Through an international consortium, we have collected 37 tau- and TAR DNA-binding protein 43 (TDP-43)-negative frontotemporal lobar degeneration (FTLD) cases, and present here the first comprehensive analysis of these cases in terms of neuropathology, genetics, demographics and clinical data. 92% (34/37) had fused in sarcoma (FUS) protein pathology, indicating that FTLD-FUS is an important FTLD subtype. This FTLD-FUS collection specifically focussed on aFTLD-U cases, one of three recently defined subtypes of FTLD-FUS. The aFTLD-U subtype of FTLD-FUS is characterised clinically by behavioural variant frontotemporal dementia (bvFTD) and has a particularly young age of onset with a mean of 41 years. Further, this subtype had a high prevalence of psychotic symptoms (36% of cases) and low prevalence of motor symptoms (3% of cases). We did not find FUS mutations in any aFTLD-U case. To date, the only subtype of cases reported to have ubiquitin-positive but tau-, TDP-43- and FUS-negative pathology, termed FTLD-UPS, is the result of charged multivesicular body protein 2B gene (CHMP2B) mutation. We identified three FTLD-UPS cases, which are negative for CHMP2B mutation, suggesting that the full complement of FTLD pathologies is yet to be elucidated.
Purpose: To explore the effect of dihydropyrimidine dehydrogenase (DPD) single nucleotide polymorphisms (SNP) and haplotypes on outcome of capecitabine.Experimental Design: Germline DNA was available from 568 previously untreated patients with advanced colorectal cancer participating in the CAIRO2 trial, assigned to capecitabine, oxaliplatin, and bevacizumab AE cetuximab. The coding region of dihydropyrimidine dehydrogenase gene (DPYD) was sequenced in 45 cases with grade 3 or more capecitabine-related toxicity and in 100 randomly selected controls (cohort). Most discriminating (P < 0.1) or frequently occurring (>1%) nonsynonymous SNPs were analyzed in all 568 patients. SNPs and haplotypes were associated with toxicity, capecitabine dose modifications, and survival.Results: A total of 29 SNPs were detected in the case-cohort analysis, of which 8 were analyzed in all 568 patients. Of the patients polymorphic for DPYD IVS14þ1G>A, 2846A>T, and 1236G>A, 71% (5 of 7), 63% (5 of 8), and 50% (14 of 28) developed grade 3 to 4 diarrhea, respectively, compared with 24% in the overall population. All patients polymorphic for IVS14þ1G>A developed any grade 3 to 4 toxicity, including one possibly capecitabine-related death. Because of toxicity, a mean capecitabine dose reduction of 50% was applied in IVS14þ1G>A and 25% in 2846A>T variant allele carriers. Patients were categorized into six haplotype groups: one predicted for reduced (10%), and two for increased risks (41% and 33%) for severe diarrhea. Individual SNPs were not associated with overall survival, whereas one haplotype was associated with overall survival [HR (95% CI) ¼ 0.57 (0.35-0.95)].Conclusions: DPYD IVS14þ1G>A and 2846A>T predict for severe toxicity to capecitabine, for which patients require dose reductions. Haplotypes assist in selecting patients at risk for toxicity to capecitabine.
This study indicates that the presently evaluated variant alleles in the CYP2B6, CYP2C9, CYP2C19, CYP3A4, CYP3A5, GSTA1, GSTP1, ALDH1A1 and ALDH3A1 genes do not explain the interindividual variability in cyclophosphamide and 4-hydroxycyclophosphamide pharmacokinetics and are, probably, not the cause of the observed variability in toxicity.
