The biology and treatment of EML4-ALK non-small cell lung cancer

Lung cancer in never smokers

Lung cancer in never smokers (LCINS) has lately been recognized as a unique disease based on rapidly gained knowledge from genomic changes to treatment responses. The focus of this article is on current knowledge and challenges with regard to LCINS expanded from recent reviews highlighting five areas: (1) distribution of LCINS by temporal trends, geographic regions, and populations; (2) three well-recognized environmental risk factors; (3) other plausible environmental risk factors; (4) prior chronic lung diseases and infectious diseases as risk factors; and (5) lifestyles as risk or protective factors. This article will also bring attention to recently published literature in two pioneering areas: (1) histological characteristics, clinical features with emerging new effective therapies, and social and psychological stigma; and (2) searching for susceptibility genes using integrated genomic approaches.

Tailoring tyrosine kinase inhibitors to fit the lung cancer genome

Tyrosine kinase inhibitors (TKIs) have been in use as cancer therapeutics for nearly a decade, and their utility in targeting specific malignancies with defined genetic lesions has proven to be remarkably effective. Recent efforts to characterize the spectrum of genetic lesions found in non-small cell lung carcinoma (NSCLC) have provided important insights into the molecular basis of this disease and have also revealed a wide array of tyrosine kinases that might be effectively targeted for rationally designed therapies. The findings of these studies, however, also provide a cautionary tale about the limitations of single-agent therapies, which fail to account for the genetic heterogeneity and pathway redundancy that characterize advanced NSCLC. Emergence of drug resistance mechanisms to specific TKIs, such as gefitinib and erlotinib, suggests that more sophisticated chemotherapeutic paradigms that target multiple pathways at the same time will be required to effectively treat this disease.

Role of ERK-BIM and STAT3-survivin signaling pathways in ALK inhibitor-induced apoptosis in EML4-ALK-positive lung cancer

PURPOSE

EML4-ALK (echinoderm microtubule-associated protein-like 4 anaplastic lymphoma kinase) was recently identified as a transforming fusion gene in non-small cell lung cancer. The purpose of the present study was to characterize the mechanism of malignant transformation by EML4-ALK.

EXPERIMENTAL DESIGN

We established NIH 3T3 cells that stably express variant 1 or 3 of EML4-ALK and examined the signaling molecules that function downstream of EML4-ALK.

RESULTS

Forced expression of EML4-ALK induced marked activation of extracellular signal-regulated kinase (ERK) and STAT3, but not that of AKT. Inhibition of ERK or STAT3 signaling resulted in substantial attenuation of the proliferation of cells expressing either variant of EML4-ALK, suggesting that these signaling pathways function downstream of EML4-ALK in lung cancer cells. The specific ALK inhibitor TAE684 induced apoptosis that was accompanied both by upregulation of BIM, a proapoptotic member of the Bcl-2 family, and by downregulation of survivin, a member of the inhibitor of apoptosis protein (IAP) family, in EML4-ALK-expressing NIH 3T3 cells as well as in H3122 human lung cancer cells harboring endogenous EML4-ALK. Depletion of BIM and overexpression of survivin each inhibited TAE684-induced apoptosis, suggesting that both upregulation of BIM and downregulation of survivin contribute to TAE684-induced apoptosis in EML4-ALK-positive lung cancer cells. Furthermore, BIM and survivin expression was found to be independently regulated by ERK and STAT3 signaling pathways, respectively.

CONCLUSIONS

ALK inhibitor-induced apoptosis is mediated both by BIM upregulation resulting from inhibition of ERK signaling as well as by survivin downregulation resulting from inhibition of STAT3 signaling in EML4-ALK-positive lung cancer cells.

New molecular targeted therapies for advanced non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) is a uniformly fatal disease and most patients will present with advanced stage. Treatment outcomes remain unsatisfactory, with low long-term survival rates. Standard treatment, such as palliative chemotherapy and radiotherapy, offers a median survival not exceeding 1 year. Hence, considerable efforts have started to be made in order to identify new biological agents which may safely and effectively be administered to advanced NSCLC patients. Two cancer cell pathways in particular have been exploited, the epidermal growth factor receptor (EGFR) and the vascular endothelial growth factor receptor (VEGFR) pathways. However, novel targeted therapies that interfere with other dysregulated pathways in lung cancer are already in the clinic. This review outlines the most promising research approaches to the treatment of NSCLC, discussed according to the specific molecular pathway targeted.

Crizotinib for EML4-ALK positive lung adenocarcinoma: a hope for the advanced disease? Evaluation of Kwak EL, Bang YJ, Camidge DR, et al. Anaplastic lymphoma kinase inhibition in non-small-cell lung cancer. N Engl J Med 2010;363(18):1693-703

INTRODUCTION

In lung adenocarcinoma, certain mutations such as echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (ALK) are associated with lower sensitivity to chemotherapy, when used conventionally as the first-line therapy in the advanced stage of the disease.

AREAS COVERED

This paper discusses the clinical and therapeutic importance of ALK mutations in NSCLC and the early clinical results of a Phase I study assessing crizotinib in patients with ALK mutations.

EXPERT OPINION

Abnormal ALK is evolving as an important therapeutic target in patients with more aggressive lung adenocarcinoma. Further clinical studies are needed in order to assess if crizotinib, an ALK inhibitor, is able to increase the efficacy of the conventional chemotherapy in this disease subset.

EGFR and EML4-ALK gene mutations in NSCLC: a case report of erlotinib-resistant patient with both concomitant mutations

The fusion gene EML4-ALK (echinoderm microtubule-associated protein-like 4 gene and the anaplastic lymphoma kinase gene) was recently identified as a novel genetic alteration in non-small cell lung cancer (NSCLC). EML4-ALK translocations correlate with specific clinical and pathological features, in particular lack of EGFR and K-ras mutations, and may be associated with resistance to EGFR tyrosine-kinase inhibitors (TKIs). Here, we report a case of a patient with a concomitant EGFR mutation and ALK translocation resistant to erlotinib. Considering this report, ALK status should be investigated in unexplained cases of EGFR-TKI-resistance of EGFR mutated NSCLCs.

Discovery of a potent inhibitor of anaplastic lymphoma kinase with in vivo antitumor activity

A series of novel 7-amino-1,3,4,5-tetrahydrobenzo[b]azepin-2-one derivatives within the diaminopyrimidine class of kinase inhibitors were identified that target anaplastic lymphoma kinase (ALK). These inhibitors are potent against ALK in an isolated enzyme assay and inhibit autophosphorylation of the oncogenic fusion protein NPM-ALK in anaplastic large cell lymphoma (ALCL) cell lines. The lead inhibitor 15, which incorporates a bicyclo[2.2.1]hept-5-ene ring system in place of an aryl moiety, activates the pro-apoptotic caspases (3 and 7) and displays selective cytotoxicity against ALK-positive ALCL cells. Furthermore, 15 provides more than 40-fold selectivity against the structurally related insulin receptor, is orally bioavailable in multiple species, and displays in vivo antitumor efficacy when dosed orally in ALK-positive ALCL tumor xenografts in Scid mice.