Prudence A. Russell

Frequent and Focal FGFR1 Amplification Associates with Therapeutically Tractable FGFR1 Dependency in Squamous Cell Lung Cancer

FGFR1 amplification provides a therapeutic target for squamous cell lung cancer, which is resistant to other targeted lung cancer drugs. A Smoking Gun for Lung Cancer Detectives and scientists alike need strong evidence to take their cases to the judge, who for scientists is often a patient with a deadly disease. Yet, new culprits are sometimes found that can break a case wide open. Lung cancer, which accounts for more than 10% of the global cancer burden, has a poor prognosis and inadequately responds to chemotherapy and radiotherapy. New targeted treatments for lung adenocarcinomas inhibit the oncogenic versions of signaling protein kinases that arise from mutations typically found in lung cancer patients who have never smoked. However, smokers frequently suffer from a different deviant, squamous cell lung cancers, for which there are no known molecular genetic targets for therapy. Now, Weiss et al. have fingered a new suspect in smoking-related lung cancer: amplification of the FGFR1 gene, which encodes the fibroblast growth factor receptor 1 tyrosine kinase (FGFR1). To identify therapeutically viable genetic alterations that may influence squamous cell lung cancer, Weiss et al. performed genomic profiles on a large set of lung cancer specimens. Squamous cell lung cancer samples showed FGFR1 amplification, which was not found in other lung cancer subtypes. The authors then determined that a molecule that broadly inhibits FGF receptor function could block tumor growth and cause cell death in the cancers that expressed high amounts of the FGFR1 gene product in a manner that was dependent on FGFR1 expression. Moreover, FGFR1 inhibition resulted in a considerable decrease in tumor size in a mouse model of FGFR1-amplified lung cancer. This culmination of evidence implies that inhibition of this receptor tyrosine kinase should be explored as a candidate therapy for corralling squamous cell lung cancer in smokers. Lung cancer remains one of the leading causes of cancer-related death in developed countries. Although lung adenocarcinomas with EGFR mutations or EML4-ALK fusions respond to treatment by epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) inhibition, respectively, squamous cell lung cancer currently lacks therapeutically exploitable genetic alterations. We conducted a systematic search in a set of 232 lung cancer specimens for genetic alterations that were therapeutically amenable and then performed high-resolution gene copy number analyses. We identified frequent and focal fibroblast growth factor receptor 1 (FGFR1) amplification in squamous cell lung cancer (n = 155), but not in other lung cancer subtypes, and, by fluorescence in situ hybridization, confirmed the presence of FGFR1 amplifications in an independent cohort of squamous cell lung cancer samples (22% of cases). Using cell-based screening with the FGFR inhibitor PD173074 in a large (n = 83) panel of lung cancer cell lines, we demonstrated that this compound inhibited growth and induced apoptosis specifically in those lung cancer cells carrying amplified FGFR1. We validated the FGFR1 dependence of FGFR1-amplified cell lines by FGFR1 knockdown and by ectopic expression of an FGFR1-resistant allele (FGFR1V561M), which rescued FGFR1-amplified cells from PD173074-mediated cytotoxicity. Finally, we showed that inhibition of FGFR1 with a small molecule led to significant tumor shrinkage in vivo. Thus, focal FGFR1 amplification is common in squamous cell lung cancer and associated with tumor growth and survival, suggesting that FGFR inhibitors may be a viable therapeutic option in this cohort of patients.

Integrative genome analyses identify key somatic driver mutations of small-cell lung cancer

Small-cell lung cancer (SCLC) is an aggressive lung tumor subtype with poor prognosis. We sequenced 29 SCLC exomes, 2 genomes and 15 transcriptomes and found an extremely high mutation rate of 7.4 ± 1 protein-changing mutations per million base pairs. Therefore, we conducted integrated analyses of the various data sets to identify pathogenetically relevant mutated genes. In all cases, we found evidence for inactivation of TP53 and RB1 and identified recurrent mutations in the CREBBP, EP300 and MLL genes that encode histone modifiers. Furthermore, we observed mutations in PTEN, SLIT2 and EPHA7, as well as focal amplifications of the FGFR1 tyrosine kinase gene. Finally, we detected many of the alterations found in humans in SCLC tumors from Tp53 and Rb1 double knockout mice. Our study implicates histone modification as a major feature of SCLC, reveals potentially therapeutically tractable genomic alterations and provides a generalizable framework for the identification of biologically relevant genes in the context of high mutational background.

