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1.  Global assessment of genetic variation influencing response to retinoid chemoprevention in head and neck cancer patients 
Head and neck squamous cell carcinoma (HNSCC) patients are at an increased risk of developing a second primary tumor (SPT) or recurrence following curative treatment. 13-cis-retinoic acid (13-cRA) has been tested in chemoprevention clinical trials but the results have been inconclusive. We genotyped 9,465 SNPs in 450 patients from the Retinoid Head and Neck Second Primary Trial. SNPs were analyzed for associations with SPT/recurrence in patients receiving placebo to identify prognosis markers and further analyzed for effects of 13-cRA in patients with these prognostic loci. Thirteen loci identified a majority subgroup of patients at a high risk of SPT/recurrence and in whom 13-cRA was protective. Patients carrying the common genotype of rs3118570 in the retinoid X receptor (RXRA) were at a 3.33-fold increased risk (95% confidence interval [CI], 1.67–6.67) and represented over 70% of the study population. This locus also identified individuals who received benefit from chemoprevention with a 38% reduced risk (95% CI, 0.43–0.90). Analyses of cumulative effect and potential gene-gene interactions also implicated CDC25C:rs6596428 and JAK2:rs1887427 as two other genetic loci with major roles in prognosis and 13-cRA response. Patients with all three common genotypes had a 76% reduction in SPT/recurrence (95% CI, 0.093–0.64) following 13-cRA chemoprevention. Carriers of these common genotypes constituted a substantial percentage of the study population, indicating that a pharmacogenetics approach could help select patients for 13-cRA chemoprevention. The lack of any alternatives for reducing risk in these patients highlights the need for future clinical trials to prospectively validate our findings.
doi:10.1158/1940-6207.CAPR-10-0125
PMCID: PMC3955084  PMID: 21292633
HNSCC; SPT; single nucleotide polymorphisms; retinoids
2.  Genome-Wide Association Study of Survival in Non–Small Cell Lung Cancer Patients Receiving Platinum-Based Chemotherapy 
Background
Interindividual variation in genetic background may influence the response to chemotherapy and overall survival for patients with advanced-stage non–small cell lung cancer (NSCLC).
Methods
To identify genetic variants associated with poor overall survival in these patients, we conducted a genome-wide scan of 307 260 single-nucleotide polymorphisms (SNPs) in 327 advanced-stage NSCLC patients who received platinum-based chemotherapy with or without radiation at the University of Texas MD Anderson Cancer Center (the discovery population). A fast-track replication was performed for 315 patients from the Mayo Clinic followed by a second validation at the University of Pittsburgh in 420 patients enrolled in the Spanish Lung Cancer Group PLATAX clinical trial. A pooled analysis combining the Mayo Clinic and PLATAX populations or all three populations was also used to validate the results. We assessed the association of each SNP with overall survival by multivariable Cox proportional hazard regression analysis. All statistical tests were two-sided.
Results
SNP rs1878022 in the chemokine-like receptor 1 (CMKLR1) was statistically significantly associated with poor overall survival in the MD Anderson discovery population (hazard ratio [HR] of death = 1.59, 95% confidence interval [CI] = 1.32 to 1.92, P = 1.42 × 10−6), in the PLATAX clinical trial (HR of death = 1.23, 95% CI = 1.00 to 1.51, P = .05), in the pooled Mayo Clinic and PLATAX validation (HR of death = 1.22, 95% CI = 1.06 to 1.40, P = .005), and in pooled analysis of all three populations (HR of death = 1.33, 95% CI = 1.19 to 1.48, P = 5.13 × 10−7). Carrying a variant genotype of rs10937823 was associated with decreased overall survival (HR of death = 1.82, 95% CI = 1.42 to 2.33, P = 1.73 × 10−6) in the pooled MD Anderson and Mayo Clinic populations but not in the PLATAX trial patient population (HR of death = 0.96, 95% CI = 0.69 to 1.35).
Conclusion
These results have the potential to contribute to the future development of personalized chemotherapy treatments for individual NSCLC patients.
doi:10.1093/jnci/djr075
PMCID: PMC3096796  PMID: 21483023
3.  A genetic variant near the PMAIP1/Noxa gene is associated with increased bleomycin sensitivity 
Human Molecular Genetics  2010;20(4):820-826.