Purpose: Despite the extensive clinical experience with docetaxel, unpredictable interindividual variability in efficacy and toxicity remain important limitations associated with the use of this anticancer drug. Large interindividual pharmacokinetic variability has been associated with variation in toxicity profiles. Genetic polymorphisms in drug-metabolizing enzymes and drug transporters could possibly explain the observed pharmacokinetic variability. The aim of this study was therefore to investigate the influence of polymorphisms in the CYP3A and ABCB1 genes on the population pharmacokinetics of docetaxel. Experimental Design: Whole blood samples were obtained from patients with solid tumors and treated with docetaxel to quantify the exposure to docetaxel. DNA was collected to determine polymorphisms in the CYP3A and ABCB1 genes with DNA sequencing. A population pharmacokinetic analysis of docetaxel was done using nonlinear mixed-effect modeling. Results: In total, 92 patients were assessable for pharmacokinetic analysis of docetaxel. A threecompartmental model adequately described the pharmacokinetics of docetaxel. Several polymorphisms in the CYP3A and ABCB1 genes were found, with allele frequencies of 0.54% to 48.4%. The homozygous C1236T polymorphism in the ABCB1 gene (ABCB1*8) was significantly correlated with a decreased docetaxel clearance (À25%; P = 0.0039). No other relationships between polymorphisms and pharmacokinetic variables reached statistical significance. Furthermore, no relationship between haplotypes of CYP3A and ABCB1and the pharmacokinetics could be identified. Conclusions: The polymorphism C1236T in the ABCB1 gene was significantly related to docetaxel clearance. Our current finding may provide a meaningful tool to explain interindividual differences in docetaxel treatment in daily practice.The anticancer drug docetaxel (Taxotere) is approved for the treatment of patients with early-stage, locally advanced and/or metastatic breast cancer, non -small-cell lung cancer, and androgen-independent metastatic prostate cancer. The recommended dose ranges from 75 to 100 mg/m 2 given as a 1-hour infusion once every 3 weeks. An important limitation associated with docetaxel use is the unpredictable interindividual variability in efficacy and toxicity. Potential causes for such variability in drug effects include the pathogenesis and severity of the disease being treated, the occurrence of unintended drug interactions, and impairment of hepatic and renal function (1). Despite the potential importance of these clinical variables in determining drug effects, it is recognized that inherited differences in metabolism and excretion can have an even greater effect on the efficacy and toxicity of drugs (1).The metabolism of docetaxel consists of a CYP3A-mediated oxidation of the tert-butylpropionate side chain, which results in the formation of four metabolites with reduced cytotoxic activity (2). The elimination pathway is mediated by the membrane-localized, energy-dependent drug efflux ABC tran...
Primary mouse embryonic fibroblasts lacking expression of all three retinoblastoma protein family members (TKO MEFs) have lost the G1 restriction point. However, in the absence of mitogens these cells become highly sensitive to apoptosis. Here, we show that TKO MEFs that survive serum depletion pass G1 but completely arrest in G2. p21CIP1 and p27KIP1 inhibit Cyclin A-Cdk2 activity and sequester Cyclin B1-Cdk1 in inactive complexes in the nucleus. This response is alleviated by mitogen restimulation or inactivation of p53. Thus, our results disclose a cell cycle arrest mechanism in G2 that restricts the proliferative capacity of mitogen-deprived cells that have lost the G1 restriction point. The involvement of p53 provides a rationale for the synergism between loss of Rb and p53 in tumorigenesis.
