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

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
   

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