Oncogene-driven Non-small Cell Lung Cancer Research Articles

Advances in Molecular Biology of Lung Disease: Aiming for Precision Therapy in Non-small Cell Lung Cancer

Lung cancer is the principal cause of cancer-related mortality in the developed world, accounting for almost one-quarter of all cancer deaths. Traditional treatment algorithms have largely relied on histologic subtype and have comprised pragmatic chemotherapy regimens with limited efficacy. However, because our understanding of the molecular basis of disease in non-small cell lung cancer (NSCLC) has improved exponentially, it has become apparent that NSCLC can be radically subdivided, or molecularly characterized, based on recurrent driver mutations occurring in specific oncogenes. We know that the presence of such mutations leads to constitutive activation of aberrant signaling proteins that initiate, progress, and sustain tumorigenesis. This persistence of the malignant phenotype is referred to as "oncogene addiction." On this basis, a paradigm shift in treatment approach has occurred. Rational, targeted therapies have been developed, the first being tyrosine kinase inhibitors (TKIs), which entered the clinical arena > 10 years ago. These were tremendously successful, significantly affecting the natural history of NSCLC and improving patient outcomes. However, the benefits of these drugs are somewhat limited by the emergence of adaptive resistance mechanisms, and efforts to tackle this phenomenon are ongoing. A better understanding of all types of oncogene-driven NSCLC and the occurrence of TKI resistance will help us to further develop second- and third-generation small molecule inhibitors and will expand our range of precision therapies for this disease.

Brain metastases in patients with EGFR-mutated or ALK-rearranged non-small-cell lung cancers.

Brain metastases (BM) are common in non-small-cell lung cancer (NSCLC). However, the baseline incidence and evolution of BM over time in oncogene-driven NSCLCs are seldom reported. In this study, we evaluated the frequency of BM in patients with epidermal growth factor receptor (EGFR)-mutated or anaplastic lymphoma kinase (ALK)-rearranged NSCLC. The presence of BM, clinicopathologic data, and tumor genotype were retrospectively compiled and analyzed from a cohort of 381 patients. We identified 86 EGFR-mutated (90.7% with metastatic disease; 85.9% received an EGFR inhibitor) and 23 ALK-rearranged (91.3% with metastatic disease; 85.7% received an ALK inhibitor) NSCLCs. BM were present in 24.4% of EGFR-mutated and 23.8% of ALK-rearranged NSCLCs at the time of diagnosis of advanced disease. This study did not demonstrate a difference in the cumulative incidence of BM over time between the two cohorts (EGFR/ALK cohort competing risk regression [CRR] coefficient of 0.78 [95% CI 0.44-1.39], p=0.41). In still living patients with advanced EGFR-mutated NSCLC, 34.2% had BM at 1 year, 38.4% at 2 years, 46.7% at 3 years, 48.7% at 4 years, and 52.9% at 5 years. In still living patients with advanced ALK-rearranged NSCLC, 23.8% had BM at 1 year, 45.5% at 2 years, and 58.4% at 3 years. BM are frequent in advanced EGFR-mutated or ALK-rearranged NSCLCs, with an estimated >45% of patients with CNS involvement by three years of survival with the use of targeted therapies. These data point toward the CNS as an important unmet clinical need in the evolving schema for personalized care in NSCLC.

Management and future directions in non-small cell lung cancer with known activating mutations.

Lung cancer accounts for a quarter of all cancer deaths. Non-small cell lung cancer (NSCLC) is currently segregated by the presence of actionable driver oncogenes. This review will provide an overview of molecular subsets of lung cancer, including descriptions of the defining oncogenes (EGFR, ALK, KRAS, ROS1, RET, BRAF, ERBB2, NTRK1, FGFR, among others) and how these predict for response to small molecule tyrosine kinase inhibitors (TKIs) that are either clinically available or in clinical trial development for advanced NSCLC. Particular focus will be placed on subsets with EGFR mutated and ALK rearranged NSCLC. Somatic TKI-sensitizing EGFR mutations (such as exon 19 deletions and L858R substitutions) are the most robust predictive biomarker for symptom improvement, radiographic response, and increment in progression-free survival (PFS) when EGFR TKIs (gefitinib, erlotinib, and afatinib) are used for patients with advanced NSCLC. However, the palliative benefits that EGFR TKIs afford are limited by multiple biologic mechanisms of tumor adaptation/resistance (such as the EGFR-T790M mutation and oncogene bypass tracks), and future efforts toward delaying, preventing, and treating resistance are underway. Similar to EGFR mutations, ALK rearrangements exemplify an oncogene-driven NSCLC that can be effectively palliated with a precision TKI therapy (the multitargeted ALK/MET/ROS1 TKI crizotinib). When resistance to first-line crizotinib therapy occurs, multiple second generation ALK TKIs have demonstrated impressive rates of disease control in clinical trials, and these may modify long-term outcomes for patients with ALK-positive NSCLC. The development of TKIs for other oncogene-driven NSCLCs may expand the portfolio of precision therapies for this recalcitrant cancer.

