Mesenchymal intravenous stromal cell infusions in children with recessive dystrophic epidermolysis bullosa: MissionEB protocol for a randomised, double-blinded, placebo-controlled, two-centre, crossover trial with an internal phase I dose de-escalation phase and open-label extension.

introductionRecessive dystrophic epidermolysis bullosa (RDEB) is a severe genetic mucocutaneous fragility disorder characterised by chronic blistering, slow wound healing and increased risk of squamous cell carcinoma. Current management options are very limited.

methodsThis is a randomised (1:1), placebo-controlled, double-blinded crossover (A/B) trial with an internal phase I dose de-escalation (4+5 design) in the first 3 months and a 12-month continued treatment follow-on open-label study if 3-month outcome data from the crossover trial indicate safe and beneficial effects. RDEB is a rare condition, so we expect to recruit a maximum of 36 participants based on feasibility and not formal power considerations. Participants aged>6 months and <16 years will be recruited at Great Ormond Street Hospital and Birmingham Children's Hospital. They will receive 2-3×10 ETHICS AND DISSEMINATION: North East-York Research Ethics Committee approved the protocol (ref: 21/NE/0016) on 16 March 2021. Findings will be published in peer-reviewed scientific journals, presented at relevant national and international conferences, and an open-access final report submitted to the funder. TRIAL REGISTRATION NUMBER: ISRCTN14409785. Protocol V. 8.0, 14 November 2022.