KRAS mutation: should we test for it, and does it matter?

Differential KrasV12 protein levels control a switch regulating lung cancer cell morphology and motility

INTRODUCTION

Oncogenic Kras mutations are important drivers of lung cancer development and metastasis. They are known to activate numerous cellular signaling pathways implicated in enhanced proliferation, survival, tumorigenicity and motility during malignant progression.

OBJECTIVES

Most previous studies of Kras in cancer have focused on the comparison of cell states in the absence or presence of oncogenic Kras mutations. Here we show that differential expression of the constitutively active mutation Kras^V12 has profound effects on cell morphology and motility that drive metastatic processes.

METHODS

The study relies on lung cancer cell transformation models, patient-derived lung cancer cell lines, and human lung tumor sections combined with molecular biology techniques, live-cell imaging and staining methods.

RESULTS

Our analysis shows two cell functional states driven by Kras^V12 protein levels: a non-motile state associated with high Kras^V12 levels and tumorigenicity, and a motile state associated with low Kras^V12 levels and cell dissemination. Conversion between the states is conferred by differential activation of a mechano-sensitive double-negative feedback between Kras^V12/ERK/Myosin II and matrix-adhesion signaling. Kras^V12 expression levels change upon cues such as hypoxia and integrin-mediated cell-matrix adhesion, rendering Kras^V12 levels an integrator of micro-environmental signals that translate into cellular function. By live cell imaging of tumor models we observe shedding of mixed high and low Kras^V12 expressers forming multi-functional collectives with potentially optimal metastatic properties composed of a highly mobile and a highly tumorigenic unit.

DISCUSSION

Together these data highlight previously unappreciated roles for the quantitative effects of expression level variation of oncogenic signaling molecules in conferring fundamental alterations in cell function regulation required for cancer progression.

Optimized Multiplex Detection of 7 KRAS Mutations by Taqman Allele-Specific qPCR

Establishing the KRAS mutational status of tumor samples is essential to manage patients with colorectal or lung cancer, since these mutations preclude treatment with monoclonal anti-epidermal growth factor receptor (EGFR) antibodies. We report an inexpensive, rapid multiplex allele-specific qPCR method detecting the 7 most clinically relevant KRAS somatic mutations with concomitant amplification of non-mutated KRAS in tumor cells and tissues from CRC patients. Positive samples evidenced in the multiplex assay were further subjected to individual allele-specific analysis, to define the specific mutation. Reference human cancer DNA harbouring either G12A, G12C, G12D, G12R, G12S, G12V and G13D confirmed assay specificity with ≤1% sensitivity of mutant alleles. KRAS multiplex mutation analysis usefulness was also demonstrated with formalin-fixed paraffin embedded (FFPE) from CRC biopsies.

CONCLUSION

Co-amplification of non-mutated DNA avoided false negatives from degraded samples. Moreover, this cost effective assay is compatible with mutation detection by DNA sequencing in FFPE tissues, but with a greater sensitivity when mutant DNA concentrations are limiting.

KRAS mutations affect prognosis of non-small-cell lung cancer patients treated with first-line platinum containing chemotherapy

KRAS mutations seem to indicate a poor outcome in Non-Small-Cell Lung Cancer (NSCLC) but such evidence is still debated. The aim of this planned ancillary study within the TAILOR trial was to assess the prognostic value of KRAS mutations in advanced NSCLC patients treated with platinum-based first-line chemotherapy. Patients (N = 540), enrolled in the study in 52 Italian hospitals, were centrally genotyped twice in two independent laboratories for EGFR and KRAS mutational status.

Of these, 247 patients were eligible and included in the present study. The primary endpoint was overall survival (OS) according to KRAS mutational status in patients harboring EGFR wild-type.

Sixty (24.3%) out of 247 patients harbored KRAS mutations. Median OS was 14.3 months and 10.6 months in wild-type and mutated KRAS patients, respectively (unadjusted Hazard Ratio [HR]=1.41, 95%Confidence Interval [CI]: 1.03-1.94 P = 0.032; adjusted HR=1.39, 95%CI: 1.00-1.94 P = 0.050). This study, with all consecutive patients genotyped, indicates that the presence of KRAS mutations has a mild negative impact on OS in advanced NSCLC patient treated with a first-line platinum-containing regimen. Trial Registration: clinicaltrials.gov identifier NCT00637910

Ercc1 Deficiency Promotes Tumorigenesis and Increases Cisplatin Sensitivity in a Tp53 Context-Specific Manner

KRAS-mutant lung adenocarcinoma is among the most common cancer entities and, in advanced stages, typically displays poor prognosis due to acquired resistance against chemotherapy, which is still largely based on cisplatin-containing combination regimens. Mechanisms of cisplatin resistance have been extensively investigated, and ERCC1 has emerged as a key player due to its central role in the repair of cisplatin-induced DNA lesions. However, clinical data have not unequivocally confirmed ERCC1 status as a predictor of the response to cisplatin treatment. Therefore, we employed an autochthonous mouse model of Kras-driven lung adenocarcinoma resembling human lung adenocarcinoma to investigate the role of Ercc1 in the response to cisplatin treatment. Our data show that Ercc1 deficiency in Tp53-deficient murine lung adenocarcinoma induces a more aggressive tumor phenotype that displays enhanced sensitivity to cisplatin treatment. Furthermore, tumors that relapsed after cisplatin treatment in our model develop a robust etoposide sensitivity that is independent of the Ercc1 status and depends solely on previous cisplatin exposure. Our results provide a solid rationale for further investigation of the possibility of preselection of lung adenocarcinoma patients according to the functional ERCC1- and mutational TP53 status, where functionally ERCC1-incompetent patients might benefit from sequential cisplatin and etoposide chemotherapy.

IMPLICATIONS

This study provides a solid rationale for the stratification of lung adenocarcinoma patients according to the functional ERCC1- and mutational TP53 status, where functionally ERCC1-incompetent patients could benefit from sequential cisplatin and etoposide chemotherapy. Mol Cancer Res; 14(11); 1110-23. ©2016 AACR.

Survival outcome according to KRAS mutation status in newly diagnosed patients with stage IV non-small cell lung cancer treated with platinum doublet chemotherapy

Introduction

Mutations (MT) of the KRAS gene are the most common mutation in non-small cell lung cancer (NSCLC), seen in about 20–25% of all adenocarcinomas. Effect of KRAS MT on response to cytotoxic chemotherapy is unclear.

Methods

We undertook a single-institution retrospective analysis of 93 consecutive patients with stage IV NSCLC adenocarcinoma with known KRAS and EGFR MT status to determine the association of KRAS MT with survival. All patients were treated between January 1, 2008 and December 31, 2011 with standard platinum based chemotherapy at the University of Pennsylvania. Overall and progression free survival were analyzed using Kaplan-Meier and Cox proportional hazard methods.

