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1.
J Clin Oncol ; 38(7): 674-685, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-31841383

RESUMO

PURPOSE: To estimate age-specific relative and absolute cancer risks of breast cancer and to estimate risks of ovarian, pancreatic, male breast, prostate, and colorectal cancers associated with germline PALB2 pathogenic variants (PVs) because these risks have not been extensively characterized. METHODS: We analyzed data from 524 families with PALB2 PVs from 21 countries. Complex segregation analysis was used to estimate relative risks (RRs; relative to country-specific population incidences) and absolute risks of cancers. The models allowed for residual familial aggregation of breast and ovarian cancer and were adjusted for the family-specific ascertainment schemes. RESULTS: We found associations between PALB2 PVs and risk of female breast cancer (RR, 7.18; 95% CI, 5.82 to 8.85; P = 6.5 × 10-76), ovarian cancer (RR, 2.91; 95% CI, 1.40 to 6.04; P = 4.1 × 10-3), pancreatic cancer (RR, 2.37; 95% CI, 1.24 to 4.50; P = 8.7 × 10-3), and male breast cancer (RR, 7.34; 95% CI, 1.28 to 42.18; P = 2.6 × 10-2). There was no evidence for increased risks of prostate or colorectal cancer. The breast cancer RRs declined with age (P for trend = 2.0 × 10-3). After adjusting for family ascertainment, breast cancer risk estimates on the basis of multiple case families were similar to the estimates from families ascertained through population-based studies (P for difference = .41). On the basis of the combined data, the estimated risks to age 80 years were 53% (95% CI, 44% to 63%) for female breast cancer, 5% (95% CI, 2% to 10%) for ovarian cancer, 2%-3% (95% CI females, 1% to 4%; 95% CI males, 2% to 5%) for pancreatic cancer, and 1% (95% CI, 0.2% to 5%) for male breast cancer. CONCLUSION: These results confirm PALB2 as a major breast cancer susceptibility gene and establish substantial associations between germline PALB2 PVs and ovarian, pancreatic, and male breast cancers. These findings will facilitate incorporation of PALB2 into risk prediction models and optimize the clinical cancer risk management of PALB2 PV carriers.

2.
Breast Cancer Res Treat ; 177(1): 145-153, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31119570

RESUMO

PURPOSE: PARP4 has been proposed as a candidate breast cancer susceptibility gene. However, its function and involvement in breast carcinogenesis is unclear. We sought to determine the variant frequency of PARP4 in BRCA-negative women referred for genetic testing from Singapore and to perform functional analyses of PARP4. METHODS: Next-generation sequencing of PARP4 was conducted for 198 BRCA-negative cases from Singapore. Three independent case-control association analyses of PARP4 were performed for (1) our Singaporean cohort, (2) three dbGaP datasets, and (3) cases from TCGA, with controls from the Exome Aggregation Consortium (ExAC). PARP4 knockout cells were generated utilizing the CRISPR-Cas9 approach in MDA-MB-231 (breast cancer) and MCF10A (normal breast) cell lines, and colony formation, cell proliferation, and migration assays carried out. RESULTS: Candidate variants in PARP4 were identified in 5.5% (11/198) of our Singapore cohort. Case-control association studies for our cases and the dbGaP datasets showed no significant association. However, a significant association was observed for PARP4 variants when comparing 988 breast cancer cases from the TCGA provisional data and 53,105 controls from ExAC (ALL) (OR 0.249, 95% CI 0.139-0.414, P = 2.86 × 10-11). PARP4 knockout did not affect the clonogenicity, proliferation rate, and migration of normal breast cells, but appeared to decrease the proliferation rate and clonogenicity of breast cancer cells. CONCLUSIONS: Taken together, our results do not support that PARP4 functions as a cancer susceptibility gene. This study highlights the importance of performing functional analyses for candidate cancer predisposition genes.


Assuntos
Biomarcadores Tumorais , Neoplasias da Mama/genética , Predisposição Genética para Doença , Proteínas Nucleares/genética , Adulto , Idoso , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/mortalidade , Estudos de Casos e Controles , Linhagem Celular Tumoral , Proliferação de Células , Biologia Computacional , Feminino , Técnicas de Silenciamento de Genes , Estudos de Associação Genética/métodos , Testes Genéticos , Heterozigoto , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Estadiamento de Neoplasias , Células-Tronco Neoplásicas/metabolismo , Medição de Risco , Fatores de Risco , Singapura , Ensaio Tumoral de Célula-Tronco , Adulto Jovem
3.
Oncotarget ; 9(16): 12796-12804, 2018 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-29560110