BACKGROUND:The authors assessed the impact of germline polymorphisms on clinical outcome in patients with advanced nonsmall cell lung cancer (NSCLC) who received platinum-gemcitabine (PG) chemotherapy. METHODS: In total, 137 patients with stage IIIB/IV NSCLC were included who received first-line PG chemotherapy (74% of patients received cisplatin, and 26% received carboplatin). Twenty-three germline polymorphisms that were identified in peripheral blood samples were analyzed for progression-free survival (PFS), treatment response, overall survival (OS), and toxicity. RESULTS: The median PFS was 5.8 months, the median OS was 10.2 months, and 44 patients (32%) had a partial treatment response. Carriers of the excision repair cross-complementation group 1 (ERCC1) mutant thymine (T) allele had a lower treatment response rate (29% vs 52%; P ¼ .02), shorter PFS (adjusted hazard ratio [HR], 1.60; P ¼ .04), and shorter OS (adjusted HR, 1.54; P ¼ .05) compared with carriers of the wild-type cytosine/cytosine (CC) genotype. The xeroderma pigmentosum group A member 10 (XPD10) mutant adenine (A) allele (adjusted HR, 0.64; P ¼ .04) and the x-ray cross-complementing group 1 (XRCC1) mutant guanine (G) allele (adjusted HR, 0.51; P ¼ .02) also were independent predictors of OS. Carriers of the mutant adenosine triphosphate-dependent DNA helicase Q1 (RECQ1) C allele or the mutant cytidine deaminase (CDA) C allele were more likely to experience severe leukocytopenia (26% vs 10% [P ¼ .03] and 28% vs 11% [P ¼ .02], respectively) compared with wild-type genotype carriers. Patients who carried the homozygous mutant glutathione S-transferase p 1(GSTP1) GG genotype were at considerable risk for severe platinum-associated polyneuropathy (18% vs 3% in wild-type vs heterozygous mutant patients, respectively; P ¼ .01). CONCLUSIONS: To the authors' knowledge, this is the first prospective study to date in patients with advanced NSCLC describing predictive germline polymorphisms not only for the clinical activity of PG chemotherapy (ERCC1, XPD10) but also for its toxicity (GSTP1, RECQ1, CDA). Nonplatinum-containing chemotherapy in carriers of the ERCC1 T allele or the XPD10 G allele should be studied prospectively. Cancer 2012;118:2466-
Germline polymorphisms of DPYD, TYMS and GSTP1 have a significant effect on toxicity and clinical outcome in patients receiving capecitabine-based chemotherapy for advanced colorectal or gastroesophageal cancer. These data should further be validated in prospective clinical studies.
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Thiotepa is metabolized by oxidative desulphuration by the cytochrome P450 (CYP) enzymes CYP2B6 and CYP3A4 to tepa. • Furthermore, thiotepa and tepa are conjugated to glutathione, which is catalysed by glutathione S-transferase (GST) isoenzymes A1-1 and P1-1. • Polymorphisms in these enzymes could influence exposure to thiotepa and tepa.• Little is known about the influence of polymorphisms in these enzymes on the pharmacokinetics of thiotepa and tepa. WHAT THIS STUDY ADDS• The presently evaluated variant alleles explain only a small part of the substantial interindividual variability in thiotepa and tepa pharmacokinetics.• We show that probably only the GSTP1 C341T variant allele influences thiotepa exposure to a clinically relevant extent. AIMSThiotepa is widely used in high-dose chemotherapy. Previous studies have shown relations between exposure and severe organ toxicity. Thiotepa is metabolized by cytochrome P450 and glutathione S-transferase enzymes. Polymorphisms of these enzymes may affect elimination of thiotepa and tepa, its main metabolite. The purpose of this study was to evaluate effects of known allelic variants in CYP2B6, CYP3A4, CYP3A5, GSTA1 and GSTP1 genes on pharmacokinetics of thiotepa and tepa. METHODSWhite patients (n = 124) received a high-dose regimen consisting of cyclophosphamide, thiotepa and carboplatin as intravenous infusions. Genomic DNA was analysed using polymerase chain reaction and sequencing. Plasma concentrations of thiotepa and tepa were determined using validated GC and LC-MS/MS methods. Relations between allelic variants and elimination pharmacokinetic parameters were evaluated using nonlinear mixed effects modelling (NONMEM). RESULTSThe polymorphisms CYP2B6 C1459T, CYP3A4*1B, CYP3A5*3, GSTA1 (C-69T, G-52A) and GSTP1 C341T had a significant effect on clearance of thiotepa or tepa. Although significant, most effects were generally not large. Clearance of thiotepa and tepa was predominantly affected by GSTP1 C341T polymorphism, which had a frequency of 9.3%. This polymorphism increased non-inducible thiotepa clearance by 52% [95% confidence interval (CI) 41, 64, P < 0.001] and decreased tepa clearance by 32% (95% CI 29, 35, P < 0.001) in heterozygous patients, which resulted in an increase in combined exposure to thiotepa and tepa of 45% in homozygous patients. CONCLUSIONSThis study indicates that the presently evaluated variant alleles explain only a small part of the substantial interindividual variability in thiotepa and tepa pharmacokinetics. Patients homozygous for the GSTP1 C341T allele may have enhanced exposure to thiotepa and tepa.
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