DPYD*2A and MTHFR C677T predict toxicity and efficacy, respectively, in patients on chemotherapy with 5-fluorouracil for colorectal cancer

Influence of DPYD gene polymorphisms on 5-Fluorouracil toxicities in Thai colorectal cancer patients

DPYD polymorphisms have been widely found to be related to 5-FU-induced toxicities. The aim of this study was to establish significant associations between five single-nucleotide polymorphisms of DPYD and 5-FU hematological toxicities in Thai colorectal cancer patients. The toxicities were analyzed at the first and second cycles of 5-FU administration in 75 patients. Genotyping was performed using TaqMan real-time PCR. The genotype frequencies of DPYD*2A,1905 + 1 G > A and DPYD 1774 C > T were all wild type. The frequencies of genetic testing for DPYD*5, 1627 A > G, DPYD 1896T > C, and DPYD*9A, 85 A > G were 37.30% (AG; 34.60%, GG; 2.70%), 32.00% (TC; 25.30%, CC; 6.70%), and 13.40% (AG; 10.70%, GG; 2.70%), respectively. The results reveal significant findings with neutropenia occurring in 100% (2/2) of the patients with homozygous variant DPYD*9A (GG) from the first cycle of treatment for both Grade 1-4 and Grade 3-4 toxicities (P = 0.003 and P < 0.001 respectively). DPYD *9A was related to Grade 1-4 leukopenia (P = 0.001) and both Grade 1-4 and severe thrombocytopenia (P < 0.001 and P < 0.001) in the first cycle. In the second cycle, DPYD*5 was shown to be closely associated with no Grade 1-4 toxicity (P = 0.02). However, we found that 100% (2/2) of patients carrying the homozygous variant (GG) DPYD*5, presented no significant toxicity, so, DPYD*5 may be a predictive marker of neutropenia in patients treated with 5-FU. These outcomes suggest that there may be an increased risk of developing 5-FU-induced neutropenia in patients carrying the DPYD*9A, which should be considered as part of the standard procedure.

Single nucleotide polymorphisms: impact on susceptibility to chemotherapy in patients with colorectal cancer

BACKGROUND

Single-nucleotide polymorphisms (SNPs) in enzyme-coding genes play a role in susceptibility to anti-cancer therapy.

MATERIALS & METHODS

A prospective study was performed of the relationship between enzyme activity and treatment response, drug toxicity and hypersensitivity reactions in 51 patients with colorectal cancer treated with fluoropyrimidine-based chemotherapy. SNP analysis was performed in 22 enzyme-coding genes with a previously described role in treatment efficacy.

RESULTS

SLC6 and MTHR enzyme activity was related with rates of progressive disease, GSTP1 activity with anti-EGFR antibodies-related skin toxicity, CYP3A5 and MTHR with chemotherapy dose reduction, CYP2B6, IL10, MTHR and TYMS activity with the risk of drug hypersensitivity reactions.

CONCLUSION

Pharmacogenetics is a valuable predictive marker in oncology, related to chemotherapy treatment response, toxicity and hypersensitivity.

Pharmacogenetics of DPYD and treatment-related mortality on fluoropyrimidine chemotherapy for cancer patients: a meta-analysis and trial sequential analysis

BACKGROUND

Fluoropyrimidines are chemotherapy drugs utilized to treat a variety of solid tumors. These drugs predominantly rely on the enzyme dihydropyrimidine dehydrogenase (DPD), which is encoded by the DPYD gene, for their metabolism. Genetic mutations affecting this gene can cause DPYD deficiency, disrupting pyrimidine metabolism and increasing the risk of toxicity in cancer patients treated with 5-fluorouracil. The severity and type of toxic reactions are influenced by genetic and demographic factors and, in certain instances, can result in patient mortality. Among the more than 50 identified variants of DPYD, only a subset has clinical significance, leading to the production of enzymes that are either non-functional or impaired. The study aims to examine treatment-related mortality in cancer patients undergoing fluoropyrimidine chemotherapy, comparing those with and without DPD deficiency.