RESUMO

Genome-wide association studies (GWAS) have proven highly successful in identifying single nucleotide polymorphisms (SNPs) associated with breast cancer (BC) risk. The majority of these studies are on European populations, with limited SNP association data in other populations. We genotyped 51 GWAS-identified SNPs in two independent cohorts of Singaporean Chinese. Cohort 1 comprised 1294 BC cases and 885 controls and was used to determine odds ratios (ORs); Cohort 2 had 301 BC cases and 243 controls for deriving polygenic risk scores (PRS). After age-adjustment, 11 SNPs were found to be significantly associated with BC risk. Five SNPs were present in <1% of Cohort 1 and were excluded from further PRS analysis. To assess the cumulative effect of the remaining 46 SNPs on BC risk, we generated three PRS models: Model-1 included 46 SNPs; Model-2 included 11 statistically significant SNPs; and Model-3 included the SNPs in Model-2 but excluded SNPs that were in strong linkage disequilibrium with the others. Across Models-1, -2 and -3, women in the highest PRS quartile had the greatest ORs of 1.894 (95% CI = 1.157-3.100), 2.013 (95% CI = 1.227-3.302) and 1.751 (95% CI = 1.073-2.856) respectively, suggesting a direct correlation between PRS and BC risk. Given the potential of PRS in BC risk stratification, our findings suggest the need to tailor the selection of SNPs to be included in an ethnic-specific PRS model.

4.
Cancer Res ; 77(19): 5428-5437, 2017 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-28775167

RESUMO

It has been estimated that >1,000 genetic loci have yet to be identified for breast cancer risk. Here we report the first study utilizing targeted next-generation sequencing to identify single-nucleotide polymorphisms (SNP) associated with breast cancer risk. Targeted sequencing of 283 genes was performed in 240 women with early-onset breast cancer (≤40 years) or a family history of breast and/or ovarian cancer. Common coding variants with minor allele frequencies (MAF) >1% that were identified were presumed initially to be SNPs, but further database inspections revealed variants had MAF of ≤1% in the general population. Through prioritization and stringent selection criteria, we selected 24 SNPs for further genotyping in 1,516 breast cancer cases and 1,189 noncancer controls. Overall, we identified the JAK2 SNP rs56118985 to be significantly associated with overall breast cancer risk. Subtype analysis performed for patient subgroups defined by ER, PR, and HER2 status suggested additional associations of the NOTCH3 SNP rs200504060 and the HIF1A SNP rs142179458 with breast cancer risk. In silico analysis indicated that coding amino acids encoded at these three SNP sites were conserved evolutionarily and associated with decreased protein stability, suggesting a likely impact on protein function. Our results offer proof of concept for identifying novel cancer risk loci from next-generation sequencing data, with iterative data analysis from targeted, whole-exome, or whole-genome sequencing a wellspring to identify new SNPs associated with cancer risk. Cancer Res; 77(19); 5428-37. ©2017 AACR.


Assuntos
Biomarcadores Tumorais/genética , Neoplasias da Mama/genética , Carcinoma Ductal de Mama/genética , Carcinoma Lobular/genética , Loci Gênicos , Polimorfismo de Nucleotídeo Único/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/metabolismo , Carcinoma Ductal de Mama/patologia , Carcinoma Lobular/metabolismo , Carcinoma Lobular/patologia , Estudos de Casos e Controles , Feminino , Seguimentos , Predisposição Genética para Doença , Genótipo , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/química , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Janus Quinase 2/química , Janus Quinase 2/genética , Janus Quinase 2/metabolismo , Pessoa de Meia-Idade , Gradação de Tumores , Estadiamento de Neoplasias , Prognóstico , Conformação Proteica , Estabilidade Proteica , Receptor ErbB-2/metabolismo , Receptor Notch3/química , Receptor Notch3/genética , Receptor Notch3/metabolismo , Receptores Estrogênicos/metabolismo , Receptores de Progesterona/metabolismo , Adulto Jovem
5.
Clin Pharmacokinet ; 55(10): 1239-1250, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27098059

RESUMO

Tamoxifen (TAM) is an established endocrine treatment for all stages of oestrogen receptor (ER)-positive breast cancer. Its complex metabolism leads to the formation of multiple active and inactive metabolites. One of the main detoxification and elimination pathways of tamoxifen and its active metabolites, 4-hydroxytamoxifen (4-OHT) and endoxifen, is via glucuronidation catalysed by uridine 5'-diphospho-glucuronosyltransferases (UGTs). However, few studies have comprehensively examined the impact of variations in the genes encoding the major hepatic UGTs on the disposition of tamoxifen and its metabolites. In the present study, we systematically sequenced exons, exon/intron boundaries, and flanking regions of UGT1A4, UGT2B7 and UGT2B15 in 240 healthy subjects of different Asian ethnicities (Chinese, Malays and Indians) to identify haplotype tagging single nucleotide polymorphisms. Subsequently, 202 Asian breast cancer patients receiving tamoxifen were genotyped for 50 selected variants in the three UGT genes to comprehensively investigate their associations with steady-state plasma levels of tamoxifen, its active metabolites and their conjugated counterparts. The UGT1A4 haplotype (containing variant 142T>G, L48 V defining the *3 allele) was strongly associated with higher plasma levels of TAM-N-glucuronide, with a twofold higher metabolic ratio of TAM-N-glucuronide/TAM observed in carriers of this haplotype upon covariate adjustment (P < 0.0001). Variants in UGT2B7 were not associated with altered O-glucuronidation of both 4-OHT and endoxifen, while UGT2B15 haplotypes had a modest effect on (E)-endoxifen plasma levels after adjustment for CYP2D6 genotypes. Our findings highlight the influence of UGT1A4 haplotypes on tamoxifen disposition in Asian breast cancer patients, while genetic variants in UGT2B7 and UGT2B15 appear to be of minor importance.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Neoplasias da Mama/tratamento farmacológico , Glucuronosiltransferase/genética , Tamoxifeno/farmacocinética , Tamoxifeno/uso terapêutico , Adulto , Idoso , Grupo com Ancestrais do Continente Asiático/etnologia , Neoplasias da Mama/etnologia , Citocromo P-450 CYP2D6/genética , Grupos Étnicos , Feminino , Genótipo , Humanos , Pessoa de Meia-Idade , Farmacogenética , Polimorfismo de Nucleotídeo Único , Tamoxifeno/análogos & derivados , Tamoxifeno/sangue , Tamoxifeno/metabolismo
6.
Br J Clin Pharmacol ; 81(6): 1142-52, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26799162

