A 52-Week Study Evaluating the Efficacy and Safety of Arumakimig (MAS825) in Participants With VEXAS Followed by Open-Label Extension (OLE) Period

Inclusion Criteria: * 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. * Ability to communicate well with the Investigator, understand and agree to comply with the requirements of the study. Exclusion Criteria: * Participants meeting any of the following criteria are not eligible for this study: * Positive serology for hepatitis B surface antigen (HBsAg) excludes the participant. HBsAg negative participants who are hepatitis B core antibody (HBcAb) positive are also excluded unless protocol-defined criteria are met. * 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 …