Results

All patients in this series received platinum doublet chemotherapy, and 42 (45%) received bevacizumab. Overall survival and progression free survival for patients with KRAS MT was no worse than for patients with wild type KRAS. Median overall survival for patients with KRAS MT was 19 months (mo) vs. 15.6 mo for KRAS WT, p = 0.34, and progression-free survival was 6.2 mo in patients with KRAS MT vs. 7mo in patients with KRAS WT, p = 0.51. In multivariable analysis including age, race, gender, and ECOG PS, KRAS MT was not associated with overall survival (HR 1.12, 95% CI 0.58–2.16, p = 0.74) or progression free survival (HR 0.80, 95% CI 0.48–1.34, p = 41). Of note, receipt of bevacizumab was associated with improved overall survival only in KRAS WT patients (HR 0.34, p = 0.01).

Conclusions

KRAS MT are not associated with inferior progression-free and overall survival in advanced NSCLC patients treated with standard first-line platinum-based chemotherapy.

Next-Generation Sequencing and Immunotherapy Biomarkers: A Medical Oncology Perspective

The two most important scientific developments of the past decade regarding therapies for patients with non-small cell lung cancer are the ability to exploit particular genetic mutations with targeted therapies and the discovery of drugs that can help the patient's own immune system attack the cancer. Despite these advances, many patients do not yet benefit from either approach. To maximize patient benefit, clinicians and pathologists will need to rationally apply the growing scientific knowledge to best characterize a patient's tumor and possible driver mutations. A growing understanding of host-tumor immune interactions will hopefully help expand our therapeutic options. Lastly, the still elusive identification of immunotherapy biomarkers will hopefully help identify patients most likely to derive a therapeutic response to immune checkpoint inhibitors, and promises to be an important field of study for years to come.

A genetic cell context-dependent role for ZEB1 in lung cancer

The Zinc-finger E-box-binding Homeobox-1 (ZEB1) is a transcription factor that promotes epithelial–mesenchymal transition (EMT) and acts as an oncogene in KRAS-mutated lung cancer models. Here we report that ZEB1 exerts the opposite effect in EGFR-mutated lung cancer cells, where it suppresses growth by increasing microRNA-200 targets to antagonize ERBB3, a driver of mutant EGFR-dependent cell growth. Among these targets, NOTCH1 represses ERBB3 promoter activity and the expression of ERBB3. Furthermore, we find that EGFR inhibitor treatment, which inhibits the growth of EGFR-mutated cells, induces ZEB1. Despite its growth-inhibiting effect, EGFR inhibitor-induced ZEB1 strongly promotes EMT-dependent resistance to EGFR inhibitors partially through NOTCH1, suggesting a multifunctional role for NOTCH1 in EGFR-mutated cells. These results support a previously unrecognized genetic cell context-dependent role for ZEB1 and suggest that NOTCH1 may be a useful target for treating resistance to EGFR inhibitors, especially EMT-driven resistance.

ZEB1 is a driver of epithelial-to-mesenchymal transition that usually promotes lung cancer in the context of KRAS mutation. Here, the authors uncover a growth suppressive role for ZEB1 in EGFR mutant lung adenocarcinoma, thus elucidating the context dependent function of this protein.

Phosphoproteomics Reveals MAPK Inhibitors Enhance MET- and EGFR-Driven AKT Signaling in KRAS-Mutant Lung Cancer

Pathway inhibition of the RAS-driven MAPK pathway using small-molecule kinase inhibitors has been a key focus for treating cancers driven by oncogenic RAS, yet significant clinical responses are lacking. Feedback reactivation of ERK driven by drug-induced RAF activity has been suggested as one of the major drug resistance mechanisms, especially in the context of oncogenic RAS. To determine whether additional adaptive resistance mechanisms may coexist, we characterized global phosphoproteomic changes after MEK inhibitor selumetinib (AZD6244) treatment in KRAS-mutant A427 and A549 lung adenocarcinoma cell lines employing mass spectrometry-based phosphoproteomics. We identified 9,075 quantifiable unique phosphosites (corresponding to 3,346 unique phosphoproteins), of which 567 phosphosites were more abundant and 512 phosphosites were less abundant after MEK inhibition. Selumetinib increased phosphorylation of KSR-1, a scaffolding protein required for assembly of MAPK signaling complex, as well as altered phosphorylation of GEF-H1, a novel regulator of KSR-1 and implicated in RAS-driven MAPK activation. Moreover, selumetinib reduced inhibitory serine phosphorylation of MET at Ser985 and potentiated HGF- and EGF-induced AKT phosphorylation. These results were recapitulated by pan-RAF (LY3009120), MEK (GDC0623), and ERK (SCH772984) inhibitors, which are currently under early-phase clinical development against RAS-mutant cancers. Our results highlight the unique adaptive changes in MAPK scaffolding proteins (KSR-1, GEF-H1) and in RTK signaling, leading to enhanced PI3K-AKT signaling when the MAPK pathway is inhibited.

IMPLICATIONS

This study highlights the unique adaptive changes in MAPK scaffolding proteins (KSR-1, GEF-H1) and in RTK signaling, leading to enhanced PI3K/AKT signaling when the MAPK pathway is inhibited. Mol Cancer Res; 14(10); 1019-29. ©2016 AACR.

Effect of KRAS mutation status on efficacy of EGFR monoclonal antibody treatment in colorectal cancer

Colorectal cancer is one of the most common malignant tumors. With the development of economy and the improvement of living standard in China, which have resulted in great changes in lifestyle and eating habits, the incidence of colorectal cancer has increased year by year. Among all treatments currently available, targeted therapy is considered to be the most ideal treatment for metastatic colorectal cancer. KRAS mutation is closely related to the efficacy of targeted therapy for colorectal cancer. Thus, it is important to clarify the KRAS mutation status before targeted therapy is considered. This paper mainly elaborates the effect of KRAS mutation status on the efficacy of epidermal growth factor receptor monoclonal antibody treatment of colorectal cancer with regard to the structure and function of KRAS gene, KRAS mutations and heterogeneity.

From Uniplex to Multiplex Molecular Profiling in Advanced Non-Small Cell Lung Carcinoma

Non-small cell lung carcinoma is a leading cause of cancer death worldwide. Understanding the molecular biology of survival and proliferation of cancer cells led to a new molecular classification of lung cancer and the development of targeted therapies with promising results. With the advances of image-guided biopsy techniques, tumor samples are becoming smaller, and the molecular testing techniques have to overcome the challenge of integrating the characterization of a panel of abnormalities including gene mutations, copy-number changes, and fusions in a reduced number of assays using only a small amount of genetic material. This article reviews the current knowledge about the most frequent actionable molecular abnormalities in non-small cell lung carcinoma, the new approaches of molecular analysis, and the implications of these findings in the context of clinical practice.

Hybridization-Induced Aggregation Technology for Practical Clinical Testing: KRAS Mutation Detection in Lung and Colorectal Tumors

KRAS mutations have emerged as powerful predictors of response to targeted therapies in the treatment of lung and colorectal cancers; thus, prospective KRAS genotyping is essential for appropriate treatment stratification. Conventional mutation testing technologies are not ideal for routine clinical screening, as they often involve complex, time-consuming processes and/or costly instrumentation. In response, we recently introduced a unique analytical strategy for revealing KRAS mutations, based on the allele-specific hybridization-induced aggregation (HIA) of oligonucleotide probe-conjugated microbeads. Using simple, inexpensive instrumentation, this approach allows for the detection of any common KRAS mutation in <10 minutes after PCR. Here, we evaluate the clinical utility of the HIA method for mutation detection (HIAMD). In the analysis of 20 lung and colon tumor pathology specimens, we observed a 100% correlation between the KRAS mutation statuses determined by HIAMD and sequencing. In addition, we were able to detect KRAS mutations in a background of 75% wild-type DNA-a finding consistent with that reported for sequencing. With this, we show that HIAMD allows for the rapid and cost-effective detection of KRAS mutations, without compromising analytical performance. These results indicate the validity of HIAMD as a mutation-testing technology suitable for practical clinical testing. Further expansion of this platform may involve the detection of mutations in other key oncogenic pathways.

