A Phase II Trial to Evaluate the Clinical Efficacy, Safety and Tolerability of MAS825 in Pediatric and Adult Participants With Still's Disease

This is a multicenter, open-label, single-arm study to assess clinical efficacy, safety and tolerability of MAS825 in participants (both pediatric and adult) with Still's disease who have had inadequate response to IL-1 and/or IL-6 or other available therapies. Participants with associated lung disease and/or macrophage activation syndrome may also be included.

This study has three periods (Screening, Treatment Period 1, and Treatment Period 2) and a total duration of approximately 16 months.

Inclusion criteria

• Age ≥ 1 with a diagnosis of Still's Disease
• Active diseases defined as:
• CRP or ferritin levels greater than ULN, and any of:

• Fever ≥ 38°C attributed to Still's Disease activity and documented for a number of days prior to Day 1 or
• Rash attributed to Still's Disease activity or
• Musculoskeletal involvement: arthritis in a number of joints per ACP criteria for active joint or
• Serositis or
• Macrophage activation syndrome activity as defined by ferritin levels and at least one of: platelet count, a biomarker or fibrinogen levels attributed to Still's Disease activity by the investigator
• Intolerance or inadequate response to available biologic therapy

Exclusion criteria

• Patients out of weight range
• Ongoing or previous treatment with immunomodulatory drugs

• A limited number of Still's Disease patients that have previously received MAS825 through a managed access program are permitted on the study
• Glucocorticoid dose exceeding a set limit
• Any conditions or significant medical problems which places the patient at unacceptable risk for MAS825 therapy

• Still's disease patients with evidence of macrophage activation syndrome are permitted in the study
• Still's Disease patients with evidence of interstitial lung disease including those requiring supplemental oxygen therapy are permitted in the study
• History of ongoing, chronic or possibly recurrent infection (e.g. HIV, TB, HCV, HBV) and/or symptoms and signs of clinically significant active bacterial, fungal or viral infections
• Live vaccinations within a set time prior to MAS825 treatment. Live vaccines are prohibited up to several months following the last dose
• History of malignancy of any organ system, including post-transplant lymphoproliferative disorder, treated or untreated, within a number of years, regardless of whether there is evidence of local recurrence and metastases
• History of hypersensitivity to any of the study drugs or to drugs of similar chemical classes or to any of the excipients
• Pregnant or breastfeeding women
• Women of child-bearing potential who do not agree to comply with required contraceptive use

Other protocol-defined inclusion/exclusion criteria may apply.