European Academy of Dermatology and Venereology Congress | 2026

Merck's Tulisokibart Produces Strong Mid-Stage Results in Hidradenitis Suppurativa, Setting Up Phase 3 Development

Merck has reported positive Phase 2b findings for tulisokibart, an experimental antibody designed to block TL1A, in people with moderate to severe hidradenitis suppurativa. At 16 weeks, two dosing regimens outperformed placebo on the trial's primary measure of clinical response, offering an early signal that a new immune target may have a role in a condition with substantial unmet need.

A Difficult Disease to Treat

Hidradenitis suppurativa is a chronic inflammatory skin disease that causes painful nodules, abscesses, draining tunnels, scarring, and recurrent flares. It often affects areas where skin rubs together, including the underarms, groin, buttocks, and breast folds. Beyond skin symptoms, the condition can disrupt mobility, sleep, work, relationships, and mental health.

Many patients cycle through antibiotics, surgery, hormonal approaches, and biologic drugs without achieving sustained control. That therapeutic gap has created intense interest in new inflammatory pathways that might influence both active disease and the scarring process that can accumulate over time.

What the Trial Tested

The MK-7240-012 study was a multicenter, randomized, double-blind, placebo-controlled Phase 2b trial involving people with moderate to severe hidradenitis suppurativa. Participants received one of three tulisokibart regimens or placebo for 16 weeks.

The high-dose arm received 480 milligrams every two weeks. The medium-dose arm received 480 milligrams every four weeks. A lower-dose exploratory arm received 240 milligrams every four weeks.

The main outcome was HiSCR50, a standard outcome measure in hidradenitis studies. It requires at least a 50 percent reduction in the combined number of abscesses and inflammatory nodules, with no increase in abscesses or draining tunnels.

Primary Endpoint Results

• At week 16, 72 percent of people in the high-dose group achieved HiSCR50, compared with 35 percent of patients who received placebo. The high-dose group included 42 participants, while the placebo group included 44.

• The medium-dose regimen also met the primary endpoint. A total of 64 percent of its 42 participants achieved HiSCR50, a 29 percentage point difference from placebo.

• In the exploratory lower-dose group, 52 percent of 21 patients met HiSCR50. This was 17 percentage points above the placebo response rate, although this arm was smaller and was not part of the primary confirmatory analysis.

Secondary Measures and Quality of Life

Merck also reported results on HiSCR75, a more demanding threshold that reflects at least a 75 percent reduction in abscesses and inflammatory nodules without worsening of abscesses or draining tunnels. These endpoints were not formally ranked for statistical testing, so the results should be interpreted as supportive numerical findings rather than confirmatory proof.

HiSCR75 was reached by 41 percent of high-dose patients, 40 percent of medium-dose patients, and 29 percent of lower-dose patients. The placebo rate was 15 percent.

Why TL1A Is Being Studied

Tulisokibart is a humanized monoclonal antibody directed against tumor necrosis factor-like cytokine 1A, commonly called TL1A. The protein is thought to participate in several immune pathways, including Th1, Th2, and Th17 signaling.