ERCC1 and RRM1: ready for prime time?

6:2 Cl-PFESA, a proposed safe alternative for PFOS, diminishes the gemcitabine effectiveness in the treatment of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC)/pancreatic cancer, is a highly aggressive malignancy with poor prognosis. Gemcitabine-based chemotherapy remains the cornerstone of PDAC treatment. Nonetheless, the development of resistance to gemcitabine among patients is a major factor contributing to unfavorable prognostic outcomes. The resistance exhibited by tumors is modulated by a constellation of factors such as genetic mutations, tumor microenvironment transforms, environmental contaminants exposure. Currently, comprehension of the relationship between environmental pollutants and tumor drug resistance remains inadequate. Our study found that PFOS/6:2 Cl-PFESA exposure increases resistance to gemcitabine in PDAC. Subsequent in vivo trials confirmed that exposure to PFOS/6:2 Cl-PFESA reduces gemcitabine's efficacy in suppressing PDAC, with the inhibition rate decreasing from 79.5 % to 56.7 %/38.7 %, respectively. Integrative multi-omics sequencing and molecular biology analyses have identified the upregulation of ribonucleotide reductase catalytic subunit M1 (RRM1) as a critical factor in gemcitabine resistance. Subsequent research has demonstrated that exposure to PFOS and 6:2 Cl-PFESA results in the upregulation of the RRM1 pathway, consequently enhancing chemotherapy resistance. Remarkably, the influence exerted by 6:2 Cl-PFESA exceeds that of PFOS. Despite 6:2 Cl-PFESA being regarded as a safer substitute for PFOS, its pronounced effect on chemotherapeutic resistance in PDAC necessitates a thorough evaluation of its potential risks related to gastrointestinal toxicity.

Combination drug screen targeting glioblastoma core vulnerabilities reveals pharmacological synergisms

BACKGROUND

Pharmacological synergisms are an attractive anticancer strategy. However, with more than 5000 approved-drugs and compounds in clinical development, identifying synergistic treatments represents a major challenge.

METHODS

High-throughput screening was combined with target deconvolution and functional genomics to reveal targetable vulnerabilities in glioblastoma. The role of the top gene hit was investigated by RNA interference, transcriptomics and immunohistochemistry in glioblastoma patient samples. Drug combination screen using a custom-made library of 88 compounds in association with six inhibitors of the identified glioblastoma vulnerabilities was performed to unveil pharmacological synergisms. Glioblastoma 3D spheroid, organotypic ex vivo and syngeneic orthotopic mouse models were used to validate synergistic treatments.

FINDINGS

Nine targetable vulnerabilities were identified in glioblastoma and the top gene hit RRM1 was validated as an independent prognostic factor. The associations of CHK1/MEK and AURKA/BET inhibitors were identified as the most potent amongst 528 tested pairwise drug combinations and their efficacy was validated in 3D spheroid models. The high synergism of AURKA/BET dual inhibition was confirmed in ex vivo and in vivo glioblastoma models, without detectable toxicity.

INTERPRETATION

Our work provides strong pre-clinical evidence of the efficacy of AURKA/BET inhibitor combination in glioblastoma and opens new therapeutic avenues for this unmet medical need. Besides, we established the proof-of-concept of a stepwise approach aiming at exploiting drug poly-pharmacology to unveil druggable cancer vulnerabilities and to fast-track the identification of synergistic combinations against refractory cancers.

FUNDING

This study was funded by institutional grants and charities.

A novel prognostic system combining carbonic anhydrase II and preoperative CA19-9 for intrahepatic cholangiocarcinoma after curative resection

BACKGROUND

The role of carbonic anhydrase II (CAII) in intrahepatic cholangiocarcinoma (ICC) was investigated and a novel prognostic system combining CAII and preoperative carbohydrate antigen 19-9 (CA19-9) was established to predict the survival of patients with ICC after curative resection.

METHODS

A total of 110 patients who underwent curative-intent resection for ICC between 2012 and 2020 were retrospectively analyzed. CAII in tumor and peritumor regions was examined by immunohistochemistry, and the relationships between clinicopathological factors and the prognostic value of CAII and CA19-9 were analyzed.

RESULTS

CAII was frequently downregulated in ICC tissues (p < .001). Multivariate analyses indicated that showed that both low CAII expression level and preoperative CA19-9 ≥236 U/ml were independent risk factors for overall survival (OS) and recurrence-free survival (RFS) in patients with ICC after radical resection. Survival analysis revealed that patients with high CAII and low CA19-9 were significantly associated with a better OS and RFS (p < .001). The time-dependent receiver operating characteristic curves showed that CAII + CA19-9 had better prognostic predictive ability than CAII or CA19-9 alone. The nomogram constructed on independent factors including T stage, lymph node metastasis, CA19-9 (continuous variable), and CAII achieved C-indexes of 0.754 (95% CI, 0.701-0.807) and 0.730 (0.674-0.785) for OS and RFS, respectively. The calibration curve revealed acceptable agreement between actual and predicted OS and RFS.

CONCLUSIONS

The combination of CAII and preoperative CA19-9 is a novel and useful prognostic tool for predicting the survival of patients with ICC after curative resection and guiding clinical decisions.

PLAIN LANGUAGE SUMMARY

Carbonic anhydrase II (CAII) was frequently downregulated in intrahepatic cholangiocarcinoma (ICC) tissues. Survival analysis revealed that CAII is a novel independent factor for prognosis in patients with ICC after curative resection. CAII could be a useful prognostic marker for patients with ICC after surgery. The combination of CAII and preoperative carbohydrate antigen 19-9 is a novel and useful prognostic tool for predicting the survival of patients with ICC after curative resection and guiding clinical decisions.

Cancer chemotherapy: insights into cellular and tumor microenvironmental mechanisms of action

Chemotherapy has historically been the mainstay of cancer treatment, but our understanding of what drives a successful therapeutic response remains limited. The diverse response of cancer patients to chemotherapy has been attributed principally to differences in the proliferation rate of the tumor cells, but there is actually very little experimental data supporting this hypothesis. Instead, other mechanisms at the cellular level and the composition of the tumor microenvironment appear to drive chemotherapy sensitivity. In particular, the immune system is a critical determinant of chemotherapy response with the depletion or knock-out of key immune cell populations or immunological mediators completely abrogating the benefits of chemotherapy in pre-clinical models. In this perspective, we review the literature regarding the known mechanisms of action of cytotoxic chemotherapy agents and the determinants of response to chemotherapy from the level of individual cells to the composition of the tumor microenvironment. We then summarize current work toward the development of dynamic biomarkers for response and propose a model for a chemotherapy sensitive tumor microenvironment.

DNA Damage Repair Proteins, HSP27, and Phosphorylated-HSP90α as Predictive/Prognostic Biomarkers of Platinum-based Cancer Chemotherapy: An Exploratory Study

Platinum analogs are commonly used for cancer treatment. There is increasing interest in finding biomarkers which could predict and overcome resistance, because to date there is no reliable predictive/prognostic marker for these compounds. Here we studied the immunohistochemical expression of proteins involved in DNA damage response and repair (γH2AX, 53BP1, ERCC1, MLH1, and MSH2) in primary tumor tissues from patients treated with platinum-based chemotherapy. Levels and localization of Heat Shock Protein (HSP)27 and phospho-(Thr5/7)-HSP90α (p-HSP90α) were also determined. The implications in clinical response, disease-free survival and overall survival were analyzed. High γH2AX and 53BP1 expressions were associated with poor clinical response. Nuclear p-HSP90α, as well as nuclear absence and low cytoplasmic expression of HSP27 correlated with good response. Patients with high γH2AX and high cytoplasmic HSP27 expressions had shorter overall survival and disease-free survival. MLH1, MSH2, or ERCC1 were not associated with clinical response or survival. We report the potential utility of p-HSP90α, HSP27, γH2AX, and 53BP1 as predictive/prognostic markers for platinum-based chemotherapy. We present the first study that evaluates the predictive and prognostic value of p-HSP90α in primary tumors. Our research opens new possibilities for clinical oncology and shows the usefulness of immunohistochemistry for predicting chemotherapy response and prognosis in cancer.

