Resilient Mesoblast: FDA Meeting Sparks New Hope for Previously Rejected Cell Therapy

In a remarkable twist of fate, Mesoblast has emerged from the shadows with renewed determination, claiming a newfound understanding of the FDA’s demands following a Type A meeting. This meeting could potentially pave the way for the long-awaited approval of remestemcel-L, a groundbreaking cell therapy designed to combat steroid-refractory acute graft versus host disease (SR-aGVHD) in both children and adults, as announced by the company on Thursday.

Mesoblast’s journey has been fraught with regulatory challenges. The saga began in 2019 when they filed their first Biologics License Application, which seemed promising after receiving strong support from the FDA’s Oncologic Drugs Advisory Committee in August 2020. However, the FDA’s surprise rejection in October 2020 sent shockwaves through the company.

Undeterred, Mesoblast resubmitted their application, only to face another rejection in the fateful month of August 2023. The FDA’s objections centered on two critical issues— the potency assay and the need for an adult-population study.

The potency assay conundrum proved to be a stumbling block during the Phase III trial in pediatric patients. The FDA insisted that this hurdle must be overcome for the trial to qualify as an “adequate study” demonstrating the efficacy of remestemcel-L.

To address this, Mesoblast now embarks on a mission to generate fresh potency assay data, demonstrating that the product used in the Phase III pediatric trial meets rigorous standards of identity, strength, quality, purity, and dosage form. This data will also attest that future batches for the pediatric indication will adhere to the same exacting standards.

For remestemcel-L’s adult application, Mesoblast proposes an innovative single-arm registrational trial for patients with SR-aGVHD who have exhausted both steroid and second-line interventions. This trial will be fortified by an appropriate potency assay, creating a vital link between the pediatric study and the upcoming adult trial.

Although the FDA and Mesoblast are yet to see eye to eye on the adult study’s design, there is a glimmer of hope, with the FDA showing willingness to entertain the proposed protocol.

CEO Silviu Itescu hailed the Type A meeting as “very productive,” marking a turning point that could potentially lead to the coveted approval of remestemcel-L in the battle against SR-aGVHD.

On Mesoblast’s stage, remestemcel-L takes center spotlight as an investigational allogeneic cell therapy, armed with culture-expanded mesenchymal stromal cells. These cells work their magic by quelling pro-inflammatory cytokines and rallying the body’s anti-inflammatory defenses. This remarkable mechanism empowers remestemcel-L to temper the immune response that fuels aGVHD.

While remestemcel-L awaits its moment in the U.S. limelight, it has already earned its stripes elsewhere, securing regulatory nods in countries like Canada and New Zealand, where it goes by the name Ryoncil, heralding hope for patients around the world.

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