Entrada reports Cohort 1 safety data for DMD exon-skipping drug

Entrada Therapeutics has reported topline data from the first cohort of its Phase 1/2 ELEVATE-45-201 study of ENTR-601-45, an exon 45-skipping candidate for Duchenne muscular dystrophy (DMD). The Boston-based company said the cohort met its primary objective of favourable safety and tolerability at the initial 5 mg/kg dose, and that plasma exposures were consistent with predictions from juvenile non-human primate data.

Eight participants aged between four and 20, all carrying a DMD gene mutation amenable to exon 45 skipping, were randomised 3:1 to receive three doses of ENTR-601-45 or placebo. The most common adverse event was headache, occurring in two participants across five events. One participant experienced two serious adverse events, vomiting and pyrexia, which subsequently resolved. There were no study discontinuations, and all participants have now progressed to the open-label Phase 2 extension.

Early efficacy signals

On secondary endpoints, treated participants showed a mean 0.10% increase in dystrophin production versus a 0.02% decrease in the placebo group (nominal p = 0.03), and a mean 0.15% increase in exon skipping versus a 0.04% decrease. The company acknowledged that, given the age of participants and low baseline function levels, no functional benefit was expected or observed at this initial dose and duration.

Natarajan Sethuraman, President of Research and Development at Entrada, highlighted the dosing convenience as a potential differentiator: "For families currently managing a weekly infusion schedule, ENTR-601-45's current dosing schedule translates to a potential therapy built around approximately nine administrations per year instead of more than fifty."

Professor Giovanni Baranello, Professor of Paediatric Neuromuscular Disorders at UCL and principal investigator for the study, described the dystrophin signal as "an encouraging early signal," noting that establishing a clean safety profile at the starting dose is the essential precondition for escalation.

Competitive and regulatory context

The exon-skipping field in DMD has been shaped by the approvals of eteplirsen (Sarepta Therapeutics) and golodirsen and casimersen, all phosphorodiamidate morpholino oligomer (PMO) based approaches. ENTR-601-45 uses Entrada's proprietary Endosomal Escape Vehicle (EEV) conjugate technology, which the company positions as a next-generation PMO designed to achieve greater intracellular delivery. The exon 45-skipping population represents roughly 9% of DMD patients globally, making it one of the larger addressable sub-segments alongside exon 51.

Regulatory precedent in this space is relevant: the FDA's accelerated approval pathway for DMD exon-skipping drugs has relied on dystrophin production as a surrogate endpoint, a framework that has also attracted ongoing scrutiny. Entrada will need to demonstrate meaningful functional benefit at higher doses to support a prospective approval case, and the eventual label claim will likely depend on functional outcome data from the open-label extension.

Cohort 2, dosed at 10 mg/kg, has completed enrolment and Entrada said it remains on track to report data in the first half of 2027. The company is targeting a further dose escalation to up to 15 mg/kg in Cohort 3, supported by an independent data monitoring committee's recommendation to advance to 18 mg/kg in the parallel ELEVATE-44-201 study. Investors will be watching whether higher doses can produce the step-change in dystrophin levels needed to validate the EEV platform's clinical promise.