RESUMO

AIM: The aim was to examine the influence of CYP2C19 variants and associated haplotypes on the disposition of tamoxifen and its metabolites, particularly norendoxifen (NorEND), in Asian patients with breast cancer. METHODS: Sixty-six CYP2C19 polymorphisms were identified in healthy Asians (n = 240), of which 14 were found to be tightly linked with CYP2C19*2, CYP2C19*3 and CYP2C19*17. These 17 SNPs were further genotyped in Asian breast cancer patients receiving tamoxifen (n = 201). Steady-state concentrations of tamoxifen and its metabolites were quantified using liquid chromatography­mass spectrometry. Non-parametric tests and regression methods were implemented to evaluate genotypic­phenotypic associations and haplotypic effects of the SNPs. RESULTS: CYP2C19 functional polymorphisms and their linked SNPs were not significantly associated with plasma concentrations of tamoxifen and its main metabolites N-desmethyltamoxifen, (Z)-4-hydroxytamoxifen and (Z)-Endoxifen. However, CYP2C19*2 and its seven linked SNPs were significantly associated with lower NorEND concentrations, MRNorEND/NDDM and MRNorEND/(Z)-END. Specifically, patients carrying the CYP2C19*2 variant allele A had significantly lower NorEND concentrations [median (range), GG vs. GA vs. AA: 1.51 (0.38­3.28) vs. 1.28 (0.30­3.36) vs. 1.15 ng ml−1 (0.26­2.45, P = 0.010)] as well as significantly lower MRNorEND/(Z)-END [GG vs. GA vs. AA: 9.40 (3.27­28.35) vs. 8.15 (2.67­18.9) vs. 6.06 (4.47­14.6), P < 0.0001] and MRNorEND/NDDM [GG vs. GA vs. AA: 2.75 (0.62­6.26) vs. 2.43 (0.96­4.18) vs. 1.75 (1.10­2.49), P < 0.00001]. CYP2C19 H2 haplotype, which included CYP2C19*2, was also significantly associated with lower NorEND concentrations (P = 0.0020), MRNorEND/NDDM (P < 0.0001) and MRNorEND/(Z)-END (P < 0.0001), indicating significantly lower formation rates of NorEND. CONCLUSION: These data highlight the potential relevance of CYP2C19 pharmacogenetics in influencing NorEND concentrations in tamoxifen-treated patients, which may influence treatment outcomes.


Assuntos
Antineoplásicos Hormonais/farmacocinética , Neoplasias da Mama/metabolismo , Citocromo P-450 CYP2C19/genética , Tamoxifeno/análogos & derivados , Tamoxifeno/farmacocinética , Adulto , Idoso , Antineoplásicos Hormonais/sangue , Antineoplásicos Hormonais/uso terapêutico , Grupo com Ancestrais do Continente Asiático , Biotransformação , Neoplasias da Mama/tratamento farmacológico , Citocromo P-450 CYP2D6/genética , Feminino , Frequência do Gene , Haplótipos , Voluntários Saudáveis , Humanos , Desequilíbrio de Ligação , Pessoa de Meia-Idade , Polimorfismo Genético/genética , Polimorfismo de Nucleotídeo Único , Tamoxifeno/sangue , Tamoxifeno/uso terapêutico
7.
NPJ Genom Med ; 1: 15003, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-29263802

