HLA-C*06:02 genotype is a predictive biomarker of biologic treatment response in psoriasis.

BACKGROUND: Biologic therapies can be highly effective for the treatment of severe psoriasis, but response for individual patients can vary according to drug. Predictive biomarkers to guide treatment selection could improve patient outcomes and treatment cost-effectiveness. OBJECTIVE: We sought to test whether HLA-C*06:02, the primary genetic susceptibility allele for psoriasis, predisposes patients to respond differently to the 2 most commonly prescribed biologics for psoriasis: adalimumab (anti-TNF-α) and ustekinumab (anti-IL-12/23). METHODS: This study uses a national psoriasis registry that includes longitudinal treatment and response observations and detailed clinical data. HLA alleles were imputed from genome-wide genotype data for 1326 patients for whom 90% reduction in Psoriasis Area and Severity Index score (PASI90) response status was observed after 3, 6, or 12 months of treatment. We developed regression models of PASI90 response, examining the interaction between HLA-C*06:02 and drug type (adalimumab or ustekinumab) while accounting for potentially confounding clinical variables. RESULTS: HLA-C*06:02-negative patients were significantly more likely to respond to adalimumab than ustekinumab at all time points (most strongly at 6 months: odds ratio [OR], 2.95; P = 5.85 × 10-7), and the difference was greater in HLA-C*06:02-negative patients with psoriatic arthritis (OR, 5.98; P = 6.89 × 10-5). Biologic-naive patients who were HLA-C*06:02 positive and psoriatic arthritis negative demonstrated significantly poorer response to adalimumab at 12 months (OR, 0.31; P = 3.42 × 10-4). Results from HLA-wide analyses were consistent with HLA-C*06:02 itself being the primary effect allele. We found no evidence for genetic interaction between HLA-C*06:02 and ERAP1. CONCLUSION: This large observational study suggests that reference to HLA-C*06:02 status could offer substantial clinical benefit when selecting treatments for severe psoriasis.

Assessing the validity and response distribution of the simplified psoriasis index in patients receiving phototherapy.

BACKGROUND/OBJECTIVES: The simplified psoriasis index (SPI) is a three-part multidimensional tool incorporating disease severity, psychosocial impact and historical course completed by the health-care professional (professional SPI, [proSPI]) or the patient (self-assessment SPI, [saSPI]). We aimed to assess the validity and response distribution of proSPI and saSPI in patients with psoriasis undergoing phototherapy. METHODS: The validity and response distribution of SPI was assessed by recording saSPI and proSPI in patients with psoriasis before and after a course of phototherapy. Recruitment ended once 100 complete data sets were available for analysis. RESULTS: Altogether 52 of the 100 patients evaluated were male and most (93) underwent narrowband UVB phototherapy. There was a close correlation between the proSPI-current severity score (proSPI-s) with the psoriasis area and severity index (PASI) score (r = 0.76, r = 0.86) before and after treatment, respectively. Although pretreatment correlation between the saSPI-current severity score (saSPI-s) and PASI was weak (r = 0.39), a more close correlation was noted at the end of treatment (r = 0.50). A moderate correlation was observed between the SPI-psychosocial impact score (SPI-p) and the dermatology life quality index (DLQI), both before and after phototherapy (r = 0.64, r = 0.73). The SPI had wide response distributions in all three domains. CONCLUSIONS: Both versions of SPI demonstrated wide response distributions and the proSPI-s in particular was shown to have good validity with PASI.

Use of Phototherapy in Children.

BACKGROUND: Phototherapy is a well-recognized treatment in adults and children. Previous articles have reported success in treating recalcitrant skin disorders such as atopic dermatitis (AD), psoriasis, pityriasis lichenoides chronica, and vitiligo in children. METHODS: This was a retrospective review over an 18-month period from June 2012 to December 2013 of all children receiving phototherapy in a tertiary pediatric dermatology center. RESULTS: Seventy-five patients 3 to 17 years of age (mean 10.6 years; 35 male, 40 female) were included. Forty-eight (64%) patients had AD and 21 (28%) had psoriasis. Seventy received narrowband ultraviolet B (NBUVB) treatment and five received hand and foot psoralen and ultraviolet A (PUVA) treatment. All patients with AD were treated with NBUVB and four (8.3%) were also treated with hand PUVA. After phototherapy, 76% had documented clear to almost clear skin. At the 12-month follow-up, 52% of the patients with AD remained clear. All 21 patients with psoriasis underwent NBUVB phototherapy. The clearance rate after phototherapy was 86%. At the 12-month follow-up, 43% of the patients with psoriasis remained clear. CONCLUSION: Phototherapy can reduce disease burden in individuals with severe AD and psoriasis and should be considered as a second-line therapy if standard topical regimens are unsuccessful.