Platycodon D-induced A549 cell apoptosis through RRM1-regulated p53/VEGF/MMP2 pathway

BACKGROUND

Lung cancer is one of the leading causes of cancer-related deaths worldwide. Platycodin D (PD), a major pharmacological constituent from the Chinese medicinal herb named Platycodonis Radix, has shown potent anti-tumor activity. Also, it is also reported that PD could inhibit cellular growth in the non-small-cell lung carcinoma (NSCLC) A549 cell line. However, the underlying mechanism is not fully clarified.

METHODS

Cell proliferation was measured by MTT assay. Annexin V and propidium iodide (PI) assay were employed to study the apoptosis effects of PD on A549 cells. Western blot analysis was used to evaluate protein expression. Also, we used a siRNA against p53, as well as a plasmid-based RRM1 over-expression to investigate their functions.

RESULTS

It demonstrated PD inhibited A549 cell proliferation in a dose- and time-dependent manner. Further investigations showed that PD induced cell apoptosis, which was supported by dose-dependent and time-dependent caspase-3 activation and p53/VEGF/MMP2 pathway regulation. Also, PD demonstrated the inhibition effect of ribonucleotide reductase M1 (RRM1), whose role in various tumors is contradictory. Remarkably, in this work, RRM1 overexpression in A549 cells could have a negative impact on the regulation of the p53/VEGF/MMP2 pathway induced by PD treatment. Note as well that RRM1 overexpression also attenuated cell apoptosis and inhibition of cell proliferation of A549 treated with PD.

CONCLUSION

The results suggested that PD could inhibit A549 cell proliferation and induce cell apoptosis by regulating p53/VEGF/MMP2 pathway, in which RRM1 plays an important role directly.

Prospective Clinical Study of Postoperative Individualized Adjuvant Chemotherapy for Patients with Non-Small-Cell Lung Cancer Based on mRNA Expression of the Molecular Markers RRM1, TUBB3, and ERCC1

Objective

To investigate the clinical significance of the mRNA expression of RRM1, TUBB3, and ERCC1 in non-small-cell lung cancer (NSCLC) tissues for the selection of adjuvant/postoperative chemotherapy regimens.

Methods

Patients diagnosed with stage Ib-IIIa NSCLC were enrolled and randomly divided into a control group (undetected group) and an experimental group (detected group) after radical operation. The control group randomly received chemotherapy with gemcitabine plus cisplatin or paclitaxel plus cisplatin. The mRNA expression of RRM1, TUBB3, and ERCC1 was detected in the experimental group before chemotherapy, and based on the detected expression, the chemotherapy regimen of cisplatin plus gemcitabine or cisplatin plus paclitaxel was chosen. The disease-free survival (DFS) of the control group and experimental group was compared.

Results

Pathological type, stage, gene expression detection, and treatment method were not significantly correlated with DFS (P > 0.05). In the subgroups treated with gemcitabine, the median DFS was 17 months in the detected group and 10.5 months in the undetected group (hazard ratio = 0.2147, 95% confidence interval: 0.07909–0.5827, P=0.0025). Multivariate regression analysis was performed to analyse whether gene expression detection was independently correlated with DFS in the subgroups treated with gemcitabine (P=0.025). In the detected group, the prognosis of patients with low expression of RRM1 was better than that of patients with high expression of RRM1 after paclitaxel treatment (P=0.0039).

Conclusions

The selection of chemotherapy regimen based on mRNA expression of the RRM1, TUBB3, and ERCC1 genes may improve selection of candidate patients to receive clinical chemotherapy. However, large-scale prospective clinical studies are needed for in-depth investigation.

Predictive Value of ERCC1 mRNA Level from Receiver-Operator Characteristic and Pretreatment EBV-DNA Virus Load in Stage II Nasopharyngeal Carcinoma Patients Receiving Intensity-Modulated Radiotherapy with Concurrent Cisplatin

Background: The molecular mechanisms underlying chemoresistance are still poorly understood in nasopharyngeal cancer; the protein expression of ERCC1 in DNA repair genes has been reported related to resistance platinum and predicting treatment outcomes in various malignant carcinomas, but the benefit for predicting outcomes with optimal cutoff value of ERCC1mRNA is controversial. The level of plasma Epstein-Barr virus (EBV) DNA is positively correlated with clinical stages of nasopharyngeal carcinoma (NPC). The predictive value of ERCC1mRNA from receiver-operator characteristic (ROC) and EBV-DNA level for stratified treatment with stage II NPC is exactly unclear. This study aims to assess the predictive value of combined EBV-DNA and ERCC1 in stage II nasopharyngeal cancer (NPC) patients treated with intensity-modulated radiotherapy (IMRT) with concurrent cisplatin, and provide guidance for future stratified treatment. Methods: A total of 86 stage II NPC patients who received IMRT and concurrent cisplatin-based chemotherapy with or without cisplatin-based adjuvant chemotherapy had measurements of ERCC1 mRNA, and pretreatment EBV-DNA levels were analyzed by real-time PCR (RT-PCR). Associations of ERCC1 mRNA and pretreatment EBV-DNA levels with clinical characteristics and survivals were evaluated. Results: Cutoff value of ERCC1 mRNA obtained from ROC curve was used, and there were significant differences in progression-free survival (PFS) and overall survival (OS) and overall response rate (ORR) between high expression group and low expression group (p = 0.021 and 0.030 and 0.000, respectively). Patients with pretreatment EBV-DNA <2000 copies/mL had significantly better PFS and ORR (p = 0.024 and 0.043, respectively) and a marginally significant impact on OS (p = 0.062) than those with pretreatment EBV-DNA ≥2000 copies/mL. Patients were divided into three groups by combination of ERCC1 mRNA and EBV-DNA level: ERCC1 mRNA low expression/pre-EBV-DNA <2000 copies/mL, ERCC1 mRNA low expression/pre-EBV-DNA ≥2000 copies/mL, and ERCC1 mRNA high expression/pre-EBV-DNA ≥2000 copies/mL. There were significant differences in ORR among the three groups (p = 0.005). The median follow-up was 62 months (range 22-84) with a follow-up rate of 90.70%. In these groups by combination of ERCC1 mRNA and EBV-DNA level, 1, 3, 5-year OS were 100%, 100%, 100%; 100%, 94.1%, 90.9%; and 100%, 85%, 72.9%, respectively (p = 0.038); 1, 3, 5-year PFS were 100%, 100%, 100%; 97.1%, 91.2%, 84.8%; and 95%, 85%, 71.4%, respectively (p = 0.028). Multivariate analysis showed that combination of ERCC1 mRNA and EBV-DNA levels remained independent prognostic factor but not ERCC1 mRNA and EBV-DNA alone. Conclusions: Combined ERCC1 mRNA and pre-EBV-DNA is a better prognostic biomarker in stage II NPC patients treated with concurrent chemoradiation. Patients with ERCC1 mRNA high expression/pre-EBV-DNA ≥2000 copies/mL may benefit from more aggressive treatment.

Double-staining Immunohistochemistry Reveals in Malignant Pleural Mesothelioma the Coexpression of ERCC1 and RRM1 as a Frequent Biological Event Related to Poorer Survival

Malignant pleural mesothelioma (MPM) is a rare cancer with a poor prognosis. To date, standard MPM therapy is still limited to surgery, radiotherapy, and chemotherapy, including pemetrexed and platinum compounds. The main mechanisms of platinum resistance are associated with DNA repair pathways. Excision repair cross-complementing group 1 (ERCC1) and ribonucleotide reductase subunit M1 (RRM1) are important components of the DNA repair, considered as prognostic and predictive biomarkers in various cancer types. The main goal of the present study was to investigate the ERCC1 and RRM1 expression and their potential impact on outcome in this tumor. A series of 73 MPM, mainly treated with a platin-based regimen, was collected and the immunohistochemistry tests were performed to assess ERCC1 and RRM1 expression. In addition, a multiplex immunohistochemistry has been validated to detect simultaneously the 2 proteins on the same slide. In our series, 36 of 73 cases showed ERCC1 expression and 55 of 73 showed RRM1 expression. The double immunohistochemical staining showed the coexpression of ERCC1/RRM1 in 34 of 73 cases. A significant association between ERCC1 and RRM1 expression was observed in our series (P<0.05). Patients with ERCC1/RRM1 coexpression experienced shorter median overall survival (6.6 vs. 13.8 mo, log-rank=7688; P=0.006). Our results suggest that the coexpression of ERCC1/RRM1 could define a group of MPM patients with the worst prognosis who should need likely alternative treatment. In conclusion, we propose the putative usefulness of ERCC1/RRM1 coexpression as prognostic biomarkers for overall survival in MPM.

