Gene Therapy

Fibrocell Science sees light at the end of the tunnel with Castle Creek deal to develop ‘butterfly’ disease gene therapy

Embattled cell and gene therapy company Fibrocell Science — which last year initiated a review of strategic alternatives — has found a way forward by joining forces with Jeff Aronin’s Castle Creek Pharmaceuticals, shepherding its lead gene therapy for “butterfly” disease into late-stage development.

Jeff Aronin

Aronin, former chief of the controversial Marathon Pharmaceuticals, already has one drug in the Castle Creek pipeline for the disease. He raised $71.8 million last October to repurpose an oral orphan drug called diacerein (approved to treat joint swelling or pain in the EU, but restricted due to the risks of diarrhea and liver problems) into a topical treatment for epidermolysis bullosa simplex, a form of rare genetic condition known as “butterfly skin.”

Fibrocell’s therapy, FCX-007, is designed to encode the gene for type VII collagen (COL7).  The proposed late-stage trial — planned to begin in the second quarter — is expected to enroll 15-20 patients.

Under the deal, FCX-007 will be exclusively licensed to Castle Creek in the United States for $7.5 million upfront. Fibrocell will also get $2.5 million for the first patient enrolled in the Phase III trial and another $30 million upon approval. Castle Creek is in charge of all development expenses up to $20 million prior to the submission of the marketing application — but if R&D costs exceed that, Castle Creek will take on a further 70% of the additional costs, with Fibrocell picking up the rest of the bill.

If approved, Fibrocell will retain sole ownership of the Rare Pediatric Disease Priority Review Voucher (PRV), which may be granted upon FCX-007 approval. Castle will pay Fibrocell a 30% share of the gross profits from FCX-007 sales. In addition, Fibrocell is also eligible to receive up to $75 million in sales milestones.

But Fibrocell was developing FCX-007 in partnership with Intrexon and as such, the company will pay them the latter half of all upfront, milestone, and profit share payments from Castle Creek. Still, it will have enough cash to fund its operations into the third quarter of 2020.

Fibrocell’s shares $FCSC shot up nearly 61% to $2.86 in early Monday trading.


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Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT
Director of Operations
Atlas Venture Cambridge, MA

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