Plasma microRNA-192-5p can predict the response to neoadjuvant chemotherapy and prognosis in esophageal cancer.

Esophageal cancer (EC) is the sixth leading cause of cancer-related death worldwide. Recently, neoadjuvant chemotherapy (NAC) before curative surgery has become a standard treatment for clinical stage II or III EC patients. Some EC patients receive a complete response (CR) by NAC; thus, curative surgery may be unnecessary for such patients. MicroRNA levels in plasma have the potential to be a predictor of response to NAC. In the present study, we focused on miR-192-5p, which is highly expressed in EC tissue. The purpose was to investigate the correlations between levels of plasma miR-192-5p and the response to NAC. Furthermore, molecular functions of miR-192-5p associated with chemosensitivity were examined using EC cell lines. The levels of miR-192-5p in plasma before surgery were evaluated in 113 EC patients. Sixty-nine patients received NAC. miR-192-5p levels in the CR group were significantly higher than in the other groups (p = 0.002). The downregulation of miR-192-5p in the EC cell line inhibited sensitivity to cisplatin, and the overexpression of miR-192-5p in the EC cell line promoted sensitivity to cisplatin. miR-192-5p regulated sensitivity to cisplatin by targeting ERCC3 and ERCC4. Plasma miR-192-5p could be used as a predictor of response to chemotherapy and prognosis in EC patients.

Polymorphisms in ERCC1, ERCC4 and ERCC5 genes as biomarkers of susceptibility for pesticide-induced DNA damage in North-West Indian agricultural workers.

BACKGROUND: Occupational pesticides exposure has raised health concerns due to genotoxicity and accumulation of DNA damage. Polymorphisms in genes encoding enzymes involved in nucleotide excision repair (NER) may affect the individual's susceptibility to pesticide toxicity. METHODS: This study evaluates the association of excision repair cross complementation group 1 (ERCC1) (8092 C > A, 3'UTR, rs3212986) and ERCC1 (19007 C > T, Asn118Asn, rs11615), ERCC4 (1244 G > A, Arg415Gln, rs1800067) and ERCC5 (3507 G > C, Asp1104His, rs17655) polymorphisms with pesticide-induced DNA damage in North-West Indian agricultural workers. The study population comprised 225 agricultural workers exposed to pesticides and 225 non-exposed controls. RESULTS: Our study demonstrate that exposed workers carrying variant ERCC1 8092AA genotype showed higher total comet DNA migration (p = 0.015) as well as increased frequency of cells showing DNA migration (p = 0.027). Exposed agricultural workers with variant ERCC4 1244AA (415Gln/Gln) and ERCC5 3507CC (1104His/His) genotypes exhibited elevation in total comet DNA migration (p < 0.01). However, genotypes of ERCC1 19007 C > T (Asn118Asn) showed no association with total comet DNA migration (p = 0.963), frequency of cells showing DNA migration (p = 0.423) as well as mean tail length (p = 0.432). CONCLUSION: ERCC1, ERCC4 and ERCC5 polymorphisms influence DNA damage and can be used as biomarkers of susceptibility for pesticide-induced DNA damage in North-West Indian agricultural workers.

The link of ERCC2 rs13181 and ERCC4 rs2276466 polymorphisms with breast cancer in the Bangladeshi population.

BACKGROUND: Breast cancer (BC) is the most common disease in women and the leading cause of death from cancer globally. Epidemiological studies examined that nucleotide excision repair genes ERCC2 (rs13181) and ERCC4 (rs2276466) SNPs might increase cancer risk. Based on the previous investigation, this study was conducted to explore the correlation between these polymorphisms and BC susceptibility in Bangladeshi women. METHODS AND RESULTS: Between January 2019 and January 2020, 140 blood samples were collected from female patients histologically diagnosed with BC, and 111 female controls were recruited from non-cancer subjects. Genotyping was performed applying the PCR-RFLP method, and all statistical analyzes were conducted using SPSS, version 25.0. Comparison of characteristics and clinicopathological features between ERCC2 rs13181 and ERCC4 rs2276466 carriers and non-carriers showed no significant link with BC. Analysis of ERCC2 rs13181 with the risk of BC showed that the GG genotype and G allele carriers showed a fourfold and 1.78-fold higher risk (OR 4.00, P = 0.001 and OR 1.78, P = 0.002) that are statistically significant. In addition, the patients with combined TG+GG genotype revealed a 2.09-fold increased chance (OR 2.09, P = 0.020) BC development. Analysis of recessive model (GG vs. TT+TG) also depicted 2.74-times significantly higher risk (OR 2.74, P = 0.002). On the other hand, ERCC4 rs2276466 polymorphism did not show any significant association with BC (P > 0.05). CONCLUSIONS: Our findings show that ERCC2 rs13181 is linked to an elevated risk of BC. Our study also shows that ERCC4 rs2276466 polymorphism has no substantial risk of BC in the Bangladeshi population.

