Pharmacogenomics of cisplatin-based chemotherapy in ovarian cancer patients of different ethnic origins

Genetic Variability of CYP4F2, CYP2D6, CYP2E1, and ACE in the Chinese Yi Population

Genetic polymorphisms of very important pharmacogenes (VIP) are a significant factor contributing to inter-individual variability in drug therapy. The purpose of this study was to identify significantly different loci in the Yi population and to enrich their pharmacogenomic information. 54 VIP variants were selected from the Pharmacogenomics Knowledge Base (PharmGKB) and genotyped in 200 Yi individuals. Then, we compared their genotype distribution between the Yi population and the other 26 populations using the χ2 test. Compared with the other 26 populations, the genotype frequencies of 4 single nucleotide polymorphisms (SNPs), rs2108622 (CYP4F2), rs1065852 (CYP2D6), rs2070676 (CYP2E1), and rs4291 (ACE), had significant differences in the Yi population. For example, the TT genotype frequency of rs2108622 (8.1%) was higher than that of African populations, and the AA genotype frequency of rs1065852 (27.3%) was higher than that of other populations except East Asians. We also found that the Yi populations differed the least from East Asians and the most from Africans. Furthermore, the differences in these variants might be related to the effectiveness and toxicity risk of using warfarin, iloperidone, cisplatin cyclophosphamide, and other drugs in the Yi population. Our data complement the pharmacogenomic information of the Yi population and provide theoretical guidance for their personalized treatment.

A phase I dose-finding trial of hyperthermic intraperitoneal docetaxel combined with cisplatin in patients with advanced-stage ovarian cancer

OBJECTIVE

To identify the maximum tolerated dose (MTD) of docetaxel combined with a fixed dose of cisplatin (75 mg/m²) delivered as hyperthermic intraperitoneal chemotherapy (HIPEC) in patients with ovarian cancer.

METHODS

In this phase I trial, a time-to-event Bayesian optimal interval design was used. Docetaxel was given at a starting dose of 60 mg/m² and was increased in 5 mg/m² increments until the MTD was determined or the maximum dose level of 75 mg/m² was reached. The dose-limiting toxicity (DLT) rate was set at 25%, with a total sample size of 30 patients. HIPEC was delivered immediately following debulking surgery at a target temperature of 43°C for 90 minutes.

RESULTS

From August 2022 to November 2022, 30 patients were enrolled. Among the patients who received a dose of docetaxel ≤65 mg/m², no DLT was reported. DLTs were observed in one patient who received 70 mg/m² docetaxel (grade 3 anaemia) and in three patients who received 75 mg/m² docetaxel (one case of grade 3 anaemia, one case of grade 3 hepatic impairment and one case of grade 4 thrombocytopenia). Patients treated with docetaxel 75 mg/m² in combination with cisplatin 75 mg/m² had an estimated DLT rate of 25%, which was the closest to the target DLT rate and was therefore chosen as the MTD.

CONCLUSION

Docetaxel, in combination with a fixed dose of cisplatin (75 mg/m²), can be used safely at intraperitoneal doses of 75 mg/m² in ovarian cancer patients who received HIPEC (43°C, 90 minutes) following debulking surgery.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05410483.

Machine Learning Application Identifies Germline Markers of Hypertension in Patients With Ovarian Cancer Treated With Carboplatin, Taxane, and Bevacizumab

Pharmacogenomics studies how genes influence a person's response to treatment. When complex phenotypes are influenced by multiple genetic variations with little effect, a single piece of genetic information is often insufficient to explain this variability. The application of machine learning (ML) in pharmacogenomics holds great potential - namely, it can be used to unravel complicated genetic relationships that could explain response to therapy. In this study, ML techniques were used to investigate the relationship between genetic variations affecting more than 60 candidate genes and carboplatin-induced, taxane-induced, and bevacizumab-induced toxicities in 171 patients with ovarian cancer enrolled in the MITO-16A/MaNGO-OV2A trial. Single-nucleotide variation (SNV, formerly SNP) profiles were examined using ML to find and prioritize those associated with drug-induced toxicities, specifically hypertension, hematological toxicity, nonhematological toxicity, and proteinuria. The Boruta algorithm was used in cross-validation to determine the significance of SNVs in predicting toxicities. Important SNVs were then used to train eXtreme gradient boosting models. During cross-validation, the models achieved reliable performance with a Matthews correlation coefficient ranging from 0.375 to 0.410. A total of 43 SNVs critical for predicting toxicity were identified. For each toxicity, key SNVs were used to create a polygenic toxicity risk score that effectively divided individuals into high-risk and low-risk categories. In particular, compared with low-risk individuals, high-risk patients were 28-fold more likely to develop hypertension. The proposed method provided insightful data to improve precision medicine for patients with ovarian cancer, which may be useful for reducing toxicities and improving toxicity management.

Clinical outcomes of chemotherapy in cancer patients with different ethnicities

BACKGROUND

Choosing the most effective chemotherapeutic agent with safest side effect profile is a common challenge in cancer treatment. Although there are standardized chemotherapy protocols in place, protocol changes made after extensive clinical trials demonstrate significant improvement in the efficacy and tolerability of certain drugs. The pharmacokinetics, pharmacodynamics, and tolerance of anti-cancer medications are all highly individualized. A driving force behind these differences lies within a person's genetic makeup.

RECENT FINDINGS

Pharmacogenomics, the study of how an individual's genes impact the processing and action of a drug, can optimize drug responsiveness and reduce toxicities by creating a customized medication regimen. However, these differences are rarely considered in the initial determination of standardized chemotherapeutic protocols and treatment algorithms. Because pharmacoethnicity is influenced by both genetic and nongenetic variables, clinical data highlighting disparities in the frequency of polymorphisms between different ethnicities is steadily growing.  Recent data suggests that ethnic variations in the expression of allelic variants may result in different pharmacokinetic properties of the anti-cancer medication. In this article, the clinical outcomes of various chemotherapy classes in patients of different ethnicities were reviewed.