RESUMO

Genetic testing for germline mutations in breast cancer predisposition genes can potentially identify individuals at a high risk of developing breast and/or ovarian cancer. There is a paucity of such mutational information for Asians. Panel testing of 25 cancer susceptibility genes and BRCA1/2 deletion/duplication analysis was performed for 220 Asian breast cancer patients or their family members referred for genetics risk assessment. All 220 participants had at least one high-risk feature: having a family history of breast and/or ovarian cancer in first- and/or second-degree relatives; having breast and ovarian cancer in the same individual or bilateral breast cancer; having early-onset breast cancer or ovarian cancer (⩽40 years of age). We identified 67 pathogenic variants in 66 (30.0%) patients. Of these, 19 (28.3%) occurred in BRCA1, 16 (23.9%) in BRCA2, 7 (10.4%) in PALB2, 6 (9.0%) in TP53, 2 (3.0%) in PTEN, 2 (3.0%) in CDH1 and 15 (22.4%) in other predisposition genes. Notably, 47.8% of pathogenic variants were in non-BRCA1/2 genes. Of the 66 patients with pathogenic mutations, 63.6% (42/66) were under the age of 40 years. Family history of breast and/or ovarian cancer is enriched in patients with BRCA1/2 pathogenic variants but less predictive for non-BRCA1/2 related pathogenic variations. We detected a median of three variants of unknown significance (VUS) per gene (range 0-21). Custom gene panel testing is feasible and useful for the detection of pathogenic mutations and should be done in the setting of a formal clinical cancer genetics service given the rate of VUS.

8.
PLoS One ; 10(7): e0134408, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26221963

RESUMO

PURPOSE: The National Comprehensive Cancer Network (NCCN) has proposed guidelines for the genetic testing of the BRCA1 and BRCA2 genes, based on studies in western populations. This current study assessed potential predictive factors for BRCA mutation probability, in an Asian population. METHODS: A total of 359 breast cancer patients, who presented with either a family history (FH) of breast and/or ovarian cancer or early onset breast cancer, were accrued at the National Cancer Center Singapore (NCCS). The relationships between clinico-pathological features and mutational status were calculated using the Chi-squared test and binary logistic regression analysis. RESULTS: Of 359 patients, 45 (12.5%) had deleterious or damaging missense mutations in BRCA1 and/or BRCA2. BRCA1 mutations were more likely to be found in ER-negative than ER-positive breast cancer patients (P=0.01). Moreover, ER-negative patients with BRCA mutations were diagnosed at an earlier age (40 vs. 48 years, P=0.008). Similarly, triple-negative breast cancer (TNBC) patients were more likely to have BRCA1 mutations (P=0.001) and that these patients were diagnosed at a relatively younger age than non-TNBC patients (38 vs. 46 years, P=0.028). Our analysis has confirmed that ER-negative status, TNBC status and a FH of hereditary breast and ovarian cancer (HBOC) are strong factors predicting the likelihood of having BRCA mutations. CONCLUSIONS: Our study provides evidence that TNBC or ER-negative patients may benefit from BRCA genetic testing, particularly younger patients (<40 years) or those with a strong FH of HBOC, in Asian patients.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Neoplasias da Mama/genética , Genes BRCA1 , Genes BRCA2 , Testes Genéticos/métodos , Adulto , Fatores Etários , Idoso , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/metabolismo , Distribuição de Qui-Quadrado , Análise Mutacional de DNA/métodos , Análise Mutacional de DNA/estatística & dados numéricos , Feminino , Testes Genéticos/estatística & dados numéricos , Humanos , Modelos Logísticos , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Valor Preditivo dos Testes , Receptores Estrogênicos/metabolismo , Fatores de Risco , Singapura , Neoplasias de Mama Triplo Negativas/diagnóstico , Neoplasias de Mama Triplo Negativas/genética , Neoplasias de Mama Triplo Negativas/metabolismo , Adulto Jovem
10.
PLoS One ; 7(9): e45798, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23029247

RESUMO

The emergence of benchtop sequencers has made clinical genetic testing using next-generation sequencing more feasible. Ion Torrent's PGM™ is one such benchtop sequencer that shows clinical promise in detecting single nucleotide variations (SNVs) and microindel variations (indels). However, the large number of false positive indels caused by the high frequency of homopolymer sequencing errors has impeded PGM™'s usage for clinical genetic testing. An extensive analysis of PGM™ data from the sequencing reads of the well-characterized genome of the Escherichia coli DH10B strain and sequences of the BRCA1 and BRCA2 genes from six germline samples was done. Three commonly used variant detection tools, SAMtools, Dindel, and GATK's Unified Genotyper, all had substantial false positive rates for indels. By incorporating filters on two major measures we could dramatically improve false positive rates without sacrificing sensitivity. The two measures were: B-Allele Frequency (BAF) and VARiation of the Width of gaps and inserts (VARW) per indel position. A BAF threshold applied to indels detected by UnifiedGenotyper removed ~99% of the indel errors detected in both the DH10B and BRCA sequences. The optimum BAF threshold for BRCA sequences was determined by requiring 100% detection sensitivity and minimum false discovery rate, using variants detected from Sanger sequencing as reference. This resulted in 15 indel errors remaining, of which 7 indel errors were removed by selecting a VARW threshold of zero. VARW specific errors increased in frequency with higher read depth in the BRCA datasets, suggesting that homopolymer-associated indel errors cannot be reduced by increasing the depth of coverage. Thus, using a VARW threshold is likely to be important in reducing indel errors from data with higher coverage. In conclusion, BAF and VARW thresholds provide simple and effective filtering criteria that can improve the specificity of indel detection in PGM™ data without compromising sensitivity.


