The role of anaplastic lymphoma kinase in pediatric cancers

The anaplastic lymphoma kinase (ALK) gene was initially identified as a fusion partner of the nucleophosmin gene in anaplastic large‐cell lymphoma with t(2;5)(p23;q35) translocation, and then described with different genetic abnormalities in a number of tumors. Although ALK is known to be involved in the pathogenesis of neuroblastoma through activating mutations or gene amplification, its role in the pathogenesis of other pediatric cancers is still elusive. In addition to neuroblastoma, the high‐grade amplification of ALK has been described in a subset of rhabdomyosarcoma cases. Normal ALK protein expression is restricted to the nervous systems of adult mammals, but the aberrant expression of ALK has been observed in a variety of pediatric cancers, including glioma and Ewing sarcoma. The discovery of oncogenic activation of ALK in neuroblastoma suggests that this cancer could be potentially treated with an ALK inhibitor, as could other cancers, such as non‐small‐cell lung cancer and anaplastic large‐cell lymphoma. However, cellular responses to mutant ALK are complex when compared to rearranged ALK, and treatment remains a challenge. This review focuses on the biology of ALK in pediatric cancers and possible therapeutic strategies for ALK‐associated tumors.     

Differential expression of the enzyme that esterifies retinol, lecithin:retinol acyltransferase, in subtypes of human renal cancer and normal kidney.

PURPOSE: Retinoids, a group of compounds, including vitamin A (retinol), and related metabolites, have been shown to regulate the growth and differentiation of many types of cells. IFN-alpha and either 13-cis-retinoic acid or liposomal all-trans retinoic acid have been used in the treatment of patients with metastatic renal cell carcinoma. We knew that samples from renal cell carcinomas contained greatly reduced levels of retinol and retinyl esters relative to samples from normal human kidney. This prompted us to examine the levels of LRAT (lecithin:retinol acyltransferase) protein in various subtypes of human kidney cancers relative to normal human kidney by immunohistochemistry. EXPERIMENTAL DESIGN: We examined 31 partial or radical nephrectomy specimens diagnosed with kidney tumors between 1997 and 1998. Representative paraffin-embedded tissue blocks from each tumor, with each containing adjacent nonneoplastic renal parenchyma, were used for immunohistochemical analysis with affinity purified antibodies to human LRAT protein. RESULTS: LRAT protein was detected at high levels in the epithelial cells in the tubules and the lining of Bowman's capsule in the glomeruli of normal, nonneoplastic kidney sections. Among the 31 tumors, there were 13 cases of conventional (clear cell) renal cell carcinoma (RCC; including 2 multilocular cystic RCCs), 7 papillary RCC, 6 chromophobe RCC, 1 RCC, unclassified, and 4 renal oncocytoma. All tumors showed diffuse immunoreactivity for LRAT. In each case, the staining was uniform throughout the tumor, with only minimal variation in the staining intensity between different areas. All 4 renal oncocytomas, 2 of 6 chromophobe RCCs, 1 conventional (clear cell) carcinoma, 1 RCC, unclassified, and 2 conventional RCCs, which were of the multilocular cystic-type stained strongly (3+) for LRAT. In contrast, the remaining conventional RCCs and the papillary RCC samples stained much less intensely for LRAT. Of the 10 tumors that stained 3+ for LRAT in the study, 9 were either benign tumors or tumors with low malignant potential. CONCLUSIONS: These data show that LRAT expression is higher in renal tumors with an indolent biological behavior. Additional studies will ascertain if LRAT possesses any prognostic or therapeutic role in renal cancer.     

Activated extracellular signal‐regulated kinase is an independent prognostic factor in clinically confined renal cell carcinoma

BACKGROUND:

Extracellular signal‐regulated kinase (ERK) promotes proliferation, metastasis, and poor survival in cancers of the breast, lung, and liver. Advanced localized renal cell carcinoma (RCC) is extraordinarily treatment resistant and has high recurrence rates despite surgery. Limited data exist regarding the prognostic significance of activated (phosphorylated) ERK in RCC. The authors hypothesized that activated ERK (pERK) promotes disease progression and metastasis in localized RCC and may be of value as a biomarker to predict disease recurrence.

METHODS:

The expression profile of pERK was examined by immunocytochemistry using a tissue microarray constructed from 174 drug treatment–naive patients who had undergone radical nephrectomy for localized RCC. Levels of tumor‐cell specific pERK were scored and correlated with clinicopathologic parameters of RCC and disease‐free survival.

