DNA repair polymorphisms and treatment outcomes of patients with malignant mesothelioma treated with gemcitabine-platinum combination chemotherapy

Understanding Role of DNA Repair and Cytochrome p-450 Gene Polymorphisms in Cervical Cancer Patient Treated With Concomitant Chemoradiation

Background: Evidences suggest that single nucleotide polymorphisms (SNPs) can be considered as potential biomarkers for disease progression and therapeutic response in cervical cancer. The present study investigated the association of CYP1A1 T>C (rs4646903), CYP1A1 A>G (rs1048943), CYP2E1 T>A (rs6413432), RAD51 G>C (rs1801320), XRCC1 G>A (rs25487), XRCC2 G>A (rs3218536) and XRCC3 C>T (rs861539) polymorphisms with treatment outcome of cisplatin based chemoradiation (CRT).

Methods: Total 227 cervical cancer cases, treated with the same chemoradiotherapy regimen were selected for the study. Genotyping analysis was performed by PCR-restriction fragment length polymorphisms (PCR-RFLP). Treatment response was evaluated by Response Evaluation Criteria in Solid Tumors (RECIST). Association of all clinical data (responses, recurrence and survival of patients) and single nucleotide polymorphisms (SNPs) was analysed by using SPSS (version 21.0).

Results: Patients with TA/AA genotype of CYP2E1 T>A polymorphism showed significantly poor response while those with GC/CC genotype of RAD51 G>C showed better response (p = 0.008, p = 0.014 respectively). Death was significantly higher in patients with GG genotypes of RAD51 G>C and XRCC1 G>A (p = 0.006, p = 0.002 respectively). Women with GC+CC genotype of RAD51 G>C and AG+GG of XRCC1 showed better survival and also reduced risk of death (HR = 0.489, p = 0.008; HR = 0.484, p = 0.003 respectively).

Conclusion: Results suggested that CYP2E1 T>A (rs6413432), RAD51 G>C (rs1801320), and XRCC1 G>A (rs25487) polymorphisms may be used as predictive markers for clinical outcomes in cervical cancer patients undergoing cisplatin based concomitant chemoradiotherapy.

Impact of genetic factors on platinum-induced gastrointestinal toxicity

Severe gastrointestinal (GI) toxicity is a common side effect after platinum-based chemotherapy. The incidence and severity of GI toxicity vary among patients with the same chemotherapy. Genetic factors involved in platinum transport, metabolism, detoxification, DNA repair, cell cycle control, and apoptosis pathways may account for the interindividual difference in GI toxicity. The influence of gene polymorphisms in the platinum pathway on GI toxicity has been extensively analyzed. Variations in study sample size, ethnicity, design, treatment schedule, dosing, endpoint definition, and assessment of toxicity make it difficult to precisely interpret the results. Hence, we conducted a review to summarize the most recent pharmacogenomics studies of GI toxicity in platinum-based chemotherapy and identify the most promising avenues for further research.

Micronuclei Formation upon Radioiodine Therapy for Well-Differentiated Thyroid Cancer: The Influence of DNA Repair Genes Variants

Radioiodine therapy with ¹³¹I remains the mainstay of standard treatment for well-differentiated thyroid cancer (DTC). Prognosis is good but concern exists that ¹³¹I-emitted ionizing radiation may induce double-strand breaks in extra-thyroidal tissues, increasing the risk of secondary malignancies. We, therefore, sought to evaluate the induction and 2-year persistence of micronuclei (MN) in lymphocytes from 26 ¹³¹I-treated DTC patients and the potential impact of nine homologous recombination (HR), non-homologous end-joining (NHEJ), and mismatch repair (MMR) polymorphisms on MN levels. MN frequency was determined by the cytokinesis-blocked micronucleus assay while genotyping was performed through pre-designed TaqMan^® Assays or conventional PCR-restriction fragment length polymorphism (RFLP). MN levels increased significantly one month after therapy and remained persistently higher than baseline for 2 years. A marked reduction in lymphocyte proliferation capacity was also apparent 2 years after therapy. MLH1 rs1799977 was associated with MN frequency (absolute or net variation) one month after therapy, in two independent groups. Significant associations were also observed for MSH3 rs26279, MSH4 rs5745325, NBN rs1805794, and tumor histotype. Overall, our results suggest that ¹³¹I therapy may pose a long-term challenge to cells other than thyrocytes and that the individual genetic profile may influence ¹³¹I sensitivity, hence its risk-benefit ratio. Further studies are warranted to confirm the potential utility of these single nucleotide polymorphisms (SNPs) as radiogenomic biomarkers in the personalization of radioiodine therapy.

Is DNA repair a potential target for effective therapies against malignant mesothelioma?

Malignant pleural mesothelioma (MPM) is a rare malignancy mainly caused by asbestos exposure. Germinal and acquired mutations in genes of DNA repair pathways, in particular of homologous recombination repair, are frequent in MPM. Here we overview the available experimental data suggesting that an impaired DNA repair system affects MPM pathogenesis by leaving lesions through the genome unresolved. DNA repair defects represent a vulnerability of MPM, and it seems plausible to propose that leveraging these deficiencies could have therapeutic potential for patients with MPM, for whom there is an urgent need of more effective therapies.

