Using germ-line genetic variation to investigate and treat cancer

Cancer pharmacogenetics

Cancer pharmacogenetics is a burgeoning field. There are now many published associations between genotype and outcome or toxicity from chemotherapy treatment. Performing pharmacogenetics studies in cancer requires careful consideration of the sample type to be used (germline vs tumor); the genotyping platform to be used (medium, low, or high throughput); and the analysis and reporting of associations and observations.

Molecular-based choice of cancer therapy: realities and expectations

Current choice of cancer therapy is usually empirical and relies mainly on the statistical prediction of the treatment success. Molecular research provides some opportunities to personalize antitumor treatment. For example, life-threatening toxic reactions can be avoided by the identification of subjects, who carry susceptible genotypes of drug-metabolizing genes (e.g. TPMT, UGT1A1, MTHFR, DPYD). Tumor sensitivity can be predicted by molecular portraying of targets and other molecules associated with drug response. Tailoring of antiestrogen and trastuzumab therapy based on hormone and HER2 receptor status has already become a classical example of customized medicine. Other predictive markers have been identified both for cytotoxic and for targeted therapies, and include, for example, expression of TS, TP, DPD, OPRT, ERCC1, MGMT, TOP2A, class III beta-tubulin molecules as well as genomic alterations of EGFR, KIT, ABL oncogenes.

High-throughput genomic technology in research and clinical management of breast cancer. Evolving landscape of genetic epidemiological studies

Candidate polymorphism-based genetic epidemiological studies have yielded little success in the search for low-penetrance breast cancer susceptibility genes. The lack of progress is partially due to insufficient coverage of genomic regions with genetic markers, as well as economic constraints, limiting both the number of genetic targets and the number of individuals being studied. Recent rapid advances in high-throughput genotyping technology and our understanding of genetic variation patterns across the human genome are now revolutionizing the way in which genetic epidemiological studies are being designed and conducted. Genetic epidemiological studies are quickly progressing from candidate gene studies to comprehensive pathway investigation and, further, to genomic epidemiological studies where the whole human genome is being interrogated to identify susceptibility alleles. This paper reviews the evolving approaches in the search for low-penetrance breast cancer susceptibility gene variants and discusses their potential promises and pitfalls.

The emerging importance of DNA mapping and other comprehensive screening techniques, as tools to identify new drug targets and as a means of (cancer) therapy personalisation

Every human being is genetically unique and this individuality is not only marked by morphologic and physical characteristics but also by an individual's response to a particular drug. Single nucleotide polymorphisms (SNPs) are largely responsible for one's individuality. A drug may be ineffective in one patient, whereas the exact same drug may cure another patient. Recent advances in DNA mapping and other screening technologies have provided researchers and drug developers with crucial information needed to create drugs that are specific for a given individual. In the future, physicians will be able to prescribe individualised drugs adjusted to, for example, activities of specific enzymatic pathways that would either be targeted by these drugs, or would be responsible for drug conversion or inactivation. Furthermore, the mapping of the human genome allows broader development and application of drugs that act on the level of gene transcription rather than as simple biochemical inhibitors or activators of certain enzymes. Such new approaches will maximise desired therapeutic results and may completely eliminate severe side effects. To illustrate the potential of genetic translational research, the authors discuss available analytical methodologies such as; gene arrays, flow cytometry-based screening for SNPs, proteomics, metabolomics, real-time PCR, and other methods capable of detecting both SNPs, as well as more profound changes in cell metabolism. Finally, the authors provide several examples that focus mostly on targeting protein-DNA interactions, but also other processes.

CEPH individuals are representative of the European American population: implications for pharmacogenetics

Previous studies have highlighted the use of phenotype generation in immortalized lymphoblastoid cells from the Centre d'Etude du Polymorphisme Humain (CEPH) pedigrees as a powerful means of discovering genes involved in complex biological and pharmacological phenotypes. However, there is no data on how representative CEPH pedigrees are of the general population of European origin for genetic variants of pharmacogenetic significance. A vast amount of data in a population of restricted applicability would be of little value. Genotype and allele frequencies of 28 variants in 15 pharmacogenetically relevant genes were analyzed in germ-line DNA from European- and African-origin blood donors, and CEPH cell lines of European origin. The results demonstrate that allele frequencies for the 28 polymorphisms are highly similar between the CEPH and the European-origin populations. However, genotype frequencies in the CEPH population did not provide a high level of prediction for the African-origin population. These data support the usefulness of the CEPH panel in pharmacogenetic discovery efforts for European-derived populations.