assessment of remestemcel‑L or independent post‑market outcomes — the sources do not permit definitive statements, and further primary EMA documents or public assessment reports would be needed to close that gap.