Genetic polymorphisms and platinum-induced hematological toxicity: a systematic review

Background

Platinum-based chemotherapy bring severe hematological toxicity that can lead to dose reduction or discontinuation of therapy. Genetic variations have been reported to influence the risk and extent of hematological toxicity; however, the results are controversial and a comprehensive overview is lacking. This systematic review aimed to identify genetic biomarkers of platinum-induced hematological toxicity.

Method

Pubmed, Embase and Web of science database were systematically reviewed for studies that evaluated the association of genetic variants and platinum-related hematological toxicity in tumor patients with no prior history of chemotherapy or radiation, published from inception to the 28th of January 2022. The studies should have specific toxicity scoring system as well as defined toxicity end-point. The quality of reporting was assessed using the Strengthening the Reporting of Genetic Association Studies (STREGA) checklist. Results were summarized using narrative synthesis.

Results

83 studies were eligible with over 682 single-nucleotide polymorphisms across 110 genes. The results are inconsistent and diverse with methodological issues including insufficient sample size, population stratification, various treatment schedule and toxicity end-point, and inappropriate statistics. 11 SNPs from 10 genes (ABCB1 rs1128503, GSTP1 rs1695, GSTM1 gene deletion, ERCC1 rs11615, ERCC1 rs3212986, ERCC2 rs238406, XPC rs2228001, XPCC1 rs25487, MTHFR rs1801133, MDM2 rs2279744, TP53 rs1042522) had consistent results in more than two independent populations. Among them, GSTP1 rs1695, ERCC1 rs11615, ERCC1 rs3212986, and XRCC1 rs25487 present the most promising results.

Conclusion

Even though the results are inconsistent and several methodological concerns exist, this systematic review identified several genetic variations that deserve validation in well-defined studies with larger sample size and robust methodology.

Systematic Review Registration

https://www.crd.york.ac.uk/, identifier CRD42021234164.

Genome-Wide Analyses of Nephrotoxicity in Platinum-Treated Cancer Patients Identify Association with Genetic Variant in RBMS3 and Acute Kidney Injury

Nephrotoxicity is a common and dose-limiting side effect of platinum compounds, which often manifests as acute kidney injury or hypomagnesemia. This study aimed to investigate the genetic risk loci for platinum-induced nephrotoxicity. Platinum-treated brain tumor and head–neck tumor patients were genotyped with genome-wide coverage. The data regarding the patient and treatment characteristics and the laboratory results reflecting the nephrotoxicity during and after the platinum treatment were collected from the medical records. Linear and logistic regression analyses were performed to investigate the associations between the genetic variants and the acute kidney injury and hypomagnesemia phenotypes. A cohort of 195 platinum-treated patients was included, and 9,799,032 DNA variants passed the quality control. An association was identified between RBMS3 rs10663797 and acute kidney injury (coefficient −0.10 (95% confidence interval −0.13–−0.06), p-value 2.72 × 10⁻⁸). The patients who carried an AC deletion at this locus had statistically significantly lower glomerular filtration rates after platinum treatment. Previously reported associations, such as BACH2 rs4388268, could not be replicated in this study’s cohort. No statistically significant associations were identified for platinum-induced hypomagnesemia. The genetic variant in RBMS3 was not previously linked to nephrotoxicity or related traits. The validation of this study’s results in independent cohorts is needed to confirm this novel association.