Reactive Oxygen Species Modulator 1 (Romo1) Predicts Poor Outcomes in Advanced Non-small Cell Lung Cancer Patients Treated with Platinum-Based Chemotherapy

Purpose

Reactive oxygen species modulator 1 (Romo1) is a key mediator of intracellular reactive oxygen species production. However, examination of the clinical usefulness of Romo1 in cancers has been limited. We evaluated the association of Romo1 expression with clinical outcomes in advanced non-small cell lung cancer (NSCLC) patients treated with platinum-based chemotherapy.

Materials and Methods

Romo1 expression in tumor tissue was examined by immunohistochemistry and evaluated by histological score. Survival analyses were performed according to Romo1 expression and the association between Romo1 expression and clinical parameters was evaluated.

Results

A total of 88 tumor specimens were analyzed. Significantly shorter median progression-free survival (PFS) was observed in the high Romo1 group compared with the low Romo1 group (4.5 months vs. 9.8 months, p < 0.001), and the median overall survival (OS) of the high Romo1 group was also significantly shorter than that of the low Romo1 group (8.4 months vs. 15.5 months, p < 0.001). Results of multivariate analyses showed significant association of high Romo1 expression with both poor PFS (hazard ratio [HR], 2.75; 95% confidence interval [CI], 1.71 to 4.44) and poor OS (HR, 3.99; 95% CI, 2.36 to 6.74). Results of the subgroup analysis showed a similar association regardless of tumor histology. Romo1 expression showed no association with any clinical parameter including age, sex, smoking status, stage, differentiation, or tumor histology.

Conclusion

Romo1 overexpression was associated with poor response to treatment and shorter survival in advanced NSCLC patients treated with platinum-based chemotherapy. Romo1 could be a potential adverse predictive marker in this setting.

Building a Robust Tumor Profiling Program: Synergy between Next-Generation Sequencing and Targeted Single-Gene Testing

Next-generation sequencing (NGS) is a powerful platform for identifying cancer mutations. Routine clinical adoption of NGS requires optimized quality control metrics to ensure accurate results. To assess the robustness of our clinical NGS pipeline, we analyzed the results of 304 solid tumor and hematologic malignancy specimens tested simultaneously by NGS and one or more targeted single-gene tests (EGFR, KRAS, BRAF, NPM1, FLT3, and JAK2). For samples that passed our validated tumor percentage and DNA quality and quantity thresholds, there was perfect concordance between NGS and targeted single-gene tests with the exception of two FLT3 internal tandem duplications that fell below the stringent pre-established reporting threshold but were readily detected by manual inspection. In addition, NGS identified clinically significant mutations not covered by single-gene tests. These findings confirm NGS as a reliable platform for routine clinical use when appropriate quality control metrics, such as tumor percentage and DNA quality cutoffs, are in place. Based on our findings, we suggest a simple workflow that should facilitate adoption of clinical oncologic NGS services at other institutions.

KRAS G12D Mutation Subtype Is A Prognostic Factor for Advanced Pancreatic Adenocarcinoma

OBJECTIVES

There is no molecular biomarker available in the clinical practice to assess the prognosis of advanced pancreatic carcinoma. This multicenter prospective study aimed to investigate the role of KRAS mutation subtypes within the primary tumor to determine the prognosis of advanced pancreatic cancer.

METHODS

The exon-2 KRAS mutation status was tested on endoscopic ultrasound-guided fine-needle aspiration biopsy material (primary tumor; restriction fragment-length polymorphism plus sequencing and TaqMan allelic discrimination) of patients with proven locally advanced and/or metastatic pancreatic ductal carcinoma. We used the Kaplan-Meier method, log-rank test, and Cox's model to evaluate the impact of KRAS status on the overall survival (OS), adjusting for age, stage of disease, clinical performance status, CA 19-9 levels, and treatment.

RESULTS

A total of 219 patients (men: 116; mean age: 67±9.4 years) were included: 147 harbored a codon-12 KRAS mutation (G12D: 73; G12V: 53; G12R: 21) and 72 had a wild-type KRAS. There was no difference in the OS between patients with a mutant KRAS (8 months; 95% confidence interval (95% CI): 8.7-12.3) and the wild-type (9 months; 95% CI: 8.7-12.8; hazard ratio (HR): 1.03; P=0.82). However, the patients with a G12D mutation had a significantly shorter OS (6 months; 95% CI: 6.4-9.7) compared with the other patients (OS: 9 months; 95% CI: 10-13; HR: 1.47; P=0.003; i.e., wild type: 9 months, G12V: 9 months, G12R: 14 months). Similar results were observed in the subgroup of 162 patients who received chemotherapy (HR: 1.66; P=0.0013; G12D (n=49): 8 months, wild type (n=56): 10 months, G12V (n=38): 10 months, G12R (n=19): 14 months). Multivariate analyses identified KRAS G12D as an independent predictor for worse prognosis within the entire series (HR: 1.44; P=0.01) and in the subgroup of patients that received chemotherapy (HR: 1.84; P=0.02).

CONCLUSIONS

The KRAS G12D mutation subtype is an independent prognostic marker for advanced pancreatic ductal carcinoma. Codon and amino-acid-specific mutations of KRAS should be considered when evaluating the prognoses as well as in trials testing drugs that target RAS and downstream RAS pathways.

The prevalence and prognostic significance of KRAS mutation subtypes in lung adenocarcinomas from Chinese populations

BACKGROUND

We performed this retrospective study to identify the prevalence of KRAS mutation in Chinese populations and make a comprehensive investigation of the clinicopathological features of KRAS mutation in these patients.

PATIENTS AND METHODS

Patients from 2007 to 2013 diagnosed with primary lung adeno-carcinoma who received a radical resection were examined for KRAS, EGFR, HER2, BRAF mutations, and ALK, RET, and ROS1 fusions. Clinicopathological features, including sex, age, tumor-lymph node-metastasis stage, tumor differentiation, smoking status, histological subtypes, and survival information were analyzed.

RESULT

KRAS mutation was detected in 113 of 1,368 patients. Nine different subtypes of KRAS mutation were identified in codon 12, codon 13, and codon 61. KRAS mutation was more frequently found in male patients and former/current smoker patients. Tumors with KRAS mutation had poorer differentiation. Invasive mucinous adenocarcinoma predominant and solid predominant subtypes were more frequent in KRAS mutant patients. No statistical significance was found in relapse-free survival or overall survival between patients with KRAS mutation and patients with other mutations.