METHODS

The meta-analysis selected and evaluated 9685 studies from Pubmed, Cochrane, Embase and Web of Science databases. Only studies examining the main DPYD variants (DPYD*2A, DPYD p.D949V, DPYD*13 and DPYD HapB3) were included. Statistical Analysis was performed using R, version 4.2.3. Data were examined using the Mantel-Haenszel method and 95% CIs. Heterogeneity was assessed with I2 statistics.

RESULTS

There were 36 prospective and retrospective studies included, accounting for 16,005 patients. Most studies assessed colorectal cancer, representing 86.49% of patients. Other gastrointestinal cancers were evaluated by 11 studies, breast cancer by nine studies and head and neck cancers by five studies. Four DPYD variants were identified as predictors of severe fluoropyrimidines toxicity in literature review: DPYD*2A (rs3918290), DPYD p.D949V (rs67376798), DPYD*13 (rs55886062) and DPYD Hap23 (rs56038477). All 36 studies assessed the DPYD*2A variant, while 20 assessed DPYD p.D949V, 7 assessed DPYD*13, and 9 assessed DPYDHap23. Among the 587 patients who tested positive for at least one DPYD variant, 13 died from fluoropyrimidine toxicity. Conversely, in the non-carrier group there were 14 treatment-related deaths. Carriers of DPYD variants was found to be significantly correlated with treatment-related mortality (OR = 34.86, 95% CI 13.96-87.05; p < 0.05).

CONCLUSIONS

This study improves our comprehension of how the DPYD gene impacts cancer patients receiving fluoropyrimidine chemotherapy. Identifying mutations associated with dihydropyrimidine dehydrogenase deficiency may help predict the likelihood of serious side effects and fatalities. This knowledge can be applied to adjust medication doses before starting treatment, thus reducing the occurrence of these critical outcomes.

DPYD genetic polymorphisms in non-European patients with severe fluoropyrimidine-related toxicity: a systematic review

BACKGROUND

Pre-treatment DPYD screening is mandated in the UK and EU to reduce the risk of severe and potentially fatal fluoropyrimidine-related toxicity. Four DPYD gene variants which are more prominently found in Europeans are tested.

METHODS

Our systematic review in patients of non-European ancestry followed PRISMA guidelines to identify relevant articles up to April 2023. Published in silico functional predictions and in vitro functional data were also extracted. We also undertook in silico prediction for all DPYD variants identified.

RESULTS

In 32 studies, published between 1998 and 2022, 53 DPYD variants were evaluated in patients from 12 countries encompassing 5 ethnic groups: African American, East Asian, Latin American, Middle Eastern, and South Asian. One of the 4 common European DPYD variants, c.1905+1G>A, is also present in South Asian, East Asian and Middle Eastern patients with severe fluoropyrimidine-related toxicity. There seems to be relatively strong evidence for the c.557A>G variant, which is found in individuals of African ancestry, but is not currently included in the UK genotyping panel.

CONCLUSION

Extending UK pre-treatment DPYD screening to include variants that are present in some non-European ancestry groups will improve patient safety and reduce race and health inequalities in ethnically diverse societies.

Phenotype versus genotype to optimize cancer dosing in the clinical setting-focus on 5-fluorouracil and tyrosine kinase inhibitors

Cancer medicines often have narrow therapeutic windows; toxicity can be severe and sometimes fatal, but inadequate dose intensity reduces efficacy and survival. Determining the optimal dose for each patient is difficult, with body-surface area used most commonly for chemotherapy and flat dosing for tyrosine kinase inhibitors, despite accumulating evidence of a wide range of exposures in individual patients with many receiving a suboptimal dose with these strategies. Therapeutic drug monitoring (measuring the drug concentration in a biological fluid, usually plasma) (TDM) is an accepted and well validated method to guide dose adjustments for individual patients to improve this. However, implementing TDM in routine care has been difficult outside a research context. The development of genotyping of various proteins involved in drug elimination and activity has gained prominence, with several but not all Guideline groups recommending dose reductions for particular variant genotypes. However, there is increasing concern that dosing recommendations are based on limited data sets and may lead to unnecessary underdosing and increased cancer mortality. This Review discusses the evidence surrounding genotyping and TDM to guide decisions around best practice.