Impact of metallothionein-knockdown on cisplatin resistance in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare, but aggressive tumor with dismal prognosis. Platinum-based chemotherapy is regularly used as part of multimodality therapy. The expression of metallothioneins (MT) has been identified as a reason for cisplatin resistance, which often leads to early therapy failure or relapse. Thus, knockdown of MT expression may improve response to cisplatin treatment. The MT gene- and protein expression of the MPM-cell lines MSTO-211H, NCI-H2052 and NCI-H2452 and the human fibroblast cell line MRC-5, as well as their sensitivity to cisplatin treatment have been evaluated. Knockdown of MT1A, 1B and 2A expression was induced by RNA interference. MT expression was measured using quantitative real-time PCR. An in vitro Assay based on enzyme activity was used to detect cell viability, necrosis and apoptosis before and after incubation with cisplatin. MT2A gene expression could be detected in all MPM cell lines, showing the highest expression in NCI-H2452 and NCI-H2052, whereas gene expression levels of MT1A and MT1B were low or absent. The immunohistochemically protein expression of MT-I/II reflect MT2A gene expression levels. Especially for MSTO-211H cell presenting low initial MT2A levels, a strong induction of MT2A expression could be observed during cisplatin treatment, indicating a cell line-specific and platin-dependent adaption mechanism. Additionally, a MT2A-dependent cellular evasion of apoptosis during cisplatin could be observed, leading to three different MT based phenotypes. MSTO-211H cells showed lower apoptosis rates at an increased expression level of MT2A after cisplatin treatment (from sixfold to fourfold). NCI-H2052 cells showed no changes in MT2A expression, while apoptosis rate is the highest (8-12-fold). NCI-H2452 cells showed neither changes in alteration rate of MT2A expression nor changes in apoptosis rates, indicating an MT2A-independent resistance mechanism. Knockdown of MT2A expression levels resulted in significantly induced apoptotic rates during cisplatin treatment with strongest induction of apoptosis in each of the MPM cell lines, but in different markedness. A therapeutic meaningful effect of MT2A knockdown and subsequent cisplatin treatment could be observed in MSTO-211H cells. The present study showed MT2A to be part of the underlying mechanism of cisplatin resistance in MPM. Especially in MSTO-211H cells we could demonstrate major effects by knockdown of MT2A expression, verifying our hypothesis of an MT driven resistance mechanism. We could prove the inhibition of MT2A as a powerful tool to boost response rates to cisplatin-based therapy in vitro. These data carry the potential to enhance the clinical outcome and management of MPM in the future.

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.

Outcome Definition Influences the Relationship Between Genetic Polymorphisms of ERCC1, ERCC2, SLC22A2 and Cisplatin Nephrotoxicity in Adult Testicular Cancer Patients

Although previous research identified candidate genetic polymorphisms associated with cisplatin nephrotoxicity, varying outcome definitions potentially contributed to the variability in the effect size and direction of this relationship. We selected genetic variants that have been significantly associated with cisplatin-induced nephrotoxicity in more than one published study (SLC22A2 rs316019; ERCC1 rs11615 and rs3212986; ERCC2 rs1799793 and rs13181) and performed a replication analysis to confirm associations between these genetic polymorphisms and cisplatin nephrotoxicity using various outcome definitions. We included 282 germ cell testicular cancer patients treated with cisplatin from 2009-2014, aged >17 years recruited by the Canadian Pharmacogenomics Network for Drug Safety. Nephrotoxicity was defined using four grading tools: (1) Common Terminology Criteria for Adverse Events (CTCAE) v4.03 for acute kidney injury (AKI) or CTCAE-AKI; (2) adjusted cisplatin-induced AKI; (3) elevation of serum creatinine; and (4) reduction in the estimated glomerular filtration rate (eGFR). Significant associations were only found when using the CTCAE v4.03 definition: genotype CA of the ERCC1 rs3212986 was associated with decreased risk of cisplatin nephrotoxicity (ORadj = 0.24; 95% CI:0.08-0.70; p= 0.009) compared to genotype CC. In contrast, addition of allele A at SLC22A2 rs316019 was associated with increased risk (ORadj = 4.41; 95% CI:1.96-9.88; p < 0.001) while genotype AC was associated with a higher risk of cisplatin nephrotoxicity (ORadj = 5.06; 95% CI:1.69-15.16; p= 0.004) compared to genotype CC. Our study showed that different case definitions led to variability in the genetic risk ascertainment of cisplatin nephrotoxicity. Therefore, consensus on a set of clinically relevant outcome definitions that all such studies should follow is needed.

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.