Mechanisms of resistance to pemetrexed in non-small cell lung cancer

Currently, lung cancer has remained the most common cause of cancer death while non-small cell lung cancer (NSCLC) accounts for the most of all lung cancer cases. Regardless of multiple existing managements, chemotherapy regimens are still the mainstay of treatment for NSCLC, where pemetrexed has shown cytotoxic activity and has increasingly been used, especially for advanced cases. However, chemo-resistance may inhibit clinical efficacy after long-term use. Mechanisms responsible for chemo-resistance to pemetrexed in NSCLC are plethoric but can be separated into two categories to be discussed: tumor cells and their interactions with drugs. Phenomena relevant to tumor cells such as oncogene or oncoprotein alterations, DNA synthesis, DNA repair, and tumor cell biology behavior are discussed, as well as processes associated with drug dynamics, including drug uptake, drug elimination, and antifolate polyglutamylation. This review will focus on clinical trials and the basic biomedical mechanisms of NSCLC treated with pemetrexed and will describe the underlying mechanisms of resistance to facilitate more efficient clinical therapies to treat patients.

Low ERCC1 expression is a good predictive marker in lung adenocarcinoma patients receiving chemotherapy based on platinum in all TNM stages - a single-center study

BACKGROUND

High ERCC1 expression is thought to be related with resistance to chemotherapy based on platinum. The aim of this study was to present our institutional observations regarding to the association of ERCC1 and overall survival (OS) of the lung adenocarcinoma patients who received chemotherapy based on platinum.

MATERIAL/METHODS

A total of 253 lung adenocarcinoma patients in all TNM stages were retrospectively investigated. The diagnosis was based on small biopsy samples obtained during bronchoscopy. Depending on the TNM stage of the disease and clinical condition, patients received only the chemotherapy based on platinum, or in combination with radiotherapy or surgery. Tissue sample for ERCC1 immunohistochemical analysis was sufficient in 129 patients. Low from high ERCC1 expression was separated by the semi-quantitative H-score median.

RESULTS

High ERCC1 expression was found in 47.3% patients, and was correlated with higher TNM (p = 0.021), tumor enlargement (p = 0.002), positive lymph nodes (p = 0.001), positive distant metastasis (p = 0.005), and higher relative risk of death (p < 0.001). Furthermore, significance association was observed for low ERCC1 expression and better performance status (ECOG) (p = 0.023). Longer OS was strongly associated with a low ERCC1 expression, not only in the group of patients in TNM stage I-III, who were treated with combination of chemotherapy with surgery or radiotherapy (p = 0.002), but also in the group of patients in TNM stage IV who received only chemotherapy based on platinum (p < 0.001), compared with the patients in the same TNM stage and high ERCC1 expression.

CONCLUSIONS

ERCC1 expression in lung adenocarcinoma is a useful prognostic marker and moreover, a useful predictive marker in patients receiving chemotherapy based on platinum in all stages of the disease.

Appendix-derived Pseudomyxoma Peritonei (PMP): Molecular Profiling Toward Treatment of a Rare Malignancy

OBJECTIVES

Pseudomyxoma peritonei (PMP) is a rare malignancy originating from the appendix, characterized by disseminated mucinous tumor implants on peritoneal surfaces. We examined the role of multiplatform molecular profiling to study biomarker-guided treatment strategies for this rare malignancy.

METHODS

A total of 54 patients with appendix-derived PMP were included in the study. Tests included one or more of the following: gene sequencing (Sanger or next generation sequencing), protein expression (immunohistochemistry), and gene amplification (C/fluorescent in situ hybridization).

RESULTS

Targeted sequencing of 47 genes detected variants in KRAS (81%), GNAS (74%), SMAD4 (16%), and ATM (16%). Mutations were found at low frequencies (n=1 to 2) in APC, BRAF, PIK3CA, MLH1, and TP53. GNAS and KRAS co-occurrence was found in 87%. Protein overexpression was found in epidermal growth factor receptor (83%), cyclooxygenase-2 (73%), cMET (63%), cKIT (58%), and platelet-derived growth factor receptor alpha (58%). Immune checkpoint expression was found in 36% (programmed cell death protein 1) and 18% (programmed death-ligand 1). Surrogate markers of cell proliferation were found at low rates (TLE3 23%, TOP2A 22%), consistent with the slow-growing biology of PMP. Phosophatase and tensin homolog was intact (wild type [100%]) and positive (immunohistochemistry [80%]). Patients exhibited stable microsatellite status and mismatch repair proficiency (93%). Importantly, multidrug resistance protein expression was elevated (100% BCRP, 94% MRP1, 88% PGP). Markers for gemcitabine (RRM1), fluorouracil (TS), oxaliplatin (ERCC1), and irinotecan (TOPO1) chemosensitivities were detected at favorable rates: 93%, 87%, 77% and 65%, respectively.

CONCLUSIONS

Molecular profiling by multiple platforms identified potential therapies for the nontargetable KRAS-mutated population. The role of cMET-targeted therapeutics and immune checkpoint inhibitors merits further investigation. Biomarker-guided selection of cytotoxic chemotherapies may facilitate efficacy to systemic treatment.

Prognostic role of beclin-1 in locally advanced non-small cell lung cancer in patients receiving docetaxel-platinum induction chemotherapy

BACKGROUND/AIMS

The outcome of local treatment for advanced non-small cell lung cancer (NSCLC) remains poor, with therapies such as induction chemotherapy (IC) yielding conflicting results. This study aimed to assess the clinicopathologic and prognostic significance of the excision repair cross-complementation group 1 (ERCC1), beclin-1, and glucose-regulated protein of molecular mass 78 (GRP78) in patients with locally advanced NSCLC receiving docetaxel-platinum IC, along with efficacy and safety.

METHODS

This is a retrospective observational cohort study. We reviewed medical records of 31 NSCLC patients receiving docetaxel-platinum IC, and conducted immunohistochemical staining of ERCC1, beclin-1, and GRP78.

RESULTS

Response rate was 67.8% with 10.7 months of median relapse-free survival (RFS) and 23.1 months of median overall survival (OS), and no treatment-related death was reported. High expression of ERCC1, beclin-1, and GRP78 was identified in 67.7%, 87.1%, and 67.7%, respectively. Expression of ERCC1 and GRP78 did not reveal statistical significance in survival, whereas high beclin-1 expression revealed longer OS (7.6 months vs. 23.2 months; log-rank p = 0.024). In multivariate analysis, histologic differentiation (hazard ratio [HR], 3.48; p < 0.001), stage (HR, 8.5; p = 0.024), and adjuvant treatment (HR, 16.1; p = 0.001) were related to RFS, and in OS, stage (HR, 5.4; p = 0.037), adjuvant treatment (HR, 8.6; p = 0.004), and beclin-1 expression (HR, 8.2; p = 0.011) were identified as significant prognostic factors.

CONCLUSION

Our findings suggest that high beclin-1 expression predicts longer survival in locally advanced NSCLC and docetaxel-platinum IC is a treatment option that deserves consideration.

Demethoxycurcumin sensitizes the response of non-small cell lung cancer to cisplatin through downregulation of TP and ERCC1-related pathways

BACKGROUND

Excision repair cross-complementary 1 (ERCC1) overexpression in lung cancer cells is strongly correlated with its resistance to platinum-based chemotherapy. Overexpression of thymidine phosphorylase (TP) reverts platinum-induced cancer cell death.