Comprehensive genomic profiles of small cell lung cancer

We have sequenced the genomes of 110 small cell lung cancers (SCLC), one of the deadliest human cancers. In nearly all the tumours analysed we found bi-allelic inactivation of TP53 and RB1, sometimes by complex genomic rearrangements. Two tumours with wild-type RB1 had evidence of chromothripsis leading to overexpression of cyclin D1 (encoded by the CCND1 gene), revealing an alternative mechanism of Rb1 deregulation. Thus, loss of the tumour suppressors TP53 and RB1 is obligatory in SCLC. We discovered somatic genomic rearrangements of TP73 that create an oncogenic version of this gene, TP73Δex2/3. In rare cases, SCLC tumours exhibited kinase gene mutations, providing a possible therapeutic opportunity for individual patients. Finally, we observed inactivating mutations in NOTCH family genes in 25% of human SCLC. Accordingly, activation of Notch signalling in a pre-clinical SCLC mouse model strikingly reduced the number of tumours and extended the survival of the mutant mice. Furthermore, neuroendocrine gene expression was abrogated by Notch activity in SCLC cells. This first comprehensive study of somatic genome alterations in SCLC uncovers several key biological processes and identifies candidate therapeutic targets in this highly lethal form of cancer.

Does Lung Adenocarcinoma Subtype Predict Patient Survival?: A Clinicopathologic Study Based on the New International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society International Multidisciplinary Lung Adenocarcinoma Classification

Introduction: Lung adenocarcinoma is a heterogeneous group of tumors with a highly variable prognosis, not well predicted by the current pathologic classification system. The 2004 World Health Organization classification results in virtually all tumors encountered in clinical practice being allocated to the adenocarcinoma of mixed subtype category. A new classification developed by an international multidisciplinary expert panel sponsored by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society, is based on histomorphologic subtype and has recently been validated in a North American series of 514 stage I lung adenocarcinomas. We investigated the relationship between the new classification and patient survival in a series of Australian patients with stages I, II, and III lung adenocarcinoma. Methods: We identified 210 patients from a surgical database who underwent resection of lung adenocarcinoma from 1996 to 2009. Two pathologists, blinded to patient outcome, independently performed histopathologic subtyping according to the new classification. Kaplan-Meier curves were used to calculate 5-year survival for each separate histopathologic subtype/variant. Univariate and multivariate analyses were undertaken to control for validated prognostic factors. Results: We confirmed that the new subtypes of adenocarcinoma in situ, minimally invasive adenocarcinoma and lepidic-predominant adenocarcinoma had a 5-year survival approaching 100%, whereas micropapillary-predominant and solid with mucin-predominant adenocarcinomas were associated with particularly poor survival. Papillary-predominant and acinar-predominant adenocarcinomas had an intermediate prognosis. This effect persisted after controlling for stage. Conclusions: Classification of lung adenocarcinoma according to the new International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification correlated with 5-year survival. These relationships persisted after controlling for known prognostic patient and tumor characteristics. The new classification has advantages not only for individual patient care but also for better selection and stratification for clinical trials and molecular studies.

Rationale for co-targeting IGF-1R and ALK in ALK fusion-positive lung cancer

Crizotinib, a selective tyrosine kinase inhibitor (TKI), shows marked activity in patients whose lung cancers harbor fusions in the gene encoding anaplastic lymphoma receptor tyrosine kinase (ALK), but its efficacy is limited by variable primary responses and acquired resistance. In work arising from the clinical observation of a patient with ALK fusion–positive lung cancer who had an exceptional response to an insulin-like growth factor 1 receptor (IGF-1R)-specific antibody, we define a therapeutic synergism between ALK and IGF-1R inhibitors. Similar to IGF-1R, ALK fusion proteins bind to the adaptor insulin receptor substrate 1 (IRS-1), and IRS-1 knockdown enhances the antitumor effects of ALK inhibitors. In models of ALK TKI resistance, the IGF-1R pathway is activated, and combined ALK and IGF-1R inhibition improves therapeutic efficacy. Consistent with this finding, the levels of IGF-1R and IRS-1 are increased in biopsy samples from patients progressing on crizotinib monotherapy. Collectively these data support a role for the IGF-1R–IRS-1 pathway in both ALK TKI–sensitive and ALK TKI–resistant states and provide a biological rationale for further clinical development of dual ALK and IGF-1R inhibitors.