Assuntos
Análise Mutacional de DNA/instrumentação , Mutação INDEL , Proteína BRCA1/genética , Proteína BRCA2/genética , Escherichia coli/genética , Reações Falso-Positivas , Frequência do Gene , Genoma Bacteriano , Haploidia , Humanos , Polimorfismo de Nucleotídeo Único , Sensibilidade e Especificidade , Software
11.
J Mol Diagn ; 14(6): 602-12, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22921312

RESUMO

In a clinical setting, next-generation sequencing (NGS) approaches for the enrichment and resequencing of DNA targets may have limitations in throughput, cost, or accuracy. We evaluated an NGS workflow for targeted DNA sequencing for mutation detection. Targeted sequence data of the BRCA1 and BRCA2 genes, generated using a PCR-based, multiplexed NGS approach using the SOLiD 4 (n = 24) and Ion Torrent PGM (n = 20) next-generation sequencers, were evaluated against sequence data obtained by Sanger sequencing. The overall sensitivity for SOLiD and PGM were 97.8% (95% CI = 94.7 to 100.0) and 98.9% (95% CI = 96.8 to 100.0) respectively. The specificity for the SOLiD platform was high, at 100.0% (95% CI = 99.3 to 100.0). PGM correctly identified all 3 indels, but 68 false-positive indels were also called. Equimolar normalization of amplicons was not necessary for successful NGS. Both platforms are highly amenable to scale-up, potentially reducing the reagent cost for BRCA testing to

Assuntos
Proteína BRCA2/genética , Análise Mutacional de DNA/métodos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Mutação , Análise Mutacional de DNA/economia , Genes BRCA2 , Sequenciamento de Nucleotídeos em Larga Escala/economia , Humanos , Sensibilidade e Especificidade
12.
Breast Cancer Res ; 14(1): R19, 2012 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-22289271

RESUMO

INTRODUCTION: The Gail model (GM) is a risk-assessment model used in individual estimation of the absolute risk of invasive breast cancer, and has been applied to both clinical counselling and breast cancer prevention studies. Although the GM has been validated in several Western studies, its applicability outside North America and Europe remains uncertain. The Singapore Breast Cancer Screening Project (SBCSP) is a nation-wide prospective trial of screening mammography conducted between Oct 1994 and Feb 1997, and is the only such trial conducted outside North America and Europe to date. With the long-term outcomes from this study, we sought to evaluate the performance of GM in prediction of individual breast cancer risk in a Asian developed country. METHODS: The study population consisted of 28,104 women aged 50 to 64 years who participated in the SBSCP and did not have breast cancer detected during screening. The national cancer registry was used to identify incident cases of breast cancer. To evaluate the performance of the GM, we compared the expected number of invasive breast cancer cases predicted by the model to the actual number of cases observed within 5-year and 10-year follow-up. Pearson's Chi-square test was used to test the goodness of fit between the expected and observed cases of invasive breast cancers. RESULTS: The ratio of expected to observed number of invasive breast cancer cases within 5 years from screening was 2.51 (95% confidence interval 2.14 - 2.96). The GM over-estimated breast cancer risk across all age groups, with the discrepancy being highest among older women aged 60 - 64 years (E/O = 3.53, 95% CI = 2.57-4.85). The model also over-estimated risk for the upper 80% of women with highest predicted risk. The overall E/O ratio for the 10-year predicted breast cancer risk was 1.85 (1.68-2.04). CONCLUSIONS: The GM over-predicts the risk of invasive breast cancer in the setting of a developed Asian country as demonstrated in a large prospective trial, with the largest difference seen in older women aged between 60 and 64 years old. The reason for the discrepancy is likely to be multifactorial, including a truly lower prevalence of breast cancer, as well as lower mammographic screening prevalence locally.


Assuntos
Neoplasias da Mama/epidemiologia , Carcinoma Ductal de Mama/epidemiologia , Carcinoma Intraductal não Infiltrante/epidemiologia , Modelos Biológicos , Neoplasias da Mama/diagnóstico por imagem , Carcinoma Ductal de Mama/diagnóstico por imagem , Carcinoma Intraductal não Infiltrante/diagnóstico por imagem , Estudos de Coortes , Detecção Precoce de Câncer , Feminino , Humanos , Incidência , Mamografia , Programas de Rastreamento , Pessoa de Meia-Idade , Risco , Medição de Risco , Singapura/epidemiologia
13.
Pharmacogenet Genomics ; 21(11): 760-8, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21849928