PURPOSE

Curcumin has been reported to enhance antitumor properties through the suppression of TP and ERCC1 in non-small cell lung carcinoma cells (NSCLC). Nevertheless, whether two other curcuminoids, demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC) from Curcuma longa demonstrate antitumor activity like that of curcumin remain unknown.

METHODS

MTT assay was conducted to determine the cell cytotoxicity. Western blotting was used to determine the protein expressions. Docking is the virtual screening of a database of compounds and predicting the strongest binders based on various scoring functions. BIOVIA Discovery Studio 4.5 (D.S. 4.5) were used for docking.

RESULTS

Firstly, when compared with curcumin and BDMC, DMC exhibited the most potent cytotoxic effect on NSCLC, most importantly, MRC-5, a lung fetal fibroblast, was insensitive to DMC (under 30 µM). Secondly, DMC alone significantly inhibited on-target cisplatin (CDDP) resistance protein, ERCC1, via PI3K-Akt-snail pathways, and TP protein expression in A549 cells. Thirdly, DMC treatment markedly increased post-target CDDP resistance pathway including Bax and cytochrome c. DMC significantly decreased Bcl-2 protein expressions. Finally, MTT assay indicated that DMC significantly increased CDDP-induced cytotoxicity and was confirmed with an increased Bax/Bcl-2 ratio, indicating upregulation of caspase-3.

CONCLUSIONS

We concluded that enhancement of the cytotoxicity to CDDP by coadminstration with DMC was mediated by down-regulation of the expression of TP and ERCC1, regulated by PI3K-Akt-Snail pathway inactivation.

KRAS mutation and DNA repair and synthesis genes in non-small-cell lung cancer

The aim of the present study was to assess the expression of select DNA repair and synthesis genes in non-small-cell lung cancer (NSCLC) according to KRAS mutation status. ERCC1, TS, RRM1, and BRCA1 mRNA expression levels were assessed from either primary or metastatic tumor specimens of patients diagnosed with epidermal growth factor receptor (EGFR) wild-type (WT) advanced NSCLC. Total RNA was isolated from paraffin-embedded tumor specimens using the RNeasy FFPE kit and automatically purified using a QiaCube instrument. Quantification levels were analyzed by real-time one-step RT-PCR using QuantiFast technology, and the results were compared considering β-actin as the internal reference gene. One hundred and eighty-four patients with advanced NSCLC were evaluated for the analysis, of which 92 were KRAS-mutants. Nearly all patients had adenocarcinoma histology (96.7%). Among KRAS-mutants, the majority had a KRAS codon 12 mutation (88%), the most common being G12C (44.4% of cases). Mean ERCC1 levels were indicated to be significantly higher in KRAS-mutants when compared with KRAS WT patients (3,234±6.63 vs. 184±1.24; P=0.05). However, mean TS levels were significantly lower in the KRAS-mutant subgroup compared with the KRAS WT subgroup (4,481±3.756 vs. 5,941±6.4; P=0.039). KRAS-mutant NSCLCs are more likely to express high ERCC1 and low TS levels. This finding may suggest different sensitivity to cytotoxic chemotherapy according to KRAS mutation status.

Distinct roles of XPF-ERCC1 and Rad1-Rad10-Saw1 in replication-coupled and uncoupled inter-strand crosslink repair

Yeast Rad1-Rad10 (XPF-ERCC1 in mammals) incises UV, oxidation, and cross-linking agent-induced DNA lesions, and contributes to multiple DNA repair pathways. To determine how Rad1-Rad10 catalyzes inter-strand crosslink repair (ICLR), we examined sensitivity to ICLs from yeast deleted for SAW1 and SLX4, which encode proteins that interact physically with Rad1-Rad10 and bind stalled replication forks. Saw1, Slx1, and Slx4 are critical for replication-coupled ICLR in mus81 deficient cells. Two rad1 mutations that disrupt interactions between Rpa1 and Rad1-Rad10 selectively disable non-nucleotide excision repair (NER) function, but retain UV lesion repair. Mutations in the analogous region of XPF also compromised XPF interactions with Rpa1 and Slx4, and are proficient in NER but deficient in ICLR and direct repeat recombination. We propose that Rad1-Rad10 makes distinct contributions to ICLR depending on cell cycle phase: in G1, Rad1-Rad10 removes ICL via NER, whereas in S/G2, Rad1-Rad10 facilitates NER-independent replication-coupled ICLR.

Quantification and expert evaluation of evidence for chemopredictive biomarkers to personalize cancer treatment

Predictive biomarkers have the potential to facilitate cancer precision medicine by guiding the optimal choice of therapies for patients. However, clinicians are faced with an enormous volume of often-contradictory evidence regarding the therapeutic context of chemopredictive biomarkers.

We extensively surveyed public literature to systematically review the predictive effect of 7 biomarkers claimed to predict response to various chemotherapy drugs: ERCC1-platinums, RRM1-gemcitabine, TYMS-5-fluorouracil/Capecitabine, TUBB3-taxanes, MGMT-temozolomide, TOP1-irinotecan/topotecan, and TOP2A-anthracyclines. We focused on studies that investigated changes in gene or protein expression as predictors of drug sensitivity or resistance. We considered an evidence framework that ranked studies from high level I evidence for randomized controlled trials to low level IV evidence for pre-clinical studies and patient case studies.

We found that further in-depth analysis will be required to explore methodological issues, inconsistencies between studies, and tumor specific effects present even within high evidence level studies. Some of these nuances will lend themselves to automation, others will require manual curation. However, the comprehensive cataloging and analysis of dispersed public data utilizing an evidence framework provides a high level perspective on clinical actionability of these protein biomarkers. This framework and perspective will ultimately facilitate clinical trial design as well as therapeutic decision-making for individual patients.

5'-nucleotidase cN-II emerges as a new predictive biomarker of response to gemcitabine/platinum combination chemotherapy in non-small cell lung cancer

A number of pharmacogenetic studies have been carried out in non-small-cell lung cancer (NSCLC) to identify and characterize genes involved in chemotherapy activity. However, the results obtained so far are controversial and no reliable biomarker is currently used to predict clinical benefit from platinum-based chemotherapy, which represents the cornerstone of treatment of advanced NSCLC. This study investigated the expression levels of ERCC1 and of six genes (RRM1, RRM2, hENT1, dCK, cN-II and CDA) involved in gemcitabine metabolism in locally/advanced NSCLC patients treated with gemcitabine/platinum combination. Gene expression was assessed by quantitative-PCR in laser-microdissected specimens and correlated with tumor response. Frequency distribution of responses above and below the median expression level of biomarkers was compared using a two-sided Fisher's test. 5'-nucleotidase (cN-II) was the only gene differently expressed (p = 0.016) in the responders (complete/partial-response) compared to non-responders (stable/progressive disease). In the multivariate analysis, overexpression of this catabolic enzyme of gemcitabine remained a significant negative predictive factor. Patients with low cN-II had a modest trend toward increased survival, while both survival and progression-free survival were significantly longer in a more homogenous validation cohort of 40 advanced NSCLC (8.0 vs. 5.1 months, p = 0.026). Moreover, in vitro studies showed that silencing or pharmacological inhibition of cN-II increased the cytotoxicity of gemcitabine. This is the first study demonstrating the role of cN-II as a predictor of response to gemcitabine/platinum combinations in NSCLC. Its validation in prospective studies may improve clinical outcome of selected patients.