Genetic Variations and Cisplatin Nephrotoxicity: A Systematic Review

Background: Nephrotoxicity is a notable adverse effect in cisplatin treated patients characterized by tubular injury and/or increased serum creatinine (SCr) with incidence varying from 20 to 70%. Pharmacogenomics has been shown to identify strongly predictive genetic markers to help determine which patients are more likely to experience, for example, a serious adverse drug reaction or receive optimal benefit through enhanced efficacy. Genetic variations have been reported to influence the risk of cisplatin nephrotoxicity; however, a comprehensive overview is lacking. Methods: A systematic review was performed using Pubmed, Embase and Web of Science on clinical studies that used cisplatin-based chemotherapy as treatment, had available genotyping data, and evaluated nephrotoxicity as an outcome. The quality of reporting was assessed using the STrengthening the REporting of Genetic Association Studies (STREGA) checklist. Results: Twenty-eight eligible studies were included; all were candidate gene studies. Over 300 SNPs across 135 genes were studied; 29 SNPs in 14 genes were significantly associated with cisplatin-induced nephrotoxicity. A variation in SLC22A2 rs316019, a gene involved in platinum uptake by the kidney, was associated with different measures of nephrotoxicity in four independent studies. Further, variants of ERCC1 (rs11615 and rs3212986) and ERCC2 (rs13181), two genes involved in DNA repair, were found to be positively associated with increased risks of nephrotoxicity in two independent studies. Conclusion: Three genes consistently associated with cisplatin-induced nephrotoxicity. Further research is needed to assess the biological mechanism and the clinical value of modifying treatment based on SLCC22A2 and ERCC1/2 genotypes.

The Influence of Genetic Variability on the Risk of Developing Malignant Mesothelioma

Background

Malignant mesothelioma is a rare cancer with poor outcome, associated with asbestos exposure. Reactive oxygen species may play an important role in the mechanism of carcinogenesis; therefore, genetic variability in antioxidative defence may modify an individual’s susceptibility to this cancer. This study investigated the influence of functional polymorphisms of NQO1, CAT, SOD2 and hOGG1 genes, gene-gene interactions and gene-environment interactions on malignant mesothelioma risk.

Patients and methods

In total, 150 cases with malignant mesothelioma and 122 controls with no asbestos-related disease were genotyped for NQO1, CAT, SOD2 and hOGG1 polymorphisms.

Results

The risk of malignant mesothelioma increased with smoking, odds ratio (OR) 9.30 [95% confidence interval (CI): 4.83–17.98] and slightly with age, OR 1.10 (95% CI: 1.08–1.14). Medium and high asbestos exposures represented 7-times higher risk of malignant mesothelioma compared to low exposure, OR 7.05 (95% CI 3.59–13.83). NQO1 rs1800566 was significantly associated with increased malignant mesothelioma risk, OR 1.73 (95% CI 1.02–2.96). Although there was no independent association between either CAT rs1001179 or hOGG1 rs1052133 polymorphism and malignant mesothelioma, interaction between both polymorphisms showed a protective effect, OR_int 0.27 (95% CI 0.10–0.77).

Conclusions

Our findings suggest a role of both genetic variability in antioxidative defence and repair as well as the impact of gene-gene interactions in the development of malignant mesothelioma. The results of this study could add to our understanding of pathogenesis of malignant mesothelioma and contribute to prevention and earlier diagnosis of this aggressive cancer.

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.

Trabectedin Is Active against Malignant Pleural Mesothelioma Cell and Xenograft Models and Synergizes with Chemotherapy and Bcl-2 Inhibition In Vitro

Malignant pleural mesothelioma (MPM) is characterized by widespread resistance to systemic therapy. Trabectedin is an antineoplastic agent targeting both the malignant cells and the tumor microenvironment that has been approved for the treatment of advanced soft tissue sarcoma and ovarian cancer. In this preclinical study, we evaluated the antineoplastic potential of trabectedin as a single agent and in drug combination approaches in human MPM. Therefore, we utilized an extended panel of MPM cell lines (n = 6) and primary cell cultures from surgical MPM specimens (n = 13), as well as nonmalignant pleural tissue samples (n = 2). Trabectedin exerted a dose-dependent cytotoxic effect in all MPM cell cultures in vitro when growing as adherent monolayers or nonadherent spheroids with IC₅₀ values ≤ 2.6 nmol/L. Nonmalignant mesothelial cells were significantly less responsive. The strong antimesothelioma activity was based on cell-cycle perturbation and apoptosis induction. The activity of trabectedin against MPM cells was synergistically enhanced by coadministration of cisplatin, a drug routinely used for systemic MPM treatment. Comparison of gene expression signatures indicated an inverse correlation between trabectedin response and bcl-2 expression. Accordingly, bcl-2 inhibitors (Obatoclax, ABT-199) markedly synergized with trabectedin paralleled by deregulated expression of the bcl-2 family members bcl-2, bim, bax, Mcl-1, and bcl-x_L as a consequence of trabectedin exposure. In addition, trabectedin exerted significant antitumor activity against an intraperitoneal MPM xenograft model. Together, these data suggest that trabectedin exerts strong activity in MPM and synergizes with chemotherapy and experimental bcl-2 inhibitors in vitro Thus, it represents a promising new therapeutic option for MPM. Mol Cancer Ther; 15(10); 2357-69. ©2016 AACR.

