Predictive Genetic Markers Research Articles

Vinorelbine (VRB) plus gemcitabine (GEM) as first-line treatment for elderly patients (p) with advanced non-small cell lung cancer (NSCLC): Molecular correlates

18040 Background: The clinical benefit of non-cisplatin doublets vs a single agent in elderly or unfit p is still controversial. The present study focuses on clinical outcome with VRB/GEM in elderly p and the role of functional status and comorbidities. Genetic predictive markers of response to VRB/GEM will also be examined in genomic and cDNA from tumor and circulating tumor DNA. Methods: 145 chemonaive p with stage IIIB (pleural effusion or supraclavicular lymph nodes)-IV or recurrent NSCLC and age > 70 years were accrued at 32 sites between April 2004 and January 2006. Treatment consisted of VRB 25 mg/m2 IV or 60–80 mg/m2 oral plus GEM 1200 mg/m2, days 1, 8 every 21 days. Activities of daily living (ADL), instrumental activities of daily living (IADL) and comorbidities were evaluated. DNA samples were collected from primary tumors for the assessment of microtubule associated protein 4 (MAP4) and from serum for the checkpoint with forkhead-associated and ring finger (CHFR) methylation. Results: Data on 130 p is available. Median age 76 years (69–83); males: 86.8%; smokers: 70.5%; PS 0–1: 83.9%; adenocarcinoma: 34.4% / squamous: 48%; stage IIIB: 22.7%, IV: 77.3%. Self-sufficiency in ADL and IADL was 77.4% and 45.2% of the p analyzed. 68% of the p had comorbidities. Median cycles: 3 (1–8). Hematological toxicities (%p): grade 3/4 neutropenia, 7.8%/4.7%; grade 3/4 thrombocytopenia, 2.3%/0.8%; grade 3 anemia, 3.1%. Efficacy in evaluable population: PR, 23.2% (95% CI, 15.1% to 32.9%); SD, 41.1%. 24 p died during the treatment period (non toxicity related) and 21 p were not evaluable. With a median follow up of 5.8 months, median survival for the whole population was 4.97 months (m), progression free survival 4.53 m, event free survival 3.43 m, 1-year survival 26.6%. Statistically significant differences in median survival were observed among subgroups: PS 0–1/2, 6.5/2.3 m (p<0.001); sex male/female, 4.5/9.7 m (p 0.027); ADL <6/=6, 3.4/7.1 m (p 0.023). Conclusions: This trial confirms that VRB/GEM is effective, presenting a favorable toxicity profile in elderly p with advanced NSCLC. Complete data on genetic markers will be presented. No significant financial relationships to disclose.

Radiosensitivity of Human Fibroblasts is Associated With Amino Acid Substitution Variants in Susceptible Genes And Correlates With The Number of Risk Alleles

Genetic predictive markers of radiosensitivity are being sought for stratifying radiotherapy for cancer patients and risk assessment of radiation exposure. We hypothesized that single nucleotide polymorphisms in susceptible genes are associated with, and the number of risk alleles has incremental effect on, individual radiosensitivity. Six amino acid substitution variants (ATM 1853 Asp/Asn G>A, p53 72 Arg/Pro G>C, p21 31 Ser/Arg C>A, XRCC1 399 Arg/Gln G>A, XRCC3 241 Thr/Met C>T, and TGFbeta1 10 Leu/Pro T>C) were genotyped by direct sequencing in 54 fibroblast strains of different radiosensitivity. The clonogenic survival fraction at 2 Gy range was 0.15-0.50 (mean, 0.34, standard deviation, 0.08). The mean survival fraction at 2 Gy divided the cell strains into radiosensitive (26 cases) and normal (28 controls). A significant association was observed between the survival fraction at 2 Gy and ATM 1853 Asn, XRCC3 241 Met, and TGFbeta1 10 Leu alleles (p = 0.05, p = 0.02, and p = 0.02, respectively). The p53 72 Arg allele showed a borderline association (p = 0.07). The number of risk alleles increased with increasing radiosensitivity, and the group comparison showed a statistically significant difference between the radiosensitive and control groups (p < or = 0.001). The results of our study have shown that single nucleotide polymorphisms in susceptible genes influence cellular radiation response and that the number of risk alleles has a combined effect on radiosensitivity. Individuals with multiple risk alleles could be more susceptible to radiation effects than those with fewer risk alleles. These results may have implications in predicting normal tissue reactions to radiotherapy and risk assessment of radiation exposure.

