The purpose of this study is to evaluate clinical efficacy and safety of arumakimig (MAS825) compared to placebo in patients with Vacuoles, E1 Enzyme, X-linked, Autoinflammatory, Somatic (VEXAS) syndrome. In addition, the study will evaluate the long-term efficacy, safety and tolerability of arumakimig in this population.
Male and female participants aged ≥18 years at screening.
Somatic mutation in UBA1 gene known to be associated with VEXAS.
Participants must have at least two manifestations of VEXAS at screening or in the past 6 months.
Participants must be able to start treatment for Pneumocystis jiroveci pneumonia (PJP) during the study if indicated according to the local guidelines.
Positive serology for hepatitis B surface antigen (HBsAg) excludes the participant.
Participants with a positive HCV antibody test should have HCV ribonucleic acid (RNA) levels measured. Participants with positive (detectable) HCV RNA must be excluded. Chronic hepatitis C patients who have completed HCV anti-viral treatment must be HCV-RNA negative at least 12 weeks after treatment before randomization to be eligible.
Active viral, bacterial, or other infections requiring systemic treatment at the time of screening or randomization, or history of recurrent clinically significant infection or of recurrent bacterial infections.
Known or suspected Human Immunodeficiency Virus (HIV) infection. Should it be required by local regulations and/or considered appropriate by the Investigator, an HIV test can be performed locally to confirm eligibility.