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Summary

Background

Early identification of responsiveness to biologic treatments in psoriasis has significant clinical and economic implications.

Objectives

To evaluate whether early clinical improvements in Psoriasis Area and Severity Index (PASI) scores could predict subsequent clinical responses in patients treated with ixekizumab, an anti-interleukin-17 monoclonal antibody.

Methods

This post hoc analysis was derived from a phase II study in patients with moderate-to-severe plaque psoriasis (= 114) who received multiple doses of ixekizumab 10, 25, 75 or 150 mg subcutaneously over 20 weeks. PASI score improvements from baseline to weeks 2, 4 and 6 were evaluated to determine the optimal threshold for predicting subsequent PASI responses at week 12.

Results

Early clinical improvement in disease symptoms at weeks 4 and 6 was predictive of ≥ 75% improvement in PASI score (PASI 75) at week 12 with ≥ 90% predictability. A 40–50% improvement in PASI (PASI 40 to PASI 50) from baseline to weeks 4 and 6 was the optimum range for predicting PASI 75 response at week 12. For all doses combined, achieving PASI 40 at week 4 or week 6 was associated with high negative predictive values (NPVs) (80% and 95%, respectively) and positive predictive values (PPVs) (89% and 84%, respectively). For all doses combined, achieving PASI 50 at week 4 or week 6 was associated with NPVs of 71% and 89% and PPVs of 94% and 89%, respectively. Sensitivity analysis with the high-dose group (75 and 150 mg) results confirmed these findings.

Conclusions

Early clinical responses (and nonresponse) may help predict later clinical responses in patients treated with ixekizumab.