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.

Can pharmacogenetics explain efficacy and safety of cisplatin pharmacotherapy?

Several recent pharmacogenetic studies have investigated the variability in both outcome and toxicity in cisplatin-based therapies. These studies have focused on the genetic variability of therapeutic targets that could affect cisplatin response and toxicity in diverse type of cancer including lung, gastric, ovarian, testicular, and esophageal cancer. In this review, we seek to update the reader in this area of investigation, focusing primarily on DNA reparation enzymes and cisplatin metabolism through Glutathione S-Transferases (GSTs). Current evidence indicates a potential application of pharmacogenetics in therapeutic schemes in which cisplatin is the cornerstone of these treatments. Therefore, a collaborative effort is required to study these molecular characteristics in order to generate a genetic panel with clinical utility.

Correlation between TS, MTHFR, and ERCC1 gene polymorphisms and the efficacy of platinum in combination with pemetrexed first-line chemotherapy in mesothelioma patients

INTRODUCTION

The combination of pemetrexed and platinum compound represents the standard regimen for first-line chemotherapy in malignant pleural mesothelioma patients. Pemetrexed is a multitarget antifolate agent that inhibits folate-dependent enzymes (eg, thymidylate synthase [TS]) and thus synthesis of nucleotides and DNA. Expression of TS and folate availability, regulated by gene polymorphisms, have implications for effectiveness of chemotherapy and the outcome of mesothelioma patients. The aim of this retrospective multicenter study was to assess the correlation between TS, 5,10-methylenetetrahydrofolate reductase (MTHFR) and excision repair cross-complementing group 1 (ERCC1) gene polymorphisms and the efficacy of pemetrexed-based first-line chemotherapy of mesothelioma patients.

PATIENTS AND METHODS

Fifty-nine mesothelioma patients (31 men with a median age of 62 years) treated in first-line chemotherapy with platinum in combination with pemetrexed or pemetrexed monotherapy were enrolled. Genomic DNA was isolated from peripheral blood. Using polymerase chain reaction and high resolution melt methods, the variable number of tandem repeat, the G>C single nucleotide polymorphism (SNP) in these repeats, and 6-base pair (bp) insertion/deletion polymorphism of the TS gene, the SNP of 677C>T in MTHFR, and 19007C>T in the ERCC1 gene were analyzed and correlated with disease control rate, progression-free survival (PFS), and overall survival (OS) of mesothelioma patients.

RESULTS

Greater risk of early disease progression (PD), and shortening of PFS and OS were associated with several clinical factors (eg, anemia for early PD and OS), weight loss (for PFS and OS), and previous surgical treatment (for early PD, PFS, and OS). Insertion of 6-bp in both alleles of the TS gene (1494del6) was the only genetic factor that increased the incidence of early progression (P = .028) and shortening of median PFS (P = .06) in patients treated with pemetrexed-based chemotherapy. In multivariate analysis, the 1494del6 in the 3' untranslated region (UTR) of the TS gene also had a predictive role for PFS (P = .0185; hazard ratio, 2.3258 for +6/+6 homozygotes) in analyzed mesothelioma patients.

CONCLUSION

Most analyzed polymorphisms in TS, MTHFR, and ERCC1 genes failed to predict outcome in mesothelioma patients treated with pemetrexed-based chemotherapy. However, different variants of 1494del6 in the 3' UTR of the TS gene were associated with differences in disease control rate and PFS of our patients.

ERCC1 Cys8092Ala and XRCC1 Arg399Gln polymorphisms predict progression-free survival after curative radiotherapy for nasopharyngeal carcinoma

Background

Single nucleotide polymorphisms (SNPs) in DNA repair genes can alter gene expression and activity and affect response to cancer treatment and, correspondingly, survival. The present study was designed to evaluate the utility of the XRCC1 Arg399Gln and ERCC1 Cys8092Ala SNPs, measured in pretreatment biopsy samples, as predictors of response to radiotherapy in patients with non-metastatic nasopharyngeal carcinoma (NPC).

