Tulisokibart delivers first positive anti-TL1A phase 2 results in hidradenitis suppurativa

Merck announced positive phase 2b results for tulisokibart in patients with moderate to severe hidradenitis suppurativa (HS), providing the first positive clinical data for an anti-TL1A monoclonal antibody in dermatology. The findings support TL1A inhibition as a potential new therapeutic approach for this difficult-to-treat disease, where many patients fail to achieve durable disease control despite available advanced therapies.

At 16 weeks, 72% of patients receiving the high-dose regimen and 64% receiving the medium-dose regimen achieved Hidradenitis Suppurativa Clinical Response 50 (HiSCR50), compared with 35% of patients receiving placebo. This represented response rates that were 37 and 29 percentage points higher than placebo, respectively. In an exploratory analysis, 52% of patients receiving the low-dose regimen achieved HiSCR50.

More stringent disease control measures also favored tulisokibart. Hidradenitis Suppurativa Clinical Response 75 (HiSCR75) was achieved by 41% of patients in the high-dose group and 40% in the medium-dose group, compared with 15% of those receiving placebo. Patients receiving higher doses also reported numerically greater improvements in dermatology-specific quality of life.

HS is a chronic inflammatory skin disease characterized by painful nodules, abscesses, tunnels, fibrosis, and scarring. Tulisokibart targets tumor necrosis factor-like cytokine 1A (TL1A), a pathway implicated in both inflammation and fibrosis that may contribute to disease progression.

The safety profile was generally comparable to placebo. Adverse events occurred at similar rates across groups, serious adverse events were uncommon, and no serious or opportunistic infections were reported.

Interpretation of the findings is tempered by several factors. The primary analysis used a Bayesian design that incorporated historical placebo data rather than relying solely on a concurrent control group. Also, the study was small, with about 42 to 44 patients in the main arms and 21 in the low-dose arm.

If confirmed in larger studies, the findings could expand treatment options for HS and further validate TL1A inhibition beyond inflammatory bowel disease. Merck said the results will inform phase 3 development of tulisokibart in HS.

Source: Merck. (2026 Sep 30). Merck’s Tulisokibart Met Primary and Key Secondary Endpoints in Phase 2b Study in Patients With Moderate to Severe Hidradenitis Suppurativa (HS)