Upfront DPYD Genotype-Guided Treatment for Fluoropyrimidine-Based Chemotherapy in Advanced and Metastatic Colorectal Cancer: A Cost-Effectiveness Analysis

OBJECTIVES

Fluoropyrimidines are the most widely used chemotherapy drugs for advanced and metastatic colorectal cancer (CRC). Individuals with certain DPYD gene variants are exposed to an increased risk of severe fluoropyrimidine-related toxicities. This study aimed to evaluate the cost-effectiveness of preemptive DPYD genotyping to guide fluoropyrimidine therapy in patients with advanced or metastatic CRC.

METHODS

Overall survival of DPYD wild-type patients who received a standard dose and variant carriers treated with a reduced dose were analyzed by parametric survival models. A decision tree and a partitioned survival analysis model with a lifetime horizon were designed, taking the Iranian healthcare perspective. Input parameters were extracted from the literature or expert opinion. To address parameter uncertainty, scenario and sensitivity analyses were also performed.

RESULTS

Compared with no screening, the genotype-guided treatment strategy was cost-saving ($41.7). Nevertheless, due to a possible reduction in the survival of patients receiving reduced-dose regimens, it was associated with fewer quality-adjusted life-years (9.45 vs 9.28). In sensitivity analyses, the prevalence of DPYD variants had the most significant impact on the incremental cost-effectiveness ratio. The genotyping strategy would remain cost-saving, as long as the genotyping cost is < $49 per test. In a scenario in which we assumed equal efficacy for the 2 strategies, genotyping was the dominant strategy, associated with less costs (∼$1) and more quality-adjusted life-years (0.1292).

CONCLUSIONS

DPYD genotyping to guide fluoropyrimidine treatment in patients with advanced or metastatic CRC is cost-saving from the perspective of the Iranian health system.

Pharmacogenetics and Adverse Events in the Use of Fluoropyrimidine in a Cohort of Cancer Patients on Standard of Care Treatment in Zimbabwe

Fluoropyrimidines are commonly used in the treatment of colorectal cancer. They are, however, associated with adverse events (AEs), of which gastrointestinal, myelosuppression and palmar-plantar erythrodysesthesia are the most common. Clinical guidelines are used for fluoropyrimidine dosing based on dihydropyrimidine dehydrogenase (DPYD) genetic polymorphism and have been shown to reduce these AEs in patients of European ancestry. This study aimed to evaluate, for the first time, the clinical applicability of these guidelines in a cohort of cancer patients on fluoropyrimidine standard of care treatment in Zimbabwe. DNA was extracted from whole blood and used for DPYD genotyping. Adverse events were monitored for six months using the Common Terminology Criteria for AEs (CTCAE) v.5.0. None of the 150 genotyped patients was a carrier of any of the pathogenic variants (DPYD*2A, DPYD*13, rs67376798, or rs75017182). However, severe AEs were high (36%) compared to those reported in the literature from other populations. There was a statistically significant association between BSA (p = 0.0074) and BMI (p = 0.0001) with severe global AEs. This study has shown the absence of the currently known actionable DPYD variants in the Zimbabwean cancer patient cohort. Therefore, the current pathogenic variants in the guidelines might not be feasible for all populations hence the call for modification of the current DPYD guidelines to include minority populations for the benefit of all diverse patients.

