This first-in-human study evaluates the safety, tolerability, pharmacokinetics, pharmacodynamics, and immunogenicity of HBM7020. The study will enroll healthy participants at low doses, followed by participants with moderate to severe autoimmune diseases with predominant B-cell involvement. Eligible participants include patients with systemic lupus erythematosus (SLE), systemic sclerosis (SSc), Sjögren's disease (SjD), and rheumatoid arthritis (RA).

Key Inclusion Criteria for Healthy Participants (Part 1)

1. Participants who are of non-childbearing potential or are using acceptable contraception.
2. Body mass index (BMI) and body weight within an acceptable range.
3. Good general health based on medical history, physical examination, electrocardiogram (ECG), and laboratory assessments.

Key Disease-Agnostic Inclusion Criteria for Patient Participants (Part 1)

1. BMI and body weight within an acceptable range.
2. Adequate hematologic, renal, hepatic, immunologic, and lymphocyte parameters.

Key Disease-Specific Inclusion Criteria for Patient Participants (Part 1)

1. Confirmed autoimmune disease with appropriate supporting autoantibody findings.

2. Stable background therapy prior to dosing.

3. Active moderate to severe disease consistent with protocol-defined disease activity criteria for:

   • Systemic lupus erythematosus (SLE)
   • Systemic sclerosis (SSc)
   • Rheumatoid arthritis (RA)
   • Sjögren's disease (SjD)

Key Inclusion Criteria for Rescreening Participants (Part 2)

1. Meets Part 1 disease-agnostic inclusion criteria.
2. Stable background autoimmune therapy prior to dosing.
3. Ongoing active moderate to severe disease based on protocol-defined disease-specific criteria.

Key Exclusion Criteria for Parts 1 and 2

1. Pregnant or breastfeeding participants.
2. Recent vaccination within protocol-defined timelines.
3. Clinically significant medical history or abnormal physical examination findings.
4. Clinically significant cardiovascular abnormalities, including blood pressure, heart rate, syncope, or ECG findings.
5. Prior or recent therapies or conditions that may interfere with study participation or safety evaluations.
6. Severe pulmonary, renal, or cardiac disease, or clinically significant pulmonary hypertension.

Anonymized individual participant data (IPD) that underlie the results of this study will be shared with researchers to achieve aims pre-specified in a methodologically sound research proposal. Small studies with less than 25 participants are excluded from data sharing.

Data will be available after marketing approval in global markets, or beginning 1-3 years following article publication. There is no end date to the availability of the data.

Otsuka will share data on the Vivli data sharing platform: https://vivli.org/ourmember/Otsuka/

Open-label