ABIVAX (ABVX) Study Result summary

Study design and population

• Two global, multicenter, randomized, double-blind, placebo-controlled Phase 3 induction trials (ABTECT-1 and ABTECT-2) enrolled 1,275 adults with moderate to severe ulcerative colitis across 36 countries and over 600 sites, including both advanced therapy-naive and refractory patients.

• Randomization was 2:1:1 for 50 mg, 25 mg, and placebo, with primary endpoints at week 8 for induction and week 52 for maintenance; endpoints differed for FDA (clinical remission) and EMA (symptomatic remission, endoscopic improvement).

• Patient population was balanced for prior advanced therapy exposure, with 47.3% having failed advanced therapies and 9.7% with prior JAK inhibitor failure, including the largest JAK inhibitor-experienced cohort in Phase 3 UC trials.

• Study design minimized placebo response and improved upon Phase 2b by limiting concomitant medications, diversifying trial sites, and matching Phase 2 and 3 populations.

Efficacy results

• 50 mg obefazimod achieved statistically significant and clinically meaningful clinical remission in both ABTECT-1 (21.7%, Δ19.3%) and ABTECT-2 (19.8%, Δ13.4%) compared to placebo; pooled placebo-adjusted remission rate was 16.4% (p<0.0001).

• 25 mg dose was statistically significant in ABTECT-1 (23.8%, Δ21.4%) but not in ABTECT-2 (11.3%, Δ5.1%) for the FDA primary endpoint; it met EMA co-primary endpoints in both trials and showed a strong pooled clinical response.

• All key secondary endpoints, including endoscopic improvement and symptomatic remission, were met with 50 mg in both trials with high statistical significance.

• Pooled analysis confirmed a clear dose response, with the 25 mg group in one trial representing the most difficult-to-treat population.

Safety and tolerability

• Obefazimod was generally well tolerated, with no new safety signals observed and low discontinuation rates due to adverse events, similar to placebo.

• Rates of treatment-emergent adverse events were similar across groups; headache was the most common adverse event, transient and rarely led to discontinuation.

• Serious adverse events and infections were infrequent and balanced between treatment and placebo arms; only one case of malignancy (prostate cancer, stage 1) was reported.

• No pre-initiation testing requirements indicated by safety data.