Materials and methods

The study included 75 consecutive patients with stage II-IVA-B NPC. XRCC1 Arg399Glu and ERCC1 Cys8092Ala SNPs were identified from paraffin-embedded biopsy specimens via Sanger sequencing. Expression of p53 and pAkt protein was analyzed by immunohistochemical staining. Potential relationships between genetic polymorphisms and progression-free survival (PFS) were analyzed by using a Cox proportional hazards model, the Kaplan-Meier method, and the log-rank test.

Results

Multivariate analysis showed that carriers of the ERCC1 8092 Ala/Ala genotype [hazard ratio (HR) 1.882; 95% confidence interval (CI) 1.031–3.438; P = 0.039] and heavy smokers (≥20 pack-years) carrying the XRCC1 Arg/Arg genotype (HR 2.019; 95% CI 1.010–4.036; P = 0.047) had significantly lower PFS rates. Moreover, combined positive expression of p53 and pAkt led to significantly increased PFS in subgroups carrying the XRCC1 Gln allele (HR 7.057; 95% CI 2.073–24.021; P = 0.002) or the ERCC1 Cys allele (HR 2.568; 95% CI 1.056–6.248; P = 0.038).

Conclusions

The ERCC1 Cys8092Ala polymorphism is an independent predictor of response to radiotherapy for NPC, and the XRCC1 Arg399Glu mutation combined with smoking status seems to predict PFS as well. Our results further suggest a possible correlation between these genetic polymorphisms and p53 protein status on survival.

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.

ERCC1 C8092A (rs3212986) polymorphism as a predictive marker in esophageal cancer patients treated with cisplatin/5-FU-based neoadjuvant therapy

OBJECTIVE

At present, no consensus exists on the beneficial effect of preoperative cisplatin/5-fluorouracil (5-FU)-based chemotherapy versus primary surgery in the management of patients with esophageal cancer. The aim of this study was to evaluate the impact of some relevant genetic polymorphisms, within drug-related and DNA repair genes, on the clinical outcome of esophageal cancer patients subjected to cisplatin/5-FU-based neoadjuvant treatment.

METHODS

DNA from 143 esophageal cancer patients, 63 receiving neoadjuvant therapy and 80 receiving primary surgery, was analyzed for the following polymorphisms: the GSTM1 null, GSTT1 null, and GSTP1 Ile105Val (rs16953) in glutathione S-transferase (GST) family, 2 in thymidylate synthase (TS) gene, and the ERCC1 Asn118Asn (rs11615), ERCC1 C8092A (rs3212986), XPD/ERCC2 Asp312Asn (rs1799793), and XPD/ERCC2 Lys751Gln (rs13181) of the nucleotide excision repair pathway.

RESULTS

We found that the ERCC1 rs3212986, although not associated with therapeutic response, is an independent predictive marker of better outcome in a cisplatin/5-FU-based neoadjuvant setting (hazard ratio: 0.38, 95% confidence interval: 0.2-0.73, P=0.008). In contrast, no association with clinical outcome was observed for this polymorphism in the primary surgery group.

CONCLUSION

Our study indicates the ERCC1 rs3212986 as a predictive marker in the cisplatin/5-FU-based neoadjuvant setting, and also suggests its use as a marker to select the appropriate therapeutic approach in esophageal cancer patients.

GSTT1 null and MPO -463G>a polymorphisms and carboplatin toxicity in an Indian population

Carboplatin, a second generation platinum drug, is widely used to treat different types of cancers. However, myelosuppression remains a major consideration in its use. Genetic polymorphisms of enzymes involved in drug disposition can influence therapeutic outcome. The homozygous null deletion of phase II metabolic gene GSTT1 that abolishes its xenobiotic- detoxifying ability may be associated with carboplatin toxicity. Further, since carboplatin generates oxidative stress, polymorphisms of oxidative stress genes that regulate the cellular level of free radicals may have important roles in generating drug- related adverse effects. We here investigated the null polymorphism of GSTT1, and the -463G>A promoter polymorphism of oxidative stress gene myeloperoxidase (MPO) for carboplatin toxicity in a population of northern India. Cancer patients who were treated with carboplatin, and developed toxicity was considered. The study group comprised of 10 patients who developed therapy- related adverse effects. Peripheral blood was taken from patients for DNA isolation. GSTT1 null genotype was determined by conducting duplex PCR and MPO-463 G>A was determined by PCR followed by RFLP. Hematologic toxicity was experienced by 5 patients, 2 of them had grade 3 and 4 toxicity and 3 others had grade 2 toxicity. They also had gastrointestinal (GI) toxicity. Remaining 5 individuals developed GI toxicity but no hematological toxicity. While GG homozygous of MPO was present in majority of patients having hematologic toxicity (in 4 out of 5 individuals), one A allele (AG genotype) was present in 4 patients who did not have any hematological toxicity. Thus variant A allele of MPO -463G>A may be related to lower hematological toxicity. These preliminary data, however, are required to be confirmed in larger studies along with other relevant polymorphisms.

