Last reviewed 2026-04-22 · How we verify

Abatacept (W12-W48)

Abatacept is a fusion protein that blocks T-cell costimulation by binding to CD80/CD86 on antigen-presenting cells, thereby inhibiting T-cell activation and proliferation.

Abatacept is a fusion protein that blocks T-cell costimulation by binding to CD80/CD86 on antigen-presenting cells, thereby inhibiting T-cell activation and proliferation. Used for Rheumatoid arthritis, Polyarticular juvenile idiopathic arthritis, Psoriatic arthritis.

At a glance

Mechanism of action

Abatacept (CTLA4-Ig) works by interrupting the second signal required for full T-cell activation. It binds to CD80 and CD86 molecules on antigen-presenting cells, preventing their interaction with CD28 on T cells. This selective costimulation blockade reduces pathogenic T-cell responses while preserving regulatory T-cell function, making it effective in autoimmune and inflammatory conditions.

Approved indications

• Rheumatoid arthritis
• Polyarticular juvenile idiopathic arthritis
• Psoriatic arthritis
• Ankylosing spondylitis
• Systemic lupus erythematosus

Common side effects

• Infection (upper respiratory, urinary tract)
• Headache
• Nausea
• Dizziness
• Hypertension
• Serious infections

Key clinical trials

• Efficacy of a Sequential Treatment Strategy in Rheumatoid Arthritis (PHASE3)

Primary sources

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