CONCLUSION

Genetic and nongenetic variables contribute to the interindividual variability in response to chemotherapeutic drugs. Considering pharmacoethnicity in the initial determination of standard chemotherapeutic protocols and treatment algorithms can lead to better clinical outcomes of patients of different ethnicities.

Cisplatin nephrotoxicity: new insights and therapeutic implications

Cisplatin is an effective chemotherapeutic agent for various solid tumours, but its use is limited by adverse effects in normal tissues. In particular, cisplatin is nephrotoxic and can cause acute kidney injury and chronic kidney disease. Preclinical studies have provided insights into the cellular and molecular mechanisms of cisplatin nephrotoxicity, which involve intracellular stresses including DNA damage, mitochondrial pathology, oxidative stress and endoplasmic reticulum stress. Stress responses, including autophagy, cell-cycle arrest, senescence, apoptosis, programmed necrosis and inflammation have key roles in the pathogenesis of cisplatin nephrotoxicity. In addition, emerging evidence suggests a contribution of epigenetic changes to cisplatin-induced acute kidney injury and chronic kidney disease. Further research is needed to determine how these pathways are integrated and to identify the cell type-specific roles of critical molecules involved in regulated necrosis, inflammation and epigenetic modifications in cisplatin nephrotoxicity. A number of potential therapeutic targets for cisplatin nephrotoxicity have been identified. However, the effects of renoprotective strategies on the efficacy of cisplatin chemotherapy needs to be thoroughly evaluated. Further research using tumour-bearing animals, multi-omics and genome-wide association studies will enable a comprehensive understanding of the complex cellular and molecular mechanisms of cisplatin nephrotoxicity and potentially lead to the identification of specific targets to protect the kidney without compromising the chemotherapeutic efficacy of cisplatin.

Pharmacogenetics of chemotherapy treatment response and -toxicities in patients with osteosarcoma: a systematic review

BACKGROUND

Osteosarcoma is the most common bone tumor in children and adolescents. Despite multiagent chemotherapy, only 71% of patients survives and these survivors often experience long-term toxicities. The main objective of this systematic review is to provide an overview of the discovery of novel associations of germline polymorphisms with treatment response and/or chemotherapy-induced toxicities in osteosarcoma.  METHODS: MEDLINE and Embase were systematically searched (2010-July 2022). Genetic association studies were included if they assessed > 10 germline genetic variants in > 5 genes in relevant drug pathways or if they used a genotyping array or other large-scale genetic analysis. Quality was assessed using adjusted STrengthening the REporting of Genetic Association studies (STREGA)-guidelines. To find additional evidence for the identified associations, literature was searched to identify replication studies.

RESULTS

After screening 1999 articles, twenty articles met our inclusion criteria. These range from studies focusing on genes in relevant pharmacokinetic pathways to whole genome sequencing. Eleven articles reported on doxorubicin-induced cardiomyopathy. For seven genetic variants in CELF4, GPR35, HAS3, RARG, SLC22A17, SLC22A7 and SLC28A3, replication studies were performed, however without consistent results. Ototoxicity was investigated in one study. Five small studies reported on mucosistis or bone marrow, nephro- and/or hepatotoxicity. Six studies included analysis for treatment efficacy. Genetic variants in ABCC3, ABCC5, FasL, GLDC, GSTP1 were replicated in studies using heterogeneous efficacy outcomes.

CONCLUSIONS

Despite that results are promising, the majority of associations were poorly reproducible due to small patient cohorts. For the future, hypothesis-generating studies in large patient cohorts will be necessary, especially for cisplatin-induced ototoxicity as these are largely lacking. In order to form large patient cohorts, national and international collaboration will be essential.

Association between rs735482 polymorphism and risk of cancer: A meta-analysis of 10 case-control studies

Several studies have inspected the relationship between rs735482 polymorphism and the risk of some human cancers, but the findings remain controversial. We designed this meta-analysis to validate the association between rs735482 polymorphism and cancer risk. All articles were published before September 1, 2018 and searched in Pubmed, Embase, Web of Science, China National Knowledge Infrastructure, WangFang, and Chinese BioMedical databases, STATA 12.0 software was used for statistical analysis, which provides reasonable data and technical support for this article. A total of 10 studies were included in the meta-analysis, including 2652 cancer cases and 3536 rs735482 polymorphic controls. Data were directly extracted from these studies and odds ratios with 95% confidence intervals were computed to estimate the strength of the association. By pooling all eligible studies, the rs735482 polymorphism showed no significant association with susceptibility of several cancers in all the five genetic models (the allelic model: OR = 1.019, 95% CI: 0.916-1.134, P = .731). In addition, another adjusted OR data showed a significant increased risk between the rs735482 and susceptibility of several cancers (the codominant model BB vs AA: OR = 1.353, 95% CI: 1.033-1.774, P = .028) and the stratification analysis by ethnicity indicated the rs735482 is associated with an increased risk of cancer in Chinese group (BB vs AA, OR = 1.391, 95% CI = 1.054-1.837, P = .020; AB+BB vs AA OR = 1.253, 95% CI = 1.011-1.551, P = .039). However, the ERCC1 rs735482 is associated with a decreased risk of cancer in Italian group (AB vs AA, OR = 0.600, 95% CI = 0.402-0.859, P = .012; AB + BB vs AA, OR = 0.620, 95% CI = 0.424-0.908, P = .014). The results of this meta-analysis do not support the association between rs735482 polymorphism and cancer risk. But stratified analysis showed that rs735482 significantly increased the risk of cancer in Chinese while decreased the risk of cancer in Italian. Because of the limited number of samples, larger and well-designed researches are needed to estimate this association in detail.

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.

