[Therapeutic vaccination for tumors and neurodegenerative diseases]. / Therapeutische Immunisierungen gegen Tumore und neurodegenerative Erkrankungen.

Therapeutic vaccines are intended for the treatment of established diseases by harnessing the patient's own immune system. In this article we discuss therapeutic areas that are of relevance for therapeutic vaccination, i.e., oncology and neurodegenerative diseases. Clinical and regulatory aspects related to the manufacture and clinical use of actively personalized cancer vaccines are thoroughly reviewed. This applies to the regulatory classification of genomic sequencing approaches to identify tumor-specific mutations, combination therapies with checkpoint inhibitors, clinical study designs, and the use of suitable adjuvants and drug substances. Huge amounts of data (big data) are increasingly being generated in the area of personalized therapies; we briefly address the impact and usability of big data in regulatory procedures.

Pharmacokinetic drug-drug interaction between ethinyl estradiol and gestodene, administered as a transdermal fertility control patch, and two CYP3A4 inhibitors and a CYP3A4 substrate.

Pharmacokinetic (PK) interactions between the cytochrome P450 3A4 (CYP3A4) pathway and transdermally administered ethinyl estradiol (EE) and gestodene (GSD) were investigated. This paper reports the findings of three open-label, intra-individual, one-way crossover, Phase I trials. In two studies, women used a novel contraceptive patch for 3 weeks during two 4-week study periods; in the second period, the CYP3A4 inhibitors erythromycin (Study 1) or ketoconazole (Study 2) were administered concurrently. In a third study, women received single doses of the CYP3A4 model substrate midazolam, alone and after 3 weeks of concurrent patch application. In each period, the EE/GSD patch (delivering low EE and GSD doses resulting in the same systemic exposure as a combined oral contraceptive containing 0.02 mg EE and 0.06 mg GSD) was applied once weekly for 3 weeks, with one patch-free week. Erythromycin, ketoconazole, and midazolam were administered orally. Main outcome measures were area under the curves (AUCs) and maximum plasma concentration (C max) of EE, and total and unbound GSD (Studies 1 and 2). AUC and C max of midazolam (Study 3). Co-administration of CYP3A4 inhibitors did not affect EE metabolism, and had only weak effects on the PK of total and unbound GSD. The patch had no clinically relevant effect on metabolism of the CYP3A4 substrate midazolam.

An anomalous haplotype distribution of the arrestin domain-containing 4 gene (ARRDC4) haplotypes in Caucasians.

Little was known about the sequence variability of the human Arrestin domain-containing 4 gene (ARRDC4). We sequenced its DNA from exon 2 to exon 8 in a sample of 92 Russians. Seven variants were identified; one of them has not been described yet. It causes an amino acid change from Thr to Met. Identified variants were genotyped in the complete sample of 253 unrelated men and women to analyze haplotype distribution. Fifteen haplotypes were inferred. Nine haplotypes had estimated frequencies > 1%. Ninety-five percent of all haplotypes were determined by five haplotype-tagging single nucleotide polymorphisms. Haplotypes form two clades. The two most common haplotypes cover 76% of all haplotypes. The certainty of the haplotype reconstruction does not depend on the haplotype-inferring algorithms, but is a result of the anomalous haplotype distribution of ARRDC4, which makes this gene a suitable candidate gene for haplotype association studies. Interestingly, there is a great evolutionary distance between the two most common haplotypes, which could suggest a more complicated coalescent process with either past gene flow, selections, or bottlenecks.

Vitamin D receptor haplotypes protect against development of colorectal cancer.

OBJECTIVE: We investigated the association of vitamin D receptor polymorphisms and colorectal cancer incidence in a Caucasian population. METHODS: Frequencies of the vitamin D receptor gene polymorphisms 23005G>A (CDX-2), 27823C>T (FokI), 60890G>A (BsmI), 61050G>A (Tru9I), 61888G>T (ApaI), and 61968T>C (TaqI) were determined in a series of 256 colorectal cancer patients and 256 patients without malignant disease (case-control study) using polymerase chain reaction and restriction fragment length polymorphism genotyping assays (PCR-RFLP). Haplotype analysis based on the six genetic loci was applied to the received genotypes. RESULTS: Pairwise linkage disequilibrium between BsmI, ApaI, TaqI, and Tru9I was confirmed (P < 0.001). Allele frequencies did not differ between the groups. There was no association between any single variant and colorectal cancer. However, haplotypes BsmI(G)#TaqI(C) and BsmI(A)#TaqI(T) were inversely associated with colorectal cancer incidence (P < 0.001), the odds being 15.0 times smaller [odds ratio (OR) 0.067; 95% confidence interval (CI), 0.016-0.284] and 5.3 times smaller (OR 0.188; 95% CI 0.077-0.461), respectively, compared with noncarriers. CONCLUSION: Our findings suggest that vitamin D receptor haplotypes BsmI(G)#TaqI(C) and BsmI(A)#TaqI(T) have a protective effect against colorectal cancer in Caucasians.

Effect of genetic polymorphisms in cytochrome p450 (CYP) 2C9 and CYP2C8 on the pharmacokinetics of oral antidiabetic drugs: clinical relevance.