Ribonucleotide Reductase Catalytic Subunit M1 (RRM1) as a Novel Therapeutic Target in Multiple Myeloma

Purpose: To investigate the biological and clinical significance of ribonucleotide reductase (RR) in multiple myeloma.Experimental Design: We assessed the impact of RR expression on patient outcome in multiple myeloma. We then characterized the effect of genetic and pharmacologic inhibition of ribonucleotide reductase catalytic subunit M1 (RRM1) on multiple myeloma growth and survival using siRNA and clofarabine, respectively, in both in vitro and in vivo mouse xenograft models.Results: Newly diagnosed multiple myeloma patients with higher RRM1 expression have shortened survival. Knockdown of RRM1 triggered significant growth inhibition and apoptosis in multiple myeloma cells, even in the context of the bone marrow microenvironment. Gene expression profiling showed upregulation of DNA damage response genes and p53-regulated genes after RRM1 knockdown. Immunoblot and qRT-PCR analysis confirmed that γ-H2A.X, ATM, ATR, Chk1, Chk2, RAD51, 53BP1, BRCA1, and BRCA2 were upregulated/activated. Moreover, immunoblots showed that p53, p21, Noxa, and Puma were activated in p53 wild-type multiple myeloma cells. Clofarabine, a purine nucleoside analogue that inhibits RRM1, induced growth arrest and apoptosis in p53 wild-type cell lines. Although clofarabine did not induce cell death in p53-mutant cells, it did trigger synergistic toxicity in combination with DNA-damaging agent melphalan. Finally, we demonstrated that tumor growth of RRM1-knockdown multiple myeloma cells was significantly reduced in a murine human multiple myeloma cell xenograft model.Conclusions: Our results therefore demonstrate that RRM1 is a novel therapeutic target in multiple myeloma in the preclinical setting and provide the basis for clinical evaluation of RRM1 inhibitor, alone or in combination with DNA-damaging agents, to improve patient outcome in multiple myeloma. Clin Cancer Res; 23(17); 5225-37. ©2017 AACR.

The Utility of Thyroid Transcription Factor 1 (TTF-1), Napsin A, Excision Repair Cross-Complementing 1 (ERCC1), Anaplastic Lymphoma Kinase (ALK) and the Epidermal Growth Factor Receptor (EGFR) Expression in Small Biopsy in Prognosis of Patients with Lung Adenocarcinoma - A Retrograde Single-Center Study from Croatia

Background

The present study was carried out in order to evaluate our institutional experience with small biopsy in diagnosis and molecular testing of lung adenocarcinoma. Few specific and predictive markers have been evaluated and correlated with clinicopathologic characteristics and survival in patients with lung adenocarcinoma who received platinum-based chemotherapy. There have not been such reports from Croatia.

Material/Methods

A total of 142 cases of lung adenocarcinoma were retrospectively investigated in small biopsies for the immunohistochemical expression of TTF-1, napsin A, ERCC1, ALK, and the EGFR mutation by real-time polymerase chain reaction (rtPCR).

Results

TTF-1, napsin A, and ERCC1 expression was found in 81%, 78%, and 69% of patients, respectively, and the expressions were not significantly associated with subtype. Expression of ALK was found in 4% and EGFR mutation in 10% of patients. Exon 19 deletions were the most common. Longer survival was significantly associated with TTF-1 positivity (p=0.007) and napsin A positivity (p=0.026). Higher relative risk of death significantly correlated with positive expression of ERCC1 (p=0.041).

Conclusions

Positive TTF-1 and napsin A expressions in lung adenocarcinoma tissues were useful diagnostic and favorable prognostic parameters. Positive ERCC1 expression was identified as a negative prognostic marker in patients treated with platinum-based chemotherapy. The percentages of EGFR and ALK mutations corresponded to those in previously published reports for Caucasians.

p53-related protein kinase confers poor prognosis and represents a novel therapeutic target in multiple myeloma

p53-related protein kinase (TP53RK, also known as PRPK) is an upstream kinase that phosphorylates (serine residue Ser15) and mediates p53 activity. Here we show that TP53RK confers poor prognosis in multiple myeloma (MM) patients, and, conversely, that TP53RK knockdown inhibits p53 phosphorylation and triggers MM cell apoptosis, associated with downregulation of c-Myc and E2F-1-mediated upregulation of pro-apoptotic Bim. We further demonstrate that TP53RK downregulation also triggers growth inhibition in p53-deficient and p53-mutant MM cell lines and identify novel downstream targets of TP53RK including ribonucleotide reductase-1, telomerase reverse transcriptase, and cyclin-dependent kinase inhibitor 2C. Our previous studies showed that immunomodulatory drugs (IMiDs) downregulate p21 and trigger apoptosis in wild-type-p53 MM.1S cells, Importantly, we demonstrate by pull-down, nuclear magnetic resonance spectroscopy, differential scanning fluorimetry, and isothermal titration calorimetry that IMiDs bind and inhibit TP53RK, with biologic sequelae similar to TP53RK knockdown. Our studies therefore demonstrate that either genetic or pharmacological inhibition of TP53RK triggers MM cell apoptosis via both p53-Myc axis-dependent and axis-independent pathways, validating TP53RK as a novel therapeutic target in patients with poor-prognosis MM.

Correlation of DNA Repair Gene Polymorphisms With Clinical Outcome in Patients With Locally Advanced Non-Small-Cell Lung Cancer Receiving Induction Chemotherapy Followed by Surgery

OBJECTIVE

The aim of this study was to evaluate whether xeroderma pigmentosum group D (XPD) and ribonucleotide reductase subunit M1 (RRM1) polymorphisms influenced clinical outcome in patients with stage IIIA-B non-small-cell lung cancer (NSCLC) treated with neoadjuvant gemcitabine/cisplatin/docetaxel followed by surgery.

MATERIALS AND METHODS

A total of 109 patients with stage IIIA and IIIB NSCLC were prospectively genotyped to examine a potential association between XPD 312 (aspartic acid [Asp]/asparagine [Asn]), XPD 751 (lysine [Lys]/glutamine [Gln]), and RRM1 (-37 C/A) polymorphisms with response and survival.

RESULTS

The median survival was 32.14 months for carriers of XPD 312 Asp/Asp and 12.04 months for those with the variant Asn allele (P = .05). In addition, event-free survival was longer for patients with the XPD 312 Asp/Asp genotype compared with patients with Asp/Asn or Asn/Asn (P = .03). A similar but nonsignificant trend was observed for the XPD 751 genotype. In a multivariate analysis, complete resection and age emerged as prognostic factors for overall survival; in patients with incomplete resection or exploratory thoracotomy, XPD 312 was the most significant prognostic factor (P = .03).

CONCLUSION

The XPD 312 single nucleotide polymorphism is a prognostic factor for survival in patients with locally advanced NSCLC receiving induction chemotherapy followed by surgery. The Asn allele is associated with unfavorable outcome and could be used for better stratification of patients.

The Challenges of Validating in Precision Medicine: The Case of Excision Repair Cross-Complement Group 1 Diagnostic Testing

Personalized medicine relies upon the successful identification and translation of predictive biomarkers. Unfortunately, biomarker development has often fallen short of expectations. To better understand the obstacles to successful biomarker development, we systematically mapped research activities for a biomarker that has been in development for at least 12 years: excision repair cross-complement group 1 protein (ERCC1) as a biomarker for predicting clinical benefit with platinum-based chemotherapy in non-small cell lung cancer. We found that although research activities explored a wide range of approaches to ERCC1 testing, there was little replication or validation of techniques, and design and reporting of results were generally poor. Our analysis points to problems with coordinating and standardizing research in biomarker development. Clinically meaningful progress in personalized medicine will require concerted efforts to address these problems. In the interim, health care providers should be aware of the complexity involved in biomarker development, cautious about their near-term clinical value, and conscious of applying only validated diagnostics in the clinic.

THE ONCOLOGIST

2017;22:89-96 IMPLICATIONS FOR PRACTICE: : Many hospitals, policy makers, and scientists have made ambitious claims about the promise of personalizing cancer care. When one uses a case example of excision repair cross-complement group 1 protein-a biomarker that has a strong biological rationale and that has been researched for 12 years-the current research environment seems poorly suited for efficient development of biomarker tests. The findings provide grounds for tempering expectations about personalized cancer care-at least in the near term-and shed light on the current gap between the promise and practice of personalized medicine.