Genetic variation of pharmacogenomic VIP variants in the Chinese Li population: an updated research

Previous studies have shown that the frequency of very important pharmacogenomic (VIP) genes varies in different populations which leads to the diversities in drug efficacy, safety, and the risk associated with adverse drug reactions (ADRs). The purpose of this study was to identify the distribution differences of VIP variants between the Li population and the other 13 populations. Based on the Pharmacogenomics Knowledgebase database (PhamGKB), we successfully genotyped 52 VIP variants within 27 genes in 200 unrelated Li population. χ² test was used to evaluate the significant differences of genotype and allele frequencies between the Li and the other 13 populations from 1000 Genomes Project. Our study showed that the genotype frequencies of single nucleotide polymorphisms (SNPs) on KCNH2, ACE, CYP4F2, and CYP2E1 were considerably different between Li and the other 13 populations, especially in rs1805123 (KCNH2), rs4291 (ACE), rs3093105 (CYP4F2), and rs6413432 (CYP2E1) loci. Meanwhile, we found several VIP variants that might alter the drug metabolism of cisplatin-cyclophosphamide (CYP2E1), vitamin E (CYP4F2), asthma amlodipine, chlorthalidone, and lisinopril (ACE) through PharmGKB. We also identified other variants which were associated with adverse effects in isoniazid and rifampicin (CYP2E1; hepatotoxicity). The four loci rs1805123 (KCNH2), rs4291 (ACE), rs3093105 (CYP4F2), and rs6413432 (CYP2E1) provided a reliable basis for the prediction of the efficacy of certain drugs. The study complemented the existed pharmacogenomics information, which could provide theoretical basis for predicting the efficacy of certain drugs in the Li population.

ERCC1 rs11615 polymorphism and chemosensitivity to platinum drugs in patients with ovarian cancer: a systematic review and meta-analysis

OBJECTIVE

To explore the relationship between ERCC1 rs11615 polymorphism and chemosensitivity to platinum drugs in ovarian cancer by the method of meta-analysis.

METHODS

Pubmed, Web of Science, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI), and China Wanfang databases were comprehensively searched up to September 2020, to identify the relationship between ERCC1 rs11615 polymorphism and chemosensitivity of ovarian cancer. The data was analyzed by Stata 15.0 statistic software.

RESULTS

A total of 10 published papers were included, including 1866 patients with ovarian cancer. The results showed that compared allele C at ERCC1 rs11615 locus with allele T, the pooled OR was 0.92 (95%CI:0.68 ~ 1.24, P > 0.05). There were no significant differences in recessive, dominant, homozygous, and heterozygous models. In accordance with a subgroup analysis of Ethnicity, all genotypes were statistically significant in the Asian population. In the allelic, dominant, recessive, homozygous and heterozygous models, the OR was 0.70 (95%CI:0.51 ~ 0.95), 0.20 (95%CI:0.07 ~ 0.56), 0.79 (95%CI:0.63 ~ 1.00), 0.21 (95%CI:0.07 ~ 0.59), 0.19 (95%CI:0.07 ~ 0.54), respectively, while in the Caucasian population, no statistically significant genotype was found.

CONCLUSION

The ERCC1 rs11615 polymorphism is associated with chemosensitivity in patients with ovarian cancer, especially in the Asian population, but not in the Caucasian population.

A Dose-Finding Trial for Hyperthermic Intraperitoneal Cisplatin in Gynecological Cancer Patients Receiving Hyperthermic Intraperitoneal Chemotherapy

Background: To identify the maximum tolerated dose (MTD) of hyperthermic intraperitoneal cisplatin at 43°C among gynecological cancer patients.

Methods: In this Phase I dose-finding trial, Bayesian optimal interval (BOIN) design was used. We sought to explore the MTD with a target dose-limiting toxicity (DLT) rate of 20%, 4 prespecified doses (70 mg/m², 75 mg/m², 80 mg/m² and 85 mg/m²), and 30 patients.

Results: Between 2019 and 2020, 30 gynecologic cancer patients were enrolled. No patients received bevacizumab in subsequent treatment. The most common adverse events related to cisplatin were nausea and vomiting (100%), followed by tinnitus (26.7%) and kidney injury (23.3%). Of the seven patients with kidney injury, four had persistent renal impairment, and finally progressed into chronic kidney injury. DLTs were noted only in the dose level 4 group (85 mg/m²) and included acute kidney injury, pulmonary embolism, anemia, and neutropenia. When cisplatin was given at dose level four (85 mg/m²), the isotonic estimate of the DLT rate (22%) was closest to the target DLT rate of 20%. Therefore, 85 mg/m² was selected as the MTD, with a 51% probability that the toxicity probability was greater than the target DLT rate.

Conclusions: For gynecological cancer patients who received HIPEC for peritoneal metastases, the MTD of cisplatin in HIPEC at 43°C was 85 mg/m². Our findings apply to patients who do not receive bevacizumab (ChiCTR1900021555).

The safety of current pharmacotherapeutic strategies for osteosarcoma

Introduction: Peri-operative chemotherapy is the backbone of treatment for patients with osteosarcoma. Methotrexate, cisplatinum, doxorubicin and ifosfamide are the main drugs used in chemotherapy regimens used for osteosarcoma.Areas covered: We have reviewed here the relevant literature related to the incidence and management of acute and late toxicities of systemic treatment used for the management of patients with osteosarcoma.Expert opinion: Early diagnosis and appropriate management of acute and late toxicities of chemotherapy is crucial for an efficient care of osteosarcoma patients. Although the incidence and management of chemotherapy-related acute toxicities are well known by most oncologists, the use of high doses of methotrexate have the potential to cause fatal toxicities and, therefore, needs careful monitoring. Moreover, the diagnosis of late toxicities is more challenging and requires long-term follow-up for an appropriate management.

Calculating the dose of cisplatin that is actually utilized in hyperthermic intraperitoneal chemotherapy among ovarian cancer patients

Background

Hyperthermic intraperitoneal chemotherapy (HIPEC) is an important treatment for ovarian cancer. A certain portion of cisplatin exits the body via the perfusate at the end of HIPEC, so full-dose utilization cannot be achieved. Herein, we sought to explore how much cisplatin is actually utilized and its prognostic influence.