228 INVITED Unbiased approach to identify predictive genetic markers for effects of cytotoxic agents

228 INVITED Unbiased approach to identify predictive genetic markers for effects of cytotoxic agents

Elderly advanced non-small-cell lung cancer (NSCLC) patients (p) treated with vinorelbine (vrb) plus gemcitabine (gem): Molecular correlates

17043 Background: The clinical benefit of non-cisplatin doublets (vrb/gem) vs a single agent (vrb or gem) in elderly p is still controversial. The present study focuses on clinical outcome with vrb/gem in the elderly and the role of functional status. Genetic predictive markers of response to vrb/gem will also be examined in genomic and cDNA from tumor and circulating tumor DNA. Methods: NSCLC p with stage IIIB (pleural effusion or supraclavicular lymph nodes)-IV or recurrent disease and age ≥ 70 years were treated with vrb (25 mg/m2 iv or 60–80 mg/m2 oral) plus gem 1200 mg/m2, days 1,8 every 21 days. Activities of daily living (ADL), instrumental activities of dalily living (IADL) and comorbidities were evaluated. Primary tumor and baseline serum DNA were collected for assessment of microtubule associated protein 4 (MAP4) in tumor and checkpoint with forkhead-associated and ring finger (CHFR) methylation in serum. A preliminary analysis of response and toxicity was performed on 51 p. Results: From April 2004 to December 2005, 145 p were included. Data on 68 p is available: median age 74.5 years (70–83); stage IIIB: 21.2%, IV: 78.7%; PS 0: 23.4%, 1: 54.6%, 2: 21.8%. Self-sufficiency in ADL and IADL was 56.2% and 25% of the p analyzed. All p but 8 had comorbidities. Response rate for 51 p: partial response, 12% (95% CI, 8.9–20%); stable disease, 32% (95% CI, 19.2–44.8%). Main hematological toxicities: grade 3/4 neutropenia, 8.3/4.1%; grade 3 thrombocytopenia, 4.1%; grade 3 anemia, 4.1% of the p respectively. Conclusions: Preliminary findings indicate that vrb/gem is feasible in elderly p with acceptable toxicity. Complete data on response, survival and genetic markers will be presented. No significant financial relationships to disclose.

Predictive and Prognostic Genetic Markers in Colorectal Cancer

TNM staging remains the most widely applied and clinically useful prognostic marker for colorectal cancer. However, on-going clinical investigations of genes involved in carcinogenesis, profiling of metabolic pathways to determine a tumor's response to chemotherapy, and the evolution of new technology for the simultaneous evaluation of thousands of potential genetic markers promise to improve our ability as surgeons to provide accurate prognoses for individual patients. We review well-known prognostic and predictive genetic markers in colorectal cancer, with emphasis on the use of genomics for determining patient outcome following surgical resection.

The role of myeloperoxidase and NADPH oxidase polymorphisms in clozapine-induced agranulocytosis

It is well-known that clozapine is oxidized by the combination of NADPH-oxidase and MPO to nitrenium ions (1). We compared the frequency of functional relevant polymorphisms in MPO and NADPH CYBA genes and screened CYBB for genetic variants in patients with clozapine induced agranulocytosis (CA), patients with other drug-induced agranulocytosis (DA) and controls. MPO AA carriers were significantly overrepresented among the clozapine group (odds ratio 5.30). MPO genotype distribution in patients suffering from ticlopidine-related agranulocytosis showed a marginally significant odds ratio of 8.44. There was no evidence for an association of the C242T polymorphism in CYBA to the risk of DA in all subjects as well as in subgroups. The CYBB gene was highly conserved. Sequencing of all exons of DA patients did not reveal deviations from the known DNA-sequence. Further research is necessary to find genetic markers for prediction of DA.

Rapid genotyping of the osteoporosis-associated polymorphic transcription factor Sp1 binding site in the COL1A1 gene by pyrosequencing.

We describe a novel polymerase chain reaction (PCR) and deoxyribonucleic acid (DNA) sequencingbased assay for rapid genotyping of the polymorphic Sp1 binding site in the COL1A1 gene (1). A single nucleotide G-->T substitution polymorphism at this GC-rich site has recently been reported to be a predictive genetic marker for low bone mineral density (BMD). To simplify screening for this marker, we optimized PCR conditions and subjected the amplicons to pyrosequencing, which is a convenient high-throughput sequence analysis technique, readily amenable to automation. The analysis of 200 deidentified convenience DNA samples extracted from blood revealed genotype frequences in Hardy-Weinberg equilibrium (SS 68.0%, Ss 28.5%, and ss 3.5%) in agreement with other studies of European populations. This study demonstrates for the first time that pyrosequencing can be used for rapid identification of the osteoporosis-associated single nucleotide polymorphism (SNP) in the COL1A1 gene.

Approaches to identifying genetic predictors of clinical outcome in rheumatoid arthritis.

Predicting which patients with rheumatoid arthritis (RA), at presentation, are likely to suffer a severe disease course based on genotype data would be a major clinical advance. It would ensure that patients at highest risk of a severe outcome could be targeted with early aggressive therapies. With a better understanding of interactions between genotype and drug response it would be possible to prescribe treatments most likely to be efficacious and safe for specific patient subgroups. While a clear genetic component has been demonstrated in RA severity, the identification of genetic factors poses a challenge to researchers in the field. Initiatives such as the SNP Consortium and advances in genotyping technology have facilitated the investigation of genetic factors in both disease susceptibility and severity. However, several other factors, such as the availability of suitable longitudinal cohorts, definition of outcome measures, study design, selection of genetic markers, and statistical power, will all contribute to the likely success of genetic studies. Several strategies that have been applied in the pursuit of genetic predictors of clinical outcome in RA. While some encouraging results have been generated, it has so far been difficult to quantify the predictive value of genetic markers and extrapolate the results from genetic studies to clinic patients. Establishing high quality prospective inception cohorts, a more systemic approach to defining suitable outcome measures, and understanding the effects of treatment, will be critical to the eventual identification of good predictive genetic markers.