Functions, Regulation, and Therapeutic Implications of the ATR Checkpoint Pathway

The ATR (ATM and rad3-related) pathway is crucial for proliferation, responding to DNA replication stress and DNA damage. This critical signaling pathway is carefully orchestrated through a multistep process requiring initial priming of ATR prior to damage, recruitment of ATR to DNA damage lesions, activation of ATR signaling, and, finally, modulation of ATR activity through a variety of post-translational modifications. Following activation, ATR functions in several vital cellular processes, including suppression of replication origin firing, promotion of deoxynucleotide synthesis and replication fork restart, prevention of double-stranded DNA break formation, and avoidance of replication catastrophe and mitotic catastrophe. In many cancers, tumor cells have increased dependence on ATR signaling for survival, making ATR a promising target for cancer therapy. Tumor cells compromised in DNA repair pathways or DNA damage checkpoints, cells reliant on homologous recombination, and cells with increased replication stress are particularly sensitive to ATR inhibition. Understanding ATR signaling and modulation is essential to unraveling which tumors have increased dependence on ATR signaling as well as how the ATR pathway can best be exploited for targeted cancer therapy.

Predictors of chemotherapy efficacy in non-small-cell lung cancer: a challenging landscape

BACKGROUND

Conventional cytotoxic chemotherapy (CCC) is the backbone of non-small-cell lung cancer (NSCLC) treatment since decades and still represents a key element of the therapeutic armamentarium. Contrary to molecularly targeted therapies and immune therapies, for which predictive biomarkers of activity have been actively looked for and developed in parallel to the drug development process ('companion biomarkers'), no patient selection biomarker is currently available for CCC, precluding customizing treatment.

MATERIALS AND METHODS

We reviewed preclinical and clinical studies that assessed potential predictive biomarkers of CCC used in NSCLC (platinum, antimetabolites, topoisomerase inhibitors, and spindle poisons). Biomarker evaluation method, analytical validity, and robustness are described and challenged for each biomarker.

RESULTS

The best-validated predictive biomarkers for efficacy are currently ERCC1, RRM1, and TS for platinum agents, gemcitabine and pemetrexed, respectively. Other potential biomarkers include hENT1 for gemcitabine, class III β-tubulin for spindle poisons, TOP2A expression and CEP17 duplication (mostly studied for predicting anthracyclines efficacy) whose applicability concerning etoposide would deserve further evaluation. However, none of these biomarkers has till now been validated prospectively in an appropriately designed and powered randomised trial, and none of them is currently ready for implementation in routine clinical practice.

CONCLUSION

The search for predictive biomarkers to CCC has been proven challenging. If a plethora of biomarkers have been evaluated either in the preclinical or in the clinical setting, none of them is ready for clinical implementation yet. Considering that most mechanisms of resistance or sensitivity to CCC are multifactorial, a combinatorial approach might be relevant and further efforts are required.

Testing the metal of ERCC2 in predicting the response to platinum-based therapy

DNA repair has been shown to affect the cellular response to platinum-based therapy in a variety of cancers; however, translating this knowledge to the clinic has proven difficult and yielded mixed results. In this issue of Cancer Discovery, Van Allen and colleagues have analyzed responders and nonresponders to neoadjuvant platinum-based therapy with locally advanced urothelial cancer and identified a series of mutations in the nucleotide excision repair (NER) gene ERCC2 that correlate with the response to platinum-based therapy. This work provides evidence that defects in NER can be exploited to maximize the efficacy of conventional platinum-based chemotherapy.

Problems of variable biomarker evaluation in stratified medicine research--A case study of ERCC1 in non-small-cell lung cancer

OBJECTIVES

Consistency of procedures for the evaluation of a predictive biomarker (including sample collection, processing, assay and scoring system) based on adequate evidence is necessary to implement research findings in clinical practice. As a case study we evaluated how a particular predictive biomarker, ERCC1, was assessed in research on platinum-based chemotherapy in non-small-cell lung cancer and what motivated the choice of procedure.

MATERIALS AND METHODS

A systematic review of studies completed since 2007 and ongoing was undertaken. Questionnaires on details of ERCC1 evaluation procedures and the rationale for their choice were sent to contacts of identified studies.

RESULTS

Thirty-three studies of platinum-based chemotherapy in non-small-cell lung cancer using ERCC1 were identified. A reply to the questionnaire was received for 16 studies. Procedures for ERCC1 evaluation varied substantially and included reverse transcriptase quantitative polymerase chain reaction (nine studies), immunohistochemistry (five studies) and other methods (multiple methods-two studies, NER polymorphism-one study). In five studies ERCC1 use was planned, but not undertaken. In nine data was insufficient to identify the procedure. For each assay there was variation across studies in the details of the laboratory techniques, scoring systems and methods for obtaining samples.

CONCLUSIONS

We found large variation across studies in ERCC1 evaluation procedures. This will limit the future comparability of results between these different studies. To enable evidence-based clinical practice, consensus is needed on a validated procedure to assess a predictive biomarker in the early phase of research. We believe that ERCC1 is not untypical of biomarkers being investigated for stratified medicine.

Induction Therapy for Mesothelioma

One particular approach of multimodality treatment for mesothelioma is induction therapy followed by surgery. Among its several advantages, the most important is downstaging of the tumor into a resectable stage, although morbidity and mortality might be increased. In this article we review the principles and outcome of different modalities for induction treatment of mesothelioma.

SMARCA4/BRG1 Is a Novel Prognostic Biomarker Predictive of Cisplatin-Based Chemotherapy Outcomes in Resected Non-Small Cell Lung Cancer

PURPOSE

Identification of predictive biomarkers is critically needed to improve selection of patients who derive the most benefit from platinum-based chemotherapy. We hypothesized that decreased expression of SMARCA4/BRG1, a known regulator of transcription and DNA repair, is a novel predictive biomarker of increased sensitivity to adjuvant platinum-based therapies in non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

The prognostic value was tested using a gene-expression microarray from the Director's Challenge Lung Study (n = 440). The predictive significance of SMARCA4 was determined using a gene-expression microarray (n = 133) from control and treatment arms of the JBR.10 trial of adjuvant cisplatin/vinorelbine. Kaplan-Meier method and log-rank tests were used to estimate and test the differences of probabilities in overall survival (OS) and disease-specific survival (DSS) between expression groups and treatment arms. Multivariate Cox regression models were used while adjusting for other clinical covariates.

RESULTS

In the Director's Challenge Study, reduced expression of SMARCA4 was associated with poor OS compared with high and intermediate expression (P < 0.001 and P = 0.009, respectively). In multivariate analysis, compared with low, high SMARCA4 expression predicted a decrease in risk of death [HR, 0.6; 95% confidence interval (CI), 0.4-0.8; P = 0.002]. In the JBR.10 trial, improved 5-year DSS was noted only in patients with low SMARCA4 expression when treated with adjuvant cisplatin/vinorelbine [HR, 0.1; 95% CI, 0.0-0.5, P = 0.002 (low); HR, 1.0; 95% CI, 0.5-2.3, P = 0.92 (high)]. An interaction test was highly significant (P = 0.01).

CONCLUSIONS

Low expression of SMARCA4/BRG1 is significantly associated with worse prognosis; however, it is a novel significant predictive biomarker for increased sensitivity to platinum-based chemotherapy in NSCLC. Clin Cancer Res; 22(10); 2396-404. ©2015 AACR.

A Single Conserved Residue Mediates Binding of the Ribonucleotide Reductase Catalytic Subunit RRM1 to RRM2 and Is Essential for Mouse Development

The ribonucleotide reductase (RNR) complex, composed of a catalytic subunit (RRM1) and a regulatory subunit (RRM2), is thought to be a rate-limiting enzymatic complex for the production of nucleotides. In humans, the Rrm1 gene lies at 11p15.5, a tumor suppressor region, and RRM1 expression in cancer has been shown to predict responses to chemotherapy. Nevertheless, whether RRM1 is essential in mammalian cells and what the effects of its haploinsufficiency are remain unknown. To model RNR function in mice we used a mutation previously described in Saccharomyces cerevisiae (Rnr1-W688G) which, despite being viable, leads to increased interaction of the RNR complex with its allosteric inhibitor Sml1. In contrast to yeast, homozygous mutant mice carrying the Rrm1 mutation (Rrm1(WG/WG)) are not viable, even at the earliest embryonic stages. Proteomic analyses failed to identify proteins that specifically bind to the mutant RRM1 but revealed that, in mammals, the mutation prevents RRM1 binding to RRM2. Despite the impact of the mutation, Rrm1(WG/+) mice and cells presented no obvious phenotype, suggesting that the RRM1 protein exists in excess. Our work reveals that binding of RRM1 to RRM2 is essential for mammalian cells and provides the first loss-of-function model of the RNR complex for genetic studies.