Methods

Cisplatin (70 mg/m²) was given at 43 °C for 90 min. The actually utilized dose (AD) of cisplatin was calculated using the following formula: AD (mg) = total dose (TD) (mg)-losing dose (LD) (mg); LD = volume (ml) of the perfusate (VP_retained) that was retained in the HIPEC treatment system at the end of HIPEC * concentration of cisplatin in the perfusate (mg/ml).

Result

Sixty-two ovarian cancer patients were included. The median TD, median LD and median AD were 95 mg, 20.7 mg and 75.8 mg, respectively. The utility rate of cisplatin (AD/TD ratio) was 79.2%. On simple linear regression analysis, the TD and VP_retained were found to significantly predict the AD. Based on these two factors, multiple linear regression analysis was conducted, and a significant regression equation was formulated [F (2, 59) = 71.419, P < 0.0001]: predicted AD (mg) = 30.079 + 0.667 TD (mg) – 0.010 VP_retained (ml) (adjusted R² = 0.698). In Cox regression analysis, AD was not noted to be associated with progression free survival or overall survival.

Conclusion

For ovarian cancer patients who receive cisplatin for HIPEC at 43 °C, the AD of cisplatin can be predicted using a regression equation and it has no prognostic impact.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00764-6.

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.

Neurotoxicity of antineoplastic drugs: Mechanisms, susceptibility, and neuroprotective strategies

This review summarizes the adverse effects on the central and/or peripheral nervous systems that may occur in response to antineoplastic drugs. In particular, we describe the neurotoxic side effects of the most commonly used drugs, such as platinum compounds, doxorubicin, ifosfamide, 5-fluorouracil, vinca alkaloids, taxanes, methotrexate, bortezomib and thalidomide. Neurotoxicity may result from direct action of compounds on the nervous system or from metabolic alterations produced indirectly by these drugs, and either the central nervous system or the peripheral nervous system, or both, may be affected. The incidence and severity of neurotoxicity are principally related to the dose, to the duration of treatment, and to the dose intensity, though other factors, such as age, concurrent pathologies, and genetic predisposition may enhance the occurrence of side effects. To avoid or reduce the onset and severity of these neurotoxic effects, the use of neuroprotective compounds and/or strategies may be helpful, thereby enhancing the therapeutic effectiveness of antineoplastic drug.

Pharmacogenomics to Predict Tumor Therapy Response: A Focus on ATP-Binding Cassette Transporters and Cytochromes P450

Pharmacogenomics is an evolving tool of precision medicine. Recently, due to the introduction of next-generation sequencing and projects generating "Big Data", a plethora of new genetic variants in pharmacogenes have been discovered. Cancer resistance is a major complication often preventing successful anticancer treatments. Pharmacogenomics of both somatic mutations in tumor cells and germline variants may help optimize targeted treatments and improve the response to conventional oncological therapy. In addition, integrative approaches combining copy number variations and long noncoding RNA profiling with germline and somatic variations seem to be a promising approach as well. In pharmacology, expression and enzyme activity are traditionally the more studied aspects of ATP-binding cassette transporters and cytochromes P450. In this review, we briefly introduce the field of pharmacogenomics and the advancements driven by next-generation sequencing and outline the possible roles of genetic variation in the two large pharmacogene superfamilies. Although the evidence needs further substantiation, somatic and copy number variants as well as rare variants and common polymorphisms in these genes could all affect response to cancer therapy. Regulation by long noncoding RNAs has also been shown to play a role. However, in all these areas, more comprehensive studies on larger sets of patients are needed.

Molecular mechanisms of ethanol biotransformation: enzymes of oxidative and nonoxidative metabolic pathways in human

Ethanol, as a small-molecule organic compound exhibiting both hydrophilic and lipophilic properties, quickly pass through the biological barriers. Over 95% of absorbed ethanol undergoes biotransformation, the remaining amount is excreted unchanged, mainly with urine and exhaled air.The main route of ethyl alcohol metabolism is its oxidation to acetaldehyde, which is converted into acetic acid with the participation of cytosolic NAD⁺ - dependent alcohol (ADH) and aldehyde (ALDH) dehydrogenases. Oxidative biotransformation pathways of ethanol also include reactions catalyzed by the microsomal ethanol oxidizing system (MEOS), peroxisomal catalase and aldehyde (AOX) and xanthine (XOR) oxidases. The resulting acetic acid can be activated to acetyl-CoA by the acetyl-CoA synthetase (ACS).It is also possible, to a much smaller extent, non-oxidative routes of ethanol biotransformation including its esterification with fatty acids by ethyl fatty acid synthase (FAEES), re-esterification of phospholipids, especially phosphatidylcholines, with phospholipase D (PLD), coupling with sulfuric acid by alcohol sulfotransferase (SULT) and with glucuronic acid using UDP-glucuronyl transferase (UGT, syn. UDPGT).The intestinal microbiome plays a significant role in the ethanol biotransformation and in the initiation and progression of liver diseases stimulated by ethanol and its metabolite - acetaldehyde, or by lipopolysaccharide and ROS.

Toxicity and Pharmacogenomic Biomarkers in Breast Cancer Chemotherapy

Breast cancer (BC) is one of the most prevalent types of cancer worldwide with high morbidity and mortality rates. Treatment modalities include systemic therapy, in which chemotherapy is a major component in many cases. Several chemotherapeutic agents are used in combinations or as single agents with many adverse events occurring in variable frequencies. These events can be a significant barrier in completing the treatment regimens. Germline genomic variants are thought of as potential determinants in chemotherapy response and the development of side effects. Some pharmacogenomic studies were designed to explore germline variants that can be used as biomarkers for predicting developing toxicity or adverse events during chemotherapy in BC. In this review, we reassess and summarize the major findings of pharmacogenomic studies of chemotherapy toxicity during BC management. In addition, deficiencies hampering utilizing these findings and the potential targets of future research are emphasized. Main insufficiencies in toxicity pharmacogenomics studies originate from study design, sample limitations, heterogeneity of selected genes, variants, and toxicity definitions. With the advent of high throughput genotyping techniques, researchers are expected to explore the identified as well as the potential genetic biomarkers of toxicity and efficacy to improve BC management. However, to achieve this, the limitations of previous work should be evaluated and avoided to reach more conclusive and translatable evidence for personalizing BC chemotherapy.

