Merck's anti-TL1A antibody shows mixed Phase 2 results in hidradenitis suppurativa and lung disease

Aug 4, 2026

Merck announced mixed Phase 2 results for its anti-TL1A antibody tulisokibart, which met its primary endpoints in a Phase 2b trial for hidradenitis suppurativa but failed in a Phase 2 trial for systemic sclerosis-associated interstitial lung disease. The drug was the centerpiece of Merck's $10.8 billion acquisition of Prometheus Biosciences in 2023. Despite the mixed clinical results, Merck reported strong second-quarter 2026 sales of $16.6 billion, beating consensus estimates.

Tulisokibart hidradenitis suppurativa success

▪The Phase 2b trial of tulisokibart for hidradenitis suppurativa enrolled 147 patients and measured the percentage of participants with an over 50% reduction in skin abscesses and inflammatory nodules.
▪Merck R&D head Dean Li stated on August 4, 2026, that the positive Phase 2b readout for hidradenitis suppurativa increases confidence in the dermatological possibilities for tulisokibart.
▪Merck announced that its Phase 2b trial of tulisokibart for hidradenitis suppurativa met its primary and key secondary endpoints.

Tulisokibart SSC-ILD failure

▪Merck R&D head Dean Li noted on August 4, 2026, that no anti-cytokine has previously worked for systemic sclerosis-associated interstitial lung disease, calling the trial of tulisokibart a bold move.
▪Merck announced on August 4, 2026, that tulisokibart failed to meet the primary goal of a Phase 2 trial for patients with systemic sclerosis-associated interstitial lung disease.
▪The Phase 2 trial of tulisokibart for systemic sclerosis-associated interstitial lung disease enrolled 154 patients and listed three safety measures and one efficacy goal as primary endpoints.
▪Merck decided to discontinue its Phase 2 study of tulisokibart in systemic sclerosis-associated interstitial lung disease after the drug failed to meet the trial's primary goal.

Prometheus acquisition for tulisokibart

▪Tulisokibart's primary promise is expected as a treatment for ulcerative colitis and Crohn's disease, and Merck reported a Phase 3 victory for the drug in ulcerative colitis in June 2026.
▪Merck acquired Prometheus Biosciences in 2023 for $10.8 billion, with the experimental anti-TL1A antibody tulisokibart, also known as MK-7240, serving as the centerpiece of the deal.

Roche afimkibart competition

▪Roche acquired the anti-TL1A antibody afimkibart through its $7.1 billion acquisition of Telavant in 2023.
▪BMO Capital Markets analysts stated that Merck's tulisokibart, which is administered intravenously, will likely need to show meaningfully improved efficacy compared to Roche's subcutaneously administered afimkibart to be competitive in ulcerative colitis.
▪Merck is developing a subcutaneous formulation of tulisokibart for maintenance treatment, which BMO Capital Markets analysts noted could help lessen competitive headwinds.

Merck Q2 2026 earnings

▪Merck narrowed and raised its sales guidance for the 2026 fiscal year to a midpoint of $66.8 billion, up from the previous midpoint of $66.4 billion.
▪Merck reported second-quarter 2026 sales of $16.6 billion, beating the consensus estimate of $16.37 billion.
▪Merck lowered its 2026 earnings per share estimates to $2.66–$2.76, down from $5.04–$5.16, due to a negative impact from its $6.7 billion acquisition of Terns Pharmaceuticals.