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

INTRODUCTION

Genetic polymorphisms that affect DNA repair capacity can modulate the efficacy and toxicity of cytotoxic agents. Therefore, the aim of our study was to evaluate the influence of genetic variability in DNA repair genes on treatment outcome in patients with malignant mesothelioma (MM) treated with gemcitabine-platinum combination chemotherapy.

METHODS

In total, 109 patients with MM were genotyped for 10 polymorphisms in XRCC1, NBN, RAD51, and XRCC3 genes. The influence of selected polymorphisms on tumor response and occurrence of treatment-related toxicity was determined by logistic regression analysis, whereas their influence on survival was estimated by Cox proportional hazards model.

RESULTS

There were no associations between the investigated polymorphisms and tumor response, but we observed a significant association between XRCC1 399Gln allele and reduced overall survival (hazards ratio = 1.70; 95% confidence interval [CI] 1.06-2.73; p = 0.028). Interaction between XRCC1 399Gln allele and C-reactive protein levels revealed that carriers of at least one XRCC1 399Gln allele with C-reactive protein levels above median had significantly shorter overall survival time compared with other patients (12.9 months versus 25.3 months, log-rank p < 0.001). We also observed an association between XRCC1 399Gln and lower frequency of leukopenia (odds ratio [OR] = 0.25; 95% CI 0.09-0.67; p = 0.006), neutropenia (OR = 0.24; 95% CI 0.09-0.68; p = 0.007), and thrombocytopenia (OR = 0.27; 95% CI 0.09-0.84; p = 0.024). In addition, NBN 3474A>C, XRCC3 -316A>G, and Thr241Met polymorphisms showed significant associations with treatment-related toxicity.

CONCLUSIONS

Our results support the hypothesis that DNA repair gene polymorphisms, particularly XRCC1 Arg399Gln, may modify the response to gemcitabine-platinum combination chemotherapy and, for the first time, show this effect in patients with MM.

5-HTTLPR polymorphism and anxious preoccupation in early breast cancer patients

Background

Difficulties in coping with cancer, and the accompanying anxious and depressive symptoms, have been shown to affect the mood and the quality of life in breast cancer patients. 5-Hydroxytryptamine Transporter Gene-linked Polymorphic Region (5-HTTLPR) functional polymorphism of serotonin transporter has been shown to influence the adaptation to stressful life events. The aim of this prospective study was therefore to examine the association of 5-HTTLPR with the mental adaptation to cancer diagnosis and treatment.

Patients and methods

Forty eight consecutive patients with early mammary carcinoma were evaluated at enrolment and at follow up after one and three months. The patients were characterized psychometrically using the Hospital Anxiety and Depression Scale (HADS) and the Mini-Mental Adjustment to Cancer Scale (Mini-MAC); 5-HTTLPR allelic variants were determined using PCR-based techniques.

Results

In women with early breast cancer, the mental adaptation to the disease was associated with high scores of avoidance and anxious preoccupation of Mini-MAC, which decreased with time at follow up. Anxious preoccupation decreased with time less in patients with the S/S and S/L genetic variant of 5-HTTLPR as compared with the L/L carriers (p=0.023), indicating gene - environment interactions.

Conclusions

These results indicate that the characterization of 5-HTTLPR allows the identification of breast cancer patients in greater risk of mental suffering, for which specific intervention may be focused; in case of drug therapy, they provide indications for the choice of most appropriate agent in a pharmacogenetic perspective.

DNA repair polymorphisms influence the risk of second neoplasm after treatment of childhood acute lymphoblastic leukemia

PURPOSE

Patients treated for childhood acute lymphoblastic leukemia (ALL) are considered to be at increased risk of developing second neoplasm. The aim of our study was to identify DNA repair polymorphisms contributing to the risk of second neoplasm in clinically well-characterized Slovenian patients treated for childhood ALL.

