Psoriatic arthritis: genetic susceptibility and pharmacogenetics

Do genetics contribute to TNF inhibitor response prediction in Psoriatic Arthritis?

Psoriatic arthritis (PsA) is a heterogeneous chronic musculoskeletal disease, affecting up to 30% of people with psoriasis. Research into PsA pathogenesis has led to the development of targeted therapies, including Tumor Necrosis Factor inhibitors (TNF-i). Good response is only achieved by ~60% of patients leading to 'trial and error' drug management approaches, adverse reactions and increasing healthcare costs. Robust and well-validated biomarker identification, and subsequent development of sensitive and specific assays, would facilitate the implementation of a stratified approach into clinical care. This review will summarise potential genetic biomarkers for TNF-i (adalimumab, etanercept and infliximab) response that have been reported to date. It will also comment upon the importance of managing clinical confounders when understanding drug response prediction. Variants in multiple gene regions including TNF-A, FCGR2A, TNFAIP3, TNFR1/TNFR1A/TNFRSF1A, TRAIL-R1/TNFRSF10A, FCGR3A have been reported to correlate with TNF-i response at various levels of statistical significance in patients with PsA. However, results were often from heterogenous and underpowered cohorts and none are currently implemented into clinical practice. External validation of genetic biomarkers in large, well-documented cohorts is required, and assessment of the predictive value of combining multiple genetic biomarkers with clinical measures is essential to clinically embed pharmacogenomics into PsA drug management.

Comorbid conditions in psoriasis - Higher frequency in females: A prospective study

Aim:

To study the association of obesity, diabetes, hypertension, and abnormal lipid profile in women above 40 years of age with psoriasis.

Materials and Methods:

Two hundred consecutive female patients with psoriasis attending private clinics were included. Complete general, systemic, and dermatological examinations were performed. Blood pressure, blood sugar, and lipid profile were recorded in all patients and the findings analyzed.

Results:

Of 200 patients, 45 were obese. Eighty-eight patients had diabetes mellitus and 29 had dyslipidemia of whom 13 and 18, respectively, were detected at the time of enrolment. All 25 patients with systemic hypertension were on treatment. A total of 177 (88.5%) patients had one or more comorbid conditions. This frequency is much higher when compared to other Indian studies where the sample included patients of both sexes.

[Study of genetic polymorphisms in the tumor necrosis factor α promoter region in Spanish patients with psoriasis]

BACKGROUND

Several studies have reported an association between tumor necrosis factor α (TNF-α) polymorphisms and inflammatory diseases such as psoriasis vulgaris and psoriatic arthritis, although the results vary according to the population studied. No studies have been performed in the Spanish population.

OBJECTIVE

To analyze the polymorphisms of the promoter region of the TNF-α gene in patients with moderate to severe psorasis and to identify potential differences in genotype compared to a group of healthy volunteers.

MATERIAL AND METHODS

Eighty-nine patients with moderate to severe psoriasis and 76 healthy controls with no personal or family history of psoriasis were selected. Polymorphisms of the TNF-α promoter region of both groups were genotyped.

RESULTS

We observed a higher prevalence of the genotype with both wild-type alleles at positions -238 (GG genotype, 86.5% vs 70.4%, respectively) and -1031 (TT genotype, 80.2% vs 45.8%, respectively) in patients compared to the healthy control group. The differences at positions -308 and -857 were not significant.

CONCLUSION

There are differences in polymorphisms at positions -238 and -1031 in patients with moderate to severe psoriasis compared to healthy volunteers. This observation provides further support for the importance of the part that TNF-α plays in the pathophysiology of this disease.

New interleukin-23 pathway inhibitors in dermatology: ustekinumab, briakinumab, and secukinumab

