Predicting treatment response in psoriasis using serum levels of adalimumab and etanercept: a single-centre, cohort study

BACKGROUND

A substantial proportion of patients with psoriasis do not respond, or lose initial response to tumour necrosis factor-α antagonists. One possible mechanism relates to subtherapeutic drug levels due to an immunogenic antibody response.

OBJECTIVES

To investigate the association between serum adalimumab and etanercept levels, antidrug antibody levels and clinical response in a cohort of patients with psoriasis using a commercially available enzyme-linked immunoassay.

METHODS

In a single-centre cohort of 56 adults with chronic plaque psoriasis initiated on adalimumab or etanercept monotherapy between 2009 and 2011, drug and antidrug antibody levels were measured at the patients' routine clinic reviews (4, 12 and 24 weeks of treatment and the last available observation). Patients' responses at 6 months were stratified into responders [75% reduction in Psoriasis Area and Severity Index from baseline (PASI 75) or Physician's Global Assessment score of 'clear' or 'nearly clear'] and nonresponders (failure to achieve PASI 50).

RESULTS

After 4 weeks, adalimumab levels were significantly higher in responders compared with nonresponders (P = 0·003) and these higher levels were sustained at 12 and 24 weeks. Anti adalimumab antibodies were detected in 25% of nonresponders (two of eight patients, average 22·5 weeks' follow-up) and none of the responders (n = 23, average 26·1 weeks' follow-up). There was no significant association between etanercept levels and clinical response at 4 weeks (P = 0·317) and no antietanercept antibodies were detected. Lack of serum trough levels may have resulted in underestimation of the prevalence of antidrug antibodies.

CONCLUSIONS

Early adalimumab drug level monitoring at 4 weeks may be useful in predicting treatment response and potentially reduce drug exposure (and associated cost) with earlier review of treatment in those with low levels. No conclusions about the value of etanercept drug monitoring can be made due to the paucity of data. Larger studies are now required to assess the clinical utility and cost-effectiveness of these assays in personalizing therapy in psoriasis.

Demyelination during tumour necrosis factor antagonist therapy for psoriasis: a case report and review of the literature

Central nervous system (CNS) demyelination in a patient receiving tumour necrosis factor alpha (TNF-α) antagonist therapy in our practice prompted a search of the literature to assess the evidence for a causal relationship between TNF antagonist therapy and demyelination. We summarise clinical data extracted on 65 reported cases of CNS demyelination in patients receiving TNF antagonist therapy and show that the data are consistent with a drug-related aetiology given the temporal relationship between TNF antagonist initiation and symptoms, de-challenge-re-challenge phenomenon and the later age of disease onset compared with sporadic multiple sclerosis. Research on TNF signalling pathways also suggests a plausible causative role of TNF antagonist therapy in demyelination. However to date, controlled trial and pharmacovigilance data do not show an increased risk of demyelination in patients receiving TNF antagonist therapy. These data may be underpowered to exclude such a risk and pooled, collaborative data from multiple registries are warranted. Given the uncertainty in this area, clinicians should adhere to existing clinical guidance advising avoidance of TNF antagonist therapy in patients with a personal or family history of demyelination, and ensure all suitable patients are enrolled in long term safety registries in countries where these are established.