A review of pharmacogenetic studies in the Bangladeshi population

Pharmacogenetics (PGx)-guided prescribing is an evidence-based precision medicine strategy. Although the past two decades have reported significant advancements in both the quality and quantity of PGx research studies, they are seldom done in developing countries like Bangladesh. This review identified and summarized PGx studies conducted in the Bangladeshi population by searching PubMed and Google Scholar. Additionally, a quality evaluation of the identified studies was also carried out. Eleven PGx studies were identified that looked at the effects of genetic variants on blood thinners (CYP2C9, VKORC1, and ITGB3), cancer drugs (TPMT, MTHFR, DPYD, ERCC1, GSTP1, XPC, XRCC1, TP53, XPD, and ABCC4), statins (COQ2, CYP2D6, and CYP3A5), and prednisolone (ABCB1, CYP3A5, and NR3C1) in the Bangladeshi population. Most studies were of low to moderate quality. Although the identified studies demonstrated the potential for PGx testing, the limited PGx literature in the Bangladeshi population poses a significant challenge in the widespread implementation of PGx testing in Bangladesh.

Capecitabine-induced enterocolitis: a case report and pharmacogenetic profile

Capecitabine is a widely-used antineoplastic drug, a prodrug to 5-fluorouracil which commonly induces gastrointestinal toxicity. Enterocolitis, as a rarely recognized gastrointestinal adverse effect (AE) of capecitabine, is potentially severe and usually results in antitumor treatment withdrawal. For the better management of severe AEs, pharmacogenetics is one promising field. Herein, we describe a case of capecitabine-induced enterocolitis presenting with severe diarrhea in order to improve recognition by clinicians. Moreover, we conduct a pharmacogenetic profile of the patient and review the current studies of gene polymorphisms of 5-fluorouracil-related diarrhea, hoping to offer a reference for further clinical pharmacogenetic practice in predicting capecitabine AEs showing diarrhea as the main symptom.

Introducing a simple and cost-effective RT-PCR protocol for detection of DPYD*2A polymorphism: the first study in Kurdish population

PURPOSE

Fluoropyrimidines, the major chemotherapeutic agents in various malignancies treatment, are metabolized by dihydropyrimidine dehydrogenase (DPD). DPD deficiency can lead to severe and sometimes fatal toxicity. In the present study, we developed a simple protocol to detect the DPYD*2A variant. Common side effects in patients treated with these drugs were also evaluated in a Kurdish population.

METHOD

We established a reverse-transcriptase polymerase chain reaction (RT-PCR) technique for detection of DPYD*2A. Sanger sequencing was used to confirm the results. 121 Kurdish patients receiving fluoropyrimidine derivatives were enrolled, and clinical information regarding the dosage and toxicity was analyzed.

RESULTS

Our RT-PCR method was able to detect one patient with heterozygous state for DPYD*2A (0.8%). The most observed adverse drug reactions were tingling, nausea, and hair loss. The frequency of patients with the toxicity of grade 3 or worse was 6.6%.

CONCLUSION

This was the first study that detect DPYD*2A polymorphism in the Kurdish population. Our method was successfully able to detect the DPYD*2A variant and, due to its simplicity and cost-effectiveness, it may be considered as an alternative to the current methods, especially in developing countries. Our detected polymorphism rate at 0.8% is comparable with other studies. Despite the low rate of DPYD*2A polymorphism, pharmacogenetics assessment before beginning the treatment process is highly recommended due to its association with a high risk of severe toxicity.

Investigation of DPYD, MTHFR and TYMS polymorphisms on 5-fluorouracil related toxicities in colorectal cancer

Aim: To investigate the association of DPYD, MTHFR and TYMS polymorphisms on 5-fluorouracil (5-FU) related toxicities and patient survival. Materials & methods: A total of 103 colorectal cancer patients prescribed 5-FU were included in the study. Genotyping was conducted for several DPYD, MTHFR and TYMS polymorphisms using a microarray analyzer. Results: DPYD 496A>G polymorphism was found to be significantly associated with 5-FU related grade 0-2, but not severe toxicities (p = 0.02). Furthermore, patients with DPYD 85TC and CC genotypes had longer progression and overall survival times compared to TT genotypes in our study group (log rank = 6.60, p = 0.01 and log rank = 4.40, p = 0.04, respectively). Conclusion: According to our results, DPYD 496AG and GG genotypes might be protective against severe adverse events compared to the AA genotype. Another DPYD polymorphism, 85T>C, may be useful in colorectal cancer prognosis. Further studies for both polymorphisms should be conducted in larger populations to achieve accurate results.