Association between nucleotide excision repair gene polymorphism and colorectal cancer risk.

BACKGROUND: The nucleotide excision repair system removes a wide variety of DNA lesions from the human genome, and plays an important role in maintaining genomic stability. Single nucleotide polymorphisms (SNPs) in nucleotide excision repair are associated with the various forms of tumor susceptibility. However, the relationship between NER polymorphism and colorectal cancer is not clear. METHODS: In this study, three candidate SNPs including ERCC4 (rs6498486), ERCC1 (rs3212986), and ERCC5 (rs17655) were analyzed in 1101colorectal cancer patients and 1175 healthy control patients from Jiangsu province (China). Then, we performed Immunohistochemistry, qPCR, and luciferase assay to determine the potential mechanisms. RESULTS: The ERCC4 rs6498486 AC/CC genotypes show lower susceptibility to CRC than those carrying rs6498486 AA (Adjusted OR = 0.82, 95% CI = 0.69-0.97). However, we did not observe any association between the colorectal cancer risk and the rs3212986(ERCC1) and rs17655(ERCC5) polymorphisms. Immunohistochemistry, qPCR, and luciferase assay revealed that rs6498486 A > C polymorphism in the ERCC4 promoter region could lessen the expression level of ERCC4 by impacting the binding ability of the transcription factor NF-kB, thereby affecting the transcription activity of the ERCC4 gene and decreased ERCC4 gene expression. CONCLUSION: In brief, our finding demonstrated that ERCC4 rs6498486 serves as a potential biomarker of CRC susceptibility for the development of colorectal cancer.

ERCC4 variants identified in a cohort of patients with segmental progeroid syndromes.

Pathogenic variants in genes, which encode DNA repair and damage response proteins, result in a number of genomic instability syndromes with features of accelerated aging. ERCC4 (XPF) encodes a protein that forms a complex with ERCC1 and is required for the 5' incision during nucleotide excision repair. ERCC4 is also FANCQ, illustrating a critical role in interstrand crosslink repair. Pathogenic variants in this gene cause xeroderma pigmentosum, XFE progeroid syndrome, Cockayne syndrome (CS), and Fanconi anemia. We performed massive parallel sequencing for 42 unsolved cases submitted to the International Registry of Werner Syndrome. Two cases, each carrying two novel heterozygous ERCC4 variants, were identified. The first case was a compound heterozygote for: c.2395C > T (p.Arg799Trp) and c.388+1164_792+795del (p.Gly130Aspfs*18). Further molecular and cellular studies indicated that the ERCC4 variants in this patient are responsible for a phenotype consistent with a variant of CS. The second case was heterozygous for two variants in cis: c.[1488A > T; c.2579C > A] (p.[Gln496His; Ala860Asp]). While the second case also had several phenotypic features of accelerated aging, we were unable to provide biological evidence supporting the pathogenic roles of the associated ERCC4 variants. Precise genetic causes and disease mechanism of the second case remains to be determined.

Fanconi anemia with sun-sensitivity caused by a Xeroderma pigmentosum-associated missense mutation in XPF.