Genetic polymorphisms in aquaporin 1 as risk factors for malignant mesothelioma and biomarkers of response to cisplatin treatment

Background Malignant mesothelioma (MM) is an asbestos related aggressive tumor with poor prognosis. The aim of this study was to investigate if aquaporin 1 (AQP1) genetic polymorphisms influence the risk of MM and the response to cisplatin based MM treatment. Patients and methods The case-control study included 231 patients with MM and a control group of 316 healthy blood donors. All subjects were genotyped for three AQP1polymorphisms (rs1049305, rs1476597 and rs28362731). Logistic and Cox regression were used in statistical analysis. Results AQP1 rs1049305 polymorphism was significantly associated with MM risk in dominant model adjusted for gender and age (OR = 0.60, 95% CI = 0.37-0.96, Padj = 0.033). This polymorphism was also significantly associated with cisplatin based treatment related anaemia (unadjusted: OR = 0.49, 95% CI = 0.27-0.90, P = 0.021; adjusted: for CRP: OR = 0.52, 95% CI = 0.27-0.99, P = 0.046), with leukopenia (OR = 2.09, 95% CI = 1.00-4.35, P = 0.049) in dominant model and with thrombocytopenia (OR = 3.06, 95% CI = 1.01-9.28, P = 0.048) and alopecia (OR = 2.92, 95% CI = 1.00-8.46, P = 0.049) in additive model. AQP1 rs28362731 was significantly associated with thrombocytopenia (unadjusted: OR = 3.73, 95% CI = 1.00-13.84, P = 0.049; adjusted for pain: OR = 4.63, 95% CI = 1.13-19.05, P = 0.034) in additive model. Conclusions AQP1 may play a role in the risk of MM. Furthermore, AQP1 genotype information could improve the prediction of MM patients at increased risk for cisplatin toxicity.

Clinical-pharmacogenetic models for personalized cancer treatment: application to malignant mesothelioma

Large interindividual differences in treatment outcome are observed in cancer patients undergoing chemotherapy. Our aim was to develop and validate clinical-pharmacogenetic prediction models of gemcitabine/cisplatin or pemetrexed/cisplatin treatment outcome and develop an algorithm for genotype-based treatment recommendations in malignant mesothelioma (MM). We genotyped 189 MM patients for polymorphisms in gemcitabine, pemetrexed and cisplatin metabolism, transport and drug target genes and DNA repair pathways. To build respective clinical-pharmacogenetic models, pharmacogenetic scores were assigned by rounding regression coefficients. Gemcitabine/cisplatin model was based on training group of 71 patients and included CRP, histological type, performance status, RRM1 rs1042927, ERCC2 rs13181, ERCC1 rs3212986, and XRCC1 rs25487. Patients with higher score had shorter progression-free (PFS) and overall survival (P < 0.001). This model’s sensitivity was 0.615 and specificity 0.812. In independent validation group of 66 patients the sensitivity and specificity were 0.667 and 0.641, respectively. Pemetrexed/cisplatin model was based on 57 patients and included CRP, MTHFD1 rs2236225, and ABCC2 rs2273697. Patients with higher score had worse response and shorter PFS (P < 0.001). This model’s sensitivity was 0.750 and specificity 0.607. In independent validation group of 20 patients the sensitivity and specificity were 0.889 and 0.500, respectively. The proposed algorithm based on these models could enable the choice of the most effective chemotherapy for 85.5% of patients and lead to improved treatment outcome in MM.

Methods: for studying pharmacogenetic profiles of combination chemotherapeutic drugs

INTRODUCTION

Molecular and genetic analysis of tumors and individuals has led to patient-centered therapies, through the discovery and identification of genetic markers predictive of drug efficacy and tolerability. Present therapies often include a combination of synergic drugs, each of them directed against different targets. Therefore, the pharmacogenetic profiling of tumor masses and patients is becoming a challenge, and several questions may arise when planning a translational study.

AREAS COVERED

The review presents the different techniques used to stratify oncology patients and to tailor antineoplastic treatments according to individual pharmacogenetic profiling. The advantages of these methodologies are discussed as well as current limits.

EXPERT OPINION

Facing the rapid technological evolution for genetic analyses, the most pressing issues are the choice of appropriate strategies (i.e., from gene candidate up to next-generation sequencing) and the possibility to replicate study results for their final validation. It is likely that the latter will be the major obstacle in the future. However, the present landscape is opening up new possibilities, overcoming those hurdles that have limited result translation into clinical settings for years.