RESUMO

OBJECTIVES: Vorinostat, a histone deacetylase inhibitor being actively evaluated in solid tumors, is metabolized by UGT2B17. UGT2B17 null genotype (UGT2B17*2) has been shown in vitro to reduce UGT2B17 activity. This variant is common in Asians but rare in Caucasians, and we studied its impact on vorinostat pharmacokinetics and pharmacodynamics in a clinical study in Asian patients with metastatic breast cancer. METHODS: Eligible patients received 400 mg of vorinostat monotherapy daily in a lead-in phase I followed by a phase II study. Patients were genotyped for UGT2B17*2, which was correlated with vorinostat pharmacokinetics and clinical outcomes. RESULTS: Twenty-six patients were treated with no complete response, one partial response, six stable disease lasting for 12 weeks or more, and 19 progressive disease. Sixteen patients (62%) were UGT2B17*2 homozygotes and had significantly lower mean area under the curve ratio of vorinostat-O-glucuronide/vorinostat (1.84 vs. 2.51 on day 1, P=0.02; 1.63 vs. 2.38 on day 15, P=0.028), and trended toward having higher vorinostat area under the curve (399.02 vs. 318.40, P=0.188), more serious adverse events (31 vs. 0%, P=0.121), higher clinical benefit rate (40 vs. 10%, P=0.179), and longer median progression-free survival (3.0 vs. 1.5 months, P=0.087) than patients with at least one wild-type allele. CONCLUSION: UGT2B17*2 genotype reduces vorinostat glucuronidation and may increase vorinostat efficacy and toxicity. These observations are important in the development of vorinostat, and may have clinical implications on other cancer and noncancer drugs that are UGT2B17 substrates such as exemestane and ibuprofen.


Assuntos
Antineoplásicos/metabolismo , Grupo com Ancestrais do Continente Asiático/genética , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/enzimologia , Glucuronosiltransferase/genética , Ácidos Hidroxâmicos/metabolismo , Ácidos Hidroxâmicos/uso terapêutico , Adulto , Antineoplásicos/efeitos adversos , Antineoplásicos/farmacocinética , Antineoplásicos/uso terapêutico , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Demografia , Intervalo Livre de Doença , Feminino , Genótipo , Humanos , Ácidos Hidroxâmicos/efeitos adversos , Ácidos Hidroxâmicos/farmacocinética , Pessoa de Meia-Idade , Antígenos de Histocompatibilidade Menor , Metástase Neoplásica , Fatores de Tempo , Resultado do Tratamento , Vorinostat
14.
J Mol Diagn ; 13(3): 305-12, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21497291

RESUMO

The current need for high-throughput genotyping platforms for targeted validation of disease-associated single nucleotide polymorphisms (SNPs) motivated us to evaluate a novel nanofluidics platform for genotyping DNA extracted from peripheral blood and buccal wash samples. SNP genotyping was performed using a Fluidigm 48.48 Dynamic Array biochip on the BioMark polymerase chain reaction platform and results were compared against standard TaqMan assays and DNA sequencing. Pilot runs using these dynamic arrays on 90 samples against 20 SNP assays had an average call rate of 99.7%, with 100% call rates for 16 of the assays. Manual TaqMan genotyping of these samples against three SNPs demonstrated 100% correlation between the two platforms. To understand the influence of DNA template variability, three sources of blood samples (CH-1, n = 20; CH-2, n = 47; KK, n = 47) and buccal washes (n = 37) were genotyped for 24 SNPs. Although both CH-1 and CH-2 batches showed good base calling (≥98.8%), the KK batch and buccal wash samples exhibited lower call rates (82.1% and 94.0%). Importantly, repurification of the KK and buccal wash samples resulted in significant improvements in their call rates (to ≥97.9%). Scale-up for genotyping 1698 cases and controls for 24 SNPs had overall call rates of 97.6% for KK and 99.2% for CH samples. The Dynamic Array approach demonstrated accuracy similar to that of TaqMan genotyping, while offering significant savings in DNA, effort, time, and costs.


Assuntos
Ensaios de Triagem em Larga Escala , Técnicas Analíticas Microfluídicas , Tipagem Molecular , Polimorfismo de Nucleotídeo Único , Humanos , Técnicas Analíticas Microfluídicas/normas , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
15.
Ann Acad Med Singap ; 39(1): 61-3, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20126818

RESUMO

INTRODUCTION: Genetic predisposition to clear cell renal cell carcinoma (ccRCC) has been linked to disorders such as von Hippel-Lindau (VHL) syndrome. While twin research is a classic approach for elucidating genetic and environmental contributions to disease, no monozygotic twin-pair concordant for ccRCC in the absence of VHL syndrome has been previously reported in the literature or in major twin registries. CLINICAL PICTURE: We describe a unique monozygotic twin-pair concordant for ccRCC, with discordant but early ages of onset of 25 and 38 respectively. Cytogenetic studies and direct sequencing for VHL gene mutations in the second twin proved unremarkable. CONCLUSIONS: This is the fi rst reported case of monozygotic twins concordant for ccRCC in the absence of VHL gene mutation. The early yet discordant, age of onset of disease in both twins suggests both genetic and environmental contributions to ccRCC.


