How Secukinumab (Cosentyx) Works
Secukinumab is a fully human monoclonal IgG1/κ antibody that selectively binds to and neutralizes interleukin-17A (IL-17A), thereby blocking its interaction with the IL-17 receptor and interrupting the inflammatory cascade that drives psoriasis, psoriatic arthritis, and axial spondyloarthritis. 1
Mechanism of Action
Secukinumab works by targeting a specific cytokine in the inflammatory pathway:
- IL-17A is a naturally occurring proinflammatory cytokine that plays a central role in normal immune responses but becomes pathologically elevated in psoriatic disease 1
- By binding to IL-17A, secukinumab prevents the cytokine from attaching to its receptor, effectively neutralizing its biological activity 2
- This blockade inhibits the release of downstream proinflammatory cytokines and chemokines that perpetuate the inflammatory cycle 1
The Biological Basis
The rationale for targeting IL-17A is based on strong pathophysiological evidence:
- Elevated levels of IL-17A are found in psoriatic plaques, hidradenitis suppurativa lesions, and the blood of patients with psoriatic arthritis and ankylosing spondylitis 1
- Increased numbers of IL-17A-producing lymphocytes and innate immune cells have been documented in affected tissues and circulation 1
- Treatment with secukinumab reduces epidermal neutrophils and IL-17A levels in psoriatic plaques, though the complete relationship between these pharmacodynamic effects and clinical outcomes is still being elucidated 1
Clinical Translation
The mechanism translates into measurable clinical effects:
- Secukinumab is a human immunoglobulin (Ig)-G1-κ monoclonal antibody with a molecular mass of approximately 151 kDa 2, 1
- The drug interrupts the IL-17A inflammatory cascade, which is fundamental to the pathogenesis of psoriasis, psoriatic arthritis, and axial spondyloarthritis 2
- Serum levels of total IL-17A (both free and secukinumab-bound) increase following treatment, reflecting target engagement 1
Important Pharmacological Considerations
Immunogenicity is minimal: Less than 1% of patients develop anti-secukinumab antibodies through 52 weeks of treatment, and these neutralizing antibodies have not been associated with loss of efficacy 3
The drug's selectivity for IL-17A distinguishes it from other biologics—it does not target IL-17F or other cytokines in the IL-17 family, providing a focused mechanism of action 4, 5
Human pharmacology studies demonstrate that secukinumab does not impair immune responses to non-live vaccines (meningococcal and influenza), suggesting preserved adaptive immunity despite IL-17A blockade 1