684 - Amlitelimab (an anti-OX40 ligand antibody) vs placebo in patients with moderate-to-severe atopic dermatitis: study design of phase 3 OCEANA clinical trials COAST 1/2, SHORE, AQUA, and ESTUARY

Abstract Introduction/Background Amlitelimab is a fully human, nondepleting anti-OX40 Ligand (OX40L) monoclonal antibody that blocks OX40L-OX40 interactions. In addition to an acceptable safety profile, phase 2a and 2b trials showed the clinical efficacy of amlitelimab in achieving lesional and symptomatic (pruritus) endpoints and demonstrating a continued durable response when patients with moderate-to-severe atopic dermatitis (AD) were withdrawn from amlitelimab during a 28-week period, suggesting the viability of extended interval dosing (every 12 weeks [Q12W]). Objectives Phase 3 clinical trials will determine the efficacy and safety of amlitelimab every four weeks (Q4W) and Q12W dosing in patients with moderate-to-severe AD with various treatment histories. Methods OCEANA phase 3 clinical trials (COAST 1, COAST 2, SHORE, AQUA, and ESTUARY) are multinational, multicenter, randomized, double-blind, parallel group, placebo-controlled trials evaluating efficacy and safety of subcutaneous amlitelimab with two different dosing regimens. Key inclusion criteria for COAST 1/2, SHORE, and AQUA include: adults and adolescents (≥12 years old) having AD ≥1 year with inadequate response to topical treatments (within 6 months before screening) and/or systemic treatment (within 12 months before screening), validated Investigator Global Assessment scale for Atopic Dermatitis (vIGA-AD) baseline score of 3 or 4, Eczema Area and Severity Index (EASI) baseline score of ≥16, AD involvement of ≥10% of body surface area at baseline, and weekly average Peak Pruritus Numerical Rating Scale score of ≥4. COAST 1/2 are 24-week monotherapy studies, while SHORE is a 24-week study with background topical corticosteroids (TCSs) and topical calcineurin inhibitors (TCIs). AQUA is a 36-week study with background TCSs and TCIs that exclusively includes participants with an inadequate response to prior treatment with AD biologics or oral Janus kinase inhibitors. Primary endpoints for COAST 1/2, SHORE, and AQUA include vIGA-AD 0/1 and a reduction from baseline of ≥2 points (for US and US reference countries) and vIGA-AD 0/1 and EASI-75 (for Japan, EU, and EU reference countries). Adult patients ≥40 kg will be randomized to amlitelimab 250 mg Q4W + 500 mg loading dose (LD), amlitelimab 250 mg Q12W + 500 mg LD, or placebo; dose will be adjusted for patients <40 kg. Trials have a 2- to 4-week screening period. Primary endpoints will be evaluated at Week 24 for COAST 1/2 and SHORE and at Week 36 for AQUA, with expected enrollment of 420, 420, 496, and 249 patients in each study, respectively. Patients who have completed COAST 1/2 or SHORE can elect to enter the ESTUARY blinded extension study; patients completing AQUA can enter RIVER-AD, an open-label long-term study. Upon entering ESTUARY, clinical responders previously on 250 mg Q4W +LD will be randomized to 250 mg Q4W, 250 mg Q12W, or treatment withdrawal (placebo), while nonresponders will continue on 250 mg Q4W. Clinical responders previously on 250 mg Q12W +LD will be randomized to 250 mg Q12W or treatment withdrawal (placebo), while nonresponders will be randomized to 250 mg Q12W or 250 mg Q4W. Clinical responders previously on placebo will continue placebo, while nonresponders on placebo will receive amlitelimab 250 mg Q4W +LD. Participants not entering the ESTUARY or RIVER-AD trials will be included in a 16-week safety follow-up. ESTUARY and RIVER-AD will evaluate long-term safety and efficacy. Biopsies and blood samples will be collected at various timepoints in the OCEANA phase 3 trials. Results Enrollment for the OCEANA phase 3 trials began Q4 2023. COAST 1/2, SHORE, and AQUA trials are expected to be completed in 2026. Conclusions Results of the clinical trials should provide further evidence demonstrating the efficacy and safety of amlitelimab in treating moderate-to-severe AD using two different dosing regimens, including an extended dosing regimen, in patients with various treatment histories.