Influence of MSI and 18q LOH markers on capecitabine adjuvant monotherapy in colon cancer patients

Nadica Matevska-Geshkovska,1 Marija Staninova-Stojovska,1 Aleksandra Kapedanovska-Nestorovska,1 Natalija Petrushevska-Angelovska,2 Milco Panovski,3 Biljana Grozdanovska,2 Nenad Mitreski,2 Aleksandar Dimovski1 1Center for Biomolecular Pharmaceutical Analyses, Faculty of Pharmacy, Ss. Cyril and Methodius University in Skopje, Skopje, Macedonia; 2University Clinic for Oncology and Radiotherapy, Ss. Cyril and Methodius University in Skopje, Skopje, Macedonia; 3University Clinic for Abdominal Surgery, Ss. Cyril and Methodius University in Skopje, Skopje, Macedonia Purpose: The aim of this study was to evaluate whether pretreatment analysis of selected molecular markers can be used for the prediction of disease-free survival (DFS)/overall survival (OS) of capecitabine adjuvant monotherapy in colon cancer patients.Patients and methods: A total of 126 patients enrolled in a capecitabine Phase IV clinical trial were analyzed for microsatellite instability (MSI), 18q loss of heterozygosity (LOH), thymidylate synthase (TYMS) 5′ variable number of tandem repeat (VNTR), and methylene tetrahydrofolate reductase (MTHFR) C677T variants. The significance in predicting 5-year DFS/OS was assessed by Kaplan–Meier and Cox regression analyses.Results: The MSI-high (MSI-H) genotype was significantly associated with DFS (HR 0.205, 95% CI 0.05–0.88, P=0.033) and OS (HR 0.208, 95% CI 0.05–0.89, P=0.035) compared to the microsatellite stable genotype. In models stratified according to clinicopathologic characteristics, the MSI-H genotype remained a positive predictive factor for DFS/OS only in patients with stage III (P=0.023) and patients with tumors localized proximally to the splenic flexure (P=0.004). Distal colon cancers with 18q LOH have a greater survival rate when treated with capecitabine than patients with stable tumors (81.3% vs 50.0%, HR for relapse 0.348, 95% CI 0.13–0.97, P=0.043). TYMS 5′VNTR and MTHFR C677T variants were not associated with DFS or OS.Conclusion: MSI and 18q LOH markers have the potential to be utilized in the selection of colon cancer patients eligible for capecitabine adjuvant monotherapy. Keywords: gastrointestinal cancer, microsatellite instability, 18q allelic imbalance, prognostic marker&nbsp

Molecular basis of inherited colorectal carcinomas in the Macedonian population: An update

Hereditary factors are assumed to play a role in ~35.0-45.0% of all colorectal cancers (CRCs) with about 5.0-10.0% associated with high penetrant disease-causing mutations in genes correlated to hereditary polyposis (HP) or hereditary non polyposis syndromes (HNPCC). Although inherited germline mutations in mismatch repair (MMR) and the APC genes contribute significantly to CRC, genetic diagnosis cannot yet be obtained in more than 50.0% of familial cases. We present updated data of 107 probands from the Macedonian population with clinically diagnosed HP (n = 41) or HNPCC (n = 66) obtained by next generation sequencing (NGS) with three different gene panels covering the coding, flanking and promoter regions of 114 cancer predisposition genes. Using this approach, we were able to detect deleterious mutations in 65/107 (60.7%) patients, 50.4% of which were in known well-established CRC susceptibility genes and 10.2% in DNA repair genes (DRG). As expected, the highest frequencies of deleterious variants were detected in familial adenomatous polyposis (FAP) and in HNPCC patients with microsatellite instability (MSI) tumors (93.8 and 87.1%, respectively). Variants of unknown significance (VUS) were detected in 24/107 (22.4%) patients, mainly in HNPCC patients with microsatellite stable (MSS) tumors or patients with oligopolyposis. The majority of VUS were also found in DRG genes, indicating the potential role of a doble-strand brake DNA repair pathway deficiency in colorectal cancerogenesis. We could not detect any variant in 18/107 (16.8%) patients, which supports the genetic heterogeneity of hereditary CRC, particularly in HNPCC families with MSS tumors and in families with oligopolyposis

Distribution of the Most Common Genetic Variants Associated with a Variable Drug Response in the Population of the Republic of Macedonia

Genetic variation in the regulation, expression and activity of genes coding for Phase I, Phase II drug metabolizing enzymes (DMEs) and drug targets, can be defining factors for the variability in both the effectiveness and occurrence of drug therapy side effects. Information regarding the geographic structure and multi-ethnic distribution of clinically relevant genetic variations is becoming increasingly useful for improving drug therapy and explaining inter-individual and inter-ethnic differences in drug response