RESULTS:

Immunostaining for pERK was present in 36% of all RCCs, with a predominance found in the clear cell histologic subtype. High expression was associated with increased tumor size, increased TNM stage, and vascular invasion. Patients with pERK‐positive tumors had a mean disease‐free survival of 4.19 years, compared with 6.38 years for patients with pERK‐negative tumors (P < .001). Cox regression models revealed pERK to be a significant independent predictor of disease‐free survival, with a hazards score of 2.9 (P < .001), a value similar to tumor grade (hazards ratio, 3.01; P < .001).

CONCLUSIONS:

Expression of pERK is an independent prognostic factor in RCC that is associated with advanced and aggressive pathologic features of renal tumors and predicts the onset of metastasis in patients with localized disease. Cancer 2009. © 2009 American Cancer Society.     

Correlations between the percentage of tumor cells showing an anaplastic lymphoma kinase (ALK) gene rearrangement, ALK signal copy number, and response to crizotinib therapy in ALK fluorescence in situ hybridization-positive nonsmall cell lung cancer

BACKGROUND:

Fluorescence in situ hybridization (FISH), using break‐apart red (3′) and green (5′) ALK (anaplastic lymphoma kinase) probes, consistently shows rearrangements in <100% of tumor cells in ALK‐positive (ALK+) nonsmall cell lung cancer (NSCLC). Increased copy numbers of fused and rearranged signals also occur. Here, correlations are explored between the percentage of ALK+ cells and signal copy number and their association with response to ALK inhibition.

METHODS:

Ninety ALK+ NSCLC cases were evaluated. The percentage of positive cells, pattern of positivity (split, single red, or both), and copy number of fused, isolated red and green signals were recorded. Thirty patients had received crizotinib.

RESULTS:

Increased isolated red signal copy number (contributing to both single red and split patterns of positivity) correlated with a higher percentage of ALK+ cells (r = 0.743, P < .0001). Mean fused copy number was negatively associated with isolated red signal copy number (r = ?0.409, P < .0001). Neither percentage of positive cells (r = 0.192, P = .3), nor copy number of isolated red signal (r = 0.274, P = .195) correlated with maximal tumor shrinkage with crizotinib.

CONCLUSIONS:

The strong association between increased copy number of key ALK signals and percentage of positive cells suggests that the <100% rate of cellular positivity in ALK+ tumors is due to technical factors, not biological factors. In ALK+ tumors, neither the percentage of positive cells nor signal copy number appear to be informative variables for predicting benefit from ALK inhibition. The inverse relationship between fused and isolated red copy number suggests ALK+ may be a distinct “near‐diploid” subtype of NSCLC that develops before significant chromosomal aneusomy occurs. Cancer 2012. © 2012 American Cancer Society.     

Molecular genetics and immunohistochemistry characterization of uncommon and recently described renal cell carcinomas

Renal cell carcinoma (RCC) compromises multiple types and has been emerging dramatically over the recent several decades. Advances and consensus have been achieved targeting common RCCs, such as clear cell carcinoma, papillary RCC and chromophobe RCC. Nevertheless, little is known on the characteristics of several newly-identified RCCs, including clear cell (tubulo) papillary RCC, Xp11 translocation RCC, t(6;11) RCC, succinate dehydrogenase (SDH)-deficient RCC, acquired cystic disease-associated RCC, hereditary leiomyomatosis RCC syndrome-associated RCC, ALK translocation RCC, thyroid-like follicular RCC, tubulocystic RCC and hybrid oncocytic/chromophobe tumors (HOCT). In current review, we will collect available literature of these newly-described RCCs, analyze their clinical pathologic characteristics, discuss their morphologic and immunohistologic features, and finally summarize their molecular and genetic evidences. We expect this review would be beneficial for the understanding of RCCs, and eventually promote clinical management strategies.     

The application of cytogenetics and fluorescence in situ hybridization to fine‐needle aspiration in the diagnosis and subclassification of renal neoplasms

BACKGROUND:

Percutaneous fine‐needle aspiration (FNA) cytology is an important diagnostic test for the evaluation and management of selected renal masses. Cytogenetic analysis of cytology specimens can serve as an adjunct for precise classification because certain tumors are associated with specific chromosomal aberrations. This study summarizes our experience with the application of conventional cytogenetics and fluorescence in situ hybridization (FISH) to renal FNA specimens.

METHODS:

All percutaneous renal FNAs performed during 2005 through 2008 were identified from the electronic pathology database. Results of cytogenetic and FISH analyses were correlated with the final diagnoses of the renal FNAs.