CONCLUSION

In Chinese populations, we identified KRAS mutation in 8.3% (113/1,368) of the patients with lung adenocarcinoma. KRAS mutation defines a molecular subset of lung adenocarcinoma with unique clinicopathological features.

Poor response to platinum-based chemotherapy is associated with KRAS mutation and concomitant low expression of BRAC1 and TYMS in NSCLC

Objective

To evaluate treatment response, survival, and the associations between KRAS mutation status and tumour expression levels of BRCA1, TYMS and SRC retrospectively in a cohort of patients with non-small cell lung cancer (NSCLC), treated exclusively with conjunctive platinum-based doublet chemotherapy.

Methods

KRAS mutation status was determined via amplification refractory mutation and multiple quantitative polymerase chain reaction (PCR) analysis. Tumour expression levels of BRCA1, TYMS and SRC were determined via real time quantitative PCR.

Results

Patients with KRAS mutations (n = 3) had significantly shorter survival duration than patients with wild type KRAS (n = 42). Tumour expression levels of BRCA1 and TYMS, but not SRC, were significantly lower in patients with, than in those without, KRAS mutations. Tumour expression level of BRCA1 was positively correlated with survival duration.

Conclusions

KRAS mutation status and BRCA1 tumour expression are potential biomarkers for tailoring chemotherapy and predicting clinical outcome.

Elderly male smokers with right lung tumors are viable candidates for KRAS mutation screening

Genetic aberrations in tumor driver genes provide specific molecular targets for therapeutic intervention, which can greatly improve therapeutic outcomes. Here, we analyzed the mutational frequency of EGFR and KRAS gene, as well as EML4-ALK rearrangement, and summarized the clinicopathological characters of Chinese lung cancer patients. We detected the mutation spectrum of 1033 primary lung cancer patients. The analyzed clinicopathological parameters included gender, age at diagnosis, smoking status, pathological TNM stage, tumor morphology and location, visceral pleural invasion, and histological type. A total of 618 patients had mutations in EGFR or KRAS gene as well as rearrangement of EML4-ALK. Exon 19 deletions and L858R in the EGFR gene were the most frequent mutations. Left-side lung cancer was more common in female patients carrying the KRAS mutation. Rearrangement of EML4-ALK was more common in non-tobacco-using male patients, who also exhibited a higher likelihood of visceral pleura invasion. Elderly females who never smoked and possessed 1–20 mm stage I adenocarcinomas in the right side exhibited a higher frequency of EGFR mutations. Elderly male smokers with right lung tumors were viable candidates for KRAS mutation screening.

Glycoproteomic Approach Identifies KRAS as a Positive Regulator of CREG1 in Non-small Cell Lung Cancer Cells

Protein glycosylation plays a fundamental role in a multitude of biological processes, and the associated aberrant expression of glycoproteins in cancer has made them attractive biomarkers and therapeutic targets. In this study, we examined differentially expressed glycoproteins in cell lines derived from three different states of lung tumorigenesis: an immortalized bronchial epithelial cell (HBE) line, a non-small cell lung cancer (NSCLC) cell line harboring a Kirsten rat sarcoma viral oncogene homolog (KRAS) activation mutation and a NSCLC cell line harboring an epidermal growth factor receptor (EGFR) activation deletion. Using a Triple SILAC proteomic quantification strategy paired with hydrazide chemistry N-linked glycopeptide enrichment, we quantified 118 glycopeptides in the three cell lines derived from 82 glycoproteins. Proteomic profiling revealed 27 glycopeptides overexpressed in both NSCLC cell lines, 6 glycopeptides overexpressed only in the EGFR mutant cells and 19 glycopeptides overexpressed only in the KRAS mutant cells. Further investigation of a panel of NSCLC cell lines found that Cellular repressor of E1A-stimulated genes (CREG1) overexpression was closely correlated with KRAS mutation status in NSCLC cells and could be down-regulated by inhibition of KRAS expression. Our results indicate that CREG1 is a down-stream effector of KRAS in a sub-type of NSCLC cells and a novel candidate biomarker or therapeutic target for KRAS mutant NSCLC.

Targeting KRAS-mutant non-small cell lung cancer: challenges and opportunities

Oncogenic mutations in Kirsten rat sarcoma viral oncogene homolog (KRAS) occur in 15%-30% of non-small cell lung cancer (NSCLC). However, despite decades of intensive research, there is still no direct KRAS inhibitor with clinically proven efficacy. Considering its association with poor treatment response and prognosis of lung cancer, developing an effective inhibitory approach is urgently needed. Here, we review different strategies currently being explored to target KRAS-mutant NSCLC, discuss opportunities and challenges, and also propose some novel methods and concepts with the promise of clinical application.

Study Design and Rationale for a Randomized, Placebo-Controlled, Double-Blind Study to Assess the Efficacy and Safety of Selumetinib in Combination With Docetaxel as Second-Line Treatment in Patients With KRAS-Mutant Advanced Non-Small Cell Lung Cancer (SELECT-1)

BACKGROUND

Oncogenic KRAS mutations represent the largest genomically defined subset of lung cancer, and are associated with activation of the RAS/RAF/MEK/ERK pathway. There are currently no therapies specifically approved for patients with KRAS-mutant (KRASm) non-small-cell lung cancer (NSCLC), and these patients derive less clinical benefit from chemotherapy than the overall NSCLC population. In a recent phase II study, selumetinib (AZD6244, ARRY-142886), an oral, potent and selective, allosteric MEK1/2 inhibitor with a short half-life, combined with docetaxel, improved clinical outcome as second-line treatment for patients with KRASm NSCLC. This combination will be further evaluated in the phase III SELECT-1 study.

PATIENTS AND METHODS

SELECT-1 (NCT01933932) is a randomized, double-blind, placebo-controlled phase III study assessing the efficacy and safety of selumetinib plus docetaxel in patients with KRASm locally advanced or metastatic NSCLC, eligible for second-line treatment. The primary endpoint is progression-free survival (PFS); secondary endpoints include overall survival, objective response rate, duration of response, and safety and tolerability. Approximately 634 patients will be randomized 1:1 to receive selumetinib (75 mg twice daily on a continuous oral administration schedule) in combination with docetaxel (75 mg/m(2), intravenously on day 1 of every 21-day cycle) or placebo in combination with docetaxel (same schedule), until objective disease progression. Patients may continue to receive treatment after objective disease progression if deemed appropriate by the investigator.

CONCLUSIONS

If the primary endpoint of PFS is met, selumetinib plus docetaxel would be the first targeted treatment for patients with KRASm advanced NSCLC who are eligible for second-line treatment.

Biomarkers in early-stage non-small-cell lung cancer: current concepts and future directions

Advances in molecular biology and bioinformatics have resulted in the identification of a number of potential biomarkers that could be relevant in the management of patients with non-small-cell lung cancer (NSCLC). Although there is an increasing amount of literature related to these biomarkers, major issues need to be resolved including validity and reproducibility of results. Additionally, in order to interpret the existing literature accurately, a clear distinction must be made between the prognostic and predictive value of biomarkers. The practical applicability of biomarker discovery for patients with lung cancer includes the identification of patients with early-stage NSCLC who are most likely to benefit from adjuvant therapy. Information gleaned from biomarkers has the potential to help in evaluating the role of targeted therapies including immunotherapy in the neoadjuvant and adjuvant setting. The role of gene signatures and the use of newer platforms such as RNA, methylation, and protein signatures is being explored in patients with early-stage NSCLC. This review focuses on the applications of biomarker discovery in patients with early-stage NSCLC.