Mutagen sensitivity, a measurement of chromatid breaks induced by various mutagens in short-term cultures of peripheral blood lymphocytes, is an established risk factor for a number of cancers and is highly heritable. The purpose of this study is to identify genetic predictors of mutagen sensitivity. Therefore, we conducted a multi-stage genome-wide association study. The primary scan analyzed 539 437 autosomal SNPs in 673 healthy individuals, followed by validations in two independent sets of 575 and 259 healthy individuals, respectively. One SNP, rs8093763, on chromosome 18q21 showed significant association with bleomycin (BLM) sensitivity (combined P = 2.64 × 10−8). We observed significantly lower BLM-induced chromotid breaks for genotypes containing wild-type allele compared with the homozygous variant genotype in the discovery set (0.71 versus 0.90, P= 3.77 × 10−5) and in replication phase 1 (0.61 versus 0.84, P= 7.00 × 10−5). The result of replication phase 2 was not statistically significant (0.65 versus 0.68, P= 0.44). This SNP is approximately 64 kb from PMAIP1/Noxa, which is a radiation-inducible gene and exhibits higher expression in BLM-sensitive lymphoblastoid cell lines than insensitive cell lines upon BLM treatment. In conclusion, we identified a biologically plausible genetic variant on 18q21 near the PMAIP1/Noxa gene that is associated with BLM sensitivity.
doi:10.1093/hmg/ddq509
PMCID: PMC3024041  PMID: 21106707
4.  PI3K/PTEN/AKT/mTOR Pathway Genetic Variation Predicts Toxicity and Distant Progression in Lung Cancer Patients Receiving Platinum-based Chemotherapy 
Summary
Non-small cell lung cancer (NSCLC) is still the leading cause of cancer-related deaths. The effect of the PI3K/PTEN/AKT/mTOR signaling pathway on cancer treatment, including NSCLC, has been well documented. In this study, we analyzed associations between genetic variations within this pathway and clinical outcomes following platinum-based chemotherapy in 168 patients with stage IIIB (wet) or stage IV NSCLC. Sixteen tagging SNPs in five core genes (PIK3CA, PTEN, AKT1, AKT2, and FRAP1) of this pathway and identified SNPs associated with development of toxicity and disease progression. We observed significantly increased toxicity for patients with PIK3CA:rs2699887 (OR: 3.86, 95% CI: 1.08 – 13.82). In contrast, a SNP in PTEN was associated with significantly reduced risk for chemotherapeutic toxicity (OR: 0.44, 95% CI: 0.20 - 0.95). We identified three SNPs in AKT1 resulting in significantly decreased risks of distant progression in patients carrying at least one variant allele with HRs of 0.66 (95% CI: 0.45 - 0.97), 0.52 (95% CI: 0.35 - 0.77), and 0.62 (95% CI: 0.42 - 0.91) for rs3803304, rs2498804, and rs1130214, respectively. Furthermore, these same variants conferred nearly two-fold increased progression-free survival times. The current study provides evidence that genetic variations within the PI3K/PTEN/AKT/mTOR signaling pathway are associated with variation in clinical outcomes of NSCLC patients. With further validation, our findings may provide additional biomarkers for customized treatment of platinum-based chemotherapy for NSCLC.
doi:10.1016/j.lungcan.2010.04.008
PMCID: PMC2952281  PMID: 20447721
lung cancer; chemotherapy; platinum-agents; AKT; clinical outcomes
5.  Genetic variants and risk of lung cancer in never smokers: a genome-wide association study 
The lancet oncology  2010;11(4):321-330.
Summary
Background
Lung cancer in individuals who have never smoked tobacco products is an increasing medical and public-health issue. We aimed to unravel the genetic basis of lung cancer in never smokers.
Methods
We did a four-stage investigation. First, a genome-wide association study of single nucleotide polymorphisms (SNPs) was done with 754 never smokers (377 matched case-control pairs at Mayo Clinic, Rochester, MN, USA). Second, the top candidate SNPs from the first study were validated in two independent studies among 735 (MD Anderson Cancer Center, Houston, TX, USA) and 253 (Harvard University, Boston, MA, USA) never smokers. Third, further replication of the top SNP was done in 530 never smokers (UCLA, Los Angeles, CA, USA). Fourth, expression quantitative trait loci (eQTL) and gene-expression differences were analysed to further elucidate the causal relation between the validated SNPs and the risk of lung cancer in never smokers.