RESULTS:

A total of 303 renal FNAs were performed. During an onsite assessment, a portion of the cytology specimen was allocated for cytogenetic analysis in 74 cases. Karyotypic analysis or FISH was successful in 44 (59%) of these. Characteristic chromosomal abnormalities were observed in 27 cases. In 17 cases, a karyotype revealed a combination of trisomies/tetrasomies and in another 5 cases, FISH revealed trisomy 7 and 17, both of which are consistent with papillary renal cell carcinoma (RCC). Two cases showed 3p deletions consistent with clear cell RCC. Trisomy 3 was observed in 1 case of clear cell RCC. Monosomy 1 and 17 was observed in a case of papillary RCC comprised oncocytic cells. In 1 case of primary renal synovial sarcoma, FISH revealed a rearrangement at the SYT locus (18q11.2).

CONCLUSIONS:

Renal FNA specimens are amenable to analysis by cytogenetics and FISH in the diagnosis and subclassification of renal neoplasms. Cancer (Cancer Cytopathol) 2010. © 2010 American Cancer Society.     

Crizotinib for the Treatment of ALK‐Rearranged Non‐Small Cell Lung Cancer: A Success Story to Usher in the Second Decade of Molecular Targeted Therapy in Oncology

Crizotinib, an ALK/MET/ROS1 inhibitor, was approved by the U.S. Food and Drug Administration for the treatment of anaplastic lymphoma kinase (ALK)‐rearranged non‐small cell lung cancer (NSCLC) in August 2011, merely 4 years after the first publication of ALK‐rearranged NSCLC. The crizotinib approval was accompanied by the simultaneous approval of an ALK companion diagnostic fluorescent in situ hybridization assay for the detection of ALK‐rearranged NSCLC. Crizotinib continued to be developed as an ALK and MET inhibitor in other tumor types driven by alteration in ALK and MET. Crizotinib has recently been shown to be an effective ROS1 inhibitor in ROS1‐rearranged NSCLC, with potential future clinical applications in ROS1‐rearranged tumors. Here we summarize the heterogeneity within the ALK‐ and ROS1‐rearranged molecular subtypes of NSCLC. We review the past and future clinical development of crizotinib for ALK‐rearranged NSCLC and the diagnostic assays to detect ALK‐rearranged NSCLC. We highlight how the success of crizotinib has changed the paradigm of future drug development for targeted therapies by targeting a molecular‐defined subtype of NSCLC despite its rarity and affected the practice of personalized medicine in oncology, emphasizing close collaboration between clinical oncologists, pathologists, and translational scientists.     

Serum cell-free DNA in renal cell carcinoma: a diagnostic and prognostic marker

BACKGROUND:

Currently, there are no established diagnostic and prognostic serum markers for renal cell carcinoma (RCC). The objective of this study was to evaluate the putative significance of serum cell‐free DNA.

METHODS:

Preoperative serum samples from 200 consecutive patients with sporadic, solid renal tumors were analyzed (157 patients with RCC and 43 patients with benign renal tumors). Quantitative real‐time polymerase chain reaction was used to assess total cell‐free DNA (ring finger protein 185 [RNF185]) and CpG island methylation of Ras association domain family member 1A (RASSF1A) von Hippel‐Lindau (VHL), prostaglandin‐endoperoxidase synthase 2 (PTGS2), and P16 (cyclin‐dependent kinase inhibitor 2A). Associations with RCC, pathologic variables, and disease‐specific survival were evaluated.

RESULTS:

Total cell‐free DNA levels and CpG island methylation of RASSF1A and VHL were highly diagnostic for RCC with an area under the receiver operating characteristic curve of 0.755, 0.705, and 0.694, respectively. VHL methylation was detected more frequently in patients with clear cell RCC than in those with other subtypes (P = .007). Total cell‐free DNA levels were higher in patients with metastatic RCC (P < .001) and necrotic RCC (P = .003) and were associated with poorer disease‐specific survival (P < .001). In multivariate analysis, the tumor stage, size, grade, and necrosis (SSIGN) score (P < .001) and categorized total cell‐free DNA levels (P = .028) were retained as independent prognostic factors.

CONCLUSIONS:

The current results indicated that cell‐free DNA represents a novel serum‐based diagnostic and prognostic biomarker for RCC. Total serum cell‐free DNA levels and CpG island methylation of RASSF1A and VHL may be useful diagnostic biomarkers for RCC. VHL methylation of cell‐free DNA is suggestive of clear cell RCC. Total serum cell‐free DNA may be a useful prognostic biomarker that may assist in tailoring postoperative surveillance and therapy. External prospective validation of these data will be required. Cancer 2012;. © 2011 American Cancer Society.     