Randomized Trial of Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration With and Without Rapid On-site Evaluation for Lung Cancer Genotyping

BACKGROUND

Experts and scientific society guidelines recommend that rapid on-site evaluation (ROSE) be used with endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) to optimize lung cancer genotyping, but no comparative trial has been carried out to confirm and quantify its usefulness.

METHODS

To assess the influence of ROSE on the yield of EBUS-TBNA for a multigene molecular analysis of lung cancer samples, consecutive patients with suspected or known advanced lung cancer were randomized to undergo EBUS-TBNA without ROSE (EBUS arm) or with ROSE (ROSE arm). The primary end point was the rate of the successful accomplishment of the institution's clinical protocol for molecular profiling of nonsquamous non-small cell lung cancer (EGFR and KRAS testing, followed by ALK testing for tumors with EGFR and KRAS wild-type status).

RESULTS

Complete genotyping was achieved in 108 of 126 patients (85.7%) (90.8% in the ROSE arm vs 80.3% in the EBUS arm, P = .09). The patients in the ROSE arm were less likely to have samples that could be used only for pathologic diagnosis because of minimal tumor burden (0 vs 6, P = .05), and were more likely to have the bronchoscopy terminated after a single biopsy site (58.9% vs 44.1%, P = .01).

CONCLUSIONS

ROSE prevents the need for a repeat invasive diagnostic procedure aimed at molecular profiling in at least one out of 10 patients with advanced lung cancer and significantly reduces the risk of retrieving samples that can be used only for pathologic subtyping because of minimal tumor burden.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01799382; URL: www.clinicaltrials.gov.

Chronic Obstructive Pulmonary Disease-Related Non-Small-Cell Lung Cancer Exhibits a Low Prevalence of EGFR and ALK Driver Mutations

Lung cancer and chronic obstructive pulmonary disease (COPD) are two major lung diseases. Epidermal growth factor receptor (EGFR) mutations, v-Ki-ras2 Kirsten rat sarcoma (KRAS) mutations and anaplastic lymphoma kinase (ALK) gene rearrangements represent driver mutations that are frequently assessed on initial evaluation of non-small-cell lung cancer (NSCLC). The present study focused on the expression of driver mutations in NSCLC patients presenting with COPD and further evaluated the association between NSCLC and COPD. Data from 501 consecutive patients with histologically proven recurrent or metastatic NSCLC were analyzed retrospectively. The patients underwent spirometry and genotyping of EGFR, ALK, and KRAS in tissue samples. Patient characteristics and expression of driver mutations were compared between the COPD and non-COPD groups. Among 350 patients with spirometric results, 106 (30.3%) were diagnosed with COPD, 108 (30.9%) had EGFR mutations, 31 (8.9%) had KRAS mutations, and 34 (9.7%) showed ALK rearrangements. COPD was independently associated with lower prevalences of EGFR mutations (95% confidence interval [CI], 0.254-0.931, p = 0.029) and ALK rearrangements (95% CI, 0.065-0.600, p = 0.004). The proportions of EGFR mutations and ALK rearrangements decreased as the severity of airflow obstruction increased (p = 0.001). In never smokers, the prevalence of EGFR mutations was significantly lower in the COPD group than in the non-COPD group (12.7% vs. 49.0%, p = 0.002). COPD-related NSCLC patients exhibited low prevalences of EGFR mutations and ALK rearrangements compared with the non-COPD group. Further studies are required regarding the molecular mechanisms underlying lung cancer associated with COPD.

[KRAS and bronchial adenocarcinoma. Between disappointments and hopes]

A better understanding of oncogenesis and the development of targeted therapies have led to improved outcomes in the treatment of lung cancer. KRAS mutation has the potential to drive the oncogenesis of almost one third of lung adenocarcinomas but it leads to a highly complex proliferation signal involving multiple signaling pathways, explaining the disappointing results of various inhibition strategies of K-ras or its effectors. Nevertheless, recent data suggest different roles of distinct KRAS mutation subtypes and KRAS interactions with new genes in the field of synthetic lethality mechanisms open the way to new therapeutic possibilities. This review aims to provide an overview of: 1) epidemiological data and particularly the prognostic impact of KRAS mutations in non-small cell lung cancer, 2) the results of different drugs either being tested in humans or sources of hope.

siRNA delivered by EGFR-specific scFv sensitizes EGFR-TKI-resistant human lung cancer cells

The overexpression of epidermal growth factor receptor (EGFR) is closely associated with a poor outcome in non-small cell lung cancer (NSCLC), and EGFR is an ideal biomarker for the targeted therapy of NSCLC. Although patients with EGFR-activating mutations respond to EGFR tyrosine kinase inhibitors (EGFR-TKIs), they eventually acquire resistance, which typically results from a secondary EGFR mutation or the activation of other signaling pathways. Novel approaches to overcome or prevent EGFR-TKI resistance are clinically important. In this study, we developed an EGFR-scFv-arginine nonamer peptide fusion protein, s-9R, as an siRNA carrier. Here, we show that s-9R effectively and specifically delivers EGFR-siRNAs, KRAS-siRNA and MET-siRNA into NSCLC cells and silences the expression of target genes. The sensitivity of NSCLC cells to gefitinib was restored after treatment with the s-9R/siRNA complex, and the apoptosis rates of the treated cells were significantly higher than those of the control groups. Furthermore, the co-administration of s-9R/siRNA and gefitinib successfully suppressed the progression of H1975 xenograft tumors and extended the life span of tumor-bearing nude mice. Collectively, the results of this study provide not only a new scFv derivative for delivering siRNA into EGFR-overexpressing, TKI-resistant NSCLC cells but also a novel method for overcoming TKI resistance.

MAP3K8/TPL-2/COT is a potential predictive marker for MEK inhibitor treatment in high-grade serous ovarian carcinomas

Ovarian cancer is a silent disease with a poor prognosis that urgently requires new therapeutic strategies. In low-grade ovarian tumours, mutations in the MAP3K BRAF gene constitutively activate the downstream kinase MEK. Here we demonstrate that an additional MAP3K, MAP3K8 (TPL-2/COT), accumulates in high-grade serous ovarian carcinomas (HGSCs) and is a potential prognostic marker for these tumours. By combining analyses on HGSC patient cohorts, ovarian cancer cells and patient-derived xenografts, we demonstrate that MAP3K8 controls cancer cell proliferation and migration by regulating key players in G1/S transition and adhesion dynamics. In addition, we show that the MEK pathway is the main pathway involved in mediating MAP3K8 function, and that MAP3K8 exhibits a reliable predictive value for the effectiveness of MEK inhibitor treatment. Our data highlight key roles for MAP3K8 in HGSC and indicate that MEK inhibitors could be a useful treatment strategy, in combination with conventional chemotherapy, for this disease.

