Dolores Ochoa

Genetics of Psoriasis and Pharmacogenetics of Biological Drugs

Psoriasis is a chronic inflammatory disease of the skin. The causes of psoriasis are unknown, although family and twin studies have shown genetic factors to play a key role in its development. The many genes associated with psoriasis and the immune response include TNFα, IL23, and IL12. Advances in knowledge of the pathogenesis of psoriasis have enabled the development of new drugs that target cytokines (e.g., etanercept, adalimumab, and infliximab, which target TNFα, and ustekinumab, which targets the p40 subunit of IL23 and IL12). These drugs have improved the safety and efficacy of treatment in comparison with previous therapies. However, not all patients respond equally to treatment, possibly owing to interindividual genetic variability. In this review, we describe the genes associated with psoriasis and the immune response, the biological drugs used to treat chronic severe plaque psoriasis, new drugs in phase II and III trials, and current knowledge on the implications of pharmacogenomics in predicting response to these treatments.

Effects of CYP2D6 Genotype on the Pharmacokinetics, Pharmacodynamics, and Safety of Risperidone in Healthy Volunteers

The objective of this study was to analyze the relationship between CYP2D6 genotype and pharmacokinetics and pharmacodynamics of risperidone. Seventy-one healthy volunteers (36 women and 35 men) received a 1-mg single oral dose of risperidone. Six major CYP2D6 polymorphisms (CYP2D6*3, *4, *5, *6, *7, and *9) and the duplication were detected. Subjects were classified into 4 phenotypic groups: 6 ultrarapid (UMs), 34 extensive (EMs), 25 intermediate (IMs), and 6 poor metabolizers (PMs). There was a clear relationship between the number of active alleles and the pharmacokinetic parameters for risperidone and 9-hydroxyrisperidone, but there were no differences for total active moiety. Area under the curve and half-life of risperidone were significantly higher in PMs and IMs compared with EMs and UMs, which showed higher area under the curve of 9-hydroxyrisperidone. Risperidone produced a small decrease in blood pressure, a mild increase in QTc and a quick increase in prolactin, without significant differences between groups. Surprisingly, the incidence of adverse reactions was lower in PMs (50%) than in other subjects (78%). In conclusion, metabolism of risperidone depends on the number of active CYP2D6 alleles. So, PM subjects show higher concentrations of risperidone and very low concentrations of 9-hydroxyrisperidone. On the contrary, EM and UM subjects show low concentrations of risperidone and high concentrations of 9-hydroxyrisperidone. However, no major pharmacodynamic differences are observed between CYP2D6 genotypes, presumably because of the similar pharmacological activity of parent drug and metabolite.

DRD2 Taq1A polymorphism modulates prolactin secretion induced by atypical antipsychotics in healthy volunteers.

Hyperprolactinemia mediated by antagonism of dopaminergic neurotransmission in the pituitary gland is a common adverse effect of antipsychotics. Recent studies have suggested that polymorphisms of dopamine receptors can affect the therapeutic response to antipsychotics. Thus, our aim was to evaluate whether 2 such polymorphisms (DRD2 Taq1A and DRD3 Ser9Gly) modulate prolactin release in healthy volunteers (n = 119) receiving a single dose of quetiapine (25 mg, n = 26), olanzapine (5 mg, n = 57), or risperidone (1 mg, n = 36). The increases in maximum concentration and in area under the curve were calculated from plasma prolactin levels after subtraction of pretreatment levels. Multiple regression analyses revealed that prolactin increases in maximum concentration and in area under the curve depended on drug (quetiapine < olanzapine < risperidone; P < 0.001), sex (women > men; P < 0.001), and Taq1A polymorphism (A1+ > A2/A2; P < 0.05). Analysis of the individual drugs revealed that prolactin secretion was modulated by sex and Taq1A polymorphism in olanzapine and risperidone (P < 0.05); however, these factors were not linked to prolactin secretion in quetiapine.

The polymorphism rs763780 in the IL-17F gene is associated with response to biological drugs in patients with psoriasis

Psoriasis improves when IL-17 is blocked. Anti-TNF drugs reduce the IL-17 signaling pathway, and anti-IL-17 drugs are being developed to treat moderate-to-severe psoriasis. We analyzed three SNPs in IL-17A (rs2275913 and rs10484879) and IL-17F (rs763780) to look for an association with psoriasis and/or with response to anti-TNF drugs or ustekinumab. We included 197 healthy controls and 194 patients with moderate-to-severe psoriasis. The results of the univariate analysis showed an association between rs10484879 and psoriasis, although this relationship disappeared after adjustment for HLA-C (rs12191877). We also found an association between rs763780 (IL-17F) and response to ustekinumab (n = 70) and infliximab (n = 37) at 3 and 6 months and an association between rs763780 and the response to adalimumab at 6 months (n = 67).

