An Ascending Dose Study of DKB903 in Participants With Rheumatoid Arthritis (RA) and Participants With Systemic Lupus Erythematosus (SLE)

The purpose of this First-In-Human (FIH), Phase 1, open-label, ascending dose study is to determine safety and tolerability of DKB903, in participants with Rheumatoid Arthritis (RA) and participants with Systemic Lupus Erythematosus (SLE) in order to enable further clinical testing in these populations.

Key Inclusion Criteria: * Signed informed consent must be obtained prior to participation in the study. * Able to communicate well with the Investigator, to understand the study and willing to comply with the requirements of the study. * Immunization (primary or from vaccinations) against pneumococcus, influenza and COVID-19 at least 2 weeks prior to the first dosing. * Male and female individuals, aged 18 to 75 years at screening, diagnosed with RA according to the 2010 American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) or 1987 ACR classification at least 12 weeks prior to screening. * Male and female individuals, aged 18 to 75 years at screening, diagnosed with SLE according to the 2019 ACR/EULAR criteria at least 12 weeks prior to screening. Key Exclusion Criteria: * Body weight \< 45 kg or \> 145 kg and Body Mass Index (BMI) \< 16 or \> 39. * Use of prohibited medication or inadequate wash-out as per protocol. * Protocol-defined cardiac conditions or clinically significant ECG abnormalities or arrhythmia. * Clinically significant active, opportunistic, chronic or recurrent infection (including Human Immunodeficiency Virus \[HIV\], Hepatitis B \[HBV\], Hepatitis C \[HBC\], and Tubercolosis \[TB\]) confirmed by clinical evidence, imaging, or positive laboratory tests (e.g., blood cultures, PCR for DNA/RNA) within one month prior to or during screening. * Serious medical illness likely to interfere with participation in this clinical study. * Women of childbearing potential (WOCBP), defined as all women physiologically capable of becoming pregnant from menarche until becoming post-menopausal, unless they are using highly effective methods of contraception (failure rate \< 1% per year) from the time of enrollment until weeks after last DKB903 administration. Other protocol-defined inclusion/exclusion criteria may apply.