Base excision repair-mediated resistance to cisplatin in KRAS(G12C) mutant NSCLC cells

KRAS mutations in NSCLC are supposed to indicate a poor prognosis and poor response to anticancer treatments but this feature lacks a mechanistic basis so far. In tumors, KRAS was found to be mutated mostly at codons 12 and 13 and a pool of mutations differing in the base alteration and the amino acid substitution have been described. The different KRAS mutations may differently impact on cancerogenesis and drug sensitivity. On this basis, we hypothesized that a different KRAS mutational status in NSCLC patients determines a different profile in the tumor response to treatments. In this paper, isogenic NSCLC cell clones expressing mutated forms of KRAS were used to determine the response to cisplatin, the main drug used in the clinic against NSCLC. Cells expressing the KRAS(G12C) mutation were found to be less sensitive to treatment both in vitro and in vivo. Systematic analysis of drug uptake, DNA adduct formation and DNA damage responses implicated in cisplatin adducts removal revealed that the KRAS(G12C) mutation might be particular because it stimulates Base Excision Repair to rapidly remove platinum from DNA even before the formation of cross-links. The presented results suggest a different pattern of sensitivity/resistance to cisplatin depending on the KRAS mutational status and these data might provide proof of principle for further investigations on the role of the KRAS status as a predictor of NSCLC response.

Lung Cancer Onset in Wild Type Mice Following Bone Marrow Reconstitution with kras(v12) Cells

A role for bone-marrow-derived cells (BMDCs) in tissue repair and malignancy onset has been proposed, but their contribution is still debated. We tested the ability of BMDCs containing the inducible kras^V12 oncogene to initiate lung adenocarcinoma. For our experimental strategy, we reconstituted lethally irradiated wild type mice with BMDCs carrying inducible kras^V12 and subsequently induced oncogene expression by 4-OHT administration. Epithelial lung lesions, from adenoma to adenocarcinomas, appeared at successive time points. These results show that lung tumors were derived from donor BMDCs and indicate a direct involvement of bone marrow cells in the development of epithelial cancers.

Outcomes of patients with advanced cancer and KRAS mutations in phase I clinical trials

Background

KRAS mutation is common in human cancer. We assessed the clinical factors, including type of KRAS mutation and treatment, of patients with advanced cancer and tumor KRAS mutations and their association with treatment outcomes.

Methods

Patients referred to the Phase I Clinic for treatment who underwent testing for KRAS mutations were analyzed.

Results

Of 1,781 patients, 365 (21%) had a KRAS mutation. The G12D mutation was the most common mutation (29%). PIK3CA mutations were found in 24% and 10% of patients with and without KRAS mutations (p<0.0001). Of 223 patients with a KRAS mutation who were evaluable for response, 56 were treated with a MEK inhibitor-containing therapy and 167 with other therapies. The clinical benefit (partial response and stable disease lasting ≥ 6 months) rates were 23% and 9%, respectively, for the MEK inhibitor versus other therapies (p=0.005). The median progression-free survival (PFS) was 3.3 and 2.2 months, respectively (p=0.09). The respective median overall survival was 8.4 and 7.0 months (p=0.38). Of 66 patients with a KRAS mutation and additional alterations, higher rates of clinical benefit (p=0.04), PFS (p=0.045), and overall survival (p=0.02) were noted in patients treated with MEK inhibitor-containing therapy (n=9) compared to those treated with targeted therapy matched to the additional alterations (n=24) or other therapy (n=33).

Conclusions

MEK inhibitors in patients with KRAS-mutated advanced cancer were associated with higher clinical benefit rates compared to other therapies. Therapeutic strategies that include MEK inhibitors or novel agents combined with other targeted therapies or chemotherapy need further investigation.

Should KRAS mutation still be used as a routine predictor of response to EGFR-TKIs in advanced non-small-cell lung cancer? A revaluation based on meta-analysis

PURPOSE

Regarding the controversial investigations characterizing the role of KRAS status for predicting patients' response to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in advanced non-small-cell lung cancer (NSCLC), we conducted a meta-analysis in unselected patients and a further subset analysis in EGFR wild-type advanced NSCLC to get a more accurate evaluation.

METHODS

We did systematically searches following the retrieval strategies. The end points were overall survival (OS), progression-free survival (PFS), and overall response rate (ORR).

RESULTS

Twelve prospective intervention trials comprised of 1,859 unselected advanced NSCLC patients were identified. KRAS mutation was associated with shorter OS and PFS [hazard ratio (HR) 2.09, 95 % confidence interval (CI) 1.56-2.80; HR 1.82, 95 % CI 1.50-2.20] and lower ORR (relative ratio 0.25, 95 % CI 0.11-0.59) in unselected advanced NSCLC. After subgroup analysis, the association with survival was strengthened in second- or later-line EGFR-TKIs treatment group, with an HR of 2.45 for OS (95 % CI 1.27-4.74) and 1.86 for PFS (95 % CI 1.51-2.29), while the association with response to EGFR-TKIs became nonsignificant (P = 0.153). Four retrospective studies on the role of KRAS status in EGFR wild-type advanced NSCLC were deemed eligible and presented that KRAS mutation was associated with none of the outcomes in EGFR wild-type patients treated with EGFR-TKIs.

CONCLUSIONS

In unselected advanced NSCLC patients, KRAS mutations could be used as a potential negative predictor of clinical benefit from EGFR-TKIs. However, KRAS testing is of limited value to identify patients for EGFR-TKIs when EGFR status is considered.

Precise Classification of Cervical Carcinomas Combined with Somatic Mutation Profiling Contributes to Predicting Disease Outcome

Introduction

Squamous cell carcinoma (SCC), adenocarcinoma (AC), and adenosquamous carcinoma (ASC) are the most common histological subtypes of cervical cancer. Differences in the somatic mutation profiles of these subtypes have been suggested. We investigated the prevalence of somatic hot-spot mutations in three well-defined cohorts of SCC, AC, and ASC and determined the additional value of mutation profiling in predicting disease outcome relative to well-established prognostic parameters.

Materials and Methods

Clinicopathological data were collected for 301 cervical tumors classified as SCC (n=166), AC (n=55), or ASC (n=80). Mass spectrometry was used to analyze 171 somatic hot-spot mutations in 13 relevant genes.

Results

In 103 (34%) tumors, 123 mutations were detected (36% in SCC, 38% in AC, and 28% in ASC), mostly in PIK3CA (20%) and KRAS (7%). PIK3CA mutations occurred more frequently in SCC than AC (25% vs. 11%, P=0.025), whereas KRAS mutations occurred more frequently in AC than SCC (24% vs. 3%, P<0.001) and ASC (24% vs. 3%, P<0.001). A positive mutation status correlated with worse disease-free survival (HR 1.57, P=0.043). In multivariate analysis, tumor diameter, parametrial infiltration, and lymph node metastasis, but not the presence of a somatic mutation, were independent predictors of survival.

Conclusion

Potentially targetable somatic mutations occurred in 34% of cervical tumors with different distributions among histological subtypes. Precise classification of cervical carcinomas in combination with mutation profiling is valuable for predicting disease outcome and may guide the development and selection of tumor-specific treatment approaches.

