The US Food and Drug Administration (FDA) has sent a clinical hold letter to Abeona Therapeutics rejecting a planned Phase III VIITAL clinical trial of the company’s EB-101 for the treatment of recessive dystrophic epidermolysis bullosa (RDEB).

The regulator requested for additional data about transport stability of the drug candidate to clinical sites.

Over the past year, Abeona collaborated with the FDA to address and narrow open chemical, manufacturing and controls (CMC) items. The company added that it is working to resolve the one item mentioned in the clinical hold letter.

CMC clearance for the Phase III trial is expected in the fourth quarter of this year.

Abeona Therapeutics CEO João Siffert said: “Efforts to gather supplemental data points on transport stability of EB-101 are ongoing and we are confident that the requested additional data will be submitted to the FDA promptly.

“Looking ahead, we believe that completion of our CMC work coupled with the durable safety and efficacy data, now out to five years in some patients, will ultimately be critical to support a future biologics licence application.”

EB-101 is an investigational, autologous, gene-corrected cell therapy being developed to treat RDEB, which is a rare connective tissue disorder.

Therapy requires gene transfer for the delivery of COL7A1 genes into a patient’s own skin cells (keratinocytes) and their transplantation back to the patient to allow the normal expression of Type VII collagen and wound healing.

The drug candidate secured regenerative medicine advanced therapy, breakthrough therapy, and rare paediatric designations in the US. It also received orphan drug designation in the US and EU.

VIITAL is a multi-centre, randomised study designed to compare EB-101 to intra-patient untreated wounds in around 10-15 patients.