Population genetic difference of pharmacogenomic VIP gene variants in the Lisu population from Yunnan Province

Individual differences in drug clinical response are related to pharmacogenomics. The genetic variation of drug-metabolizing enzymes, drug receptors, and their downstream protein genes is the main factor causing individual differences in drug response. The genetic backgrounds among different ethnic groups are quite different. In this study, we aimed to detect the distribution difference of genotype frequency in very important pharmacogenetic (VIP) gene variants in the Lisu.Using the chi-squared test, we compared the genotype frequencies of the VIP variants in 105 Lisu people with those in 26 populations from the 1000 Genome project separately. Bonferroni's multiple adjustment was also conducted (P < .05/(26*49)). Moreover, Arlequin v3.5 and Structure v2.3.4 software were used to analyze the genetic distance and genetic structure.There were 9, 9, 11, 12, 11, 11, 9, 17, 13, 13, 16, 5, 3, 5, 3, 4, 17, 14, 16, 17, 16, 10, 13, 12, 10, and 9 single nucleotide polymorphisms that differed in frequency distribution, when Lisu people compared with the 26 populations separately. Only CYP2E1 rs2070676 was different in the Lisu population compared with the 26 groups from the 1000 Genome project. PTGS2 rs5275 and CYP2D6 rs1065852 were different in the Lisu population compared with most of the populations. Additionally, genetic backgrounds of Lisu and Han Chinese in Beijing were closest according to the lowest F-statistics value and resemblance in genetic structures.Our results complete the information of the Lisu population in pharmacogenomics database.

SeqVItA: Sequence Variant Identification and Annotation Platform for Next Generation Sequencing Data

The current trend in clinical data analysis is to understand how individuals respond to therapies and drug interactions based on their genetic makeup. This has led to a paradigm shift in healthcare; caring for patients is now 99% information and 1% intervention. Reducing costs of next generation sequencing (NGS) technologies has made it possible to take genetic profiling to the clinical setting. This requires not just fast and accurate algorithms for variant detection, but also a knowledge-base for variant annotation and prioritization to facilitate tailored therapeutics based on an individual's genetic profile. Here we show that it is possible to provide a fast and easy access to all possible information about a variant and its impact on the gene, its protein product, associated pathways and drug-variant interactions by integrating previously reported knowledge from various databases. With this objective, we have developed a pipeline, Sequence Variants Identification and Annotation (SeqVItA) that provides end-to-end solution for small sequence variants detection, annotation and prioritization on a single platform. Parallelization of the variant detection step and with numerous resources incorporated to infer functional impact, clinical relevance and drug-variant associations, SeqVItA will benefit the clinical and research communities alike. Its open-source platform and modular framework allows for easy customization of the workflow depending on the data type (single, paired, or pooled samples), variant type (germline and somatic), and variant annotation and prioritization. Performance comparison of SeqVItA on simulated data and detection, interpretation and analysis of somatic variants on real data (24 liver cancer patients) is carried out. We demonstrate the efficacy of annotation module in facilitating personalized medicine based on patient's mutational landscape. SeqVItA is freely available at https://bioinf.iiit.ac.in/seqvita.

Genetic and Modifiable Risk Factors Contributing to Cisplatin-induced Toxicities

Effective administration of traditional cytotoxic chemotherapy is often limited by off-target toxicities. This clinical dilemma is epitomized by cisplatin, a platinating agent, which has potent antineoplastic activity due to its affinity for DNA and other intracellular nucleophiles. Despite its efficacy against many adult-onset and pediatric malignancies, cisplatin elicits multiple off-target toxicities that can not only severely impact a patient's quality of life but also lead to dose reductions or the selection of alternative therapies that can ultimately affect outcomes. Without an effective therapeutic measure by which to successfully mitigate many of these symptoms, there have been attempts to identify a priori those individuals who are more susceptible to developing these sequelae through studies of genetic and nongenetic risk factors. Older age is associated with cisplatin-induced ototoxicity, neurotoxicity, and nephrotoxicity. Traditional genome-wide association studies have identified single-nucleotide polymorphisms in ACYP2 and WFS1 associated with cisplatin-induced hearing loss. However, validating associations between specific genotypes and cisplatin-induced toxicities with enough stringency to warrant clinical application remains challenging. This review summarizes the current state of knowledge with regard to specific adverse sequelae following cisplatin-based therapy, with a focus on ototoxicity, neurotoxicity, nephrotoxicity, myelosuppression, and nausea/emesis. We discuss variables (genetic and nongenetic) contributing to these detrimental toxicities and currently available means to prevent or treat their occurrence.

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.

Genetic variants in nucleotide excision repair pathway predict survival of esophageal squamous cell cancer patients receiving platinum-based chemotherapy

The benefits of platinum-based chemotherapy (PBC) on survival of esophageal squamous cell carcinoma (ESCC) patients are inexplicit due to the varied therapeutic effects. Nucleotide excision repair (NER) pathway plays a vital role in removing platinum-DNA adducts in tumor cells and hence may modulate the therapeutic effect and survival outcome. The present study assessed the associations of 26 potentially functional regulatory single nucleotide polymorphisms (rSNPs) in nine core NER genes with disease-free survival (DFS) and overall survival (OS) in 339 ESCC patients. We found that ERCC2 rs2097215 T and rs3916788 A, ERCC5 rs3759497 A and XPC rs3731054 C alleles were associated with unfavorable DFS. Patients carrying high-risk allele group (HRG, 5-8 risk alleles) had a significantly shorter DFS, compared with those carrying low-risk alleles (LRG, 0-4 risk alleles) [adjusted hazards ratio (HR_adj ) = 1.64, 95%CI = 1.23-2.19, P_adj < 0.001]. Three of these SNPs (ie, ERCC2 rs2097215 T and rs3916788 A and ERCC5 rs3759497 A) were also significantly associated with a poorer OS (HRG vs LRG: HR_adj  = 1.75, 95%CI = 1.23-2.47, P_adj  = 0.002). The expression quantitative trait loci (eQTL) analysis revealed significant genotype-expression correlations for ERCC5 rs3759497 and ERCC2 2097215 and rs3916788, which suggest regulatory roles of these SNPs. It appears that these NER variants may independently or jointly exert an impact on survival outcome of Chinese ESCC patients undergoing adjuvant platinum-based therapy. Large studies are warranted to validate these findings.