METHODS

Pediatric patients diagnosed with ALL between 1971 and 2001 were included in the study. According to the identified clinical risk factors for second neoplasm, a matched set of cases with second neoplasm and controls was selected and genotyped for 11 DNA repair polymorphisms.

RESULTS

Among 359 pediatric patients with ALL, 20 second neoplasms were observed. The dose of radiotherapy (P = 0.011), administration of epipodophyllotoxins (P = 0.006), and the dose of anthracyclines (P < 0.001) showed a significant association with the risk of second neoplasm. Among genetic factors, we observed a significant association of NBN 1197G allele with increased risk of second neoplasms (RR = 4.36; 95 % CI: 1.19-15.98; P = 0.026), while the risk was decreased in carriers of XRCC3-316G allele compared with patients with wild-type genotype (RR = 0.20; 95 % CI: 0.04-0.99; P = 0.049).

CONCLUSIONS

Our results suggest an important role of NBN 1197A>G and XRCC3-316A>G polymorphisms in the development of second neoplasm in patients treated for childhood ALL.

Contrasting effect of recombinant human erythropoietin on breast cancer cell response to cisplatin induced cytotoxicity

Background

Human recombinant erythropoietin (rHuEpo) that is used for the treatment of the chemotherapy-induced anaemia in cancer patients was shown to cause detrimental effects on the course of disease due to increased adverse events inflicting patient’s survival, potentially related to rHuEpo-induced cancer progression. In this study, we elucidate the effect of rHuEpo administration on breast cancer cell proliferation and gene expression after cisplatin (cDDP) induced cytotoxicity.

Materials and methods

Two breast carcinoma models, MCF-7 and MDA-MB-231 cell lines, were used differing in oestrogen (ER) and progesterone (PR) receptors and p53 status. Cells were cultured with or without rHuEpo for 24 h or 9 weeks and their growth characteristics after cDDP treatment were assessed together with expression of genes involved in the p53-signaling pathway.

Results

Short-term exposure of breast cancer cells to rHuEpo lowers their proliferation and reduces cDDP cytotoxic potency. In contrast, long-term exposure of MCF-7 cells to rHuEpo increases proliferation and predisposes MCF-7 cells to cDDP cytotoxicity, but has no effect on MDA-MB-231 cells. MDA-MB-231 cells show altered level of ERK phosphorylation, indicating involvement of MAPK signalling pathway. Gene expression analysis of p53-dependent genes and bcl-2 gene family members confirmed differences between long and short-term rHuEpo effects, indicating the most prominent changes in BCL2 and BAD expression.

Conclusions

Proliferation and survival characteristics of MCF-7 cells are reversely modulated by the length of the rHuEpo exposure. On the other hand, MDA-MB-231 cells are almost irresponsive to long-term rHuEpo, supposedly due to the mutated p53 and ER(+)/PR(−) status. The p53 and ER/PR status may predict tumour response on rHuEpo and cDDP treatment.

The antitumor efficiency of combined electrochemotherapy and single dose irradiation on a breast cancer tumor model

Background

The aim of this study was to investigate the antitumor effectiveness of electrochemotherapy with cisplatin combined with suboptimal radiotherapy doses. Tumor radiosensitization was evaluated on large invasive ductal carcinoma tumors in Balb/C mice.

Materials and methods

Tumors of an average volume of 630 mm³ were treated with cisplatin, electric pulses, radiotherapy, electrochemotherapy, alone as well as in appropriate combinations. Tumors were irradiated with Cobalt-60 γ-rays at doses 3 Gy and 5 Gy in combination with electrochemotherapy using cisplatin. Controls included each of the treatments alone as well as the combination of the radiotherapy with electric pulses alone or with cisplatin alone. Antitumor effectiveness was evaluated by tumor growth delay, tumor-doubling time, inhibition ratio and the objective response rates.

Results

As anticipated, electrochemotherapy was more effective than the treatment with cisplatin alone or the application of the electric pulses alone. When treatments were combined with tumor irradiation at either 3 or 5 Gy, the combination with electrochemotherapy was more effective: at 5 Gy, 2 animals out of 8 were in complete remission 100 days later. In general the higher 5 Gy dose of γ-radiation was more effective than the lower one of 3 Gy.

