Anti-TL1A antibody, afimkibart, in moderately-to-severely active ulcerative colitis (TUSCANY-2): a multicentre, double-blind, treat-through, multi-dose, randomised, placebo-controlled, phase 2b trial.

Background: TNF-like ligand 1A (TL1A) is an emerging therapeutic target for inflammatory bowel disease. We evaluated the safety and efficacy of multiple doses of afimkibart, a TL1A-directed antibody, in patients with moderately-to-severely active ulcerative colitis.

Methods: The multicentre, double-blind, treat-through, multi-dose, randomised, placebo-controlled, phase 2b, TUSCANY-2 trial was conducted at 114 centres in 23 countries across North America, Europe, Asia, Africa, Australia, and South America. Adults (aged 18-75 years) with moderately-to-severely active ulcerative colitis (total Mayo score [tMS] 6-12, endoscopic subscore ≥2) were randomly assigned (2:2:2:2:2:3:1:1:1) to one of nine treatment sequences to receive subcutaneous afimkibart 50 mg, 150 mg, 450 mg, or matched placebo every 4 weeks during the 12-week induction period, and subcutaneous afimkibart 50 mg, 150 mg, or 450 mg during the treat-through 40-week maintenance period. Investigators and patients were masked to treatment. Study drugs were administered by masked site personnel following preparation by an unmasked pharmacist at the investigational site. Efficacy was assessed at weeks 14 and 56 in the intent-to-treat populations. The primary efficacy endpoint of clinical remission at week 14 by tMS (defined as tMS ≤2, with no individual subscore >1) was assessed in those who received at least one dose of drug or placebo during induction, excluding patients who had missing data due to complications resulting from COVID-19. Safety endpoints were also analysed in those who were randomly assigned and received at least one dose of assigned treatment. This study is registered with ClinicalTrials.gov, NCT04090411.

Findings: Between Dec 19, 2019, and Oct 25, 2022, 246 patients were randomly assigned treatment, of whom 245 were treated, 228 completed induction, and 178 completed maintenance. Median age was 39 years (IQR 30·0-51·0), 99 (40%) patients were female and 146 (60%) were male; median disease duration was 4·7 years (IQR 2·5-10·2). At week 14, the primary endpoint of clinical remission by tMS was reported in 12 (26%) of 47 patients in the afimkibart 50 mg group (risk difference vs placebo [RD] 13·9% [90% CI -0·2 to 27·7]; p=0·0545), 14 (23%) of 60 patients in the afimkibart 150 mg group (RD 11·7% [-1·7 to 24·1]; p=0·0823), and 21 (24%) of 88 patients in the in the afimkibart 450 mg group (RD 12·2% [-0·6 to 22·9]; p=0·0642) versus five (12%) of 43 patients in the placebo group. In alignment with updated US Food and Drug Administration guidance, clinical remission using the modified Mayo score at week 14 was reported in 14 (30%) of 47 patients in the afimkibart 50 mg group (RD 18·2% [90% CI 3·3 to 32·2]), 21 (35%) of 60 patients in the in the afimkibart 150 mg group (RD 23·4% [6·2 to 36·3]), and 28 (32%) of 88 patients in the in the afimkibart 450 mg group (RD 20·2% [3·2 to 31·3]) versus five (12%) of 43 patients in the placebo group. Overall, 117 (48%) of 245 patients in the induction phase and 132 (59%) of 224 patients in the maintenance phase reported at least one treatment-emergent adverse event; incidences of treatment-emergent adverse events during induction were similar with placebo and afimkibart. The most common treatment-emergent adverse events (occurring in ≥5% of patients) during induction were nausea, urinary tract infection, ulcerative colitis, anaemia, fatigue, headache, and pyrexia. Six serious adverse events were reported during induction in the active treatment groups and four in the placebo group. Two patients who completed induction and did not receive the study drug during maintenance had serious adverse events during safety follow-up. During the maintenance period, 12 (5%) of 224 patients had 13 serious adverse events. No deaths occurred.

Interpretation: Differences in the primary endpoint of clinical remission by tMS were not significantly different for any dose of afimkibart compared with placebo. However, secondary endpoints suggest that afimkibart was associated with a favourable benefit-risk profile, with clinically meaningful improvements in clinical remission with the modified Mayo score for patients with moderately-to-severely active ulcerative colitis. These results support the continued development of afimkibart.

Funding: Pfizer, Roivant Sciences, and F Hoffmann-La Roche.