Abstract IA20: Linking tumor genomics to patient outcomes through a large-scale patient-derived xenograft (PDX) platform.

Abstract Background: Preclinical models have generally proven suboptimal for directing clinical application of new anti-cancer therapies. Here we detail an integrated research platform engaging core resources at JAX-WEST and the clinical research and genomics facilities at UCDCCC. Pilot studies using this platform are focusing on non-small cell lung cancer (NSCLC) due to molecular targets of interest, such as epidermal growth factor receptor (EGFR), heterogeneity in NSCLC tumor biology and the complexity of related cancer signaling pathways. Methods: Clinically and demographically annotated cancer patients (pt) seen at UCDCCC and collaborating facilities undergo tumor biopsy of various types which are implanted into JAX Nod Scid Gamma (NSG) mice to develop PDXs. Pt tumors and subsequent PDXs are assessed by histomorphology, clinically applicable molecular biomarkers, gene expression arrays and genome-wide technologies (NGS). NSCLC PDXs are grouped as panels (EGFR mutant (MT), KRAS MT ALK+). PDX panels of interest undergo multi-regimen drug testing for differential efficacy, together with pre- and post-therapy NGS and timed tumor pharmacodynamics (PD) assessment, to determine mechanisms of primary and acquired resistance in individual PDX models and how to overcome them. Results: As of November 2013 over 1,200 cancer pt tumors have been xenotransplanted into NSG mice (~175 from NSCLC), including successful PDX formation from small FNA and, cell pellets and transportability of specimens by overnight shipping for implantation. NSCLC PDXs show excellent histomorphologic, gene expression and mutational fidelity to host pt tumors, including mutation status for KRAS, EGFR and gene expression levels. Pilot studies in a panel of EGFR MT PDXs with TKI-acquired resistance demonstrate differential drug activity which mimics that of the host pt to the same therapy, and tumor PD at baseline and timed intervals post-therapy provide the basis for subgrouping resistance mechanisms Conclusion: This UCDCCC-JAX collaboration has established a large resource applicable to multi-drug testing and tumor PD in a wide range of clinically and genomically characterized tumors, including PDX panels for representative oncogene-driven NSCLCs. An EGFR-directed pilot project supports the feasibility of systematically integrating data derived from these models in order to optimize drug development and treatment strategies to address drug resistance mechanisms. This approach to PDX development and testing will be prospectively integrated into a developing multi-institution clinical trial of the Southwest Oncology Group (S1403), designed to advance understanding of differences in inter- and intra-patient tumor biology and hasten the transition to personalized cancer therapy. Citation Format: David R. Gandara, T. Li, P.N. Lara, K. Kelly, D.T. Cooke, R. Gandour-Edwards, K. Yoneda, N. Goodwin, S. Kuslak-Meyer, P. Mack. Linking tumor genomics to patient outcomes through a large-scale patient-derived xenograft (PDX) platform. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr IA20.