Testing for ALK rearrangement in lung adenocarcinoma : a multicenter comparison of immunohistochemistry and fluorescent in situ hybridization

Rearrangements of anaplastic lymphoma kinase (ALK) gene in non-small cell lung cancer (NSCLC) define a molecular subgroup of tumors characterized clinically by sensitivity to ALK tyrosine kinase inhibitors such as crizotinib. Although ALK rearrangements may be detected by reverse transcriptase-PCR, immunohistochemistry or fluorescence in situ hybridization (FISH), the optimal clinical strategy for identifying ALK rearrangements in clinical samples remains to be determined. We evaluated immunohistochemistry using three different antibodies (ALK1, 5A4 and D5F3 clones) to detect ALK rearrangements and compared those with FISH. We report the frequency and clinicopathologic features of lung cancers harboring ALK translocations in 594 resected NSCLCs (470 adenocarcinomas; 83 squamous carcinomas, 26 large cell carcinomas and 15 other histological subtypes) using a tissue microarray approach. We identified an ALK gene rearrangement in 7/594 cases (1%) by FISH and all anti-ALK antibodies correctly identified the seven ALK-positive cases (100% sensitivity), although the intensity of staining was weak in some cases. These data indicate that the use of antibodies with high sensitivity and avidity to ALK may provide an effective pre-screening technique to complement the more expensive and labor-intensive approach of ALK FISH testing.

Frequent mutations in chromatin-remodelling genes in pulmonary carcinoids

Pulmonary carcinoids are rare neuroendocrine tumors of the lung. The molecular alterations underlying the pathogenesis of these tumors have not been systematically studied so far. Here we perform gene copy number analysis (n=54), genome/exome (n=44) and transcriptome (n=69) sequencing of pulmonary carcinoids and observe frequent mutations in chromatin-remodeling genes. Covalent histone modifiers and subunits of the SWI/SNF complex are mutated in 40% and 22.2% of the cases respectively, with MEN1, PSIP1 and ARID1A being recurrently affected. In contrast to small-cell lung cancer and large-cell neuroendocrine tumors, TP53 and RB1 mutations are rare events, suggesting that pulmonary carcinoids are not early progenitor lesions of the highly aggressive lung neuroendocrine tumors but arise through independent cellular mechanisms. These data also suggest that inactivation of chromatin remodeling genes is sufficient to drive transformation in pulmonary carcinoids.

Correlation of Mutation Status and Survival with Predominant Histologic Subtype According to the New IASLC/ATS/ERS Lung Adenocarcinoma Classification in Stage III (N2) Patients

Introduction: We investigated the relationship between predominant subtype, according to the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society International Multidisciplinary Lung Adenocarcinoma Classification; mutation status; and patient outcome in stage III (N2) lung adenocarcinoma. Methods: We identified 69 patients with stage III (N2) lung adenocarcinoma operated on with curative intent between 1993 and 2011 who had adequate tumor tissue for molecular analysis and adequate follow-up time for survival analysis. DNA was isolated and tested for mutations using Sequenom’s OncoCarta Panel (v1.0; Sequenom, San Diego, CA). Results: The majority of tumors were acinar (26 of 69 tumors; 38%), solid (24 of 69 tumors; 35%), and micropapillary predominant (13 of 69 tumors; 19%) subtypes. EGFR and KRAS mutations were identified in 17 of 59 tumors (29%) and 13 of 59 tumors (22%), respectively. EGFR mutations occurred most often in acinar (11 of 25 tumors; 44%) and micropapillary predominant tumors (five of 13 tumors; 38%) (p = 0.009), whereas KRAS mutations occurred most often in solid predominant tumors (nine of 21 tumors; 43%) (p = 0.016). Patients with acinar predominant tumors had significantly improved overall survival compared with those with non-acinar predominant tumors (hazard ratio: 0.45; 95% confidence interval: 0.22–0.91; p = 0.026), which remained significant after adjustment for EGFR status, T-stage, sex, and age. Patients with EGFR-mutant micropapillary predominant tumors had similar survival to those with EGFR-mutant acinar predominant tumors. The predominant subtype in the primary tumor was most often seen in the N2 node in micropapillary and solid predominant tumors but not in acinar predominant tumors. Conclusions: The predominant subtype in the primary tumor was associated with overall survival in resected stage III (N2) lung adenocarcinoma and was independent of mutation status. Histologic subtyping provides important prognostic information and potentially molecular correlates.