Findings
44 top candidate SNPs were identified that might alter the risk of lung cancer in never smokers. rs2352028 at chromosome 13q31.3 was subsequently replicated with an additive genetic model in the four independent studies, with a combined odds ratio of 1·46 (95% CI 1·26–1·70, p=5·94×10−6). A cis eQTL analysis showed there was a strong correlation between genotypes of the replicated SNPs and the transcription level of the gene GPC5 in normal lung tissues (p=1·96×10−4), with the high-risk allele linked with lower expression. Additionally, the transcription level of GPC5 in normal lung tissue was twice that detected in matched lung adenocarcinoma tissue (p=6·75×10−11).
Interpretation
Genetic variants at 13q31.3 alter the expression of GPC5, and are associated with susceptibility to lung cancer in never smokers. Downregulation of GPC5 might contribute to the development of lung cancer in never smokers.
doi:10.1016/S1470-2045(10)70042-5
PMCID: PMC2945218  PMID: 20304703
6.  Novel Susceptibility Loci for Second Primary Tumors/Recurrence in Head and Neck Cancer Patients: Large Scale Evaluation of Genetic Variants 
Background
This study was aimed to identify novel susceptibility variants for second primary tumor (SPT) or recurrence in curatively treated early stage head and neck squamous cell carcinoma (HNSCC) patients.
Methods
We constructed a custom chip containing a comprehensive panel of 9645 chromosomal and mitochondrial single nucleotide polymorphisms (SNPs) representing 998 cancer-related genes selected by a systematic prioritization schema. Using this chip, we genotyped 150 early-stage HNSCC patients with and 300 matched patients without SPT/recurrence from a prospectively conducted randomized trial and assessed the association of these SNPs with risk of SPT/recurrence.
Results
Individually, six chromosomal SNPs and seven mitochondrial SNPs (mtSNPs) were significantly associated with risk of SPT/recurrence after adjustment for multiple comparisons. A strong gene-dosage effect was observed these SNPs were combined, as evidenced by a progressively increasing SPT/recurrence risk as the number of unfavorable genotypes increased (P for trend < 1.00×10−20). Several polygenic analyses suggest an important role of interconnected functional network and gene-gene interaction in modulating SPT/recurrence. Furthermore, incorporation of these genetic markers into a multivariate model improved significantly the discriminatory ability over the models containing only clinical and epidemiologic variables.
Conclusions
This is the first large scale systematic evaluation of germline genetic variants for their roles in HNSCC SPT/recurrence. The study identified several promising susceptibility loci and demonstrated the cumulative effect of multiple risk loci in HNSCC SPT/recurrence. Furthermore, this study underscores the importance of incorporating germline genetic variation data with clinical and risk factor data in constructing prediction models for clinical outcomes.
doi:10.1158/1940-6207.CAPR-09-0025
PMCID: PMC2964280  PMID: 19584075
iSelect Infinium; Single nucleotide polymorphisms; Head and neck cancer; Secondary primary tumor; recurrence
7.  Genetic Variations in Cell Cycle Pathway and the Risk of Oral Premalignant Lesions 
Cancer  2008;113(9):2488-2495.
Background:
Cell-cycle checkpoint regulates cell cycle progression and proliferation. Alterations in cell-cycle control mechanisms are linked to tumorigenesis.
Methods:
This case-control study included 147 cases and 147 controls. We used a pathway-based approach to assess the association between 10 potential functional single-nucleotide polymorphisms from seven cell-cycle control genes and the risk of oral premalignant lesions (OPLs). We also used classification and regression tree analysis to examine high-order gene-gene and gene-smoking interactions.
Results:
Compared with the homozygous wild-type GG genotype of CCND1 P241P, individuals with the AG genotype exhibited an increased risk of OPL (odds ratio, 1.58; 95% confidence interval, 0.89–2.83), and carriers of the AA genotype had a significantly increased risk of OPL (odds ratio, 2.75; 95% confidence interval, 1.33–5.71), with risk increasing significantly with the increasing number of variant alleles (P = 0.006). The risk of OPL increased significantly as the number of unfavorable genotypes in the pathway increased (P = 0.002). The final decision tree in the CART analysis contained five terminal nodes. Compared with the never smokers (the lowest risk group), the odds ratios for terminal nodes 2 through 5 ranged from 1.21 to 5.40.
