MRK: Positive ATLAS Induction Results for Tulisokibart in UC Bode Well for Maintenance Study

Research evidence excerpt

MRK: Positive ATLAS Induction Results for Tulisokibart in UC Bode Well for Maintenance Study

EQUITY RESEARCH QUICK TAKE

RBC Capital Markets, LLC

Trung Huynh (Analyst)

Justin Burns, CFA (Vice President)

June 22, 2026

Merck & Co., Inc.

Positive ATLAS Induction Results for Tulisokibart in UC Bode Well for Maintenance Study

NYSE: MRK | USD 113.87 | Outperform | Price Target USD 142.00

Sentiment: Positive

Our View: This morning, MRK announced positive topline results from the Phase 3 ATLAS-UC induction-only study (Study

2) evaluating tulisokibart (TL1A mAb from Prometheus acquisition) in moderate-to-severe UC. We view these results as an

incremental positive for MRK and bode well for the Study 1 results in disease maintenance, which are expected later this year.

Recall, management's internal ph3 bar was to emulate ph2 efficacy (pbo-adjusted 25% clinical remission in ARTEMIS-UC), and this

readout, being the first positive ph3 for any anti-TL1A biologic, positions MRK as first-mover in a class that is increasingly viewed

as a compelling therapeutic option in IBD. We model for a 2027 launch and $5.2bn in 2034 sales.

Study Results: The study met its primary endpoint of clinical remission per the Modified Mayo Score (MMS) at week 12, as well as

key secondary endpoints including endoscopic improvement, clinical response, and histologic-endoscopic mucosal improvement.

No new safety concerns were identified, consistent with previously reported ph2 data. Recall, Study 1 includes both induction and

maintenance treatment and Study 2 includes only induction treatment. Full results from Study 1 (induction + maintenance) will

be presented alongside Study 2 at an upcoming scientific congress and shared with regulatory authorities.

All values in USD unless otherwise noted.