Aclaris Therapeutics (ACRS) Study update summary

Key clinical milestones and ATI-052 phase I-A trial results

• ATI-052, a bispecific antibody targeting TSLP and IL-4R, demonstrated dose-proportional pharmacokinetics with an estimated half-life of 45 days, supporting dosing intervals of up to three months and sustained drug levels above target for at least 12 weeks in MAD cohorts.

• Pharmacodynamic data showed robust, near-complete inhibition of TSLP- and IL-4-stimulated CCL17/TARC for up to 20 and 12 weeks, respectively, at higher doses, supporting extended dosing intervals.

• ATI-052 exhibited greater potency than the combination of Dupilumab and Tezepelumab in ex vivo assays.

• No safety signals, immunogenicity concerns, or anti-drug antibody impact were observed, with a favorable safety and tolerability profile and no serious adverse events or discontinuations.

• The phase I-A trial was randomized, blinded, and placebo-controlled, evaluating single and multiple ascending doses in healthy adults.

Ongoing and planned clinical programs

• Phase Ib proof-of-concept trials for ATI-052 in atopic dermatitis and asthma are ongoing, focusing on PK, target engagement, and biomarker response, with top-line data expected in the second half of 2026.

• The atopic dermatitis trial uses five weekly 480 mg doses, while the asthma trial uses a single 480 mg dose.

• Phase IIb planning is advancing for both asthma and atopic dermatitis, with the asthma study expected to initiate in Q4 2026.

ATI-2138 and lichen planus program

• ATI-2138, a dual ITK/JAK3 inhibitor, was selected for phase IIb development in lichen planus due to mechanistic overlap, unmet need, and regulatory opportunities.

• Lichen planus affects up to 1% of the US population, with no FDA-approved therapies and high steroid failure rates, representing a significant market opportunity estimated at over $1 billion.

• ATI-2138 inhibits both TCR and cytokine signaling, potentially offering broad and deep efficacy and rapid symptom relief in lichen planus.

• A phased multi-part phase IIb basket study in lichen planus, including erosive mucosal, cutaneous, and lichen planopilaris subtypes, is expected to start in the second half of 2026.