BACKGROUND: Fanconi anemia (FA) is an inherited genomic instability disorder with congenital and developmental abnormalities, bone marrow failure and predisposition to cancer early in life, and cellular sensitivity to DNA interstrand crosslinks. CASE PRESENTATION: A fifty-one-year old female patient, initially diagnosed with FA in childhood on the basis of classic features and increased chromosomal breakage, and remarkable sun-sensitivity is described. She only ever had mild haematological abnormalities and no history of malignancy. To identify and characterise the genetic defect in this lady, who is one of the oldest reported FA patients, we used whole-exome sequencing for identification of causative mutations, and functionally characterized the cellular phenotype. Detection of the novel splice site mutation c.793-2A > G and the previously described missense mutation c.1765C > T (p.Arg589Trp) in XPF/ERCC4/FANCQ assign her as the third individual of complementation group FA-Q. Ectopic expression of wildtype, but not mutant, XPF/ERCC4/FANCQ, in patient-derived fibroblasts rescued cellular resistance to DNA interstrand-crosslinking agents. Patient derived FA-Q cells showed impaired nuclear excision repair capacity. However, mutated XPF/ERCC4/FANCQ protein in our patient's cells, as in the two other patients with FA-Q, was detectable on chromatin, in contrast to XP-F cells, where missense-mutant protein failed to properly translocate to the nucleus. CONCLUSIONS: Patients with FA characteristics and UV sensitivity should be tested for mutations in XPF/ERCC4/FANCQ. The missense mutation p.Arg589Trp was previously detected in patients diagnosed with Xeroderma pigmentosum or Cockayne syndrome. Hence, phenotypic manifestations associated with this XPF/ERCC4/ FANCQ mutation are highly variable.

Evaluation of rare variants in the new fanconi anemia gene ERCC4 (FANCQ) as familial breast/ovarian cancer susceptibility alleles.

Recently, it has been reported that biallelic mutations in the ERCC4 (FANCQ) gene cause Fanconi anemia (FA) subtype FA-Q. To investigate the possible role of ERCC4 in breast and ovarian cancer susceptibility, as occurs with other FA genes, we screened the 11 coding exons and exon-intron boundaries of ERCC4 in 1573 index cases from high-risk Spanish familial breast and ovarian cancer pedigrees that had been tested negative for BRCA1 and BRCA2 mutations and 854 controls. The frequency of ERCC4 mutation carriers does not differ between cases and controls, suggesting that ERCC4 is not a cancer susceptibility gene. Interestingly, the prevalence of ERCC4 mutation carriers (one in 288) is similar to that reported for FANCA, whereas there are approximately 100-fold more FA-A than FA-Q patients, indicating that most biallelic combinations of ERCC4 mutations are embryo lethal. Finally, we identified additional bone-fide FA ERCC4 mutations specifically disrupting interstrand cross-link repair.

Inter-individual variation in nucleotide excision repair pathway is modulated by non-synonymous polymorphisms in ERCC4 and MBD4 genes.

Inter-individual differences in DNA repair capacity (DRC) may lead to genome instability and, consequently, modulate individual cancer risk. Among the different DNA repair pathways, nucleotide excision repair (NER) is one of the most versatile, as it can eliminate a wide range of helix-distorting DNA lesions caused by ultraviolet light irradiation and chemical mutagens. We performed a genotype-phenotype correlation study in 122 healthy subjects in order to assess if any associations exist between phenotypic profiles of NER and DNA repair gene single nucleotide polymorphisms (SNPs). Individuals were genotyped for 768 SNPs with a custom Illumina Golden Gate Assay, and peripheral blood mononuclear cells (PBMCs) of the same subjects were tested for a NER comet assay to measure DRC after challenging cells by benzo(a)pyrene diolepoxide (BPDE). We observed a large inter-individual variability of NER capacity, with women showing a statistically significant lower DRC (mean ± SD: 6.68 ± 4.76; p = 0.004) than men (mean ± SD: 8.89 ± 5.20). Moreover, DRC was significantly lower in individuals carrying a variant allele for the ERCC4 rs1800124 non-synonymous SNP (nsSNP) (p = 0.006) and significantly higher in subjects with the variant allele of MBD4 rs2005618 SNP (p = 0.008), in linkage disequilibrium (r(2) = 0.908) with rs10342 nsSNP. Traditional in silico docking approaches on protein-DNA and protein-protein interaction showed that Gly875 variant in ERCC4 (rs1800124) decreases the DNA-protein interaction and that Ser273 and Thr273 variants in MBD4 (rs10342) indicate complete loss of protein-DNA interactions. Our results showed that NER inter-individual capacity can be modulated by cross-talk activity involving nsSNPs in ERCC4 and MBD4 genes, and they suggested to better investigate SNP effect on cancer risk and response to chemo- and radiotherapies.

Case report: Variants in the ERCC4 gene as a rare cause of cerebellar ataxia with chorea.

