Efficacy, tolerability, and pharmacodynamics of apremilast in recalcitrant plaque psoriasis: a phase II open-label...

Apremilast, a small molecule specific inhibitor of phosphodiesterase 4, works intracellularly to modulate pro-inflammatory and anti-inflammatory mediators. This phase II, multicenter, open-label study evaluated the efficacy, tolerability, and pharmacodynamics of apremilast in patients with recalcitrant plaque psoriasis.

This multicenter, open-label study comprised four phases: pre-treatment (≤35 days), treatment (12 weeks), extension (12 weeks), and observational follow-up (4 weeks). Patients with recalcitrant plaque psoriasis received apremilast 20 mg BID for 12 weeks. Responders (≥75% improvement in Psoriasis Area and Severity Index [PASI-75]) continued treatment and non-responders (< PASI-75) were titrated to apremilast 30 mg BID through week 24. Efficacy assessments included change in static Physician's Global Assessment, PASI, and body surface area, and proportion of patients achieving PASI-50, PASI-75, and PASI-90. Other assessments included adverse events, lesional skin biopsies to assess changes in epidermal thickness, and immunohistochemistry to assess changes in peripheral blood subsets.

A total of 30 patients were enrolled. At week 12, 67% of patients had a ≥1-point improvement in static Physician's Global Assessment, meeting treatment effect criterion. Mean percent decreases (improvements) from baseline were -59% for PASI score and -53% for body surface area. Most adverse events were mild. Median reduction in epidermal thickness was 34% at week 12 (P=0.083); five patients showed absence of keratin 16. Significant reductions in CD11c, CD3, and CD56 indicate that apremilast reduced myeloid dendritic cell, T-cell, and NK-cell or NK-T-cell infiltration into the epidermis and dermis. Reduced inflammatory leukocytes, with a pattern of broad, partial inhibition, suggested reduced IL-23/Th17 and Th22 response pathways.

These results confirm apremilast's biological and clinical activity and support ongoing studies in psoriasis. Clinicaltrials.gov Identifier: NCT00521339.