Cyclopenta(f)isoquinoline derivatives designed to bind specifically to native deoxyribonucleic acid. 3. Interaction of 6-carbamylmethyl-8-methyl-7H-cyclopenta(f)isoquinolin-3(2H)-one with deoxyribonucleic acids and polydeoxyribonucleotides

Pharmacogenetics in colorectal cancer: a systematic review

Pharmacological treatment of colorectal cancer has improved survival rates in recent years. Individual genetic variation in genes associated with metabolism and targets of commonly used drugs can be responsible for variability in treatment outcome and toxicity. Diverse study designs have been used and heterogeneous end points evaluated by studies assessing the association of genetic markers with treatment outcome. We conducted this systematic review, including 51 studies, to present a comprehensive overview and draw further conclusions. To facilitate comparison of reported study results, risk estimates for observed genetic variants in 33 key genes are presented using defined reference categories and recalculated risk estimates based on data provided in original publications, where necessary. Overall, evidence indicates associations of the UGT1A1(*) 28 variant genotype with toxicity after irinotecan treatment, mutations in GSTP1-105 with improved treatment outcome and the XPD-751 variant genotype with poor treatment outcome after oxaliplatin treatment, and amplification of the EGFR gene with improved treatment outcome after therapy with monoclonal antibodies. Adequately powered prospective investigations designed specifically for pharmacogenetics are needed.

Predictive and prognostic markers in colorectal cancer

Despite recent advances in the treatment of both early and advanced colorectal cancer, it remains the second leading cause of cancer deaths in the western world. There is, therefore, a pressing need to optimize the use of the currently available systemic therapies and to identify active new agents for the treatment of this disease. Pharmacogenomic studies have shown that genetically determined variability in key cellular functions can influence toxicity, response to treatment and survival. Numerous examples of these single ‘classical’ markers have been identified for a wide range of agents and each has been studied with regard to its effect on response. However, in any individual or tumor it is likely that a number of complex, interacting factors are involved in determining the likelihood of benefit with a given therapeutic agent. Microarray-based gene-expression profiling has allowed the complex range of molecular changes occurring in the cell and surrounding stroma to be assessed in relation to response and prognosis. Predictive gene sets have been developed and, along with other markers, are being assessed in prospective clinical trials. Treatment may soon be individualized by using this technology to predict which patients will benefit from a particular systemic therapy or which are likely to develop recurrence.

Prediction of efficacy and side effects of chemotherapy in colorectal cancer

Treatment of gastrointestinal cancers has significantly advanced over the last several years with the introduction of effective chemotherapeutic and targeted drugs. Providing individual treatment with low toxicity but maximum benefit is still an unsolved problem. Inter-individual variation of drug toxicity and efficacy is mainly determined by genetic polymorphisms. The genetic approach of pharmacogenetics and pharmacogenomics is developing as a valuable tool to design tailored therapy. This review focuses on clinically significant polymorphisms in genes involved in metabolism of chemotherapy used in gastrointestinal cancer: fluoropyrimidines, irinotecan, and platinum. In addition, the first results of pharmacogenetics in targeted therapy including cetuximab and bevacizumab are discussed.

Pharmacogenetics in Gastrointestinal Tumors

Treatment of gastrointestinal cancers has significantly advanced over the last few years with the introduction of effective chemotherapeutic and targeted drugs. To provide individual treatment with low toxicity on the one hand but maximum benefit on the other hand is still an unsolved problem. Interindividual variation of drug toxicity and efficacy is determined by genetic polymorphisms. The genetic approach based on single-gene (pharmacogenetics) or multi-gene (pharmacogenomics) analyses is developing as a valuable tool to design tailored therapy. This review focuses on clinically significant polymorphisms in genes involved in the metabolism of the major players in the chemotherapy of gastrointestinal cancer: fluoropyrimidines, irinotecan and platinum. In addition, first results of pharmacogenetics in targeted therapy including cetuximab and bevacizumab are discussed. The pharmacogenetic approach to individualize therapy in gastrointestinal cancers is promising, but additional larger and controlled studies are needed to justify changes of treatment strategies.

Pharmacogenetic aspects in treatment of colorectal cancer – an update

Pharmacogenomic analyses will become crucial to predict patients’ toxicity to treatment and will also help to predict the tumor response. Processes of drug metabolism, drug efflux, DNA-repair and characteristics of drug targets are critical checkpoints of drug efficacy. These crucial pathways for drug action have been part of pharmacogenomic studies evaluating the impact of genomic variants on transcription, translation, protein structure and substrate binding of the genes involved. Promising candidates have been identified with predictive value for response and toxicity to chemotherapy in colorectal cancers. These candidates need to be incorporated into large, prospective clinical trials to confirm their impact for response and survival to chemotherapy that has been reported in retrospective analyses. Confirmed predictive markers, together with additional yet to be identified pharmacogenomic key players, will provide the basis for tailoring chemotherapy in the future.

Implications of genetic testing in the management of colorectal cancer

The prognosis of patients with colorectal cancer is impacted by various factors at the time of diagnosis, including location of the tumor, gender, age and overall performance status of the patient. Optimal postoperative management of patients who have undergone successful tumor resection involves the utilization of reliable determninants of prognosis to help select patients who would benefit from adjuvant treatment, while sparing others from drug-related adverse effects. Tailoring chemotherapy for patients with disseminated cancer, or for patients who receive adjuvant chemotherapy, is also critical. Interpatient differences in tumor response and drug toxicity are common during chemotherapy. Genomic variability of key metabolic enzyme complexes, drug targets, and drug transport molecules is an important contributing factor. The identification of genetic markers of response and prognosis will aid in the development of more individualized chemotherapuetic strategies for cancer patients. Potential prognostic indicators in colorectal cancer include oncogenes, tumor suppressor genes, genes involved in angiogenic and apoptotic pathways and cell proliferation, and those encoding targets of chemotherapy. Specifically, molecular markers such as deletion of 18q (DCC), p27 and microsatellite instability are promising as indicators of good or poor prognosis. Molecular determinants of efficacy and host toxicity of the most commonly used drugs in colorectal cancer, fluoracil, irinotecan and oxaliplatin, are being investigated. Alterations in gene expression, protein expression and polymorphic variants in genes encoding thymidylate synthase, dihydropyrimidine dehydrogenase, dUTP nucleotidehydrolase and thymidine phosphorylase (for fluoropyrimidine-based chemotherapy), uridine diphosphate glucosyltransferase (UGT) 1A1 and carboxylesterase (for irinotecan therapy), and excision repair cross-complementing genes (ERCC1 and ERCC2) and glutathione-S-transferase P1 (for oxalilplatin-based regimens) may be useful as markers for clinical drug response, survival and host toxicity.

Physico-chemical study of the complexes of "33258 Hoechst" with DNA and nucleohistone

The degree of binding of "33258 Hoechst" to DNA and nucleohistone has been determined by equilibrium dialysis and the properties of the complexes have been followed by different optical and electro-optical methods, after determining the orientation of the main transition moments within the dye molecule. The binding isotherm was found composed of a Langmuir-type and of a strongly cooperative component. The existence of two bound species yielded a continuous variation of most of the properties of the complexes studied as the amount of binding increased, while the hydrodynamic properties of the macromolecules were not affected. At low binding, the strongly bound dye molecules appeared to bind to highly fluorescent sites with their long axis oriented at 45 degree to the helix axis. As the binding proceeds, less fluorescent sites are cooperatively occupied and the inclination of these ligand molecules becomes closer to that of the base planes. These results are compatible with the formation of two external complexes with the double helical structure.