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Mesoblast Receives FDA Approval for New Potency Assay to Release Commercial Ryoncil Product

Key Takeaway: Mesoblast Limited has received FDA approval for a new potency assay, the T-cell Proliferation Inhibition BioAssay (TIBA), to monitor its Ryoncil product. This assay will help ensure the product's potency and consistency during manufacturing. Ryoncil is the first FDA-approved mesenchymal stromal cell therapy for pediatric patients with steroid-refractory acute graft versus host disease.

Market Sentiment Analysis

POSITIVE FACTORS

  • FDA approval for a new potency assay enhances product quality control.
  • The TIBA assay ensures consistent potency of Ryoncil during manufacturing.
  • Ryoncil is the first FDA-approved MSC product for steroid-refractory aGvHD.

BiopharmaWatch Analysis

From our catalyst data and publicly available data · not financial advice
Best trade, last catalyst
+91%
120-day peak, hindsight
Typical move
31.6%
average across 4 past catalysts
Lead asset
Prochymal adult human mesenchymal stem cells
Phase 3 · Crohn's Disease

Full Press Release Details

NEW YORK, Sept. 24, 2026 (GLOBE NEWSWIRE) -- Mesoblast Limited (Nasdaq:MESO; ASX:MSB), global leader in allogeneic cellular medicines for inflammatory diseases, today announced that it has received approval from the United States Food and Drug Administration (FDA) to implement a new potency assay, T-cell Proliferation Inhibition BioAssay (TIBA), for release and stability monitoring of all new commercial product lots of its FDA-approved mesenchymal stromal cell (MSC) product Ryoncil ® (remestemcel-L-rknd).
The TIBA assay will ensure sufficient sensitivity to detect any shifts in potency of the commercial product that could arise during changes in manufacturing processes or production in new facilities. This assay will be used as part of a matrix to release each commercial batch of RYONCIL in conjunction with the existing potency assays which determine IL-2Rα inhibition and CAP (Cell Adhesion and Proliferation), as per the product's Biologics License. Together these assays ensure that the RYONCIL product is consistent, potent, and clinically effective.
RYONCIL is the first industrially-manufactured allogeneic MSC product approved by FDA for any indication, and the only MSC product to be approved for patients with steroid-refractory acute graft versus host disease (SR-aGvHD) aged 2 months or older. 1 Mesoblast and FDA have been working closely together since RYONCIL was approved for commercial use to ensure alignment on continued advancements to the product’s manufacturing processes and implementation of assays measuring the product’s ongoing quality control.
About Mesoblast Mesoblast (the Company) is a world leader in developing allogeneic (off-the-shelf) cellular medicines for the treatment of severe and life-threatening inflammatory conditions. The therapies from the Company’s proprietary mesenchymal lineage cell therapy technology platform respond to severe inflammation by releasing anti-inflammatory factors that counter and modulate multiple effector arms of the immune system, resulting in significant reduction of the damaging inflammatory process.
Mesoblast’s Ryoncil ® (remestemcel-L-rknd) for the treatment of steroid-refractory acute graft versus host disease (SR-aGvHD) in pediatric patients 2 months and older is the first FDA-approved mesenchymal stromal cell (MSC) therapy. Please see the full Prescribing Information at www.ryoncil.com.
Mesoblast is committed to developing additional cell therapies for distinct indications based on its remestemcel-L and rexlemestrocel-L allogeneic stromal cell technology platforms. Ryoncil ® is being developed for additional inflammatory diseases including SR-aGvHD in adults and biologic-resistant inflammatory bowel disease. Rexlemestrocel-L is being developed for heart failure and chronic low back pain. The Company has established commercial partnerships in Japan, Europe and China.
About Mesoblast intellectual property: Mesoblast has a strong and extensive global intellectual property portfolio, with over 1,000 granted patents or patent applications covering mesenchymal stromal cell compositions of matter, methods of manufacturing and indications. These granted patents and patent applications provide commercial protection extending through to at least 2044 in all major markets.
About Mesoblast manufacturing: The Company’s proprietary manufacturing processes yield industrial-scale, cryopreserved, off-the-shelf, cellular medicines. These cell therapies, with defined pharmaceutical release criteria, are planned to be readily available to patients worldwide.
Mesoblast has locations in Australia, the United States and Singapore and is listed on the Australian Securities Exchange (MSB) and on the Nasdaq (MESO). For more information, please see www.mesoblast.com, LinkedIn: Mesoblast Limited and X: @Mesoblast