Conclusions:
Our results illustrated the advantage of using a pathway-based approach for analyzing gene-gene and gene-smoking interactions. Specifically, we showed that genetic polymorphisms in cell-cycle control pathway genes may contribute to the risk of OPL.
doi:10.1002/cncr.23854
PMCID: PMC2577230  PMID: 18823025
Cell-cycle pathway; SNP; Oral premalignant lesion; CART
8.  Germline Genetic variations in drug action pathways predict clinical outcomes in advanced lung cancer treated with platinum-based chemotherapy 
Pharmacogenetics and genomics  2008;18(11):955-965.
Purpose
Genetic polymorphisms contribute to interindividual variation in drug response. However, a single polymorphism is likely to exhibit a modest effect. Therefore, we applied a pathway-based approach to evaluate the cumulative effect of multiple polymorphisms on clinical outcome of patients with non-small cell lung cancer (NSCLC).
Methods
We genotyped 25 functional polymorphisms in 16 key genes involved in cisplatin metabolism and action and evaluated their associations with overall survival in 229 NSCLC patients receiving first-line cisplatin-based chemotherapy.
Results
Several biologically plausible main effects were identified in individual analysis. More importantly, when 6 polymorphisms in nucleotide excision repair genes were analyzed jointly, a significant trend of reduced risk of death with decreasing number of putative unfavorable genotypes was observed (P for trend <0.001 and log-rank p<0.001). Survival tree analysis revealed potential higher-order gene-gene interactions and categorized subgroups with dramatically different survival experiences, based on distinct genotype profiles. The median survival time was 78.5 months for terminal node 1 in the low-risk group, 15.1 months for terminal node 10 in the medium-risk group, and 6.7 months for terminal node 9 in the high-risk group (log rank P<0.001). We also constructed a prediction hazard model. The area under the curve (AUC) increased from 0.71 (using clinical variables only) to 0.84 (using clinical, epidemiological, and genetic variations from survival tree analysis).
Conclusions
Our results highlight the clinical potential of taking a pathway-based approach and using survival tree analytic approach to identify subgroups of patients with distinctly differing outcomes.
doi:10.1097/FPC.0b013e32830efdd4
PMCID: PMC2665725  PMID: 18854777
9.  Genetic Variants in Inflammation-Related Genes Are Associated with Radiation-Induced Toxicity Following Treatment for Non-Small Cell Lung Cancer 
PLoS ONE  2010;5(8):e12402.
Treatment of non-small cell lung cancer (NSCLC) with radiotherapy or chemoradiotherapy is often accompanied by the development of esophagitis and pneumonitis. Identifying patients who might be at increased risk for normal tissue toxicity would help in determination of the optimal radiation dose to avoid these events. We profiled 59 single nucleotide polymorphisms (SNPs) from 37 inflammation-related genes in 173 NSCLC patients with stage IIIA/IIIB (dry) disease who were treated with definitive radiation or chemoradiation. For esophagitis risk, nine SNPs were associated with a 1.5- to 4-fold increase in risk, including three PTGS2 (COX2) variants: rs20417 (HR:1.93, 95% CI:1.10–3.39), rs5275 (HR:1.58, 95% CI:1.09–2.27), and rs689470 (HR:3.38, 95% CI:1.09–10.49). Significantly increased risk of pneumonitis was observed for patients with genetic variation in the proinflammatory genes IL1A, IL8, TNF, TNFRSF1B, and MIF. In contrast, NOS3:rs1799983 displayed a protective effect with a 45% reduction in pneumonitis risk (HR:0.55, 95% CI:0.31–0.96). Pneumonitis risk was also modulated by polymorphisms in anti-inflammatory genes, including genetic variation in IL13. rs20541 and rs180925 each resulted in increased risk (HR:2.95, 95% CI:1.14–7.63 and HR:3.23, 95% CI:1.03–10.18, respectively). The cumulative effect of these SNPs on risk was dose-dependent, as evidenced by a significantly increased risk of either toxicity with an increasing number of risk genotypes (P<0.001). These results suggest that genetic variations among inflammation pathway genes may modulate the development of radiation-induced toxicity and, ultimately, help in identifying patients who are at an increased likelihood for such events.
doi:10.1371/journal.pone.0012402
PMCID: PMC2928273  PMID: 20811626

Results 1-9 (9)