Merck touted a win for its anti-TL1A antibody in a phase 2b trial in patients with moderate to severe hidradenitis suppurativa (HS).
The study met its primary and secondary endpoints at week 16, informing phase 3 development for tulisokibart in HS, according to the company. The win was first announced in August during its second quarter earnings update.
“We are excited to expand the clinical data for tulisokibart beyond inflammatory bowel disease with these positive Phase 2b results,” Aileen Pangan, M.D., vice president and therapeutic area head, immunology clinical research, Merck Research Laboratories said in the release. “We look forward to advancing tulisokibart to Phase 3 for patients living with HS.”
Merck inherited tulisokibart in the $10.8 billion acquisition of Prometheus Biosciences in 2023. Since then, tulisokibart has been hit-or-miss. In June, Merck reported a phase 3 victory for tulisokibart in ulcerative colitis (UC), followed by a phase 2 fail in systemic sclerosis associated with interstitial lung disease (SSc-ILD) in August.
Tulisokibart is an anti-TL1A antibody designed to block TL1A signaling and downregulating key T cells (Th1, Th2, Th17), a core pathway deemed immuno-fibrosis. This process is a destructive loop driven by inflammation and fibroblast activation, leading to tissue damage, draining tunnel tracts, and scarring seen in autoimmune diseases, such as HS.
The phase 2b study is a randomized, double-blind, placebo-controlled study evaluating the safety and efficacy of tulisokibart in participants with moderate to severe HS. 149 patients were stratified to receive either a high dose (480 mg every four weeks), medium dose (480 mg every 2 weeks), low dose (240 mg every four weeks) or placebo.
By week 16, 72% of patients in the high dose group, 64% in the medium dose group and 52% in the low dose group achieved hidradenitis suppurativa clinical response 50 (HiSCR50), defined by at least a 50% reduction in total abscesses and inflammatory nodules with no increase in abscess count.
Secondary endpoints showed that an HiSCR75 was achieved by 41% of high dose, 40% of medium dose, and 29% of low dose patients, compared to 15% in the placebo group. In the high and medium dose groups, patients’ quality of life with the skin condition, measured by the dermatology life quality index (DLQI), showed a 3.16 point and a 1.02 point improvement over placebo, respectively.
Adverse events occurred in 42.9% of the high dose, 47.6% of the medium dose, and 52.4% of the low dose group compared to 40.9% in the placebo treated group. Serious adverse events occurred in 2.4% in both the high and medium dose groups, 4.8% in the low dose group and 2.3% in the placebo group.
The HS space is densely populated with both FDA approved drugs and drugs in mid-stage development. Avalo Therapeutics recently reported a phase 2 win with its anti-IL-1β antibody (abdakibart) in HS. In March 2025, Incyte delivered a pair of phase 3 wins in HS for its JAK1 inhibitor, povorcitinib, which could offer an oral alternative to biologics in multiple indications.
UCB’s Bimzelx, Novartis’ biologic Cosentyx, and AbbVie’s off-patent Humira are all approved in the indication.