Treatment of Nail Psoriasis With TNF-α or IL12/23 Inhibitors

Psoriasis is a common skin disease with a significant negative impact on health as well as quality of life and cumulative life course.^1,2,3 In addition to systemic co-morbidities and arthritis, the disease may also affect the nails, where it poses particular problems to patients and physicians.⁴ It has been estimated that 50% of all psoriasis patients have nail psoriasis, and that 4 to 5 patients with nail psoriasis have psoriatic arthritis (PsA).⁵ It is speculated that the close proximity between the enthesitis of the extensor tendons of the fingers and the nail apparatus, provide an anatomical link between PsA associated enthesitis and nail changes.⁶ It may furthermore be estimated that approximately 10% of psoriasis patients have nail changes without concomitant PsA, most often associated with severe cutaneous involvement.

The nail abnormalities range from discrete pitting of the dorsal nail plate to severe nail dystrophy, and while 90% of the affected patients have cosmetic problems from psoriatic nail changes, physical problems are not infrequent.⁵ In a large Dutch study, approximately half of the 1,728 interviewed patients reported to suffered from pain caused by nail changes, and similarly large groups of patients were hindered in their private or professional daily activities due to the nail changes.⁷ Nail involvement appears to significantly impair the patients' quality of life (QoL).^8,9

A number of treatments are available for nail psoriasis, although the outcome is often unsatisfactory. Furthermore, only lower levels of evidence are generally available, and patients and physicians therefore often experience a need for intensified therapy. Although nail involvement is by nature limited, providing only low scores in, for example, PASI scores, impaired QoL may indicate the need for treatment with TNF-α inhibitors and other biologicals according to guidelines. We have therefore reviewed the effect of TNF-α inhibitors and other biologicals on nail psoriasis.

The Nail Psoriasis Severity Index (NAPSI) is an established score of nail pathology in psoriasis which allows direct comparisons of results, within the limits provided by any clinical score.¹⁰ Simple numerical scores are given for nail-bed and nail-matrix features (Table 2). It may be applied as a total score (combined scores of all nails) or an individual nail score. The interclass correlation coefficients (ICC) for total NAPSI score and nail score have been shown to be 0.781 and 0.649, indicating good agreement.¹¹ Randomized, controlled trials of psoriasis treatment with adalimumab, alefacept, briakinumab, etanercept, golimumab, or ustekinumab were retrieved from Pubmed and Web of Science and abstracts scanned for references to nails or general physical symptoms. If nails were not specifically mentioned, the manuscripts were scanned for the words: NAPSI or nail, and only those containing references to the nail score used for further analysis. Only data from fingernails were included in the review, because of their greater impact on patients and the lower prevalence of onychomycosis on the fingernails. In addition fingernails grow faster than toenails, thereby making any therapeutic effect evident earlier.

Adalimumab
Adalimumab is a human monoclonal antibody against TNF-α, and has been studied in several randomized controlled trials in patients with psoriasis or psoriatic arthritis, although only one RCT reports data on nail psoriasis. Adalimumab is most commonly administered subcutaneously with a loading dose of 80 mg followed by 40 mg every other week (e.o.w.) thereafter.

Open trials have been published. In a trial of 21 psoriasis patients, Rigopoulos et al. reported significant improvements in NAPSI scores over a 24-week observation period.¹² Patients with cutaneous psoriasis only improved their score from 10.57±3.21 at baseline to 1.57±0.20 at week 24, while patients with predominant