The Effects and Molecular Mechanisms of MiR-106a in Multidrug Resistance Reversal in Human Glioma U87/DDP and U251/G Cell Lines

Chemotherapy resistance is one of the major obstacles to effective glioma therapy. Currently, the mechanism underlying chemotherapy resistance is unclear. A recent study showed that miR-106a is an important molecule involved in chemotherapy resistance. To explore the effects and mechanisms of miR-106a on multidrug resistance reversal in human glioma cells, we silenced miR-106a expression in the cisplatin-resistant U87 (U87/DDP) and the gefitinib-resistant U251 (U251/G) glioma cell lines and measured the resulting drug sensitivity, cell apoptosis rate and rhodamine 123 content. In addition, we detected decreased expression of P-glycoprotein, MDR1, MRP1, GST-π, CDX2, ERCC1, RhoE, Bcl-2, Survivin and Topo-II, as well as reduced production of IL-6, IL-8 and TGF-β in these cell lines. Furthermore, we found decreased expression of p-AKT and transcriptional activation of NF-κB, Twist, AP-1 and Snail in these cell lines. These results suggest that miR-106a is a promising therapeutic target for the treatment of human multidrug resistant glioma.

[Molecular diagnostics of non-small cell lung cancer: New markers and technologies]

Lung cancer is the prototypical tumor entity for the development of new diagnostic and individualized therapeutic strategies based on molecular patient stratification. Developments in this field specifically concentrate on predictive biomarkers for the response to conventional therapeutic agents, novel drugs targeting specific mutations and also new immunomodulatory drugs. The multitude of upcoming new predictive biomarkers requires the development and implementation of efficient test strategies and comprehensive technical methods, specifically when tissue restrictions inherent to lung cancer diagnostics are also taken into account. Novel procedures and technical aspects of these issues are discussed in this review.

Importance of excision repair cross-complementation group 1 and ribonucleotide reductase M1 as prognostic biomarkers in malignant pleural mesothelioma treated with platinum-based induction chemotherapy followed by surgery

OBJECTIVES

Survival and response to platinum-based induction chemotherapy are heterogeneous among patients with malignant pleural mesothelioma. The aim of the present study was to assess the prognostic role of DNA repair markers, such as excision repair cross-complementation group 1 and ribonucleotide reductase M1, in multimodally treated patients with malignant pleural mesothelioma.

METHODS

Tumor tissue of a malignant pleural mesothelioma cohort (n = 107) treated with platinum/gemcitabine (n = 46) or platinum/pemetrexed (n = 61) induction chemotherapy followed by extrapleural pneumonectomy was assembled on a tissue microarray. Immunohistochemical expression of excision repair cross-complementation group 1 (nuclear) and ribonucleotide reductase M1 (nuclear and cytoplasmic) was assessed for its prognostic impact (association with overall survival or freedom from recurrence).

RESULTS

Patients with high nuclear ribonucleotide reductase M1 expression before chemotherapy showed significantly longer freedom from recurrence (P = .03). When specifically analyzed in the subgroup of patients receiving platinum/gemcitabine followed by extrapleural pneumonectomy, high nuclear ribonucleotide reductase M1 was associated with prolonged freedom from recurrence (P = .03) and overall survival (P = .02). Low excision repair cross-complementation group 1 expression in prechemotherapy tumor tissues was associated with significantly longer freedom from recurrence (P = .04). Nuclear ribonucleotide reductase M1 and excision repair cross-complementation group 1 were independent prognosticators of freedom from recurrence in addition to pT stage in multivariate analysis.

CONCLUSIONS

In the present study, nuclear ribonucleotide reductase M1 and excision repair cross-complementation group 1 expression were identified as independent prognosticators for freedom from recurrence of malignant pleural mesothelioma in patients undergoing induction chemotherapy followed by extrapleural pneumonectomy.

Cancer therapy and replication stress: forks on the road to perdition

Deregulated DNA replication occurs in cancer where it contributes to genomic instability. This process is a target of cytotoxic therapies. Chemotherapies exploit high DNA replication in cancer cells by modifying the DNA template or by inhibiting vital enzymatic activities that lead to slowing or stalling replication fork progression. Stalled replication forks can be converted into toxic DNA double-strand breaks resulting in cell death, i.e., replication stress. While likely crucial for many cancer treatments, replication stress is poorly understood due to its complexity. While we still know relatively little about the role of replication stress in cancer therapy, technical advances in recent years have shed new light on the effect that cancer therapeutics have on replication forks and the molecular mechanisms that lead from obstructed fork progression to cell death. This chapter will give an overview of our current understanding of replication stress in the context of cancer therapy.

Heterogeneity of excision repair cross-complementation group 1 gene expression in non-small-cell lung cancer patients

Excision repair cross-complementation group 1 (ERCC1) gene expression analysis is currently used widely in the molecular diagnosis of cancer. According to numerous studies, ERCC1 gene expression correlates with overall survival and effectiveness of chemotherapy with platinum agents. However, the degree of this correlation differs among various studies, with certain authors reporting a complete lack of such a correlation. These contradictions may be attributed to a number of factors, including the heterogeneity of the tumor tissue. In this study, we attempted to assess the degree of genetic heterogeneity exhibited by tissue samples obtained from non-small-cell lung cancer (NSCLC) through the expression of the ERCC1 gene. This study included 25 samples of tumor tissue from patients with a morphologically confirmed NSCLC diagnosis. A total of three randomized sections of each specimen were used. The ERCC1 gene expression was assessed by quantitative polymerase chain reaction (qPCR) in the TaqMan format. When planning the experiment and analysis of qPCR data, the MIQE guidelines were taken into consideration. We established that the coefficient of variation of the relative level of ERCC1 gene expression in the majority of the samples exceeded 33% (P<0.05), indicating the significant heterogeneity of the sample. We also demonstrated that the degree of heterogeneity of the tumor tissue is largely dependent on disease stage.

Developing precision medicine in a global world

Advances in understanding the biology of cancer, as well as advances in diagnostic technologies, such as the advent of affordable high-resolution DNA sequencing, have had a major impact on the approach to identification of specific alterations in a given patient's cancer that could be used as a basis for treatment selection, and hence the development of companion diagnostics. Although there are now several examples of successful development of companion diagnostics that allow identification of patients who will achieve the greatest benefit from a new therapeutic, the path to coapproval of a diagnostic test along with a new therapeutic is complex and often inefficient. This review and the accompanying articles examine the current state of companion diagnostic development in the United States and Europe from academic, industry, regulatory, and economic perspectives. See all articles in this CCR Focus section, "The Precision Medicine Conundrum: Approaches to Companion Diagnostic Co-development."

Predictive value of excision repair cross-complementation group 1 expression for platinum-based chemotherapy and survival in gastric cancer: a meta-analysis

PURPOSE

The predictive value of excision repair cross-complementation group 1 (ERCC1) gene for survival and response to platinum-based chemotherapy in gastric cancer (GC) remains controversial. We performed a meta-analysis to clarify the precise estimation of the prognostic and predictive effect of ERCC1.

METHODS

A systematic literature search was conducted using PubMed, ScienceDirect, Wiley and American Society of Clinical Oncology (ASCO) before March 2014. Studies analyzing survival data and/or chemotherapy response in GC by ERCC1 status were identified. The principal outcome measures were hazard ratios (HRs) for survival and relative risks (RRs) for chemotherapy response. Pooled HRs and RRs were calculated using fixed- or random-effects models according to the heterogeneity.