Variants in the ERCC4 gene have been described to be associated with the following autosomal recessive diseases: xeroderma pigmentosum group F (XPF), xeroderma pigmentosum type F/Cockayne syndrome (XPF/CS), Fanconi anemia complementation group Q (FANCQ), and XFE progeroid syndrome (XFEPS). In this paper, we present a case of a 53-year-old Caucasian female patient with rare variants in the ERCC4 gene. When she was 42 years old, falls and loss of balance occurred. At the age of 48, involuntary, uncoordinated movements of the upper limbs and head, tongue stereotypes (licking and extending movements), speech problems (dysarthria), memory deterioration, and hearing loss occurred. Since childhood, she has shown hypersensitivity to UV radiation. The neurological examination revealed chorea syndrome, cerebellar ataxia, dysarthria, and bilateral hearing loss. She has numerous pigmented lesions on the skin. Brain MRI demonstrated massive cortico-subcortical atrophy. The neuropsychological examination revealed dysfunctions in the executive domain in terms of attention, working memory, organizing, and planning activities. The genetic diagnostics was performed which excluded spinocerebellar ataxia types 1, 2, 3, 6, and 17, Huntington's disease, and FMR1 premutation. In the genetic analysis of next-generation sequencing (NGS), two variants: c.2395C > T and c.1349G > A in the ERCC4 gene were identified in a heterozygote configuration. So far, a few cases of ERCC4 gene variants, which are associated with nucleotide excision repair pathways, have been described in connection with symptoms of cerebellar ataxia. In patients with ERCC4 biallelic variants, the adult neurological phenotype can sometimes be the first symptom and reason for access to genetic testing. The aforementioned case highlights the occurrence of rare genetic causes of progressive neurodegenerative diseases in adults, especially with the spectrum of autosomal recessive nucleotide excision repair pathway disorders (NERDs).

NEDD9 Restrains dsDNA Damage Response during Non-Small Cell Lung Cancer (NSCLC) Progression.

DNA damaging modalities are the backbone of treatments for non-small cell lung cancer (NSCLC). Alterations in DNA damage response (DDR) in tumor cells commonly contribute to emerging resistance to platinating agents, other targeted therapies, and radiation. The goal of this study is to identify the previously unreported role of NEDD9 scaffolding protein in controlling DDR processes and sensitivity to DNA damaging therapies. Using a siRNA-mediated approach to deplete NEDD9 in a group of human and murine KRAS/TP53-mutant NSCLC cell lines, coupled with a set of cell viability and clonogenic assays, flow cytometry analysis, and Western blotting, we evaluated the effects of NEDD9 silencing on cellular proliferation, DDR and epithelial-to-mesenchymal transition (EMT) signaling, cell cycle, and sensitivity to cisplatin and UV irradiation. Using publicly available NSCLC datasets (TCGA) and an independent cohort of primary NSCLC tumors, subsequent in silico and immunohistochemical (IHC) analyses were performed to assess relevant changes in NEDD9 RNA and protein expression across different stages of NSCLC. The results of our study demonstrate that NEDD9 depletion is associated with the increased tumorigenic capacity of NSCLC cells. These phenotypes were accompanied by significantly upregulated ATM-CHK2 signaling, shifting towards a more mesenchymal phenotype in NEDD9 depleted cells and elevated sensitivity to UV-irradiation. IHC analyses revealed an association between reduced NEDD9 protein expression and a decrease in overall (OS) and progression-free survival (PFS) of the NSCLC patients. These data, for the first time, identified NEDD9 as a negative regulator of ATM kinase activity and related DDR signaling in numerous KRAS/TP53 mutated NSCLC, with its effects on the regulation of DDR-dependent EMT signaling, sensitivity to DNA damaging modalities in tumor cells, and the survival of the patients.

Comprehensive analysis of ceRNA network of ERCC4 in colorectal cancer.