Clinical outcome of epidermal growth factor receptor-tyrosine kinase inhibitors therapy for patients with overlapping kirsten rat sarcoma 2 viral oncogene homolog and epidermal growth factor receptor gene mutations

Background

Kirsten rat sarcoma 2 viral oncogene homolog (KRAS) is the second most common mutated gene following epidermal growth factor receptor (EGFR) mutation in Chinese lung adenocarcinoma (LADC) patients. Investigating the clinical characteristics and outcomes of patients with co‐existing KRAS and EGFR mutations can provide significant information for suitable therapies.

Methods

We retrospectively investigated 2106 LADC patients who had undergone EGFR and KRAS mutation tests at the Peking University Cancer Hospital. Only advanced LADC patients who carried KRAS and/or EGFR mutations, received EGFR‐tyrosine kinase inhibitors (TKIs) and/or chemotherapy, and had completed follow‐up analysis were analyzed further. KRAS and EGFR mutations were tested by denaturing high‐performance liquid chromatography.

Results

A KRAS mutation was detected in 123 out of 2106 LADC patients (5.8%) and 38 (1.8%) had a concurrent EGFR mutation. Seventy‐two of 123 patients were advanced cases, which were divided into two sub‐groups according to EGFR mutation status: overlapping KRAS and EGFR mutations (n = 24) and KRAS mutation alone (n = 48). Clinical characteristics of the two subgroups were similar. A greater ratio of patients with double mutations received EGFR‐TKIs compared to KRAS mutation alone (75% vs. 43.8%, P = 0.012), and obtained a better objective response rate (38.9% vs. 9.5%, P = 0.027) and longer progression‐free survival (8.0 vs. 1.5 months, P = 0.028) following EGFR‐TKIs therapy. However, these differences were not observed in patients treated with platinum‐based chemotherapy.

Conclusions

Overlapping KRAS and EGFR mutations occurred in 1.8% of Chinese LADC patients studied. The co‐presence of EGFR mutations could predict a clinical benefit from EGFR‐TKIs treatment for patients with KRAS mutations.

Bone Metastases and the EGFR and KRAS Mutation Status in Lung Adenocarcinoma--The Results of Three Year Retrospective Analysis

Lung cancer is a heterogeneous group of disease and mutational profiling of lung adenocarcinomas is a routine practice in thoracic oncology. Kirsten-RAS (KRAS) and EGFR mutations play an important role in the carcinogenesis of a subset of lung adenocarcinomas. Our aim was to investigate the correlation between bone metastases and EGFR and KRAS mutation status in lung adenocarcinoma patients. Retrospectively we analysed 224 patients with recurrent or metastatic lung adenocarcinomas. Patients were treated with standard chemotherapy as first line therapy and with EGFR-TK inhibitors as a second or third line therapy. 72 of 224 patients (32 %) had verified bone metastases. Bone metastases and Skeletal Related Events (SRE) were more frequent in men, heavy smokers and without treatment of EGFR TK inhibitors. We have found that EGFR and KRAS mutation status are both predictive factors for the treatment efficacy and prognostic factors for the disease progression. However there were no significant correlation between mutation status and the presence of bone metastases (P = 0, 59). In our study the presence of bone metastases proved to be an independent prognostic factor related to poor performance status and worse Quality of Life (QL).

Unexpected oncosuppressive role for STAT3 in KRAS-induced lung tumorigenesis

Signal transducer and activator of transcription 3 (STAT3) plays a critical role in the pathogenesis of several diseases and is considered a therapeutic target in solid cancers, including lung cancer. However, we recently demonstrated a tumor suppressive function of STAT3 in kirsten rat sarcoma oncogene homolog (KRAS)-driven lung cancer. Here, we discuss these findings and their consequences.

Correlation between topoisomerase I and tyrosyl-DNA phosphodiesterase 1 activities in non-small cell lung cancer tissue

Topoisomerase I (TOP1) regulates DNA topology during replication and transcription whereas tyrosyl-DNA phosphodiesterase 1 (TDP1) is involved in the repair of several types of DNA damages, including damages from defective TOP1 catalysis. TOP1 is the target of chemotherapeutic drugs of the camptothecin family (CPT). TDP1 has in cell line based assays been shown to counteract the effect of CPT. We have quantified the enzymatic activities of TOP1 and TDP1 in paired (tumor and adjacent non-tumor) samples from non-small cell lung cancer (NSCLC) patients and show that in NSCLC TOP1 and TDP1 activities are significantly upregulated in the tumor tissue. Furthermore, we found a positive correlation between the TDP1 activity and the tumor percentage (TOP1 activity did not correlate with the tumor percentage) as well as between the activities of TOP1 and TDP1 both within the tumor and the non-tumor group. That TDP1 activity was upregulated in all tumor samples and correlated with the tumor percentage suggest that it must play a highly important function in NSCLC. This could be to protect against TOP1 mediated DNA damage as the activity of TOP1 likewise was upregulated in the majority of tumor samples and correlated positively to the TDP1 activity. Regardless, the finding that the TOP1 and TDP1 activities are upregulated and correlate positively suggests that combinatorial treatment targeting both activities could be advantageous in NSCLC.

Integrative analysis of gene expression in response to low-dose ionizing radiation in a human skin model

The advance in medical imaging and utilization has raised the concern about exposure to low-dose ionizing radiation (LDIR). Cellular and molecular responses to high-dose ionizing radiation have been characterized, but in the range of low dose, these responses are poorly understood. Here, we investigate the gene expression in response to LDIR (10 cGy) in the EpiDermFT human skin model. We identified 3299 differentially expressed genes (DEGs) in response to LDIR. Among these DEGs, we noted several well-characterized long noncoding RNAs. Gene Ontology and KEGG pathway analysis were performed to detect altered molecular response. GO and KEGG pathway results showed that genes corresponding to "regulation of cell proliferation" were enriched. Gene set enrichment analysis showed that KRAS signaling pathway was enriched in response to LDIR and transcription targets of NF-κB were also enriched when exposed to LDIR.

Expanding antitumor therapeutic windows by targeting cancer-specific nicotinamide adenine dinucleotide phosphate-biogenesis pathways

Nicotinamide adenine dinucleotide phosphate (NADPH) biogenesis is an essential mechanism by which both normal and cancer cells maintain redox balance. While antitumor approaches to treat cancers through elevated reactive oxygen species (ROS) are not new ideas, depleting specific NADPH-biogenesis pathways that control recovery and repair pathways are novel, viable approaches to enhance cancer therapy. However, to elicit efficacious therapies exploiting NADPH-biogenic pathways, it is crucial to understand and specifically define the roles of NADPH-biogenesis pathways used by cancer cells for survival or recovery from cell stress. It is equally important to select NADPH-biogenic pathways that are expendable or not utilized in normal tissue to avoid unwanted toxicity. Here, we address recent literature that demonstrates specific tumor-selective NADPH-biogenesis pathways that can be exploited using agents that target specific cancer cell pathways normally not utilized in normal cells. Defining NADPH-biogenesis profiles of specific cancer-types should enable novel strategies to exploit these therapeutic windows for increased efficacy against recalcitrant neoplastic disease, such as pancreatic cancers. Accomplishing the goal of using ROS as a weapon against cancer cells will also require agents, such as NQO1 bioactivatable drugs, that selectively induce elevated ROS levels in cancer cells, while normal cells are protected.

