Merck's experimental drug tulisokibart delivered strong results in a mid-stage trial for hidradenitis suppurativa (HS) — a chronic skin condition that causes painful lumps under the skin. The drug, which targets a protein linked to inflammation and tissue scarring, met its primary endpoint, with 72% of patients on the highest dose achieving at least a 50% reduction in inflammatory skin lesions after 16 weeks, compared to 35% on placebo.

Analysts called the data "highly competitive" with both approved and pipeline HS treatments, noting clean safety signals that boost confidence in tulisokibart's broader potential across inflammatory indications. Merck acquired the drug through its $10.8 billion purchase of Prometheus Biosciences in 2023, and it's now seen as a key asset to help offset future revenue losses from cancer blockbuster Keytruda.

By the Numbers:

• 72% of patients on the highest dose achieved ≥50% lesion reduction vs. 35% on placebo
• 41% achieved ≥75% lesion reduction vs. 15% on placebo
• HS treatment market projected to exceed $10 billion by 2035

Why it matters: With only a handful of approved HS treatments on the market, tulisokibart's strong mid-stage data could signal a meaningful new option for patients with this debilitating condition — and a major commercial opportunity for Merck.