lncRNAs are novel biomarkers for differentiating between cisplatin-resistant and cisplatin-sensitive ovarian cancer

Cisplatin-resistant ovarian cancer occurs in patients with ovarian cancer treated with cisplatin-based chemotherapy, which results in tumor progression during treatment, or recurrence of the tumor within 6 months of the treatment. It is vital that a novel biomarker for diagnosis, or an efficient therapeutic target of cisplatin-resistant ovarian is identified. Long non-coding (lnc)RNAs were determined to serve critical functions in a variety of distinct types of cancer, including ovarian cancer; however, there is limited knowledge regarding the differential expression levels of lncRNAs in cisplatin-resistant and cisplatin-sensitive ovarian cancer. Therefore, in the present study, the expression levels were determined for these cancer types. The lncRNA expression profile in cisplatin-resistant ovarian cancer was analyzed and compared with the results for cisplatin-sensitive ovarian cancer; gene ontology and pathway analysis demonstrated that the dysregulated lncRNAs participated in important biological processes. Subsequently, it was identified that these dysregulated lncRNAs were present in other ovarian cancer tissues and in SKOV3 ovarian cancer cells, as well as its cisplatin-resistant clone, SKOV3/CDDP. In addition, it was revealed that 8 lncRNAs (Enst0000435726, Enst00000585612, Enst00000566734, Enst00000453783, NR_023915, RP11_697E22.2, uc010jub.1 and tcons_00008505) were associated with cisplatin-resistant ovarian cancer. The present study may assist in improving understanding of the initiation and developmental mechanisms underlying cisplatin-resistant ovarian cancer, which could aid future studies in discovering potential biomarkers for diagnosis or therapeutic targets that may be used in clinical treatment.

Genetic variants as ovarian cancer first-line treatment hallmarks: A systematic review and meta-analysis

BACKGROUND

The potential predictive value of genetic polymorphisms in ovarian cancer first-line treatment is inconsistently reported. We aimed to review ovarian cancer pharmacogenetic studies to update and summarize the available data and to provide directions for further research.

METHODS

A systematic review followed by a meta-analysis was conducted on cohort studies assessing the involvement of genetic polymorphisms in ovarian cancer first-line treatment response retrieved through a MEDLINE database search by November 2016. Studies were pooled and summary estimates and 95% confidence intervals (CI) were calculated using random or fixed-effects models as appropriate.

RESULTS

One hundred and forty-two studies gathering 106871 patients were included. Combined data suggested that GSTM1-null genotype patients have a lower risk of death compared to GSTM1-wt carriers, specifically in advanced stages (hazard ratio (HR), 0.68; 95% CI, 0.48-0.97) and when submitted to platinum-based chemotherapy (aHR, 0.61; 95% CI, 0.39-0.94). ERCC1 rs11615 and rs3212886 might have also a significant impact in treatment outcome (aHR, 0.67; 95% CI, 0.51-0.89; aHR, 1.28; 95% CI, 1.01-1.63, respectively). Moreover, ERCC2 rs13181 and rs1799793 showed a distinct ethnic behavior (Asians: aHR, 1.41; 95% CI, 0.80-2.49; aHR, 1.07; 95% CI, 0.62-1.86; Caucasians: aHR, 0.10; 95% CI, 0.01-0.96; aHR, 0.18; 95% CI, 0.05-0.68, respectively).

CONCLUSION(S)

The definition of integrative predictive models should encompass genetic information, especially regarding GSTM1 homozygous deletion. Justifying additional pharmacogenetic investigation are variants in ERCC1 and ERCC2, which highlight the DNA Repair ability to ovarian cancer prognosis. Further knowledge could aid to understand platinum-treatment failure and to tailor chemotherapy strategies.

Acute kidney injury in ovarian cancer patients undergoing cytoreductive surgery and hyperthermic intra-peritoneal chemotherapy

BACKGROUND

Cytoreductive surgery and hyperthermic intra-peritoneal chemotherapy (CRS-HIPEC) prolongs survival in patients with metastatic peritoneal disease. We look at the incidence of acute kidney injury (AKI) in patients who have received cisplatin during CRS-HIPEC in the treatment of peritoneal carcinomatosis from an ovarian primary, and identify possible peri-operative risk factors.

METHODS

Between 2005 and 2013, we performed CRS-HIPEC on 47 patients with ovarian primaries and peritoneal metastasis. Retrospective data were collected on the patient's demographics, treatment details and outcomes. Renal impairment was graded according to the NCI-CTCAE 3.0 criteria.

RESULTS

There were 47 patients, with a median age of 50 (24-74) years. The median baseline creatinine was 53 μmol/L (23-102) and median baseline albumin of 39 g/L (13-45). All underwent pre-operative chemotherapy for a median of six cycles (0-22) with a median of 15 days between chemotherapy and surgery. They received intra-operative cisplatin at a temperature of 40 °C for 60 min at a median dose of 90 mg/kg. 19 (40.4%) experienced post-operative AKI, of which 5 (8.5%) developed grade 3 and 4 impairment. Two (4.3%) required long-term dialysis. Univariate analysis showed that risk factors for AKI included age, baseline creatinine, baseline estimated glomerular filtration rate, pre-operative albumin, number of cycles of pre-operative carboplatin, time interval between pre-operative chemotherapy and CRS-HIPEC and volume of blood transfusions.

