Palmoplantar Pustulosis (PPP) Study

Palmoplantar pustulosis (PPP) is a rare, debilitating, chronic inflammatory skin disease that affects the hands and feet. Clinical, immunological, and genetic findings suggest a pathogenic role for interleukin (IL)-1.

A group of researchers conducted a study to determine whether anakinra (an IL-1 receptor antagonist) delivers therapeutic benefit in Palmoplantar pustulosis (PPP).

This was a randomized (1:1), double-blind, two-staged, adaptive, UK multicentre, placebo-controlled trial [ISCRTN13127147 (registered 1 August 2016); EudraCT number: 2015-003600-23 (registered 1 April 2016)]. Participants had a diagnosis of PPP (> 6 months) requiring systemic therapy. Treatment was 8 weeks of anakinra or placebo via daily, self-administered subcutaneous injections. The primary outcome was the Palmoplantar Pustulosis Psoriasis Area and Severity Index (PPPASI) at 8 weeks.

Results of the Study

• A total of 374 patients were screened; 64 were enrolled (31 in the anakinra arm and 33 in the placebo arm) with a mean (SD) baseline PPPASI of 17.8 (10.5) and a PPP investigator's global assessment of severe (50%) or moderate (50%).
• The baseline adjusted mean difference in PPPASI favoured anakinra but did not demonstrate superiority in the intention-to-treat analysis [–1.65, 95% confidence interval (CI) –4.77 to 1.47; P = 0.30].
• Similarly, secondary objective measures, including fresh pustule count (2.94, 95% CI –26.44 to 32.33; favouring anakinra), total pustule count (–30.08, 95% CI –83.20 to 23.05; favouring placebo) and patient-reported outcomes, did not show superiority of anakinra.
• When modelling the impact of adherence, the PPPASI complier average causal effect for an individual who received ≥ 90% of the total treatment (48% in the anakinra group) was –3.80 (95% CI –10.76 to 3.16; P = 0.285).
• No serious adverse events occurred.

Thus, no evidence for the superiority of anakinra was found. IL-1 blockade is not a useful intervention for the treatment of PPP.

Reference

Anakinra for palmoplantar pustulosis: results from a randomized, double-blind, multicentre, two-staged, adaptive placebo-controlled trial (APRICOT)* by S. Cro, et al. published in the British Journal of Dermatology.

Read the full study