Effects of polymorphisms in the MTHFR gene on 5-FU hematological toxicity and efficacy in Thai colorectal cancer patients

Background

The two common methylenetetrahydrofolate reductase (MTHFR) polymorphisms 677G>A and 1298A>C may have been affecting 5-FU toxicity in cancer patients for decades. Drug efficacy has also been shown by previous studies to be affected. In this study, we investigated the effects of these polymorphisms on 5-FU hematological toxicity and treatment efficacy, to provide enhanced pharmacological treatment for cancer patients.

Methods

This is a retrospective study involving 52 Thai colorectal cancer patients who were treated with 5-FU based therapy, using TaqMAN real-time PCR to genotype the MTHFR polymorphisms (677G>A and 1298A>C). The toxicity and response rate were assessed using standardized measures.

Results

Neutropenia was significantly more likely to be experienced (P=0.049, OR=7.286, 95% CI=0.697-76.181) by patients with the MTHFR 677G>A polymorphism, in the same way as leukopenia (P =0.036, OR=3.333, 95%CI=2.183-5.090) and thrombocytopenia (P<0.001, OR=3.917, 95%CI=2.404-6.382). The MTHFR 1298A>C polymorphism had no statistical association with hematological toxicity in 5-FU treatment. The response rate to 5-FU was not significantly affected by these two polymorphisms.

Conclusion

The MTHFR polymorphism 677G>A is a significant risk factor for developing leukopenia, neutropenia and thrombocytopenia as toxic effects of 5-FU therapy in cancer patients. Therefore, patients receiving 5-FU-based therapy should be aware of their polymorphisms as one risk factor for experiencing severe toxicity.

Pathogenic DPYD Variants and Treatment-Related Mortality in Patients Receiving Fluoropyrimidine Chemotherapy: A Systematic Review and Meta-Analysis

BACKGROUND

Pathogenic variants of the DPYD gene are strongly associated with grade ≥3 toxicity during fluoropyrimidine chemotherapy. We conducted a systematic review and meta-analysis to estimate the risk of treatment-related death associated with DPYD gene variants.

MATERIALS AND METHODS

We searched for reports published prior to September 17, 2020, that described patients receiving standard-dose fluoropyrimidine chemotherapy (5-fluorouracil or capecitabine) who had baseline testing for at least one of four pathogenic DPYD variants (c.1129-5923C>G [HapB3], c.1679T>G [*13], c.1905+1G>A [*2A], and c.2846A>T) and were assessed for toxicity. Two reviewers assessed studies for inclusion and extracted study-level data. The primary outcome was the relative risk of treatment-related mortality for DPYD variant carriers versus noncarriers; we performed data synthesis using a Mantel-Haenszel fixed effects model.

RESULTS

Of the 2,923 references screened, 35 studies involving 13,929 patients were included. DPYD variants (heterozygous or homozygous) were identified in 566 patients (4.1%). There were 14 treatment-related deaths in 13,363 patients without identified DPYD variants (treatment-related mortality, 0.1%; 95% confidence interval [CI], 0.1-0.2) and 13 treatment-related deaths in 566 patients with any of the four DPYD variants (treatment-related mortality, 2.3%; 95% CI, 1.3%-3.9%). Carriers of pathogenic DPYD gene variants had a 25.6 times increased risk of treatment-related death (95% CI, 12.1-53.9; p < .001). After excluding carriers of the more common but less deleterious c.1129-5923C>G variant, carriers of c.1679T>G, c.1905+1G>A, and/or c.2846A>T had treatment-related mortality of 3.7%.

CONCLUSION

Patients with pathogenic DPYD gene variants who receive standard-dose fluoropyrimidine chemotherapy have greatly increased risk for treatment-related death.