CONCLUSIONS

Identification of risk factors for AKI post-CRS-HIPEC helps improve pre-operative patient selection and optimisation, facilitate tailoring of chemotherapy, and foster closer peri-operative monitoring and fluid management in at-risk patients.

TP53 codon 72 polymorphism and breast cancer risk in Bangladeshi population

BACKGROUND

Breast cancer, a hereditary or heterogeneous sporadic disease, is the most common cancer in women worldwide. The tumor suppressor TP53 gene has been found to be the most commonly mutated genes in many types of human cancers, including breast cancer. This study aimed to investigate the association of codon 72 polymorphism of TP53 gene with breast cancer risk in Bangladeshi females.

METHODS

The study included 125 cases and 125 healthy controls. Genotyping and polymorphism were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

The frequencies of the three genotypes Arg/Arg, Arg/Pro, and Pro/Pro were 43.2, 33.6, and 23.2% in cases, whereas 48.8, 40.8, and 10.4% in controls, respectively. The frequency of mutant homozygous (Pro/Pro) genotype was significantly increased in breast cancer patients as compared with controls (23.2 vs 10.4%), and showed 2.52-fold significantly increased risk for breast cancer (OR 2.5199, 95% CI 1.19-5.33, p = 0.0157). The frequencies of Pro/Pro genotype were significantly higher in breast cancer cases with non-breast feeding status. Pro allele frequency was found to be significantly increased in breast cancer cases (OR 1.4978, 95% CI 1.0357-2.1662, p = 0.0318).

CONCLUSIONS

Our data suggest that mutant (Pro/Pro) homozygosity at codon 72 of TP53 gene is significantly associated with breast cancer susceptibility in Bangladeshi women. In addition, this association was significantly related to lactating status.

Pharmacogenomics in Pediatric Oncology: Review of Gene-Drug Associations for Clinical Use

During the 3rd congress of the European Society of Pharmacogenomics and Personalised Therapy (ESPT) in Budapest in 2015, a preliminary meeting was held aimed at establishing a pediatric individualized treatment in oncology and hematology committees. The main purpose was to facilitate the transfer and harmonization of pharmacogenetic testing from research into clinics, to bring together basic and translational research and to educate health professionals throughout Europe. The objective of this review was to provide the attendees of the meeting as well as the larger scientific community an insight into the compiled evidence regarding current pharmacogenomics knowledge in pediatric oncology. This preliminary evaluation will help steer the committee’s work and should give the reader an idea at which stage researchers and clinicians are, in terms of personalizing medicine for children with cancer. From the evidence presented here, future recommendations to achieve this goal will also be suggested.

Improvement of a predictive model in ovarian cancer patients submitted to platinum-based chemotherapy: implications of a GST activity profile

PURPOSE

The success of chemotherapy in ovarian cancer (OC) is directly associated with the broad variability in platinum response, with implications in patients survival. This heterogeneous response might result from inter-individual variations in the platinum-detoxification pathway due to the expression of glutathione-S-transferase (GST) enzymes. We hypothesized that GSTM1 and GSTT1 polymorphisms might have an impact as prognostic and predictive determinants for OC.

METHODS

We conducted a hospital-based study in a cohort of OC patients submitted to platinum-based chemotherapy. GSTM1 and GSTT1 genotypes were determined by multiplex PCR.

RESULTS

GSTM1-null genotype patients presented a significantly longer 5-year survival and an improved time to progression when compared with GSTM1-wt genotype patients (log-rank test, P = 0.001 and P = 0.013, respectively). Multivariate Cox regression analysis indicates that the inclusion of genetic information regarding GSTM1 polymorphism increased the predictive ability of risk of death after OC platinum-based chemotherapy (c-index from 0.712 to 0.833). Namely, residual disease (HR, 4.90; P = 0.016) and GSTM1-wt genotype emerged as more important predictors of risk of death (HR, 2.29; P = 0.039; P = 0.036 after bootstrap). No similar effect on survival was observed regarding GSTT1 polymorphism, and there were no statistically significant differences between GSTM1 and GSTT1 genotypes and the assessed patients' clinical-pathological characteristics.

CONCLUSION

GSTM1 polymorphism seems to have an impact in OC prognosis as it predicts a better response to platinum-based chemotherapy and hence an improved survival. The characterization of the GSTM1 genetic profile might be a useful molecular tool and a putative genetic marker for OC clinical outcome.

Clinical outcome of cisplatin-based chemotherapy is associated with the polymorphisms of GSTP1 and XRCC1 in advanced non-small cell lung cancer patients

INTRODUCTION

This study is to evaluate the association of polymorphisms of glutathione S-transferase P1 (GSTP1), copper-transporting P-type adenosine triphosphatase A (ATP7A) and X-ray repair cross-complementing group 1 (XRCC1) with the efficacy and toxicity of cisplatin-based treatment in advanced non-small cell lung cancer (NSCLC) patients.

MATERIALS AND METHODS

The outcomes of 97 advanced non-small cell lung cancer patients treated with cisplatin-based chemotherapy were estimated. GSTP1, ATP7A, and XRCC1 genetic polymorphisms were determined via polymerase chain reaction of restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing. Association of the polymorphisms with the efficacy and toxicity of cisplatin was analyzed, respectively.

RESULTS

Significant associations were observed between GSTP1 A313G and response rate (RR) (p = 0.027), disease control rate (DCR) (p = 0.019), and progression-free survival (PFS) (p = 0.044), respectively. Patients with AG and GG of GSTP1 have notably lower risk of anemia (p = 0.046). XRCC1 A1196G was associated with the incidence of lymphopenia (p = 0.024) and diarrhea (p = 0.020). ATP7A C2299G was not related with RR, DCR, PFS, and the risk of toxicity.

CONCLUSIONS

Advanced NSCLC patients with AA genotype of GSTP1 would obtain better curative effect followed with more risk of anemia when treated by cisplatin-based chemotherapy. ATP7A C2299G does not impact the efficacy and toxicity of cisplatin-based chemotherapy. XRCC1 1196A allele could predict the incidence of lymphopenia and diarrhea.

