Independent Study Presented at American Society of Hematology (ASH) Annual Meeting Concludes Remestemcel-L Superior to Ruxolitinib in Clinical Outcomes as Treatment for SR-aGvHD

Rhea-AI Summary

Mesoblast (Nasdaq:MESO) announced an independent peer‑reviewed meta‑analysis presented at the 67th ASH Annual Meeting showing remestemcel‑L had superior complete and overall remission versus ruxolitinib for steroid‑refractory acute graft versus host disease (SR‑aGvHD).

The meta‑analysis included 2,732 patients across 11 studies (644 received remestemcel‑L; 1,349 received ruxolitinib). Authors reported differences in hematology, cardiac, and hepatic adverse events and concluded both therapies improved quality of life but safety profiles differ. Ryoncil is noted as the first FDA‑approved mesenchymal stromal cell product and the only product approved for children under 12 with SR‑aGvHD.

Positive

• Meta‑analysis size of 2,732 patients across 11 studies
• Remestemcel‑L superior in complete and overall remission versus ruxolitinib
• Ryoncil FDA approval as first MSC product and approved for children <12

Negative

• Differences in hematology, cardiac, and hepatic adverse events reported
• Uneven treatment sample sizes: 644 remestemcel‑L vs 1,349 ruxolitinib

Key Figures

Meta-analysis patients 2,732 patients Independent SR-aGvHD meta-analysis across 11 studies

Treatment arm size 1,993 patients Patients in treatment arms in the SR-aGvHD meta-analysis

Control arm size 523 patients Patients in control arms in the SR-aGvHD meta-analysis

Remestemcel-L patients 644 patients Patients treated with remestemcel-L in the meta-analysis

Ruxolitinib patients 1,349 patients Patients treated with ruxolitinib in the meta-analysis

Ryoncil gross revenue US$30.0+ million Expected quarter ending Dec 31, 2025

Prior quarter revenue US$21.9 million Ryoncil gross revenue quarter ended Sep 30, 2025

Net loss $102.1 million Year ended June 30, 2025 (Form 20-F)

Market Reality Check

$18.40 Last Close

Volume Volume 191,297 is below the 20-day average of 213,835, suggesting no pre-news volume spike. normal

Technical Price 18.4 is trading above the 200-day MA of 14.04, reflecting an established uptrend into this news.

Peers on Argus

MESO was down 3.41% while close biotech peers showed mixed moves (e.g., DYN -3.14%, SRPT +3.2%, AUPH +2.78%), indicating a stock-specific setup rather than a broad sector trend.

Common Catalyst Peer headlines focused on financings and balance-sheet actions, unlike MESO’s clinical/outcomes-focused news.

Historical Context

Date	Event	Sentiment	Move	Catalyst
Dec 03	Conference participation	Neutral	+2.2%	Participation in Piper Sandler healthcare conference with webcast access.
Nov 24	Trading update	Positive	+1.6%	Ryoncil revenue growth with >37% quarter-on-quarter increase highlighted.
Nov 20	Clinical trial plan	Positive	-3.6%	Announcement of pivotal Phase 3 trial of Ryoncil in severe SR-aGvHD.
Nov 17	Management change	Positive	+2.2%	Appointment of experienced CFO to support commercialization efforts.
Nov 04	FDA interaction	Positive	-0.3%	FDA meeting scheduled to discuss Phase 3 rexlemestrocel-L CLBP data.

Pattern Detected

Recent news has often produced modest, mixed price reactions, with one notable divergence on seemingly positive pivotal-trial progress.

Recent Company History

Over the last month, Mesoblast has reported multiple developments around Ryoncil® and its broader pipeline. A trading update on Nov 24, 2025 highlighted Ryoncil gross revenue of more than US$30.0 million for the quarter, up from US$21.9 million. The company also announced a pivotal Phase 3 SR-aGvHD trial with BMT CTN and a scheduled FDA meeting on rexlemestrocel-L in chronic low back pain. Management strengthened its team with a new CFO and participated in a Piper Sandler healthcare conference. Today’s ASH comparative outcomes data further builds on this clinical and commercial narrative.

Market Pulse Summary

This announcement highlights independent, peer-reviewed data from a 2,732-patient meta-analysis suggesting remestemcel-L delivers superior complete and overall remission outcomes versus ruxolitinib in SR-aGvHD, alongside differentiated adverse-event profiles. Context from recent updates shows growing Ryoncil® revenues and ongoing pivotal-trial planning in severe SR-aGvHD. Investors may focus on how such comparative outcomes data support broader adoption, while balancing this against the company’s continued net losses and execution and regulatory risks disclosed in recent filings.

Key Terms

meta-analysis technical

"The meta-analysis involved 2,732 patients (1,993 in the treatment arms"

A meta-analysis combines results from multiple independent studies on the same question to produce a single, more reliable estimate of an effect or outcome. Like averaging many temperature readings to get a truer picture of the weather, it reduces random noise and highlights consistent signals; investors use it to assess how strong and reliable the scientific or economic evidence is, which affects regulatory outlook, product prospects, and valuation risk.

adverse events medical

"as well as differences in hematology, cardiac and hepatic adverse events."