IMPLICATIONS FOR PRACTICE

The syndrome of dihydropyrimidine dehydrogenase (DPD) deficiency is an uncommon but well-described cause of severe toxicity related to fluoropyrimidine chemotherapy agents (5-fluorouracil and capecitabine). Patients with latent DPD deficiency can be identified preemptively with genotyping of the DPYD gene, or with measurement of the plasma uracil concentration. In this systematic review and meta-analysis, the authors study the rare outcome of treatment-related death after fluoropyrimidine chemotherapy. DPYD gene variants associated with DPD deficiency were linked to a 25.6 times increased risk of fluoropyrimidine-related mortality. These findings support the clinical utility of DPYD genotyping as a screening test for DPD deficiency.

Issues and limitations of available biomarkers for fluoropyrimidine-based chemotherapy toxicity, a narrative review of the literature

Fluoropyrimidine-based chemotherapies are widely used to treat gastrointestinal tract, head and neck, and breast carcinomas. Severe toxicities mostly impact rapidly dividing cell lines and can occur due to the partial or complete deficiency in dihydropyrimidine dehydrogenase (DPD) catabolism. Since April 2020, the European Medicines Agency (EMA) recommends DPD testing before any fluoropyrimidine-based treatment. Currently, different assays are used to predict DPD deficiency; the two main approaches consist of either phenotyping the enzyme activity (directly or indirectly) or genotyping the four main deficiency-related polymorphisms associated with 5-fluorouracil (5-FU) toxicity. In this review, we focused on the advantages and limitations of these diagnostic methods: direct phenotyping by evaluation of peripheral mononuclear cell DPD activity (PBMC-DPD activity), indirect phenotyping assessed by uracil levels or UH2/U ratio, and genotyping DPD of four variants directly associated with 5-FU toxicity. The risk of 5-FU toxicity increases with uracil concentration. Having a pyrimidine-related structure, 5-FU is catabolised by the same physiological pathway. By assessing uracil concentration in plasma, indirect phenotyping of DPD is then measured. With this approach, in France, a decreased 5-FU dose is systematically recommended at a uracil concentration of 16 ng/ml, which may lead to chemotherapy under-exposure as uracil concentration is a continuous variable and the association between uracil levels and DPD activity is not clear. We aim herein to describe the different available strategies developed to improve fluoropyrimidine-based chemotherapy safety, how they are implemented in routine clinical practice, and the possible relationship with inefficacy mechanisms.

Higher ETV5 Expression Associates With Poor 5-Florouracil-Based Adjuvant Therapy Response in Colon Cancer

Discovery of markers predictive for 5-Fluorouracil (5-FU)-based adjuvant chemotherapy (adjCTX) response in patients with locally advanced stage II and III colon cancer (CC) is necessary for precise identification of potential therapy responders. PEA3 subfamily of ETS transcription factors (ETV1, ETV4, and ETV5) are upregulated in multiple cancers including colon cancers. However, the underlying epigenetic mechanism regulating their overexpression as well as their role in predicting therapy response in colon cancer are largely unexplored. In this study, using gene expression and methylation data from The Cancer Genome Atlas (TCGA) project, we showed that promoter DNA methylation negatively correlates with ETV4 expression (ρ = -0.17, p = 5.6 × 10^-3) and positively correlates with ETV5 expression (ρ = 0.22, p = 1.43 × 10^-4) in colon cancer tissue. Further, our analysis in 1,482 colon cancer patients from five different cohorts revealed that higher ETV5 expression associates with shorter relapse-free survival (RFS) of adjCTX treated colon cancer patients (Hazard ratio = 2.09-5.43, p = 0.004-0.01). The present study suggests ETV5 expression as a strong predictive biomarker for 5-FU-based adjCTX response in stage II/III CC patients.