RESULTS

Twenty-one studies involving 1,628 patients met our inclusion criteria. High ERCC1 expression was significantly associated with shorter overall survival (OS) and lower response to chemotherapy in advanced GC patients receiving palliative chemotherapy (HR 1.83; 95 % CI 1.45-2.31; P < 0.001; RR 0.49; 95 % CI 0.38-0.62; P < 0.001). There was no significant difference in survival between high and low ERCC1 expression in adjuvant setting (OS: HR 1.38; 95 % CI 0.77-2.45; P = 0.276; EFS 0.72; 95 % CI 0.38-1.33; P = 0.291). Some evidence of heterogeneity and possible publication bias were discovered in few meta-analyses.

CONCLUSIONS

High ERCC1 expression might be an adverse prognostic and a drug-resistance predictive factor for advanced GC patients. However, further studies with consistent ERCC1 assessment methodology are needed.

Response to GEMOX plus erlotinib in pancreatic cancer is associated with ERCC1 overexpression

INTRODUCTION

There are no data about the efficacy of gemcitabine in combination with oxaliplatin (GEMOX) and erlotinib for the treatment of metastatic pancreatic cancer (mPC). Thus, we performed this retrospective analysis in mPC patients to investigate the activity and safety of GEMOX plus erlotinib and correlated the benefit with ERCC1 expression, a potential biomarker for treatment response.

PATIENTS AND METHODS

Patients with untreated mPC receiving off-protocol GEMOX plus erlotinib were included. Data collection included baseline demographic, response and toxicity data as well as PFS and OS. Additionally, immunohistochemistry was performed to stain for ERCC1 expression.

RESULTS

A total of 51 patients were included. The median age was 62 years and the median ECOG performance score was 1 (range, 0-1). Objective response or disease stabilization was achieved in 54% of the patients. The median PFS was 4·4 months (95% CI 4·4-5·4) and median OS was 8·5 months (95% CI 6·1-10·9). The 27 patients, who benefited from this regimen, had a median PFS of 6·7, a median OS of 11·2 months and an overexpression of ERCC1 (histoscore 10, P ≤ 0·05) compared to nonresponders (histoscore 7·2). Myelosuppression was the most frequent side effect. The most common severe nonhematological toxicities were diarrhoea and skin toxicity in six (12%) patients each.

CONCLUSIONS

These data suggest that the combination of GEMOX plus erlotinib is safe and active in about half of the patients. Patients, who had a higher ERCC1 staining pattern, benefited most from this therapy. Prospective biomarker studies are warranted to confirm these findings.

Characterization and drug sensitivity profiling of primary malignant mesothelioma cells from pleural effusions

Background

Patients with malignant mesothelioma have a poor prognosis and only 40% respond to first line treatment; a combination of pemetrexed and cisplatin or carboplatin. We used primary malignant mesothelioma cells and an ex vivo chemosensitivity assay with future purpose to predict best choice of treatment. The clinical outcome of these patients might be predicted by measuring drug sensitivity.

Methods

Pleural effusions containing primary malignant mesothelioma cells were received from the diagnostic routine. We characterized and tested the chemosensitivity of 18 malignant samples and four benign samples from 16 different patients with pleural effusions. Cells were seeded in a 384-well plate for a robotized ex vivo testing of drug sensitivity to 32 different drugs. The primary cells were further characterized by immunocytochemistry to evaluate the proportion of malignant cells and to study the RRM1 and ERCC1 reactivity, two proteins associated with drug resistance.

Results

We observed great individual variability in the drug sensitivity. Primary cell isolates were affected by between one and ten drugs, and resistant to the remaining tested drugs. Actinomycin D and daunorubicin were the two drugs effective in most cases. Adjusting efficiency of individual drugs for varying proportion of tumor cells and to the average effect on benign cells correlated with effect of pemetrexed, cisplatin and survival time. General drug sensitivity, proportion of malignant cells and reactivity to RRM1 correlated to each other and to survival time of the patients.

Conclusions

The proportion of malignant cells and RRM1 reactivity in the pleural effusions correlate to drug sensitivity and survival time. The variability in response to the commonly used chemotherapies emphasizes the need for tests that indicate best individual choice of cytotoxic drugs. The efficiency of the obtained results should preferably be corrected for admixture of benign cells and effects of given drugs on benign cells.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-709) contains supplementary material, which is available to authorized users.

Activation of Nrf2 pathways correlates with resistance of NSCLC cell lines to CBP501 in vitro

CBP501 is an anticancer drug candidate that was investigated in two randomized phase II clinical trials for patients with nonsquamous non-small cell lung cancer (NSCLC) and malignant pleural mesothelioma (MPM). CBP501 has been shown to have two mechanisms of action, namely calmodulin modulation and G2 checkpoint abrogation. Here, we searched for a biomarker to predict sensitivity to CBP501. Twenty-eight NSCLC cell lines were classified into two subgroups, CBP501-sensitive and -insensitive, by quantitatively analyzing the cis-diamminedichloro-platinum (II) (CDDP)-enhancing activity of CBP501 through treatments with short-term (1 hour) coexposure to CDDP and CBP501 or to either alone. Microarray analysis was performed on these cell lines to identify gene expression patterns that correlated with CBP501 sensitivity. We found that multiple nuclear factor erythroid-2-related factor 2 (Nrf2) target genes showed high expression in CBP501-insensitive cell lines. Western blot and immunocytochemical analysis for Nrf2 in NSCLC cell lines also indicated higher protein level in CBP501-insensitive cell lines. Moreover, CBP501 sensitivity is modulated by silencing or sulforaphane-induced overexpression of Nrf2. These results indicate that Nrf2 transcription factor is a potential candidate as a biomarker for resistance to CBP501. This study might help to identify those subpopulations of patients who would respond well to the CBP501 and CDDP combination treatment of NSCLC.

[Novel morphological and molecular aspects of lung cancer]

In recent years the classification of pulmonary cancer has seen a paradigm shift with respect to both morphological as well as molecular aspects. On the morphological side this includes novel criteria for tumor classification from biopsy material based on morphological and immunohistochemical aspects as well as a novel classification based on morphological patterns for pulmonary adenocarcinomas. In addition, this new classification now includes adenocarcinoma in situ as well as minimally invasive adenocarcinoma as novel entities and a variety of novel adenocarcinoma subtypes. This reclassification was accompanied and complemented by tremendous developments in the field of lung cancer genomics which paved the way for now widely established predictive molecular markers, e.g. epidermal growth factor receptor (EGFR) mutations and EML4-ALK translocations and will certainly lead to a variety of novel predictive markers not only for pulmonary adenocarcinoma but also for other pulmonary neoplasms.

ATR pathway inhibition is synthetically lethal in cancer cells with ERCC1 deficiency

The DNA damage response kinase ATR and its effector kinase CHEK1 are required for cancer cells to survive oncogene-induced replication stress. ATR inhibitors exhibit synthetic lethal interactions, with deficiencies in the DNA damage response enzymes ATM and XRCC1 and with overexpression of the cell cycle kinase cyclin E. Here, we report a systematic screen to identify synthetic lethal interactions with ATR pathway-targeted drugs, rationalized by their predicted therapeutic utility in the oncology clinic. We found that reduced function in the ATR pathway itself provided the strongest synthetic lethal interaction. In addition, we found that loss of the structure-specific endonuclease ERCC1-XPF (ERCC4) is synthetic lethal with ATR pathway inhibitors. ERCC1-deficient cells exhibited elevated levels of DNA damage, which was increased further by ATR inhibition. When treated with ATR or CHEK1 inhibitors, ERCC1-deficient cells were arrested in S-phase and failed to complete cell-cycle transit even after drug removal. Notably, triple-negative breast cancer cells and non-small cell lung cancer cells depleted of ERCC1 exhibited increased sensitivity to ATR pathway-targeted drugs. Overall, we concluded that ATR pathway-targeted drugs may offer particular utility in cancers with reduced ATR pathway function or reduced levels of ERCC4 activity.