---
schema_version: "secwatch.filing_event.v1"
accession: "0001558370-23-018691"
form_type: "8-K"
ticker: "ACRS"
cik: "0001557746"
company_name: "Aclaris Therapeutics, Inc."
filed_at: "2023-11-13T23:59:59+00:00"
generated_at: "2026-06-08T05:06:07.553346+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.9
calibrated_materiality_score: 0.9
confidence: "high"
source: SEC EDGAR
---

# Aclaris Phase 2b zunsemetinib fails endpoints; ATI-450 program discontinued

## Summary
- Study of oral MK2 inhibitor zunsemetinib (20mg or 50mg BID) in 251 RA patients did not meet primary endpoint ACR20 at week 12.
- No differentiation from placebo on secondary endpoints (ACR50, ACR70, DAS28-CRP); no meaningful safety findings.
- Aclaris discontinues ATI-450 development; halts enrollment in Phase 2a psoriatic arthritis trial.
- Phase 2b results for ATI-1777 (topical JAK1/3) in atopic dermatitis expected year-end 2023; Phase 2 for ATI-2138 planned early 2024.
- Cash, cash equivalents and marketable securities of $187.0M as of Sep 30, 2023.

## SEC filing metadata
- accession: 0001558370-23-018691
- form_type: 8-K
- ticker: ACRS
- cik: 0001557746
- company_name: Aclaris Therapeutics, Inc.
- filed_at: 2023-11-13T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.9
- calibrated_materiality_score: 0.9
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1557746/000155837023018691/0001558370-23-018691-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1557746/000155837023018691/acrs-20231113x8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001558370-23-018691
- JSON: https://secwatch.observer/filing/0001558370-23-018691.json
- Plain text: https://secwatch.observer/filing/0001558370-23-018691.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.