Footnotes / References

• Please see the full Prescribing Information at www.ryoncil.com
Forward-Looking Statements This press release includes forward-looking statements that relate to future events or our future financial performance and involve known and unknown risks, uncertainties and other factors that may cause our actual results, levels of activity, performance or achievements to differ materially from any future results, levels of activity, performance or achievements expressed or implied by these forward-looking statements. We make such forward-looking statements pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995 and other federal securities laws. Forward-looking statements should not be read as a guarantee of future performance or results, and actual results may differ from the results anticipated in these forward-looking statements, and the differences may be material and adverse. Forward-looking statements include, but are not limited to, statements about: the initiation, timing, progress and results of Mesoblast’s preclinical and clinical studies, and Mesoblast’s research and development programs; Mesoblast’s ability to advance product candidates into, enroll and successfully complete, clinical studies, including multi-national clinical trials; Mesoblast’s ability to advance its manufacturing capabilities; the timing or likelihood of regulatory filings and approvals, manufacturing activities and product marketing activities, if any; the commercialization of Mesoblast’s RYONCIL for pediatric SR-aGVHD and any other product candidates, if approved; regulatory or public perceptions and market acceptance surrounding the use of stem-cell based therapies; the potential for Mesoblast’s product candidates, if any are approved, to be withdrawn from the market due to patient adverse events or deaths; the potential benefits of strategic collaboration agreements and Mesoblast’s ability to enter into and maintain established strategic collaborations; Mesoblast’s ability to establish and maintain intellectual property on its product candidates and Mesoblast’s ability to successfully defend these in cases of alleged infringement; the scope of protection Mesoblast is able to establish and maintain for intellectual property rights covering its product candidates and technology; estimates of Mesoblast’s expenses, future revenues, capital requirements and its needs for additional financing; Mesoblast’s financial performance; developments relating to Mesoblast’s competitors and industry; and the pricing and reimbursement of Mesoblast’s product candidates, if approved. You should read this press release together with our risk factors, in our most recently filed reports with the SEC or on our website. Uncertainties and risks that may cause Mesoblast’s actual results, performance or achievements to be materially different from those which may be expressed or implied by such statements, and accordingly, you should not place undue reliance on these forward-looking statements. We do not undertake any obligations to publicly update or revise any forward-looking statements, whether as a result of new information, future developments or otherwise.
Release authorized by the Chief Executive.
For more information, please contact:
Corporate Communications / Investors
Paul Hughes
T: +61 3 9639 6036
Media – Global Media – Australia
Rubenstein BlueDot Media
Caroline Nelson Steve Dabkowski
T: +1 703 489 3037 T: +61 419 880 486
E: cnelson@rubenstein.com E: steve@bluedot.net.au

Frequently Asked Questions

What is the new assay approved for Ryoncil?

The FDA approved the T-cell Proliferation Inhibition BioAssay (TIBA) for Ryoncil.

What does the TIBA assay ensure?

The TIBA assay ensures sufficient sensitivity to detect potency shifts in Ryoncil.

What is Ryoncil used for?

Ryoncil is used to treat steroid-refractory acute graft versus host disease in pediatric patients.

Is Ryoncil the first MSC product approved by the FDA?

Yes, Ryoncil is the first FDA-approved mesenchymal stromal cell therapy for its indication.

Last updated: Sep 24, 2026