OBJECTIVE: ERCC4 is one of the most significant molecules of Nucleotide Excision Repair (NER), which has been researched due to its high expression in colorectal cancer (CRC). This study aimed to find out the ceRNA (competitive endogenous RNA) network of ERCC4 in CRC. METHODS AND MATERIALS: Pan cancer mRNA expression of ERCC4 was evaluated using TCGA database. The protein expression of ERCC4 was evaluated based on the Human Protein Atlas (HPA). We screened DElncRNAs and DEmiRNAs in two groups of ERCC4 high and ERCC4 low expression in CRC. Then a lncRNA-miRNA-ERCC4 regulatory network was constructed based on DElncRNAs and DEmiRNAs using Starbase database and visualized by Cytoscape software. Kaplan-Meier analysis was performed to evaluate the prognostic value of the ceRNA network. Further, RT-PCR was performed to validate the expression of the representative molecules in the ceRNA network in CRC and normal tissues. The relationship between drug sensitivity and these molecules were also evaluated using RNAactDrug database. RESULTS: ERCC4 was overexpressed in a variety of tumors at mRNA levels, including CRC. High expression of ERCC4 was also observed on protein level in CRC. A total of 1,885 DElncRNAs and 68 DEmiRNAs were identified from CRC samples in ERCC4 high and ERCC4 low expression groups. Predicted by the Starbase database, we got interacting miRNAs and lncRNAs of ERCC4 from the DEmiRNAs and DElncRNAs, and a lncRNA-miRNA-ERCC4 regulatory network was constructed. Kaplan-Meier survival curves results showed that miR-200c-3p (hazard ratio [HR] = 0.62, P = 0.032), MALAT1 (HR = 1.54, P = 0.016), and AC005520.2 (hazard ratio [HR] = 1.75, P = 0.002) were significantly associated with the prognosis of CRC. After validation by RT-PCR, we found that ERCC4 and MALAT1 were up-regulated in CRC compared with normal tissues, while miR-200c-3p was down-regulated. A strong negative correlation was observed between MALAT1 and miR-200c-3p. Drug sensitivity analysis showed that ERCC4, miR-200c and MALAT1 were all associated with Cisplatin. CONCLUSION: We constructed a ceRNA network of ERCC4 in CRC, of which the MALAT1-miR-200c-3p-ERCC4 axis may be involved in the development, prognosis and chemotherapy sensitivity of CRC. These findings might provide novel clues and insights on the molecular mechanisms of ERCC4 and NER pathway in CRC.

The ECCR1 rs11615, ERCC4 rs2276466, XPC rs2228000 and XPC rs2228001 polymorphisms increase the cervical cancer risk and aggressiveness in the Bangladeshi population.

BACKGROUND: Multiple studies around the world revealed that genetic polymorphism in different genes of the DNA repair system might affect the DNA repair capabilities and accelerate the chances of cervical cancer (CC) development. Therefore, we aimed to evaluate the association of DNA repair gene- ECCR1 rs11615, ERCC4 rs2276466, XPC rs2228000 and rs2228001 polymorphisms and CC susceptibility in the Bangladeshi population. METHODS: A case-control genetic association study was conducted among 210 patients with diagnostically confirmed CC and 200 healthy volunteers. The p-value and OR (odds ratios) with 95% CI (confidence interval) were evaluated to get the level of association. RESULTS: After the individual analysis of all SNPs, we noticed that ECCR1 rs11615 possessed a significantly lower risk, whereas ERCC4 rs2276466 possessed a significantly elevated risk of CC in all genetic models (p < 0.05). XPC rs2228000 showed a significantly lower risk of CC in TC, TC + CC genotypes and allele model (OR = 0.61, p = 0.025; OR = 0.61, p = 0.019 and OR = 0.67, p = 0.027, respectively), whereas XPC rs2228001 possessed a significantly elevated risk of CC in CA, CA + AA genotypes and allele model (OR = 1.67, p = 0.012; OR = 1.69, p = 0.009 and OR = 1.42, p = 0.022). Besides, ERCC4 rs2276466 (Grade III vs. I + II: OR = 4.01, p = 0.003) and XPC rs2228001 (Grade III vs. I + II: OR = 3.38, p = 0.003) were connected with high tumor aggressiveness and ERCC4 rs2276466 was also showed a lower risk of CC development in the younger population (<45 years). CONCLUSION: The findings supported that rs2276466 and rs2228001 polymorphisms increase CC development and aggressiveness, whereas rs11615 and rs2228000 lower the CC risk in the studied population.

Case Report: Identification of Novel Variants in ERCC4 and DDB2 Genes in Two Tunisian Patients With Atypical Xeroderma Pigmentosum Phenotype.