Epidermal growth factor receptor protein expression and genomic alterations in renal cell carcinoma

BACKGROUND:

Epidermal growth factor receptor (EGFR) is involved in the progression of many cancer types and represents an important therapeutic target.

METHODS:

To determine the role of EGFR in renal cell carcinoma (RCC), the authors analyzed 1088 tumors in a tissue microarray format by using immunohistochemistry and fluorescence in situ hybridization (FISH). A subset of 63 cancers was sequenced for EGFR exon 18 through 21 mutations.

RESULTS:

EGFR expression was observed in 83.8% of clear cell carcinomas, in 68.2% of papillary carcinomas, in 75% of chromophobe carcinomas, and in 50% of oncocytomas. Within clear cell carcinomas, the expression level of EGFR was associated with high tumor grade (P < .0001), advanced pathologic tumor classification (P < .0001), and, to a lesser extent, lymph node status (P = .0326). FISH analysis revealed increased EGFR copy numbers (high polysomy) in 5.5% of tumors and amplification in 0.1% of tumors. EGFR copy number increases were associated with EGFR protein expression (P = .0015). Within clear cell carcinomas, EGFR copy number increases were associated with high tumor grade (P < .0001), advanced pathologic tumor classification (P = .0472), and lymph node status (P = .0065). No exon 18 through 21 mutations were identified in 63 sequenced tumors.

CONCLUSIONS:

The authors concluded that increased EGFR expression occurs in a fraction of patients who have RCC with an unfavorable histologic phenotype. EGFR copy number gain represents 1 possible cause for EGFR overexpression; however, many over expressing tumors have a normal genotype. High polysomy (which is suggested to be predictive of a response to tyrosine kinase inhibitors) occurs in 5.6% of RCCs. Thus, the potential utility of anti‐EGFR medications may be worth further investigation in a small but significant subset of patients with RCC. Cancer 2012;. © 2011 American Cancer Society.     

The mammalian target of rapamycin pathway is widely activated without PTEN deletion in renal cell carcinoma metastases

BACKGROUND:

Inhibitors of the mammalian target of rapamycin (mTOR) are emerging as promising therapies for metastatic renal cell carcinoma (RCC). Because rational treatment strategies require understanding the activation status of the underlying signaling pathway being targeted at the desired stage of disease, the authors examined the activation status of different components of the mTOR pathway in RCC metastases and matched primary tumors.

METHODS:

The authors immunostained metastatic RCC samples from 132 patients and a subset of 25 matched primary RCCs with antibodies against phosphatidylinositol 3′‐kinase, PTEN, phospho‐Akt, phospho‐mTOR, and p70S6. PTEN genomic status was assessed by fluorescent in situ hybridization. Marker expression was correlated to clinicopathologic variables and to survival.

RESULTS:

The mTOR pathway showed widespread activation in RCC metastases of various sites with strong correlation between different components of this signaling cascade (P<.0001), but without significant PTEN genomic deletion. Only cytoplasmic phospho‐mTOR showed independent prognostic significance (P = .029) and fidelity between primary RCCs and their matched metastases (P = .004).

CONCLUSIONS:

Activation of various components of the mTOR signaling pathway in metastatic RCC lesions across various tumor histologies, nuclear grades, and metastatic sites suggests the potential for vertical blockade of multiple steps of this pathway. Patient selection may be improved by mTOR immunostaining of primary RCC. Cancer 2011. © 2010 American Cancer Society.     

Anaplastic lymphoma kinase (ALK) inhibitor response in neuroblastoma is highly correlated with ALK mutation status, ALK mRNA and protein levels

Background

In pediatric neuroblastoma (NBL), high anaplastic lymphoma kinase (ALK) levels appear to be correlated with an unfavorable prognosis, regardless of ALK mutation status. This suggests a therapeutic role for ALK inhibitors in NBL patients. We examined the correlation between levels of ALK, phosphorylated ALK (pALK) and downstream signaling proteins and response to ALK inhibition in a large panel of both ALK mutated and wild type (WT) NBL cell lines.

Methods

We measured protein levels by western blot and ALK inhibitor sensitivity (TAE684) by viability assays in 19 NBL cell lines of which 6 had a point mutation and 4 an amplification of the ALK gene.