The potential clinical value of GML and the p53 gene as a predictor of chemosensitivity for colorectal cancer.

Adjuvant chemotherapy with 5-fluorouracil (5-FU) and mitomycin C (MMC) has commonly been used after resection of colorectal cancer. The aim of this study was to determine the predictive value of p53 mutation or the expression of GML, a target of p53, for sensitivity to 5-FU and MMC. We analyzed p53 mutations and the expression of GML in six colorectal cancer cell lines (SW837, DLD-1, RPMI4788, WiDr, HT-29, and HCT116), and examined the correlation between genetic changes and in-vitro chemosensitivity to MMC and 5-FU by measuring the colony-forming ability in these cell lines. We also introduced GML cDNA into a cell line that lacked endogenous GML expression to investigate changes in sensitivity to MMC and 5-FU. The sensitivity to MMC was highest in HCT116, which had no p53 gene abnormalities and expressed endogenous GML, and lowest in RPMI4788 cells, which had neither p53 gene abnormalities nor expression of endogenous GML. For 5-FU treatment with 24-h exposure, HCT116 showed the highest sensitivity, and SW837, which had p53 mutations without expression of GML, showed the lowest sensitivity. The introduction of GML cDNA to RPMI4788 (RPMI4788-GML) showed that the sensitivity of RPMI4788-GML to MMC was enhanced almost to the level of HCT116 cells. However, when RPMI4788-GML were exposed to 5-FU for 24 h, the sensitivity of RPMI4788-GML was slightly increased compared with that of the parental cells, but was slightly lower than that of HCT116. GML expression and p53 mutation in colorectal cancer may be useful predictive genetic markers for sensitivity to MMC and 5-FU, respectively.

Angiotensin I converting enzyme and angiotensinogen gene polymorphisms related to 24-h blood pressure in paediatric type I diabetes mellitus.

The aim of this study was to evaluate two putative predictive genetic markers for hypertension in children and adolescents with diabetes mellitus. Ambulatory blood pressure measurements were performed in 199 patients with type I diabetes mellitus (mean age 16.5 years, mean duration of diabetes 7.7 years) and compared to those of 1141 healthy children. The local allele frequencies were established based on a control population consisting of 181 healthy subjects. The allele frequencies of the angiotensinogen gene M235T polymorphism was nearly identical in insulin-dependent diabetes mellitus patients (MM 33%, MT 51%, TT 16%) and controls (MM 35%, MT 49%, TT 16%). In contrast, the genotype distribution of the angiotensin I converting enzyme gene insertion/deletion (I/D) polymorphism was different between patients with type I diabetes mellitus (DD 26%, ID 49%, II 25%) and the control group (DD 37%, ID 44%, II 19%) (P=0.04). Relative nocturnal systolic and diastolic pressures in patients with diabetes were higher than in healthy age- and height-matched controls; no association was found with the angiotensinogen gene M235T polymorphism. Relative nocturnal diastolic blood pressure was higher in patients homozygous for the I allele of the angiotensin I converting enzyme gene. Nocturnal systolic and diastolic blood pressure is higher in patients with type I diabetes than in healthy children. The formerly described, but controversial, association of the M235T polymorphism with arterial hypertension could not be confirmed in this study.

Association analyses of the polymorphisms of angiotensin-converting enzyme and angiotensinogen genes with diabetic nephropathy in Japanese non-insulin-dependent diabetics

To investigate predictive genetic markers for diabetic nephropathy, we studied the genetic polymorphisms of angiotensin-converting enzyme (ACE) and angiotensinogen (AGN) in Japanese subjects with non-insulin-dependent diabetes mellitus (NIDDM) with and without nephropathy. Genotype distributions were studied in 132 unrelated NIDDM patients of three groups with normoalbuminuria ([Normo] n = 53), microalbuminuria ([Micro] n = 54), and macroalbuminuria ([Macro] n = 25). The ACE insertion/deletion (I/D) polymorphism of intron 16 was identified by polymerase chain reaction, and the AGN M235T polymorphism was identified by restriction fragment length polymorphism analysis. There were no significant associations between AGN 235 allele or genotype and diabetic nephropathy. The D allele of ACE was significantly more frequent in the Micro ( P = .003) and Macro ( P = .009) group than in the Normo group. Overall frequencies of the ACE genotype did not differ significantly between the Micro and Macro groups. There were significant relationships between I/D polymorphism and plasma ACE activity; the DD genotype had the highest activity. A multiple logistic regression analysis revealed that the D allele is a strong and independent risk factor for abnormal albuminuria in NIDDM patients. These results suggested that ACE I/D polymorphism, but not AGN M235T polymorphism, is a possible genetic risk factor for diabetic nephropathy in Japanese NIDDM patients.