BackgroundAtopic dermatitis (AD) is one of the most common inflammatory skin diseases. It is associated with significant itch and impaired quality of life. Systemic treatments are efficient but associated with side effects. Novel topical treatments with a favourable safety profile are needed. SNG100 is a novel composition of hydrocortisone 1% in a cream base comprising sulphated polysaccharide (SPS; extracted from in‐house cultivated Porphyridium Cruentum unicellular algae), a well‐known hydrating, moisturising and a skin barrier repairing agent.ObjectivesTo assess the safety, usability and efficacy of SNG100 cream in patients aged ≥6 years with moderate AD.MethodsIn this proof of concept phase I, double‐blind, randomised trial, participants received one of three treatments for 14 days: SNG100 twice daily (BID), hydrocortisone 1% BID or mometasone furoate once daily (QD). The primary endpoint was the safety and tolerability of SNG100 cream compared to hydrocortisone 1% and mometasone furoate. The secondary endpoint was the subject's usability of SNG100. Exploratory efficacy endpoints included percent change from baseline in SCOring AD (SCORAD), Eczema Area and Severity Index, Patient‐Oriented Eczema Measure, Dermatology Life Quality Index, pruritus Numerical Rating Score (NRS), peak pruritus‐NRS and Investigator's Global Assessment. Subjects were also followed up without any treatment for additional 14 days.ResultsOverall, 66 participants were screened, and 60 patients were randomised. SNG100 demonstrated a high safety profile, similar to marketed products hydrocortisone 1% and mometasone furoate 0.1%, with no unanticipated drug safety related events. SNG100 and mometasone furoate 0.1% cream achieved almost similar and statistically significant greater percentage reductions from baseline in SCORAD as compared to hydrocortisone 1% cream. SNG100 demonstrated significant improvement in NRS as compared to hydrocortisone 1% cream. Remarkably, SNG100 led to a lasting effect with only 29.4% of subjects returning to IGA3 during the follow‐up period compared to 50% and 38.9% in the hydrocortisone 1% and in mometasone furoate treatment arms, respectively.ConclusionsTopical SNG100 is an effective, safe, and well‐tolerated innovative treatment for moderate AD. Trial registration number: NCT04615962 (Topical Cream SNG100 for Treatment in Moderate AD Subjects).