High-dose tulisokibart achieved HiSCR50 in 72% of patients with moderate to severe hidradenitis suppurativa at week 16, a 37-percentage-point difference over placebo (35%), Merck reported on September 30, 2026. The results, presented in a late-breaking session at the 2026 EADV Congress (Abstract LB-26), mark the first positive phase 2 data for an anti-TL1A monoclonal antibody in dermatology.

Tulisokibart is an investigational monoclonal antibody against tumor necrosis factor-like cytokine 1A (TL1A). It blocks TL1A signaling and downregulates Th1, Th2, and Th17 pathways, aiming to disrupt the immuno-fibrotic loop Merck links to HS progression. The agent previously induced clinical remission in a phase 2 ulcerative colitis trial published in the New England Journal of Medicine in 2024.

"Despite available advanced therapies, many still do not achieve long-term disease control," said Alexa B. Kimball, MD, MPH, lead investigator of the study, president and CEO of Harvard Medical Faculty Physicians at Beth Israel Deaconess Medical Center, and professor of dermatology at Harvard Medical School. "Results from the MK-7240-012 trial are promising and suggest the potential for meaningful improvement in the management of this difficult-to-treat condition." Kimball is a paid consultant to Merck.

What did the trial design look like?

MK-7240-012 (NCT06956235) randomized patients with moderate to severe HS across four arms over a 16-week double-blind period:

• High dose: 480 mg every 2 weeks (n = 42)
• Medium dose: 480 mg every 4 weeks (n = 42)
• Low dose: 240 mg every 4 weeks (n = 21)
• Placebo (n = 44)

The trial used a Bayesian design that augmented concurrent placebo controls with historical placebo data for the primary endpoint. HiSCR50 required at least a 50% reduction in total abscess and inflammatory nodule count, with no increase in abscesses or draining tunnels. Merck's release did not report P values, confidence intervals, or posterior probabilities for the primary analysis.

How large were the responses?

At week 16, HiSCR50 was reached by 72% of high-dose and 64% of medium-dose patients — differences of 37 and 29 percentage points over placebo, respectively. Both regimens demonstrated superiority, according to Merck. In an exploratory analysis, the low-dose group achieved a 52% response rate, 17 percentage points above placebo.

For the non-ranked key secondary endpoints, HiSCR75 rates were:

• High dose: 41%
• Medium dose: 40%
• Low dose: 29%
• Placebo: 15%

Mean Dermatology Life Quality Index (DLQI) scores fell by 5.62 points from baseline in the high-dose group and 3.50 points in the medium-dose group, versus 2.46 points with placebo. The low-dose group showed no DLQI improvement over placebo. Merck characterized all secondary endpoint differences as numerical.

What did safety show?

Adverse events occurred in 42.9% of high-dose, 47.6% of medium-dose, and 52.4% of low-dose patients, compared with 40.9% on placebo. Serious adverse events were rare: 2.4% in the high- and medium-dose groups, 4.8% in the low-dose group, and 2.3% with placebo. No serious or opportunistic infections were observed.

What comes next?

"We look forward to advancing tulisokibart to Phase 3 for patients living with HS," said Aileen Pangan, MD, vice president and therapeutic area head, immunology clinical research, Merck Research Laboratories. Merck plans to use these findings to inform phase 3 development in HS.

The molecule already has a broad pipeline: phase 3 trials in ulcerative colitis (ATLAS-UC) and Crohn disease (ARES-CD), and phase 2 trials in rheumatoid arthritis, psoriatic arthritis, and radiographic axial spondyloarthritis. If the phase 2b HiSCR50 signal holds in pivotal HS trials, dermatology could gain its first TL1A-targeted therapy — and HS patients a mechanism distinct from currently available advanced therapies.