Interleukin (IL)-23 is an important regulator of T helper-17 lymphocytes, which influence the cutaneous immune system by production of IL-17 and several other proinflammatory cytokines. This pathway has been recently linked to the pathogenesis of psoriasis and numerous other skin diseases. A newly developed biologic drug, ustekinumab (CNTO-1275), which targets the p40 subunit of IL-12 and IL-23, was approved by the US FDA and the European Medicines Agency in 2009 for the treatment of moderate to severe psoriasis. Administered as subcutaneous injections of 45 mg at weeks 0 and 4, and then every 12 weeks, ustekinumab produces a 75% improvement in the Psoriasis Area and Severity Index (PASI) in 66.4-75.7% of patients and a Dermatology Life Quality Index (DLQI) score of 0 or 1 in 55-56% of patients after 12 weeks of therapy. A recent clinical trial also indicates the possible efficacy of ustekinumab in psoriatic arthritis. The proportion of patients who had at least one adverse event through 12 weeks in clinical studies was 51.6-57.6% in the ustekinumab group and 50.4% in the placebo group. Serious adverse events were observed in 1.4-1.6% of patients treated with ustekinumab and in 1.4% of patients receiving placebo. Injection-site reactions occurred in 1-2% of patients and 5% of patients developed anti-ustekinumab antibodies. Further studies are needed to evaluate the long-term efficacy and safety of ustekinumab. Another biologic drug that targets the same molecules, briakinumab (ABT-874), has recently had its approval application withdrawn in the US and Europe to conduct further analysis and clinical trials. The company plans resubmission at a later date. Other IL-23 pathway inhibitors in the pipeline include anti-p19 monoclonal antibody and apilimod (STA-5326), which interfere with IL-23 activity, as well as secukinumab (AIN-457), LY-2439821, and AMG-827, which exhibit their activity at other targets of the IL-23 pathway.

Comorbidities associated with psoriasis: an experience from the Middle East

Recent studies suggest that psoriasis patients have higher rates of comorbidities. We sought to determine the prevalence of comorbidities and co-medications in our psoriasis patients. We conducted case-control study in 1835 patients with psoriasis vulgaris and age- and gender-matched cohort without psoriasis. Patients were examined for clinical characteristics of psoriasis, PASI scores, and data of age, sex, body mass index (BMI), smoking status, comorbidities, and co-medications were analysed for both patients and controls. We identified 1661 (92.8%) patients with mild to moderate psoriasis (PASI < 10) and 129 patient's (7.03%) with severe psoriasis (PASI > 10). Patients with psoriasis were more likely to be current smokers (51.34% vs 32.51% controls). Respective prevalence rates of risk factors in those with mild-moderate psoriasis, severe psoriasis, and controls were as follows: inflammatory arthritis (20%, 31% and 10.68%); coronary heart disease (4.1%, 8.35% and 1.42%); obesity (BM1) (32.5%, 41% and 17%); diabetes mellitus type II (37.4%, 41% and 16%); hypertension (32%, 40.3% and 11.55%); dyslipidemia (14.1%, 22.48% and 4.96%); metabolic syndrome (16%, 26.35% and 6.76%); chronic obstructive pulmonary disease (COPD) (5.36%, 6.98% and 4.03%); cancer (0.3%, 1.55% and 0.16%). They had a higher odds of inflammatory arthritis, coronary heart disease, obesity, diabetes mellitus II, hypertension, dyslipidemia, and metabolic syndrome. They were receiving significantly wider varieties of drugs. Which most commonly included antidiabetic drugs, antihypertensives, and hypolipidemic drugs.

Folate Pathway Enzyme Gene Polymorphisms and the Efficacy and Toxicity of Methotrexate in Psoriatic Arthritis

Objective.

To determine the association between folate pathway gene polymorphisms and the effectiveness, toxicity, and drug survival of methotrexate (MTX) in psoriatic arthritis (PsA).

Methods.

Data were obtained from a longitudinal cohort of PsA patients evaluated according to a standard protocol. Data on duration of drug therapy, dose, side effects, and reasons for discontinuation are systematically recorded. Patients treated with MTX after clinic admission who had ≥ 3 swollen joints prior to initiating MTX therapy were selected for evaluation of effectiveness. Response to MTX treatment was assessed at 6 months. Data from all patients treated in the clinic with MTX were used in evaluation of toxicity and drug survival. The following single-nucleotide polymorphisms (SNP) were measured using the Sequenom platform: MTHFR 677C>T (rs1801133), MTHFR 1298A>C (rs1801131), DHFR −473T>C (rs1650697), DHFR 35289A>G (rs1232027), and RFC 80G>A (rs1051266). Fisher’s exact test, logistic regression, and Cox proportional hazard analyses were used to determine association.

Results.

Two hundred eighty-one patients were identified from the database. All patients were included in the analysis for side effects and drug survival, and 119 patients were included in the effectiveness analysis. The minor A allele of DHFR gene at +35289 was the only SNP demonstrating association with response to MTX therapy (OR 2.99, p = 0.02). Patients homozygous for the minor allele of MTHFR 677C/T (677TT) had more liver toxicity (Fisher exact test, p = 0.04).

Conclusion.

Polymorphisms of the DHFR gene may be associated with MTX efficacy. MTHFR 677TT may have a relationship with MTX-induced liver toxicity in PsA.