Effect of DPYD, MTHFR, ABCB1, XRCC1, ERCC1 and GSTP1 on chemotherapy related toxicity in colorectal carcinoma

ABCB1, DPYD, MHTFR, XRCC1, ERCC1, GSTP1 and UGT1A1 genetic variants affect proteins related to CRC chemotherapy toxicity. A retrospective cohort study was conducted in 194 CRC patients. In first line treatment, DPYD rs17376848 AG genotype was associated with hematological toxicity (OR = 4.85; p = 0.03); GSTP1 G-allele (OR = 3.01; p = 0.005) and MTHFR rs1801133 T allele (OR = 2.51; p = 0.03) with respiratory toxicity; GSTP1 G-allele with cardiovascular toxicity (OR = 4.05; p = 0.01); ERCC1 rs11615 GG genotype with neurological toxicity (OR = 3.98; p = 0.01) and with asthenia (OR = 2.91; p = 0.08); XRCC1 rs1799782 T allele (OR = 0.31; p = 0.03) and GSTP1 G-allele (OR = 1.81; p = 0.01) with cutaneous toxicity. In second line treatment, XRCC1 rs1799782 T-allele was associated with asthenia (OR = 0.17; p = 0.03) and XRCC1 rs25487 T-allele with gastrointestinal toxicity (OR = 3.03; p = 0.005). After stratifying by treatment, in the 5-Fluorouracil group, the DPYD rs17376848 AG genotype was associated with hematological toxicity (OR = 2.76; p = 0.003), ABCB1 rs1045642 T-allele with the need of treatment adjustment due to toxicity (OR = 3.06; p = 0.01), and rs1045642 CC genotype with gastrointestinal toxicity (OR = 5.80; p = 0.03). In the capecitabine group, the MTHFR rs1801131 CC genotype was associated with asthenia (OR = 3.48; p = 0.009). In the oxaliplatin group, rs1045642 TT genotype was associated with the need to adjust treatment (OR = 0.32; p = 0.02), ERCC1 rs11615 GG genotype with asthenia (OR = 3.01; p = 0.01) and rs1615 GSTP1 GG genotype with respiratory toxicity (OR = 5.07; p = 0.009). ABCB1 rs1045642 T-allele reduces the need for treatment modification with both 5FU and oxaliplatin. Although several biomarkers predicted different toxic effects, they cannot be considered as risk factors for severe toxicity.

Genetic polymorphisms of GSTP1, XRCC1, XPC and ERCC1: prediction of clinical outcome of platinum-based chemotherapy in advanced non-small cell lung cancer patients of Bangladesh

Inter-individual genetic makeup can trigger variability in platinum-based chemotherapeutic responses and corresponding adverse drug reactions and toxicities. Exploring the genetic causes behind these inter-individual variabilities in platinum-based chemotherapeutic responses by investigating the effects of GSTP1 (rs1695), XRCC1 (rs25487), XPC (rs2228001) and ERCC1 (rs11615) genetic polymorphisms on toxicity and therapeutic response of this treatment among Bangladeshi advanced non-small cell lung cancer (NSCLC) patients was the aim of this study. 285 Clinically proven either stage IIIB or IV (advanced) NSCLC patients aging not less than 18 years old and receiving platinum-based chemotherapy were recruited to assess the influence of these four single nucleotide polymorphisms (SNPs) on peripheral leukocytes. Toxicity and response were evaluated by multivariate regression analyses using SPSS statistical software (version 17.0). XRCC1 (rs25487) polymorphism was found to act as a predictive factor for not only grade 3 and 4 anemia (p = 0.008), neutropenia (p = 0.010), thrombocytopenia (p = 0.025) and gastrointestinal toxicity (p = 0.002) but also for therapeutic response (p = 0.012) in platinum-based chemotherapy. Although GSTP1 (rs1695) polymorphism might serve as prognostic factor regarding grade 3 or 4 neutropenia, a significant (p = 0.044) improvement in response to platinum-based chemotherapy was observed. However, XPC (rs2228001) and ERCC1 (rs11615) polymorphisms could not establish any significant relation with toxicity or therapeutic response. XRCC1 (rs2228001) and GSTP1 (rs1695) polymorphisms might explain platinum-induced clinical outcomes in terms of both toxicity and therapeutic response variations among Bangladeshi advanced NSCLC patients.