A 3-month-old with a blistering plaque.

Cutaneous Mastocytosis is not an uncommon condition in the pediatric setting. The eruption can have multiple clinical presentations. We present a case of a 3-month-old child with a solitary mastocytoma who was initially diagnosed with recurrent bullous impetigo. Solitary mastocytoma can present as a blister. Although bullous impetigo is a common diagnosis in children and it would be tempting to make that diagnosis in the presence of a positive skin swab culture, clinicians always have to be mindful of secondary impetiginization of another primary skin disease process.

Using Real-World Data to Guide Ustekinumab Dosing Strategies for Psoriasis: A Prospective Pharmacokinetic-Pharmacodynamic Study.

Variation in response to biologic therapy for inflammatory diseases, such as psoriasis, is partly driven by variation in drug exposure. Real-world psoriasis data were used to develop a pharmacokinetic/pharmacodynamic (PK/PD) model for the first-line therapeutic antibody ustekinumab. The impact of differing dosing strategies on response was explored. Data were collected from a UK prospective multicenter observational cohort (491 patients on ustekinumab monotherapy, drug levels, and anti-drug antibody measurements on 797 serum samples, 1,590 measurements of Psoriasis Area Severity Index (PASI)). Ustekinumab PKs were described with a linear one-compartment model. A maximum effect (Emax ) model inhibited progression of psoriatic skin lesions in the turnover PD mechanism describing PASI evolution while on treatment. A mixture model on half-maximal effective concentration identified a potential nonresponder group, with simulations suggesting that, in future, the model could be incorporated into a Bayesian therapeutic drug monitoring "dashboard" to individualize dosing and improve treatment outcomes.

Association of Serum Ustekinumab Levels With Clinical Response in Psoriasis.

IMPORTANCE: High-cost biologic therapies have transformed the management of immune-mediated inflammatory diseases. To optimize outcomes and reduce costs, dose adjustment informed by measurement of circulating drug levels has been shown to be effective in various settings. However, limited evidence exists for this approach with the interleukin 12 and interleukin 23 inhibitor ustekinumab. OBJECTIVE: To evaluate clinical utility of therapeutic drug monitoring for ustekinumab in patients with psoriasis. DESIGN, SETTING, AND PARTICIPANTS: A prospective observational cohort of 491 adults with psoriasis was recruited to the multicenter Biomarkers of Systemic Treatment Outcomes in Psoriasis study within the British Association of Dermatologists Biologic and Immunomodulators Register from June 2009 to December 2017; samples from some patients were taken between 2009 and 2011 as part of a pilot study with the same inclusion criteria. EXPOSURE: Serum ustekinumab level measured at any point during the dosing cycle using an enzyme-linked immunosorbent assay. MAIN OUTCOMES AND MEASURES: Disease activity measured using the Psoriasis Area and Severity Index (PASI) score. Treatment response outcomes were PASI75 (75% reduction in PASI score from baseline [primary outcome]), PASI90 (90% reduction of PASI score from baseline), and absolute PASI score of 1.5 or less. RESULTS: A total of 491 patients (171 women and 320 men; mean [SD] age, 45.7 [12.8] years) had 1 or more serum samples (total, 853 samples obtained 0-56 weeks from start of treatment) and 1 or more PASI scores within the first year of treatment. Antidrug antibodies were detected in only 17 of 490 patients (3.5%). Early measured drug levels (1-12 weeks after starting treatment) were associated with PASI75 response 6 months after starting treatment (odds ratio, 1.38; 95% CI, 1.11-1.71) when adjusted for baseline PASI score, age, and ustekinumab dose. However, this finding was not consistent across the other PASI outcomes (PASI90 and PASI score of ≤1.5). CONCLUSIONS AND RELEVANCE: This real-world study provides evidence that measurement of early serum ustekinumab levels could be useful to direct the treatment strategy for psoriasis. Adequate drug exposure early in the treatment cycle may be particularly important in determining clinical outcome.