The prognostic significance of aldehyde dehydrogenase 1A1 (ALDH1A1) and CD133 expression in early stage non-small cell lung cancer

Background Expression of aldehyde dehydrogenase 1A1 (ALDH1A1) and CD133 has been functionally associated with a stem cell phenotype in normal and malignant cells. The prevalence of such cells in solid tumours should therefore correlate with recurrence and/or metastasis following definitive surgical resection. The aim of this study was to evaluate the prognostic significance of ALDH1A1 and CD133 in surgically resected, early stage non-small cell lung cancer (NSCLC). Methods A retrospective analysis of ALDH1A1 and CD133 expression in 205 patients with pathologic stage I NSCLC was performed using immunohistochemistry. The association between the expression of both markers and survival was determined. Results We identified 62 relapses and 58 cancer-related deaths in 144 stage 1A and 61 stage 1B patients, analysed at a median of 5-years follow-up. Overexpression of ALDH1A1 and CD133, detected in 68.7% and 50.7% of primary tumours, respectively, was an independent prognostic indicator for overall survival by multivariable Cox proportional hazard model (p=0.017 and 0.039, respectively). Overexpression of ALDH1A1, but not of CD133, predicted poor recurrence-free survival (p=0.025). When categorised into three groups according to expression of ALDH1A1/CD133, patients with overexpression of both ALDH1A1 and CD133 belonged to the group with the shortest recurrence-free and overall survival (p=0.015 and 0.017, respectively). Conclusions Expression of ALDH1A1 and CD133, and coexpression of ALDH1A1 and CD133, is strongly associated with poor survival in early-stage NSCLC following surgical resection. These data are consistent with the hypothesis that expression of stem cell markers correlates with recurrence as an indirect measure of self-renewal capacity.

Comparison of Methods in the Detection of ALK and ROS1 Rearrangements in Lung Cancer

Introduction: The use of targeted therapies toward specific oncogenic driver mutations has become a critical factor in the treatment of patients with lung cancer. It is therefore essential to utilize tests with high performance characteristics. Fluorescence in situ hybridization (FISH) is the standard method for detecting anaplastic lymphoma kinase (ALK) and ROS1 rearrangements in non–small-cell lung cancer but the utility of other methods such as immunohistochemistry (IHC) and chromogenic in situ hybridization (CISH) is unclear. Methods: Three hundred and sixty-two lung cancer patients were tested with FISH, CISH, and IHC using three ALK antibodies (ALK1, 5A4, D5F3) and one ROS1 antibody in the detection of ALK and ROS1 rearrangements. Results: There was a 97.4% concordance (298 of 306) between FISH and CISH for detection of ALK rearrangements. The ROS1 rearrangement status had a 97% (291 of 300) concordance between CISH and FISH. ALK protein expression was observed in 6 of 341 samples with the ALK1 and 5A4 antibodies and 5 of 341 samples with D5F3. All three antibodies stained each of the ALK FISH-positive samples (100% sensitivity). ROS1 protein expression was observed in 2 of 322 samples. One of three samples with a ROS1 rearrangement by FISH showed ROS1 protein expression (33.3% sensitivity). Conclusion: Our findings show good correlation between FISH versus CISH in the detection of ALK and ROS1 rearrangements. FISH versus IHC showed good correlation in the detection of ALK rearrangements but showed weak correlation in the detection of ROS1 rearrangements. These results suggest CISH and IHC could be complimentary detection methods to FISH in the detection of ALK and ROS1 rearrangements.