Frequencies of Single-Nucleotide Polymorphisms and Haplotypes of the SLCO1B1 Gene in Selected Populations of the Western Balkans

As a membrane influx transporter, organic anion- transporting polypeptide 1B1 (OATP1B1) regulates the cellular uptake of a number of endogenous compounds and drugs. The aim of this study was to characterize the diversity of the solute carrier organic anion transporter family member 1B1 (SLCO1B1) gene encoding this transporter in two ethnic groups populating the Western Balkans. The distribution of SCLO1B1 alleles was determined at seven variant sites (c.388A>G, c.521T>C, c.571T>C, c.597C>T, c.1086C>T, c.1463G>C and c.*439T>G) in 266 Macedonians and 94 Albanians using the TaqMan allelic discrimination assay. No significant difference in the frequencies of the single nucleotide polymorphisms (SNPs) was observed between these populations. The frequency of the c.521T>C SNP was the lowest (C and c.1086 C>T SNPs were not identified in either ethnic group. The haplotype analysis revealed 20 and 21 different haplotypes in the Macedonian and Albanian population, respectively. The most common haplotype in both ethnic groups, *1J/*1K/*1L, had a frequency of 39.0% and 26.6%, respectively. In both populations, the variant alleles of the functionally significant c.521T>C and c.388A>G SNPs existed in one major haplotype (*15/*16/*17), with a frequency of 8.6 and 2.4% in the Macedonian and Albanian subjects, respectively. In conclusion, sequence variations of the SLCO1B1 gene in the studied populations occur at high frequencies, which are similar to that of the Caucasian population. Further studies are needed to evaluate the clinical significance of these SNPs and/ or the major SLCO1B1 haplotypes they form for a large number of substrates and for susceptibility to certain diseases

Analysis of TSHZ2 and TSHZ3 genes in congenital pelvi-ureteric junction obstruction

International audienc

The association of C3435T single-nucleotide polymorphism, Pgp-glycoprotein gene expression levels and carbamazepine maintenance dose in patients with epilepsy

Zoran Sterjev1, Gordana Kiteva Trencevska2, Emilija Cvetkovska2, Igor Petrov2, Igor Kuzmanovski2, Jasmina T Ribarska3, Aleksandra K Nestorovska1, Nadica Matevska1, Zorica Naumovska1, Suzana Jolevska-Trajkovic3, Aleksandar Dimovski1, Ljubica Suturkova11Institute of Pharmaceutical Chemistry, Faculty of Pharmacy Skopje, Republic of Macedonia; 2Clinic of Neurology, Faculty of Medicine, Skopje, Republic of Macedonia; 3Institute of Pharmaceutical Analysis, Faculty of Pharmacy Skopje, Republic of MacedoniaAbstract: The ABCB1 gene encodes the P-glycoprotein (Pgp) protein, which is thought to transport various antiepileptic drugs. The single nucleotide polymorphism (SNP) (C3435T) in exon 26 of this gene correlates with the altered expression levels of P-glycoprotein, range of drug response and clinical conditions. In order to investigate the influence of this polymorphism on the susceptibility to and efficacy of carbamazepine therapy, we evaluated the allelic frequency and genotype distribution of this variant in 162 epilepsy patients from the Republic of Macedonia. Statistically significant differences were detected neither in the allelic frequency and genotype distribution between carbamazepine-resistant and carbamazepine-responsive epilepsy patients nor between the subgroups of carbamazepine (CBZ)-responsive patients treated with different CBZ doses. However, the T-allele was enriched in CBZ-responsive patients who required higher maintenance CBZ doses, This observation was substantiated by the findings that the median total plasma levels were the lowest in patients with CC (20 µmol/L) followed by CT (23 µmol/L) and TT (29 µmol/L) genotypes. Patients with a CC genotype also had a higher likelihood of response compared to patients with CT or TT genotypes over a wide range (400–1000 mg/day) of initial doses of CBZ. The T allele showed a reduced expression of ~5% compared to the C allele in peripheral blood mononuclear cells in heterozygotes for the variant. This difference might be translated into ~10% difference in homozygotes for the variant, which would explain the trend towards a dose-dependent efficacy of the CBZ treatment in patients with different genotypes. A larger prospective study is warranted to clarify the clinical utility of a genotype-specific individualized CBZ therapy.Keywords: multidrug resistance protein 1 (MDR1), ABCB1 C3435T polymorphism, epilepsy treatment, carbamazepin