Type 2 diabetes mellitus affects up to 8% of the adult population in Western countries. Treatment of this disease with oral antidiabetic drugs is characterised by considerable interindividual variability in pharmacokinetics, clinical efficacy and adverse effects. Genetic factors are known to contribute to individual differences in bioavailability, drug transport, metabolism and drug action. Only scarce data exist on the clinical implications of this genetic variability on adverse drug effects or clinical outcomes in patients taking oral antidiabetics. The polymorphic enzyme cytochrome P450 (CYP) 2C9 is the main enzyme catalysing the biotransformation of sulphonylureas. Total oral clearance of all studied sulphonylureas (tolbutamide, glibenclamide [glyburide], glimepiride, glipizide) was only about 20% in persons with the CYP2C9*3/*3 genotype compared with carriers of the wild-type genotype CYP2C9*1/*1, and clearance in the heterozygous carriers was between 50% and 80% of that of the wild-type genotypes. For reasons not completely known, the resulting differences in drug effects were much less pronounced. Nevertheless, CYP2C9 genotype-based dose adjustments may reduce the incidence of adverse effects. The magnitude of how doses might be adjusted can be derived from pharmacokinetic studies. The meglitinide-class drug nateglinide is metabolised by CYP2C9. According to the pharmacokinetic data, moderate dose adjustments based on CYP2C9 genotypes may help in reducing interindividual variability in the antihyperglycaemic effects of nateglinide. Repaglinide is metabolised by CYP2C8 and, according to clinical studies, CYP2C8*3 carriers had higher clearance than carriers of the wild-type genotypes; however, this was not consistent with in vitro data and therefore further studies are needed. CYP2C8*3 is closely linked with CYP2C9*2. CYP2C8 and CYP3A4 are the main enzymes catalysing biotransformation of the thiazolidinediones troglitazone and pioglitazone, whereas rosiglitazone is metabolised by CYP2C9 and CYP2C8. The biguanide metformin is not significantly metabolised but polymorphisms in the organic cation transporter (OCT) 1 and OCT2 may determine its pharmacokinetic variability. In conclusion, pharmacogenetic variability plays an important role in the pharmacokinetics of oral antidiabetic drugs; however, to date, the impact of this variability on clinical outcomes in patients is mostly unknown and prospective studies on the medical benefit of CYP genotyping are required.

MDR1 haplotypes derived from exons 21 and 26 do not affect the steady-state pharmacokinetics of tacrolimus in renal transplant patients.

AIM: This retrospective study investigated the influence of MDR1 haplotypes derived from the polymorphisms 2677G > T (exon 21) and 3435C > T (exon 26) on the pharmacokinetics of the immunosuppressant drug tacrolimus in 73 renal transplant patients. METHODS: Based on both variants of SNPs 2677 and 3435, four different haplotypes and eight different genotypes were identified in the study sample. Tacrolimus trough concentrations (C(0)) were compared between different SNP variants and genotypes, as well as between carriers and noncarriers of each haplotype. Additionally, CYP3A5 genotype (6956G > A) was determined. RESULTS: No significant differences were observed between groups. Differences in mean tacrolimus C(0) values between carriers and noncarriers of each haplotype ranged from -0.04 microg/litre (95% confidence interval: -0.53 to 0.60) to -23 microg/litre (-1.07 to 1.53). No association was found between CYP3A5*1/*3 genotype and tacrolimus Co concentractions. CONCLUSION: MDR1 haplotypes derived from the SNPs 2677G > T (exon 21) and 3435C > T (exon 26) do not influence the pharmacokinetics of tacrolimus in renal transplant patients.

Pharmacogenetics-based new therapeutic concepts.

Pharmacogenetics, one of the fields of clinical pharmacology, studies how genetic factors influence drug response. If hereditary traits are taken into account appropriately before starting drug treatment, the type of drug and its dosage can be tailored to the individual patient's needs. Pharmacogenetics adds a considerable amount of stringency to the doctor's therapeutic approach. Today, it is the relationship between dosage requirements and genetic variations in drug metabolizing enzymes like cytochrome P450 (CYP) 2D6 and CYP2C19, or in drug transporters like p-glycoprotein, that is substantiated best. A standard dose will bring about more adverse effects than usual if enzymatic activity is lacking or feeble. Sometimes, however, therapeutic response might be better due to higher concentrations: proton pump inhibitors for eradication of Helicobacter pylori are more efficacious in carriers of a deficient CYP2C19 variant. The drug's interaction with its target (e.g. receptor) also depends on genetic factors. In some cases genetic tests can help distinguish between responders and non-responders of a specific drug treatment. The first pharmacogenetic tests are already on the market.

Impact of the ultrarapid metabolizer genotype of cytochrome P450 2D6 on metoprolol pharmacokinetics and pharmacodynamics.

