- Positivity for antidrug antibodies (ADA) is associated with higher Psoriasis Area and Severity Index (PASI) score in patients with psoriasis treated with ustekinumab, according to a cross-sectional study.
Why this matters
- The varied response of patients to ustekinumab is not well understood.
- ADAs were detected in 3.8% of patients by a drug-sensitive radioimmunoassay (RIA) and 10.6% of patients by drug-tolerant (dt) ELISA.
- ADA positivity vs negativity was associated with lower median ustekinumab levels:
- RIA: −0.62 μg/mL (95% CI, −1.190 to −0.30 μg/mL).
- dtELISA: −0.74 μg/mL (95% CI, −1.09 to −0.47 μg/mL).
- ADA positivity vs negativity was associated with higher absolute PASI score:
- RIA: +6.6 (95% CI, 3.0-9.9).
- dtELISA: +1.9 (95% CI, 0.4-4.0).
- Lack of detectable ustekinumab was associated with higher median PASI score (+6.5; 95% CI, 3.9-8.8) compared with detectable ustekinumab.
- 340 patients with psoriasis treated with ustekinumab were analyzed for ADAs, ustekinumab levels, and PASI score.
- Funding: British Association of Dermatologists; others.
- Observational study design.