This clinical trial is for people aged 18-75 with stable but active autoimmune diseases like lupus, rheumatoid arthritis, or antiphospholipid syndrome. The study involves a single **intravenous infusion** (medicine given through a vein) of a drug called belantamab. The main goal is to see if belantamab is safe and to observe how the body reacts and processes the drug over time.

**Autoimmune diseases** are conditions where the body's immune system mistakenly attacks its own cells. **Lupus** and **rheumatoid arthritis** are types of autoimmune diseases. Participants must have failed to respond to at least two treatments for their condition to qualify. **Inclusion criteria** involve certain health requirements like body measurements and test results. **Exclusion criteria** include things like recent severe disease flare-ups or unstable disease conditions.

• The study is one-time and requires only one hospital visit for the infusion.
• Participants need to meet specific health criteria to join.
• The study aims to ensure the drug is safe for people with different autoimmune diseases.