Xeroderma Pigmentosum (XP) is a rare genetic disorder affecting the nucleotide excision repair system (NER). It is characterized by an extreme sensitivity to sunlight that induces cutaneous disorders such as severe sunburn, freckling and cancers. In Tunisia, six complementation groups have been already identified. However, the genetic etiology remains unknown for several patients. In this study, we investigated clinical characteristics and genetic defects in two families with atypical phenotypes originating from the central region in Tunisia. Clinical investigation revealed mild cutaneous features in two patients who develop multiple skin cancers at later ages, with no neurological disorders. Targeted gene sequencing revealed that they carried novel variants. A homozygous variation in the ERCC4 gene c.1762G>T, p.V588F, detected in patient XP21. As for patient XP134, he carried two homozygous mutations in the DDB2 gene c.613T>C, p.C205R and c.618C>A, p.S206R. Structural modeling of the protein predicted the identified ERCC4 variant to mildly affect protein stability without affecting its functional domains. As for the case of DDB2 double mutant, the second variation seems to cause a mild effect on the protein structure unlike the first variation which does not seem to have an effect on it. This study contributes to further characterize the mutation spectrum of XP in Tunisian families. Targeted gene sequencing accelerated the identification of rare unexpected genetic defects for diagnostic testing and genetic counseling.

Functional Comparison of XPF Missense Mutations Associated to Multiple DNA Repair Disorders.

XPF endonuclease is one of the most important DNA repair proteins. Encoded by XPF/ERCC4, XPF provides the enzymatic activity of XPF-ERCC1 heterodimer, an endonuclease that incises at the 5' side of various DNA lesions. XPF is essential for nucleotide excision repair (NER) and interstrand crosslink repair (ICLR). XPF/ERCC4 mutations are associated with several human diseases: Xeroderma Pigmentosum (XP), Segmental Progeria (XFE), Fanconi Anemia (FA), Cockayne Syndrome (CS), and XP/CS combined disease (XPCSCD). Most affected individuals are compound heterozygotes for XPF/ERCC4 mutations complicating the identification of genotype/phenotype correlations. We report a detailed overview of NER and ICLR functional studies in human XPF-KO (knock-out) isogenic cells expressing six disease-specific pathogenic XPF amino acid substitution mutations. Ultraviolet (UV) sensitivity and unscheduled DNA synthesis (UDS) assays provide the most reliable information to discern mutations associated with ICLR impairment from mutations related to NER deficiency, whereas recovery of RNA synthesis (RRS) assays results hint to a possible role of XPF in resolving R-loops. Our functional studies demonstrate that a defined cellular phenotype cannot be easily correlated to each XPF mutation. Substituted positions along XPF sequences are not predictive of cellular phenotype nor reflect a particular disease. Therefore, in addition to mutation type, allelic interactions, protein stability and intracellular distribution of mutant proteins may also contribute to alter DNA repair pathways balance leading to clinically distinct disorders.

Predictive value of ERCC1, ERCC2, ERCC4, and glutathione S-Transferase Pi expression for the efficacy and safety of FOLFIRINOX in patients with unresectable pancreatic cancer.

The platinum-based chemotherapy regimen FOLFIRINOX (leucovorin, fluorouracil, irinotecan, and oxaliplatin) is currently used as a standard treatment for patients with unresectable pancreatic cancer. FOLFIRINOX is associated with severe toxicities, including neutropenia, febrile neutropenia, and anorexia; however, there are currently no reliable biomarkers to predict its efficacy and safety. Several studies of patients with various cancers have shown that tumor expression of excision repair cross-complementing (ERCC) proteins and glutathione S-transferase Pi (GSTPi) correlates with the response to platinum-based chemotherapies. Therefore, in this study, we examined the associations between expression of ERCC proteins and GSTPi and the safety and efficacy of FOLFIRINOX in 34 patients with unresectable pancreatic cancer. ERCC1, ERCC2, ERCC4, and GSTPi expression were examined by immunohistochemical staining of tumor specimens and the results were correlated with overall survival, progression-free survival, response rate, disease control rate, and the frequency of grade 3-4 neutropenia and non-hematologic toxicities. We found that ERCC1, ERCC2, ERCC4, and GSTPi were expressed in tumor samples from 64%, 24%, 18%, and 64% of patients, respectively. Notably, there were no statistically significant associations between the expression pattern of any of the proteins and either the clinical outcomes or the frequency of grade 3-4 neutropenia or grade 3-4 anorexia. Collectively, these data indicate that tumor expression of ERCC1, ERCC2, ERCC4, and GSTPi does not predict the safety or efficacy of FOLFIRINOX in patients with pancreatic cancer.