Conclusions

The results of our study demonstrate that irradiation doses, 3 Gy or 5 Gy, increase the antitumor effectiveness of electrochemotherapy with cisplatin on invasive ductal carcinoma tumors. Good antitumor results were achieved in experimental tumors with a size comparable to clinical lesions, demonstrating that this three-modality combined treatment is useful for the treatment of large lesions even at sub-optimal radiotherapy doses.

Improved survival after introduction of chemotherapy for malignant pleural mesothelioma in Slovenia: Population-based survey of 444 patients

Background

Malignant pleural mesothelioma is a rare tumour with increasing frequency throughout the world. Due to long latency after exposure to asbestos, restrictions in the production and use of asbestos have not yet alleviated the burden of mesothelioma. During the last decade, several trials confirmed the benefit of systemic treatment with drugs such as doublets with cisplatina and gemcitabine or pemetrexed for carefully selected patients in good performance status. The purpose of this survey was to assess the impact of systemic treatment for the whole national population of patients with mesothelioma.

Patients and methods.

A retrospective study included all patients in Slovenia with histologically confirmed diagnosis of malignant pleural mesothelioma in the period from 1974 till 2008. Data from the Cancer Registry of Slovenia were supplemented by review of clinical records of the Institute of Oncology in Ljubljana where virtually all non-surgical treatment for mesothelioma was performed. We analysed the incidence, treatment, and survival of patients treated in the era of infrequent chemotherapy (1974–2003, the first period) and after it (2004–2008, the second period).

Results

The survey included 444 patients, of whom 325 and 119 were diagnosed in the first and second period, respectively. Joinpoint regression analysis showed that after 1995 the trend in crude incidence rates increased more rapidly; the annual change was 0.03 per 100,000 per year before 1995 and 0.06 per 100,000 per year after. There was clear male predominance (70%) throughout the period covered by the survey. The proportion of patients above 65 years of age increased from 41.8% to 54.6% for the first and second period, respectively (p = 0.02). With a total of 52 (11.7%) operated patients, surgical treatment was rare and used only for selected patients with early disease and without comorbidity, leading to their relatively long median survival of 13.6 months. Chemotherapy was applied to 56 (17.2%) and to 96 (80.7%) patients during the first and second period, respectively. While a variety of older drugs were used in the first period, the most common regimen in the second period (applied to 91 patients) was doublet of low-dose gemcitabine in prolonged infusion and cisplatin. For the whole population of patients regardless the mode of treatment, median survival was 7.4 and 12.6 months (p-value = 0.037) for the first and second period, respectively.

Conclusions

Increasing incidence, male predominance and increased proportion of older patients confirm that the burden of mesothelioma persists in spite of a 15-years old ban in the production of asbestos. Modern chemotherapy, and in particular treatment with low-dose gemcitabine in prolonged infusion and cisplatin significantly prolonged median survival of patients with malignant pleural mesothelioma in Slovenia.

Genetic polymorphisms in homologous recombination repair genes in healthy Slovenian population and their influence on DNA damage

Background

Homologous recombination (HR) repair is an important mechanism involved in repairing double-strand breaks in DNA and for maintaining genomic stability. Polymorphisms in genes coding for enzymes involved in this pathway may influence the capacity for DNA repair. The aim of this study was to select tag single nucleotide polymorphisms (SNPs) in specific genes involved in HR repair, to determine their allele frequencies in a healthy Slovenian population and their influence on DNA damage detected with comet assay.

Materials and methods

In total 373 individuals were genotyped for nine tag SNPs in three genes: XRCC3 722C>T, XRCC3 -316A>G, RAD51 -98G>C, RAD51 -61G>T, RAD51 1522T>G, NBS1 553G>C, NBS1 1197A>G, NBS1 37117C>T and NBS1 3474A>C using competitive allele-specific amplification (KASPar assay). Comet assay was performed in a subgroup of 26 individuals to determine the influence of selected SNPs on DNA damage.

Results

We observed that age significantly affected genotype frequencies distribution of XRCC3 -316A>G (P = 0.039) in healthy male blood donors. XRCC3 722C>T (P = 0.005), RAD51 -61G>T (P = 0.023) and NBS1 553G>C (P = 0.008) had a statistically significant influence on DNA damage.

Conclusions

XRCC3 722C>T, RAD51 -61G>T and NBS1 553G>C polymorphisms significantly affect the repair of damaged DNA and may be of clinical importance as they are common in Slovenian population.