Predictive biomarkers in patients with resected non-small cell lung cancer treated with perioperative chemotherapy

The aim of this article is to summarise the published data on prognostic and predictive biomarkers for early-stage non-small cell lung cancer (NSCLC), and discuss how to integrate them into clinical trials. Large phase III trials have been published in resected NSCLC with biomarkers identifying subsets of patients benefitting from perioperative chemotherapy. Initial findings of predictive implications for the DNA repair protein, ERCC1, were not confirmed in a larger series of patients due to the versatility of the commercially available monoclonal ERCC1 antibody. Prediction of survival by RRM1 tumour expression was not confirmed in a prospective phase III trial in 275 patients with stage IV disease, precluding its use in early-stage NSCLC. BRCA1 mRNA tumour content also failed to predict platinum resistance in 287 stage IV NSCLC patients included in a phase II trial, and the results of a similar trial in early-stage patients are still pending. Of the several cDNA gene expression studies in early-stage NSCLC with non-overlapping prognostic signatures, few have been replicated in independent cohorts for prognostic value, and none received external validation for predictive value. Therefore, use of biomarkers predicting chemotherapy efficacy still needs additional validation before becoming routine practice in oncogene-driven pan-negative NSCLC patients.

509 The GATA2 Transcriptional Network is Requisite for Ras Oncogene-driven Non-small Cell Lung Cancer

509 The GATA2 Transcriptional Network is Requisite for Ras Oncogene-driven Non-small Cell Lung Cancer

Abstract PR-5: GATA2 is required for oncogene-driven non-small cell lung cancer.

Abstract Non-small cell lung cancer (NSCLC) is the most diagnosed and lethal histological type of cancer worldwide. Among NSCLC patients, the most frequently mutated oncogenes are KRAS and EGFR, constituting 40 percent of patients. Thus, there is a need to develop therapies to target these tumors. We performed a RNA interference screen for factors required in KRAS mutant cells and found mutant cells depend on the transcription factor GATA2. Analysis of 26 NSCLC lines revealed GATA2 loss specifically reduces KRAS mutant cell viability. We explored these effects in NSCLC cells mutant for KRAS or EGFR. GATA2 knockdown reduces the viability of NSCLC cells with activating mutations in either KRAS or EGFR, with wild type NSCLC cells growing comparably well. Furthermore, injection of mutant NSCLC cells depleted for GATA2 failed to form tumors, while wild type tumors were unaffected by GATA2 loss. This suggests GATA2 is required specifically in oncogene-driven NSCLC. To determine the effect of GATA2 on gene expression, we performed transcript profiling of mutant cells with and without GATA2 loss. In response to GATA2 loss in NSCLC cells, we observed suppression of the proteasome. GATA2 loss inhibited activity of the proteasome and restoration of proteasome activity rescued growth in response to GATA2 depletion. Furthermore, GATA2 loss suppressed IL-1 and NF-κB signaling in mutant NSCLC cells. Restoring IL-1 signaling reestablished both NF-κB activity and growth in response to GATA2 knockdown. We further explored GATA2 genome occupancy and gene expression through GATA2 ChIP-seq in NSCLC cells. In mutant NSCLC cells, GATA2 occupancy was enriched in Rho signaling pathway components. Further, we found GATA2 loss suppressed Rho signaling and activation of Rho signaling rescued viability in response to GATA2 loss. Analyzing the DNA motifs from our GATA2 ChIP of mutant NSCLC cells, we observed enrichment of the STAT5 response element. We subsequently isolated a GATA2-STAT5 complex in mutant NSCLC cells; importantly, this complex occupies Rho pathway target genes. Overall, our ChIP-seq suggests GATA2, via STAT5 binding, is recruited to Rho pathway target genes to control Rho signaling. To examine GATA2 loss in an autochthonous model of NSCLC, we combined conditional Gata2 with oncogenic Kras to generate compound mutant animals. Gata2 deletion suppressed tumor growth compared to wild type animals. We further tested the role for GATA2 in tumor maintenance via systemic deletion of Gata2 in established Kras-mutant lung tumors, which caused complete regression of established lesions. Beyond this, we combined bortezomib, an inhibitor of the proteasome, and fasudil, an inhibitor of Rho signaling, to see if suppression of GATA2-regulated pathways recapitulates GATA2 loss in the Kras lung tumor model. Treatment of Kras mutant mice with these compounds caused a near-complete clearance of tumors. These studies suggest GATA2 is necessary in the Kras mutant tumor model and combined inhibition of GATA2-controlled pathways suppresses lung tumor growth. Taken together, these findings suggest GATA2 is required for the survival of oncogene-mutant NSCLC cells. Moreover, these results suggest the functional pleiotropy of GATA2, not a traditional druggable target, presents a network of druggable pathways for therapeutic exploitation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr PR-5.