LncRNA HOTAIR-mediated MTHFR methylation inhibits 5-fluorouracil sensitivity in esophageal cancer cells

BACKGROUND

Esophageal cancer (EC) represents one of the most aggressive digestive neoplasms globally, with marked geographical variations in morbidity and mortality. Chemoprevention is a promising approach for cancer therapy, while acquired chemoresistance is a major obstacle impeding the success of 5-fluorouracil (5-FU)-based chemotherapy in EC, with the mechanisms underlying resistance not well-understood. In the present study, we focus on exploring the role of long non-coding RNA (lncRNA) HOTAIR in EC progression and sensitivity of EC cells to 5-FU.

METHODS

Paired cancerous and pre-cancerous tissues surgically resected from EC patients were collected in this study. Promoter methylation of the MTHFR was assessed by methylation-specific PCR. RIP and ChIP assays were adopted to examine the interaction of DNA methyltransferases (DNMTs) with lncRNA HOTAIR and MTHFR, respectively. EC cells resistant to 5-FU were induced by step-wise continuous increasing concentrations of 5-FU. The sensitivity of EC cells to 5-FU in vivo was evaluated in nude mice treated with xenografts of EC cells followed by injection with 5-FU (i.p.).

RESULTS

We found reciprocal expression patterns of lncRNA HOTAIR and MTHFR in EC tissues and human EC cells. Interference with lncRNA HOTAIR enhanced 5-FU-induced apoptosis, exhibited anti-proliferative activity, and reduced promoter methylation of the MTHFR in EC cells. Besides, overexpression of MTHFR attenuated the acquired chemoresistance induced by overexpression of lncRNA HOTAIR in EC cells. At last, enhanced chemosensitivity was observed in vivo once nude mice xenografted with lncRNA HOTAIR-depleted EC cells.

CONCLUSION

Together, our study proposes that pharmacologic targeting of lncRNA HOTAIR sensitizes EC cells to 5-FU-based chemotherapy by attenuating the promoter hypermethylation of the MTHFR in EC.

DPYD, TYMS and MTHFR Genes Polymorphism Frequencies in a Series of Turkish Colorectal Cancer Patients

Fluoropyrimidine-based chemotherapy is extensively used for the treatment of solid cancers, including colorectal cancer. However, fluoropyrimidine-driven toxicities are a major problem in the management of the disease. The grade and type of the toxicities depend on demographic factors, but substantial inter-individual variation in fluoropyrimidine-related toxicity is partly explained by genetic factors. The aim of this study was to investigate the effect of dihydropyrimidine dehydrogenase (DPYD), thymidylate synthase (TYMS), and methylenetetrahydrofolate reductase (MTHFR) polymorphisms in colorectal cancer patients. Eighty-five patients who were administered fluoropyrimidine-based treatment were included in the study. The DPYD, TYMS and MTHFR polymorphisms were scanned by a next generation Sequenom MassARRAY. Fluoropyrimidine toxicities were observed in 92% of all patients. The following polymorphisms were detected: DPYD 85T>C (29.4% heterozygote mutants, 7.1% homozygote mutants), DPYD IVS 14+1G>A (1.2% heterozygote mutants), TYMS 1494del TTAAAG (38.4% heterozygote mutants, 24.7% homozygote mutants), MTHFR 677C>T (43.5% heterozygote mutants, 9.4% homozygote mutants) and MTHFR 1298A>C (8.2% heterozygote mutants, 2.4% homozygote mutants). A statistically significant association was demonstrated between MTHFR 677C>T and fluoropyrimidine-related toxicity. Furthermore, MTHFR 1298A>C was associated with hematopoietic toxicity. MTHFR polymorphisms may be considered as related factors of fluoropyrimidine toxicity and may be useful as predictive biomarkers for the determination of the colorectal cancer patients who can receive the greatest benefit from fluoropyrimidine-based treatments.