CDK2 Inhibition Causes Anaphase Catastrophe in Lung Cancer through the Centrosomal Protein CP110

Aneuploidy is frequently detected in human cancers and is implicated in carcinogenesis. Pharmacologic targeting of aneuploidy is an attractive therapeutic strategy, as this would preferentially eliminate malignant over normal cells. We previously discovered that CDK2 inhibition causes lung cancer cells with more than two centrosomes to undergo multipolar cell division leading to apoptosis, defined as anaphase catastrophe. Cells with activating KRAS mutations were especially sensitive to CDK2 inhibition. Mechanisms of CDK2-mediated anaphase catastrophe and how activated KRAS enhances this effect were investigated. Live-cell imaging provided direct evidence that following CDK2 inhibition, lung cancer cells develop multipolar anaphase and undergo multipolar cell division with the resulting progeny apoptotic. The siRNA-mediated repression of the CDK2 target and centrosome protein CP110 induced anaphase catastrophe of lung cancer cells. In contrast, CP110 overexpression antagonized CDK2 inhibitor-mediated anaphase catastrophe. Furthermore, activated KRAS mutations sensitized lung cancer cells to CDK2 inhibition by deregulating CP110 expression. Thus, CP110 is a critical mediator of CDK2 inhibition-driven anaphase catastrophe. Independent examination of murine and human paired normal-malignant lung tissues revealed marked upregulation of CP110 in malignant versus normal lung. Human lung cancers with KRAS mutations had significantly lower CP110 expression as compared with KRAS wild-type cancers. Thus, a direct link was found between CP110 and CDK2 inhibitor antineoplastic response. CP110 plays a mechanistic role in response of lung cancer cells to CDK2 inhibition, especially in the presence of activated KRAS mutations.

Targeted therapies for small cell lung cancer: Where do we stand?

Small cell lung cancer (SCLC) accounts for 15% of lung cancer cases and is associated with a dismal prognosis. Standard therapeutic regimens have been improved over the past decades, but without a major impact on patient survival. The development of targeted therapies based on a better understanding of the molecular basis of the disease is urgently needed. At the genetic level, SCLC appears very heterogenous, although somatic mutations targeting classical oncogenes and tumor suppressors have been reported. SCLC also possesses somatic mutations in many other cancer genes, including transcription factors, enzymes involved in chromatin modification, receptor tyrosine kinases and their downstream signaling components. Several avenues have been explored to develop targeted therapies for SCLC. So far, however, there has been limited success with these targeted approaches in clinical trials. Further progress in the optimization of targeted therapies for SCLC will require the development of more personalized approaches for the patients.

Disruption of STAT3 signalling promotes KRAS-induced lung tumorigenesis

STAT3 is considered to play an oncogenic role in several malignancies including lung cancer; consequently, targeting STAT3 is currently proposed as therapeutic intervention. Here we demonstrate that STAT3 plays an unexpected tumour-suppressive role in KRAS mutant lung adenocarcinoma (AC). Indeed, lung tissue-specific inactivation of Stat3 in mice results in increased Kras^G12D-driven AC initiation and malignant progression leading to markedly reduced survival. Knockdown of STAT3 in xenografted human AC cells increases tumour growth. Clinically, low STAT3 expression levels correlate with poor survival and advanced malignancy in human lung AC patients with smoking history, which are prone to KRAS mutations. Consistently, KRAS mutant lung tumours exhibit reduced STAT3 levels. Mechanistically, we demonstrate that STAT3 controls NF-κB-induced IL-8 expression by sequestering NF-κB within the cytoplasm, thereby inhibiting IL-8-mediated myeloid tumour infiltration and tumour vascularization and hence tumour progression. These results elucidate a novel STAT3–NF-κB–IL-8 axis in KRAS mutant AC with therapeutic and prognostic relevance.

STAT3 is an intracellular transducer of cytokine signals that cooperates with Ras in tumour formation and is often activated in lung cancer. Here the authors show that STAT3 acts as a tumour suppressor in a mouse model of Kras-driven lung adenocarcinoma.

The RAS-RAL axis in cancer: evidence for mutation-specific selectivity in non-small cell lung cancer

Activating RAS mutations are common in human tumors. These mutations are often markers for resistance to therapy and subsequent poor prognosis. So far, targeting the RAF-MEK-ERK and PI3K-AKT signaling pathways downstream of RAS is the only promising approach in the treatment of cancer patients harboring RAS mutations. RAL GTPase, another downstream effector of RAS, is also considered as a therapeutic option for the treatment of RAS-mutant cancers. The RAL GTPase family comprises RALA and RALB, which can have either divergent or similar functions in different tumor models. Recent studies on non-small cell lung cancer (NSCLC) have showed that different RAS mutations selectively activate specific effector pathways. This observation requires broader validation in other tumor tissue types, but if true, will provide a new approach to the treatment of RAS-mutant cancer patients by targeting specific downstream RAS effectors according to the type of RAS mutation. It also suggests that RAL GTPase inhibition will be an important treatment strategy for tumors harboring RAS glycine to cysteine (G12C) or glycien to valine (G12V) mutations, which are commonly found in NSCLC and pancreatic cancer.

Feasibility and accuracy of molecular testing in specimens obtained with small biopsy forceps: comparison with the results of surgical specimens

BACKGROUND

During bronchoscopy, small biopsy forceps are increasingly used for the diagnosis of peripheral pulmonary lesions. However, it is unclear whether the formalin-fixed paraffin-embedded specimens sampled with the small biopsy forceps are suitable for the determination of genotypes which become indispensable for the management decision regarding patients with non-small cell lung cancer.

OBJECTIVES

The aim of this study was to evaluate the feasibility and accuracy of molecular testing in the specimens obtained with 1.5-mm small biopsy forceps.

METHODS

We examined specimens in 91 patients, who were enrolled in our previous 3 studies on the usefulness of thin bronchoscopes and given a diagnosis of non-small cell lung cancer by bronchoscopy with the 1.5-mm biopsy forceps, and then underwent surgical resection. An experienced pathologist examined paraffin-embedded specimens obtained by bronchoscopic biopsy or surgical resection in a blind fashion on epidermal growth factor receptor (EGFR) mutations, anaplastic lymphoma kinase (ALK) rearrangements and KRAS mutations.

RESULTS

Twenty-five (27%), 2 (2%) and 5 (5%) patients had an EGFR mutation, ALK rearrangement and KRAS mutation, respectively, based on the results in surgical specimens. EGFR, ALK and KRAS testing with bronchoscopic specimens was feasible in 82 (90%), 86 (95%) and 83 (91%) patients, respectively. If molecular testing was feasible, the accuracy of EGFR, ALK and KRAS testing with bronchoscopic specimens for the results with surgical specimens was 98, 100 and 98%, respectively.

CONCLUSION

The results of molecular testing in the formalin-fixed paraffin-embedded specimens obtained with the small forceps, in which the genotype could be evaluated, correlated well with those in surgically resected specimens.