Genetic variability in drug transport, metabolism or DNA repair affecting toxicity of chemotherapy in ovarian cancer

Background

This study aimed to determine whether single nucleotide polymorphisms (SNPs) in genes involved in DNA repair or metabolism of taxanes or platinum could predict toxicity or response to first-line chemotherapy in ovarian cancer.

Methods

Twenty-six selected SNPs in 18 genes were genotyped in 322 patients treated with first-line paclitaxel-carboplatin or carboplatin mono-therapy. Genotypes were correlated with toxicity events (anemia, neutropenia, thrombocytopenia, febrile neutropenia, neurotoxicity), use of growth factors and survival.

Results

The risk of anemia was increased for variant alleles of rs1128503 (ABCB1, C > T; p = 0.023, OR = 1.71, 95% CI = 1.07-2.71), rs363717 (ABCA1, A > G; p = 0.002, OR = 2.08, 95% CI = 1.32-3.27) and rs11615 (ERCC1, T > C; p = 0.031, OR = 1.61, 95% CI = 1.04-2.50), while it was decreased for variant alleles of rs12762549 (ABCC2, C > G; p = 0.004, OR = 0.51, 95% CI = 0.33-0.81). Likewise, increased risk of thrombocytopenia was associated with rs4986910 (CYP3A4, T > C; p = 0.025, OR = 4.99, 95% CI = 1.22-20.31). No significant correlations were found for neurotoxicity. Variant alleles of rs2073337 (ABCC2, A > G; p = 0.039, OR = 0.60, 95% CI = 0.37-0.98), rs1695 (ABCC1, A > G; p = 0.017, OR = 0.55, 95% CI 0.33-0.90) and rs1799793 (ERCC2, G > A; p = 0.042, OR = 0.63, 95% CI 0.41-0.98) associated with the use of colony stimulating factors (CSF), while rs2074087 (ABCC1, G > C; p = 0.011, OR = 2.09, 95% CI 1.18-3.68) correlated with use of erythropoiesis stimulating agents (ESAs). Homozygous carriers of the rs1799793 (ERCC2, G > A) G-allele had a prolonged platinum-free interval (p = 0.016).

Conclusions

Our data reveal significant correlations between genetic variants of transport, hepatic metabolism, platinum related detoxification or DNA damage repair and toxicity or outcome in ovarian cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-015-0001-5) contains supplementary material, which is available to authorized users.

Long-term results of a randomised phase III trial of weekly versus three-weekly paclitaxel/platinum induction therapy followed by standard or extended three-weekly paclitaxel/platinum in European patients with advanced epithelial ovarian cancer

BACKGROUND

Weekly paclitaxel/carboplatin might improve survival in platinum-resistant epithelial ovarian cancer (EOC). We compared efficacy of first-line weekly to three-weekly paclitaxel/cis- or carboplatin (PCw and PC3w) induction therapy, followed by either three or six PC3w cycles.

PATIENTS AND METHODS

In this multicentre, randomised phase III trial with 2×2 design, patients with FIGO stage IIb-IV EOC were randomised to six cycles PCw (paclitaxel 90mg/m(2), cisplatin 70mg/m(2) or carboplatin AUC 4) or three cycles PC3w (paclitaxel 175mg/m(2), cisplatin 75mg/m(2) or carboplatin AUC 6), followed by either three or six cycles PC3w. Primary endpoints were progression free survival (PFS) and overall survival (OS). Secondary endpoints were response rate (RR) and toxicity.

RESULTS

Of 267 eligible patients, 133 received PCw and 134 PC3w. The first 105 patients received cisplatin, after protocol amendment the subsequent 162 patients received carboplatin. Weekly cisplatin was less well tolerated than weekly carboplatin. All PC3w cycles were well tolerated. At the end of all treatments, RR was 90.8% with no differences between the treatment arms. After a follow-up of median 10.3years (range 7.1-14.8), median PFS was 18.5 (95% confidence interval (CI) 15.9-21.0) months for PCw and 16.4 (95% CI 13.5-19.2) months for PC3w (p=0.78). Median OS was 44.8 (95% CI 33.1-56.5) months for PCw and 41.1 (95% CI 34.4-47.7) months for PC3w (p=0.98).

CONCLUSIONS

There was no benefit in terms of OS, PFS or RR for a weekly regimen nor for extended chemotherapy as first-line treatment for EOC in European patients.

Allele Frequencies of the Epidermal Growth Factor Receptors Polymorphism R521K in Colorectal Cancer Patients and Healthy Subjects Indicate a Risk-Reducing Effect of K521 in Syrian Population

Background:

Colorectal cancer contributes heavily to cancer morbidity and mortality worldwide. Numerous therapies are currently in use, including monoclonal antibodies against cellular components involved in tumorigenesis such as epidermal growth factor receptors (EGFRs). Studies showed the polymorphism [R521K] GàA in the EGFR gene to be involved in both colorectal cancer susceptibility and clinical response to therapeutics (e.g., Cetuximab).

Aim:

We aimed at uncovering allele frequencies of this polymorphism among Syrian colorectal cancer patients and healthy individuals.

Materials and Methods:

Forty-seven patients with colorectal cancer were included in a case-control study along with 48 healthy subjects, all native Syrians. Individuals were genotyped using PCR-Restriction Fragment Length Polymorphism (PCR-RFLP) and results were statistically analyzed to elucidate significant differences between the two groups.

Results:

Allele frequencies were 40.4% (G/G), 57.4% (G/A) and 2.1% (A/A) in colorectal cancer patients and 41.6% (G/G), 43.7% (G/A) and 14.5% (A/A) in healthy subjects. The A/A genotype was significantly lower in colorectal cancer patients than in the control group.

Conclusions:

Homozygosity for the A allele is linked to reducing the risk of developing colorectal cancer in Syrian patients. The lower prevalence of (A/A) locally may predict sub-optimal rates of clinical response to Cetuximab compared with populations with higher frequencies of the A allele. Larger scale investigations are needed for a stronger conclusion.