Genetic variability of DNA repair mechanisms and glutathione-S-transferase genes influences treatment outcome in osteosarcoma

BACKGROUND

Osteosarcoma patients are commonly treated with cisplatin-based preoperative and postoperative chemotherapy. Cisplatin binds to DNA and forms both intrastrand and interstrand crosslinks, inhibiting DNA replication. Glutathione-S-transferases (GSTs) participate in cisplatin detoxification, while several independent DNA repair mechanisms repair cisplatin-induced lesions. The aim of our study was to investigate the influence of genetic variability of DNA repair mechanisms and GSTs on efficacy and toxicity of cisplatin-based chemotherapy in osteosarcoma patients.

METHODS

A total of 66 osteosarcoma patients were genotyped for ERCC1, ERCC2, NBN, RAD51, XRCC3, and GSTP1 polymorphisms, as well as GSTM1 and GSTT1 gene deletion. We determined the influence of polymorphisms on survival and treatment outcome using Cox regression and logistic regression.

RESULTS

Carriers of at least one polymorphic ERCC2 rs1799793 allele had longer event-free survival (EFS) (P=0.006; hazard ratio (HR)=0.28; 95% confidence interval (CI)=0.11-0.70). Polymorphic GSTP1 rs1138272 allele was associated with both shorter EFS and OS (P=0.005; HR=3.67; 95%CI=1.47-9.16; and P=0.004; HR=3.52; 95%CI=1.51-8.22, respectively). Compared to the reference NBN CAA haplotype, NBN CGA haplotype was associated with shorter EFS (P=0.001; HR=4.12; 95%CI=1.77-9.56).

CONCLUSIONS

Our results suggest that DNA repair polymorphisms and GST polymorphisms could be used as predictive factors for cisplatin-based chemotherapy in osteosarcoma patients and could contribute to treatment personalization.

Polymorphisms in translesion polymerase genes influence treatment outcome in malignant mesothelioma

Aim: We evaluated the influence of genetic variability in translesion polymerases REV1 and REV3L on the outcome of cisplatin treatment in malignant mesothelioma patients. Materials & methods: In total, 139 malignant mesothelioma patients were genotyped for seven tag SNPs in REV1 and REV3L. Logistic regression and Cox regression were used to assess the influence of SNPs on treatment outcome. Results: Polymorphic REV1 rs3087403 allele and REV1 TGT haplotype were associated with increased risk for leukopenia (p = 0.013 and p = 0.047, respectively) and neutropenia (p = 0.048 and p = 0.024, respectively). REV3L rs465646, rs462779 and REV3L CCGG haplotype were significantly associated with longer overall survival (p = 0.007, p = 0.022 and p = 0.013, respectively). Conclusion: Our results suggest for the first time that REV1 and REV3L SNPs might serve as potential predictive markers of outcome of cisplatin-based chemotherapy.

Original submitted 7 October 2013; Revision submitted 15 January 2014

Polymorphisms in folate pathway and pemetrexed treatment outcome in patients with malignant pleural mesothelioma

INTRODUCTION

A combination of pemetrexed and cisplatin has been shown to improve the outcome in patients with malignant pleural mesothelioma (MPM), however, there is a great heterogeneity in treatment response among patients. The aim of our study was to evaluate the influence of polymorphisms in folate pathway and transporter genes on pemetrexed treatment outcome in Slovenian patients with MPM.

METHODS

MPM patients treated with pemetrexed in the course of a prospective randomized clinical trial were genotyped for nineteen polymorphisms in five genes of folate pathway and six transporter genes. Logistic regression was used to assess the influence of polymorphisms on treatment efficacy and toxicity, while Cox regression was used to determine their influence on progression-free and overall survival.

RESULTS

Patients with at least one polymorphic MTHFD1 rs2236225 allele had a significantly lower response rate (p = 0.005; odds ratio [OR] = 0.12; 95% confidence interval [CI] = 0.03-0.54) and shorter progression-free survival (p = 0.032; hazard ratio [HR] = 3.10; 95% CI = 1.10-8.74) than non-carriers. Polymorphisms in transporter genes did not influence survival; however, several were associated with toxicity. Liver toxicity was significantly lower in carriers of polymorphic ABCC2 rs2273697 (p = 0.028; OR = 0.23; 95% CI = 0.06-0.85), SLCO1B1 rs4149056 (p = 0.028; OR = 0.23; 95% CI = 0.06-0.85) and rs11045879 (p = 0.014; OR = 0.18; 95% CI = 0.05-0.71) alleles compared to non-carriers, as well as in patients with SLCO1B1 GCAC haplotype (p = 0.048; OR = 0.17; 95% CI = 0.03-0.98). Gastrointestinal toxicity was much more common in patients with polymorphic ABCC2 rs717620 allele (p = 0.004; OR = 10.67; 95% CI = 2.15-52.85) and ABCC2 CAG haplotype (p = 0.006; OR = 5.67; 95% CI = 1.64-19.66).

CONCLUSIONS

MTHFD1 polymorphism affected treatment response and survival, while polymorphisms in ABCC2 and SLCO1B1 transporter genes influenced the risk for toxicity. These polymorphisms could serve as potential markers of pemetrexed treatment outcome in patients with MPM.