New York, USA & Melbourne, Australia, July 1, 2026
Mesoblast Limited announced that the U.S. Food and Drug Administration (FDA) has assigned a Biologics License Application (BLA) filing number for rexlemestrocel-L and that the company has requested a modular review of its application. The investigational allogeneic cell therapy is being developed to prevent life-threatening gastrointestinal (GI) bleeding caused by right ventricular dysfunction in patients with end-stage heart failure who are supported with left ventricular assist devices (LVADs). Rexlemestrocel-L has previously received both Regenerative Medicine Advanced Therapy (RMAT) designation and Orphan Drug Designation from the FDA for this rare indication, providing eligibility for rolling and priority review. Mesoblast stated that recent FDA guidance promoting greater regulatory flexibility for therapies addressing serious rare diseases further supports the review process for innovative cell and gene therapies targeting high unmet medical needs.
Rexlemestrocel-L Targets Inflammation in Advanced Heart Failure
Rexlemestrocel-L is an investigational allogeneic mesenchymal precursor cell (MPC) therapy designed to reduce excessive inflammation associated with heart failure. The therapy works by releasing anti-inflammatory factors that modulate multiple immune pathways involved in disease progression. Mesoblast is developing the product across several stages of heart failure, with a particular focus on patients with heart failure with reduced ejection fraction (HFrEF). In the current BLA application, the therapy is intended to prevent major gastrointestinal bleeding complications that frequently occur in patients receiving permanent LVAD support due to progressive right ventricular dysfunction. Mesoblast noted that the therapy has been evaluated in two randomized, placebo-controlled clinical studies, including a 565-patient trial involving NYHA Class II/III heart failure patients and a separate 159-patient study in end-stage heart failure patients receiving LVAD implantation.
FDA Designations Support Accelerated Regulatory Review
The company emphasized that rexlemestrocel-L benefits from both RMAT and Orphan Drug designations, reflecting the significant unmet medical need among patients with advanced heart failure. These regulatory programs allow enhanced interaction with the FDA throughout development and provide opportunities for expedited review. Mesoblast also referenced recent FDA draft guidance highlighting a more flexible approach to demonstrating substantial evidence of effectiveness for therapies addressing rare diseases with high mortality and irreversible morbidity, as well as updated guidance supporting manufacturing flexibility for cellular and gene therapies submitted through the BLA pathway. According to Mesoblast Chief Executive Officer Dr. Silviu Itescu, the company looks forward to working closely with the FDA to make rexlemestrocel-L available to patients at high risk of life-threatening GI bleeding following LVAD implantation.
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Cell Therapy Platform Continues Broad Clinical Development
Beyond the current BLA submission, Mesoblast continues advancing its proprietary allogeneic cell therapy platform across multiple inflammatory diseases. The company’s FDA-approved mesenchymal stromal cell therapy, Ryoncil® (remestemcel-L-rknd), is currently approved for pediatric steroid-refractory acute graft-versus-host disease and is also being investigated for additional inflammatory conditions. Rexlemestrocel-L remains under clinical development for heart failure and chronic low back pain, while Mesoblast maintains commercial partnerships across Japan, Europe, and China. Supported by an extensive global intellectual property portfolio extending through at least 2044 and proprietary large-scale manufacturing capabilities, the company continues positioning its off-the-shelf cellular therapies for broader commercialization in severe inflammatory and cardiovascular diseases.
Source: Mesoblast press release