Adverse events are any harmful or unwanted medical occurrences experienced by people using a drug, device, or undergoing a treatment, whether or not the problem is caused by the product. Think of them as complaints or breakdowns noticed during a trial or after a product is on the market; regulators record and investigate them. Investors care because clusters or serious adverse events can delay approvals, trigger costly studies or recalls, change labeling, and quickly alter a company’s revenue and risk profile.

mesenchymal stromal cell medical

"Ryoncil® is the first mesenchymal stromal cell (MSC) product approved"

Mesenchymal stromal cells are a type of adult cell found in bone marrow, fat and other tissues that can act like a repair crew, supporting tissue healing, reducing inflammation and helping other cells grow. Investors care because these cells are the basis for many experimental therapies and diagnostics; clinical success, manufacturing scale-up, safety and regulatory approval determine commercial potential and can strongly affect a company’s valuation.

U.S. Food and Drug Administration regulatory

"product approved by the U.S. Food and Drug Administration (FDA) for any"

The U.S. Food and Drug Administration is the federal agency that evaluates and enforces safety, effectiveness and labeling standards for medicines, medical devices, vaccines, food and related products before they reach consumers. For investors it matters because FDA approvals, warnings or recalls determine whether a product can be sold, how quickly it reaches the market and how costly compliance will be—changes that directly affect a company’s revenue, costs and stock value.

FDA regulatory

"product approved by the U.S. Food and Drug Administration (FDA) for any"

The FDA is the U.S. federal agency that evaluates and approves medical drugs, devices, biological therapies and certain foods; think of it as the gatekeeper that decides whether a medical product is safe and effective for patients. For investors, FDA decisions determine whether a company can sell a product, affect expected revenue and introduce regulatory risk, so approvals, rejections or safety warnings can quickly move a company's valuation and stock price.

AI-generated analysis. Not financial advice.

NEW YORK, Dec. 11, 2025 (GLOBE NEWSWIRE) -- Mesoblast Limited (Nasdaq:MESO; ASX:MSB), global leader in allogeneic cellular medicines for inflammatory diseases, today announced that an independent peer-reviewed comparative analysis of efficacy and safety between remestemcel-L and ruxolitinib for treatment of steroid-refractory acute graft versus host disease (SR-aGvHD) was presented at the 67^th ASH Annual meeting in Florida this past week. The independent study authors concluded that remestemcel-L showed superior outcomes in complete and overall remission compared with ruxolitinib.¹

The meta-analysis involved 2,732 patients (1,993 in the treatment arms and 523 in the control arms) across 11 studies. Among treatment groups, 644 patients received remestemcel-L and 1,349 received ruxolitinib. While both ruxolitinib and remestemcel-L significantly improved quality of life in treating SR-aGvHD, remestemcel-L showed superior outcomes in complete and overall remission as well as differences in hematology, cardiac and hepatic adverse events. The authors also concluded that while both therapies exhibit favorable safety profiles, clinical decisions should consider the differences in adverse events.

Ryoncil^® is the first mesenchymal stromal cell (MSC) product approved by the U.S. Food and Drug Administration (FDA) for any indication, and the only product approved for children under age 12 with SR-aGvHD.²

The Spotlight segment of Blood, the flagship journal of ASH, featured FDA approval of Ryoncil^® as an important advance in the field for treatment of acute GvHD.³

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

References / Footnotes

1. Ramteke HD, et al. Comparative efficacy and safety of ruxolitinib and remestemcel-L in the treatment of steroid-refractory acute graft-versus-host disease: Systematic review and meta-analysis. Poster. Blood 146 (2025) 6030. https://doi.org/10.1182/blood-2025-6030
2. Please see the full Prescribing Information at www.ryoncil.com
3. Etra A, Ferrara JLM, Levine JE. Remestemcel-L-rknd (Ryoncil): the first approved cellular therapy for steroid-refractory acute GVHD. Blood. 2025 October 16; 146(16): 1897–1901
   

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
Allison Worldwide
Emma Neal
T: +1 603 545 4843
E: emma.neal@allisonworldwide.com
Media – Australia
BlueDot Media
Steve Dabkowski
T: +61 419 880 486
E: steve@bluedot.net.au

FAQ

What did the December 11, 2025 ASH study say about Mesoblast (MESO) remestemcel‑L vs ruxolitinib?

An independent meta‑analysis of 2,732 patients concluded remestemcel‑L showed superior complete and overall remission compared with ruxolitinib.

How large was the comparative analysis presented at ASH for MESO remestemcel‑L?

The meta‑analysis pooled data from 11 studies totaling 2,732 patients (644 remestemcel‑L; 1,349 ruxolitinib).

Does remestemcel‑L (Ryoncil) have FDA approval relevant to MESO investors?

Yes. Ryoncil is the first FDA‑approved mesenchymal stromal cell product and is approved for children under 12 with SR‑aGvHD.

What safety differences did the ASH analysis report for MESO remestemcel‑L?

Authors reported differences in hematology, cardiac, and hepatic adverse events between remestemcel‑L and ruxolitinib and recommended considering these when choosing therapy.

Will the ASH findings immediately change MESO commercial outlook for remestemcel‑L?

The study reports superior remission and safety differences, but no commercial or guidance changes were reported in the announcement.