Assuntos
Carcinoma de Células Renais/patologia , Doenças em Gêmeos/patologia , Neoplasias Renais/patologia , Gêmeos Monozigóticos , Adulto , Carcinoma de Células Renais/genética , Doenças em Gêmeos/genética , Humanos , Neoplasias Renais/genética , Masculino , Doença de von Hippel-Lindau/genética
16.
Cancer Sci ; 99(10): 2045-54, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19016765

RESUMO

The present study aimed to identify polymorphic genes encoding carbonyl reductases (CBR1, CBR3) and investigate their influence on doxorubicin disposition in Asian breast cancer patients (n = 62). Doxorubicin (60 mg/m(2)) was administered every 3 weeks for four to six cycles and the pharmacokinetic parameters were estimated using non-compartmental analysis (WinNonlin). The Mann-Whitney U-test was used to assess genotypic-phenotypic correlations. Five CBR1 (-48G>A, c.219G>C, c.627C>T, c.693G>A, +967G>A) and CBR3 (c.11G>A, c.255C>T, c.279C>T, c.606G>A, c.730G>A) polymorphisms were identified. The CBR1 D2 diplotypes were characterized by the presence of at least one variant allele at the c.627C>T and +967G>A loci. Patients in the CBR1 D1 diplotype group had significantly higher clearance (CL) normalized to body surface area (BSA) (CL/BSA[L/h/m(2)]: median 25.09; range 16.44-55.66) and significantly lower exposure levels; area under curve (AUC(0-infinity)/dose/BSA [h/m(5)]; median 15.08; range 6.18-38.03) of doxorubicin compared with patients belonging to the CBR1 D2 diplotype group (CL/BSA[L/h/m(2)]; median 20.88; range 8.68-31.79, P = 0.014; and AUC(0-infinity)/dose/BSA[h/m(5)]; median 21.35; range 9.82-67.17, P = 0.007 respectively). No significant influence of CBR3 polymorphisms on the pharmacokinetics of doxorubicin were observed in Asian cancer patients. The present exploratory study shows that CBR1 D2 diplotypes correlate with significantly higher exposure levels of doxorubicin, suggesting the possibility of lowered intracellular conversion to doxorubicinol in these patients. Further evaluation of carbonyl reductase polymorphisms in influencing the treatment efficacy of doxorubicin-based chemotherapy in Asian cancer patients are warranted.


Assuntos
Oxirredutases do Álcool/genética , Antibióticos Antineoplásicos/farmacocinética , Neoplasias da Mama/genética , Doxorrubicina/farmacocinética , Adulto , Idoso , Alelos , Animais , Antibióticos Antineoplásicos/administração & dosagem , Antibióticos Antineoplásicos/sangue , Área Sob a Curva , Grupo com Ancestrais do Continente Asiático/genética , Superfície Corporal , Neoplasias da Mama/tratamento farmacológico , Estudos de Casos e Controles , Doxorrubicina/administração & dosagem , Doxorrubicina/sangue , Éxons , Feminino , Frequência do Gene/efeitos dos fármacos , Frequência do Gene/genética , Meia-Vida , Haplótipos , Humanos , Taxa de Depuração Metabólica/efeitos dos fármacos , Pessoa de Meia-Idade , Farmacogenética , Polimorfismo Genético , Análise de Sequência de DNA
17.
Clin Cancer Res ; 14(21): 7116-26, 2008 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-18981011

RESUMO

PURPOSE: To characterize pregnane X receptor (PXR) polymorphic variants in healthy Asian populations [Chinese, Malay and Indian (n=100 each)], and to investigate the association between PXR haplotypes and hepatic mRNA expression of PXR and its downstream target genes, CYP3A4 and ABCB1, as well as their influence on the clearance of doxorubicin in Asian breast cancer patients. EXPERIMENTAL DESIGN: PXR genotyping was done by direct DNA sequencing, and PXR haplotypes and haplotype clusters were derived by expectation-maximization algorithm. Genotype-phenotype correlations were done using Mann-Whitney U test and Kruskal-Wallis test. RESULTS: Significant interethnic variations were observed in PXR pharmacogenetics among the three Asian ethnic groups. The expression of PXR mRNA in liver tissues harboring the PXR*1B haplotype clusters was 4-fold lower compared with the non-PXR*1B (*1A + *1C) haplotype clusters [PXR*1B versus PXR*1A; P=0.015; PXR*1B versus PXR*1C; P=0.023]. PXR*1B-bearing liver tissues were associated with significantly lower expression of CYP3A4 (PXR*1B versus non-PXR*1B, P=0.030) and ABCB1 (PXR*1B versus non-PXR*1B, P=0.060) compared with non-PXR*1B-bearing liver tissues. Doxorubicin clearance in breast cancer patients harboring the PXR*1B haplotypes was significantly lower compared with patients carrying the non-PXR*1B haplotypes [PXR*1B versus non-PXR*1B, CL/BSA (L h(-1) m(-2)): 20.84 (range, 8.68-29.24) versus 24.85 (range, 13.80-55.66), P=0.022]. CONCLUSIONS: This study showed that PXR*1B was associated with reduced hepatic mRNA expression of PXR and its downstream targets, CYP3A4 and ABCB1. Genotype-phenotype correlates in breast cancer patients showed PXR*1B to be significantly associated with lower doxorubicin clearance, suggesting that PXR haplotype constitution could be important in influencing interindividual and interethnic variations in disposition of its putative drug substrates.


Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Citocromo P-450 CYP3A/metabolismo , Doxorrubicina/metabolismo , Receptores de Esteroides/genética , Receptores de Esteroides/metabolismo , Subfamília B de Transportador de Cassetes de Ligação de ATP , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Grupo com Ancestrais do Continente Asiático/genética , Neoplasias da Mama/tratamento farmacológico , Doxorrubicina/uso terapêutico , Feminino , Frequência do Gene , Haplótipos , Humanos , Desequilíbrio de Ligação , Fígado/metabolismo , Polimorfismo Genético , Receptor de Pregnano X , RNA Mensageiro/metabolismo
19.
Breast ; 17(5): 517-22, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18502128

RESUMO

This was a single institution phase I/II study to determine the maximum tolerated dose (MTD) and efficacy of pegylated liposomal doxorubicin (PLD) and gemcitabine in Asian women with metastatic breast cancer. PLD was administered on day 1 and gemcitabine on days 1 and 8 every 3 weeks at escalating doses from 25 mg/m(2) and 1000 mg/m(2) onwards respectively. The median age was 56 years with a median disease-free interval of 43 months. Majority of the patients had visceral involvement. At PLD 35 mg/m(2) and gemcitabine 1200 mg/m(2), the overall response rate for 23 evaluable patients was 83% (1 CR, 18 PR, 3 SD, 1 PD). Six had prior adjuvant anthracyclines (3 PR, 1 SD). The median follow-up was 81 weeks and progression free interval was 29 weeks. Overall survival was 23.9 months. The dose limiting toxicities were mucositis and myelosuppression. This regimen is active and reasonably tolerated as first-line therapy.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Desoxicitidina/análogos & derivados , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Neoplasias da Mama/etnologia , Neoplasias da Mama/patologia , Desoxicitidina/administração & dosagem , Desoxicitidina/efeitos adversos , Progressão da Doença , Doxorrubicina/administração & dosagem , Doxorrubicina/efeitos adversos , Doxorrubicina/análogos & derivados , Esquema de Medicação , Feminino , Seguimentos , Humanos , Infusões Intravenosas , Estimativa de Kaplan-Meier , Dose Máxima Tolerável , Pessoa de Meia-Idade , Polietilenoglicóis/administração & dosagem , Polietilenoglicóis/efeitos adversos , Resultado do Tratamento
20.
J Clin Oncol ; 26(18): 2999-3005, 2008 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-18458039

RESUMO

PURPOSE: This study (EGF20009) assessed the efficacy and tolerability of two lapatinib administration schedules as first-line monotherapy in women with ErbB2-amplified locally advanced or metastatic breast cancer. PATIENTS AND METHODS: Patients with ErbB2-amplified, locally advanced or metastatic breast cancer previously untreated in the metastatic setting were randomly assigned to one of two lapatinib dose cohorts and received either 1,500 mg once daily or 500 mg twice daily. Clinical response was assessed at weeks 8 and 12 and every 12 weeks thereafter. RESULTS: A total of 138 patients were treated with lapatinib for a median of 17.6 weeks. The overall response rate (complete response [CR] plus partial response [PR]) was 24% in the intent-to-treat population, and 31% of patients derived clinical benefit (CR, PR, or stable disease for >or= 24 weeks). The median time to response was 7.9 weeks, and the progression-free survival rates at 4 and 6 months were 63% and 43%, respectively. The most common lapatinib-related adverse events (AEs) were diarrhea, rash, pruritus, and nausea, and these events were primarily grade 1 or 2. There were no significant differences in clinical activity or the AE profile between the dosing schedules. CONCLUSION: Lapatinib demonstrated clinical activity and was well tolerated as first-line therapy in ErbB2-amplified locally advanced or metastatic breast cancer. This study supports further evaluation of lapatinib in first-line and early-stage ErbB2-overexpressing breast cancer.


Assuntos
Antineoplásicos/administração & dosagem , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/enzimologia , Quinazolinas/administração & dosagem , Receptor ErbB-2/biossíntese , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/efeitos adversos , Intervalo Livre de Doença , Esquema de Medicação , Feminino , Humanos , Lapatinib , Pessoa de Meia-Idade , Metástase Neoplásica , Inibidores de Proteínas Quinases/administração & dosagem , Inibidores de Proteínas Quinases/efeitos adversos , Quinazolinas/efeitos adversos , Receptor ErbB-2/antagonistas & inibidores
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