INTRODUCTION: In the treatment of heart failure and hypertension with metoprolol, ultrarapid metabolizers (UMs) may not achieve optimal target concentrations with recommended doses. We compared metoprolol pharmacokinetics and effects in UMs with extensive metabolizers (EMs) and with poor metabolizers (PM) as an additional reference group. METHODS: After a single dose of 100 mg metoprolol, pharmacokinetics, resting and exercise heart rate, and blood pressure were analyzed in relation to the CYP2D6 genotypes. We included 12 UMs, 13 EMs, and 4 PMs (healthy volunteers). CYP2D6 genotyping covered alleles *1 to *6 , *9 , *10 , *35 , and *41 and the duplications. beta 1 -Adrenergic receptor polymorphisms Ser49Gly and Arg389Gly were included as factors possibly interfering with the pharmacokinetic-pharmacodynamic relationship of metoprolol. RESULTS: Median total metoprolol clearance values were 31, 168, and 367 L/h and median maximum plasma concentrations were 260, 118, and 67 microg/L in PMs, EMs, and UMs, respectively ( P < .0001). At 6 hours after administration, metoprolol reduced the exercise heart rate by median values of 31, 21, and 18 beats/min in PMs, EMs, and UMs, respectively ( P = .01). Blood pressure did not significantly differ according to CYP2D6 . CONCLUSIONS: A linear relationship between the number of active CYP2D6 genes and metabolic clearance of metoprolol was found and the the median clearances differed by more than 10-fold between the PM and the UM groups. Metoprolol pharmacodynamics, however, differed only by less than 2-fold, and there was only a marginal difference in metoprolol efficacy on heart rate between the EM and UM groups.

MDR1 haplotypes do not affect the steady-state pharmacokinetics of cyclosporine in renal transplant patients.

This retrospective study investigated the impact of MDR1 haplotypes derived from the single-nucleotide polymorphisms (SNPs) 2677G>T (exon 21) and 3435C>T (exon 26) on the pharmacokinetics of cyclosporine in 98 renal transplant patients. Based on SNPs 2677 and 3435, four different haplotypes and nine different genotypes were identified in the study sample. Frequencies of SNPs, genotypes, and haplotypes were in agreement with previously reported values. Cyclosporine pharmacokinetics were characterized using a 2-hour AUC (AUC0-12), trough concentrations (C0), and blood concentrations 2 hours after cyclosporine administration (C2). No significant differences in dose-corrected AUC0-12, C0, or C2 values were observed between carriers of different SNP variants and genotypes (Kruskal-Wallis test), as well as between carriers and noncarriers of each haplotype (Mann-Whitney U test). Carriers of haplotype 12 (2677G and 3435T), which has previously been associated with increased digoxin AUC values, had a median AUC0-12 of 18.9 micro g*h*L-1 (range: 9.0-35.2) compared to 17.5 micro g*h*L-1 (range: 7.5-37.1) in the noncarrier group. It was concluded that MDR1 haplotypes derived from the SNPs 2677G>T (exon 21) and 3435C>T (exon 26) are not associated with cyclosporine pharmacokinetics in renal transplant patients.

Cytochrome p450 3A4 messenger ribonucleic acid induction by rifampin in human peripheral blood mononuclear cells: correlation with alprazolam pharmacokinetics.

OBJECTIVE: There is significant interest in the assessment of the individual cytochrome p450 (CYP) 3A4 activity. We analyzed whether CYP3A4 messenger ribonucleic acid (mRNA) concentrations in leukocytes reflect CYP3A activity in the liver measured by alprazolam as an in vivo probe drug. We also wanted to identify whether genetically determined high CYP3A5 expression is associated with increased alprazolam clearance. METHODS: Alprazolam plasma concentrations were measured 10 hours after intake of 1 mg alprazolam. CYP3A4 mRNA concentrations in peripheral blood mononuclear cells were quantified in 96 healthy volunteers before and after 5-day treatment with 450 mg rifampin (INN, rifampicin) daily. Genetic polymorphisms in CYP2C19, CYP3A4, and CYP3A5 were analyzed by polymerase chain reaction, restriction fragment length polymorphism, and sequencing. RESULTS: The median alprazolam concentration measured 10 hours after dosage was 8.1 mug/L (range, 4.5-14.6 mug/L) before and 1.7 mug/L (range, 0.3-4.1 mug/L) after rifampin treatment. Leukocyte CYP3A4 mRNA was detectable in all samples with a median of 28 molecules per 1 ng total ribonucleic acid before (range, 10-128 molecules per 1 ng total ribonucleic acid) and 50 molecules per 1 ng total ribonucleic acid after (range, 9-484 molecules per 1 ng total ribonucleic acid) rifampin treatment (P <.001). However, mRNA concentrations before and during rifampin induction were largely overlapping, and there was a poor correlation between mRNA concentrations and alprazolam 10-hour trough concentrations reflecting CYP3A4 activity (r = -0.4, P <.001). Alprazolam kinetics did not differ between genetically determined expressers of CYP3A5 (genotype CYP3A5*1/*3) compared with homozygous carriers of the splice site variant. A marginally significant dependence of alprazolam concentrations from the CYP2C19 allele *2 was found (P =.04). CONCLUSIONS: CYP3A4 mRNA concentrations in blood cells were very low and did not reflect systemic drug clearance mediated by CYP3A enzymes. The CYP3A5 genetic polymorphism does not appear relevant for alprazolam kinetics.