Evaluation of the Relationship between Sex, Polymorphisms in CYP2C8 and CYP2C9, and Pharmacokinetics of Angiotensin Receptor Blockers

Angiotensin II receptor blockers (ARBs) are used to treat hypertension. Most ARBs are metabolized by CYP2C9. The aim of this study is to evaluate the possible association between sex, polymorphisms in the CYP2C8 and CYP2C9 genes, and the pharmacokinetics of losartan, valsartan, candesartan, and telmisartan. The study population comprised 246 healthy volunteers from seven single-dose clinical trials: 64 from two candesartan studies, 43 from a telmisartan study, 36 from a losartan study, and 103 from three valsartan studies. DNA was extracted from blood samples and single-nucleotide polymorphisms in the CYP2C8 (CYP2C8*2, CYP2C8*3, CYP2C8*4, CYP2C8*5) and CYP2C9 (CYP2C9*2, CYP2C9*3) genes were evaluated using real-time polymerase chain reaction. Sex only affected telmisartan pharmacokinetics, since women showed a higher telmisartan Cmax than men (590.5 ± 75.8 ng/ml versus 282.1 ± 30.8 ng/ml; P ≤ 0.01). CYP2C9 variants were associated only with losartan pharmacokinetics: the half-life of losartan was higher in CYP2C9*3 allele carriers (3.1 ± 0.4 hours) than in volunteers with the wild-type genotype (2.3 ± 0.1 hours) (P ≤ 0.05). CYP2C8 polymorphisms were associated only with valsartan pharmacokinetics, since *2 allele carriers showed faster clearance (1.07 ± 0.57 l/h·kg) than those with the wild-type genotype (0.48 ± 0.72 l/h·kg; P ≤ 0.01) and carriers of the *3 allele (0.35 ± 0.49 l/h·kg; P ≤ 0.001). These results suggest that genotypes for CYP2C9 and CYP2C8 are relevant to the pharmacokinetics of losartan and valsartan, respectively, but not the pharmacokinetics of candesartan or telmisartan.

Effect of polymorphisms on the pharmacokinetics, pharmacodynamics, and safety of risperidone in healthy volunteers

To identify genetic markers capable of predicting the pharmacokinetics, pharmacodynamics, and adverse effects of risperidone.

Pharmacogenetics of topical and systemic treatment of psoriasis

Psoriasis is a chronic inflammatory skin disease. The cause of psoriasis is unknown, although genetics may play a key role in its development. Treatment of the disease varies with severity. Topical drugs, such as corticosteroids, coal tar, retinoids and vitamin D analogs, are commonly used to treat mild psoriasis. Phototherapy and systemic drugs, such as calcineurin inhibitors, methotrexate, acitretin and biological drugs, are usually used to treat moderate-to-severe psoriasis. Not all patients respond well to treatment, and some can develop severe adverse effects. Interindividual differences in several genes may explain this variation in response to treatment. Pharmacogenetics and pharmacogenomics can facilitate more personalized medicine and prevent the adverse effects associated with treatment.

Polymorphisms influencing olanzapine metabolism and adverse effects in healthy subjects

The pharmacokinetics of olanzapine and response to treatment could be affected by polymorphisms in genes coding for drug‐metabolizing enzymes, transporters, or receptors. The aim of this study was to identify genetic markers predictive of pharmacokinetics, pharmacodynamics, and adverse effects of olanzapine.

Evaluation of the relationship between polymorphisms in CYP2C8 and CYP2C9 and the pharmacokinetics of celecoxib.

Celecoxib is metabolized by enzymes of the cytochrome P450 (CYP450) superfamily, mainly CYP2C9 and CYP3A4. Polymorphisms in the CYP2C9 gene have been associated with decreased enzyme activity and alteration of celecoxib pharmacokinetic parameters. However, literature reports are limited, and some results are contradictory. We enrolled 24 healthy volunteers in a single‐dose replicated crossover trial with celecoxib 200 mg. We evaluated the association between single‐nucleotide polymorphisms in the CYP2C8 and CYP2C9 genes (CYP2C8*2, CYP2C8*3, CYP2C8*4, CYP2C9*2, and CYP2C9*3) of these individuals and the pharmacokinetic parameters of celecoxib. Subjects carrying CYP2C9*1/*3 and CYP2C9*3/*3 had a higher AUC (2‐ and 7.7‐fold, respectively) and Cmax (1.5‐ and 1.8‐fold, respectively) and lower clearance (2.3‐ and 10‐fold, respectively) than those carrying CYP2C9*1/*1. Half‐life was 2.7‐fold higher in subjects with CYP2C9*3/*3 than in those with the wild type but not in those with CYP2C9*1/*3. We did not find any significant effect of gender or CYP2C8 polymorphisms on the pharmacokinetics of celecoxib. In conclusion, the recommended dose of celecoxib should be decreased in CYP2C9*3 carriers, especially in homozygous subjects.

Paradoxical psoriasiform reactions to anti-TNFα drugs are associated with genetic polymorphisms in patients with psoriasis.

Paradoxical psoriasiform reactions to anti-tumor necrosis factor α (TNFα) agents have been described. We aimed to study the association between these reactions and polymorphisms in genes previously associated with psoriasis or other autoimmune diseases. A total of 161 patients with plaque-type psoriasis treated with anti-TNFα drugs were genotyped for 173 single-nucleotide polymorphisms (SNPs) using the Illumina Veracode genotyping platform. Among the 161 patients, 25 patients developed a paradoxical psoriasiform reaction consisting of a change in morphology, mostly to guttate psoriasis (88%). These lesions developed 9.20±13.52 months after initiating treatment, mainly with etanercept (72%). Psoriasis type and a Psoriasis Area and Severity Index (PASI) 75 response to treatment were not associated with lesions. Multivariate logistic regression revealed that five SNPs (rs11209026 in IL23R, rs10782001 in FBXL19, rs3087243 in CTLA4, rs651630 in SLC12A8 and rs1800453 in TAP1) were associated with paradoxical reactions. This is the first study to show an association between genetic polymorphisms and paradoxical reactions in patients with psoriasis treated with anti-TNFα drugs.The Pharmacogenomics Journal advance online publication, 21 July 2015; doi:10.1038/tpj.2015.53