Study Evaluating Safety, Tolerability, PK/PD of Surovatamig in Adult RA or SLE Participants

Inclusion Criteria: 1. Participant must be 18 (or the legal age of consent in the jurisdiction in which the study is taking place) to 65 years of age, inclusive, at the time of signing the informed consent. 2. For RA participants, only: 1. Diagnosis of RA as defined by the 2010 EULAR/ACR classification criteria 2. Positive for ≥ 1 disease-specific autoantibody performed by the central laboratory. (a) RF (b) ACPA 3. Moderate or severe disease activity defined as: DAS28-CRP > 3.2 AND * 4 tender joints and ≥ 4 swollen joints (a) US-Specific Criterion: DAS28-CRP > 3.2 AND ≥ 6 tender joints and ≥ 6 swollen joints 4. Intolerance to or inadequate response following approximately 3 month's treatment or longer to ≥2 b/tsDMARDs (with different mechanisms of action) after failing csDMARD therapy (unless csDMARD therapy is contraindicated). There is no minimum duration for taking a treatment in cases of intolerance.…