• The US FDA has accepted Mesoblast’s biological licence resubmission 
  • The resubmission is related to lead drug Remestemcel-L in the treatment of children with SR-aGVHD
  • There is currently a lack of any approved treatments for children under 12 years old for this condition


The US FDA has accepted Mesoblast’s (ASX:MSB) biological licence resubmission for Remestemcel-L in the treatment of children with SR-aGVHD (steroid-refractory acute graft versus host disease).

The agency said that it considered the resubmission to be a complete response, and has now set a Prescription Drug User Fee Act (PDUFA) goal date of August 2, 2023.

If approved, Remestemcel-L will be the first allogeneic “off-the-shelf” cellular medicine in the US, and the first therapy for children under 12 years old with SR-aGVHD.

The MSB share price jumped by 12% on the news, before the shares were put under a voluntary trading halt this morning.

“Over the last two years we have worked tirelessly to address the issues previously raised by FDA,” commented Mesoblast CEO, Silviu Itescu.

“We look forward to working closely with the agency over the review period, with the aim to make Remestemcel-L available as a therapy for children suffering from SR-aGVHD.”


Urgent need for SR-aGVHD therapy

Survival rates have not improved in the last two decades for SR-aGVHD, a life-threatening complication of an allogeneic bone marrow transplant following treatment for blood cancers and other conditions.

Acute GVHD occurs in approximately 50% of patients who receive an allogeneic bone marrow transplant.

The lack of any approved treatments for children under 12 means that there is an urgent need for a therapy that improves these dismal survival outcomes.

Mesoblast’s lead product candidate, Remestemcel-L, is an investigational therapy comprising culture expanded mesenchymal stromal cells derived from the bone marrow of an unrelated donor.

It is administered to patients in a series of intravenous infusions, and is believed to have immunomodulatory properties to counteract the inflammations in SR-aGVHD.

The drug works by down-regulating the production of pro-inflammatory cytokines, increasing production of anti-inflammatory cytokines, and enabling recruitment of naturally occurring anti-inflammatory cells to affected tissues.

The original FDA submission by Mesoblast contained clinical outcomes of 309 children with SR-aGVHD treated with Remestemcel-L, showing consistent treatment responses and survival across three separate trials.

The data were reviewed by the FDA panel which voted in favor 9:1 for the efficacy of Remestemcel-L in pediatric patients, however the agency also requested for more data.

The resubmission today contains additional clinical and biomarker data – including from a propensity-matched study of children with high-risk disease, based on the validated MAP biomarker score comparing outcomes in 25 children from Mesoblast’s Phase 3 trial against 27 control children treated with various biologics, including ruxolitinib.

The study showed that 67% of high-risk children treated with Remestemcel responded positively to treatment within 28 days, and were alive after 180 days compared to just 10% in both categories in the other group.

Mesobalast owns two commercialised products in Japan and Europe underlicensees, and the company has established commercial partnerships in Europe and China for certain Phase 3 assets.


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