Results

ALK 220 kDa (p?=?0.01) and ALK 140 kDa (p?=?0.03) protein levels were higher in ALK mutant than WT cell lines. Response to ALK inhibition was significantly correlated with ALK protein levels (p?ALK mutant cell lines (n?=?4) were 14,9 fold (p?Conclusion NBL cell lines often express ALK at high levels and are responsive to ALK inhibitors. Mutated cell lines express ALK at higher levels, which may define their superior response to ALK inhibition.     

Effects of SMYD2‐mediated EML4‐ALK methylation on the signaling pathway and growth in non‐small‐cell lung cancer cells

A specific subtype of non‐small‐cell lung cancer (NSCLC) characterized with an EML4‐ALK fusion gene, which drives constitutive oncogenic activation of anaplastic lymphoma kinase (ALK), shows a good clinical response to ALK inhibitors. We have reported multiple examples implying the biological significance of methylation on non‐histone proteins including oncogenic kinases in human carcinogenesis. Through the process to search substrates for various methyltransferases using an in vitro methyltransferase assay, we found that a lysine methyltransferase, SET and MYND domain‐containing 2 (SMYD2), could methylate lysine residues 1451, 1455, and 1610 in ALK protein. Knockdown of SMYD2 as well as treatment with a SMYD2 inhibitor in two NSCLC cell lines with an EML4‐ALK gene significantly attenuated the phosphorylation levels of the EML4‐ALK protein. Substitutions of each of these three lysine residues to an alanine partially or almost completely diminished in vitro methylation of ALK. In addition, we found that exogenous introduction of EML4‐ALK protein with the substitution of lysine 1610 to an alanine in these two cell lines reduced the phosphorylation levels of AKT, one of the downstream oncogenic molecules in the EML4‐ALK pathway, and suppressed the growth of the two cell lines. We further showed that the combination of a SMYD2 inhibitor and an ALK inhibitor additively suppressed the growth of these two NSCLC cells, compared with single‐agent treatment. Our results shed light on a novel mechanism that modulates the kinase activity of the ALK fused gene product and imply that SMYD2‐mediated ALK methylation might be a promising target for development of a novel class of treatment for tumors with the ALK fused gene.     

Distinctive expression patterns of glycoprotein non‐metastatic B and folliculin in renal tumors in patients with Birt–Hogg–Dubé syndrome

Birt–Hogg–Dubé syndrome (BHD) is an inherited disorder associated with a germline mutation of the folliculin gene (FLCN). The affected families have a high risk for developing multiple renal cell carcinomas (RCC). Diagnostic markers that distinguish between FLCN‐related RCC and sporadic RCC have not been investigated, and many patients with undiagnosed BHD fail to receive proper medical care. We investigated the histopathology of 27 RCCs obtained from 18 BHD patients who were diagnosed by genetic testing. Possible somatic mutations of RCC lesions were investigated by DNA sequencing. Western blotting and immunohistochemical staining were used to compare the expression levels of FLCN and glycoprotein non‐metastatic B (GPNMB) between FLCN‐related RCCs and sporadic renal tumors (n = 62). The expression of GPNMB was also evaluated by quantitative RT‐PCR. Histopathological analysis revealed that the most frequent histological type was chromophobe RCC (n = 12), followed by hybrid oncocytic/chromophobe tumor (n = 6). Somatic mutation analysis revealed small intragenic mutations in six cases and loss of heterozygosity in two cases. Western blot and immunostaining analyses revealed that FLCN‐related RCCs showed overexpression of GPNMB and underexpression of FLCN, whereas sporadic tumors showed inverted patterns. GPNMB mRNA in FLCN‐related RCCs was 23‐fold more abundant than in sporadic tumors. The distinctive expression patterns of GPNMB and FLCN might identify patients with RCCs who need further work‐up for BHD.     

Inactivation of BHD in sporadic renal tumors

Studies of families with Birt-Hogg-Dubé syndrome (BHD) have recently revealed protein-truncating mutations in the BHD gene, leading to tumorigenesis of the skin and of different cell types of kidney. To additionally evaluate the role of BHD in kidney tumorigenesis, we studied 39 sporadic renal tumors of different cell types: 7 renal oncocytomas, 9 chromophobe renal cell carcinomas (RCCs), 11 papillary RCCs, and 12 clear cell RCCs. We screened for BHD mutations and identified a novel somatic mutation in exon 13: c.1939_1966delinsT in a papillary RCC. We performed loss of heterozygosity (LOH) analysis on 28 matched normal/tumor sets, of which 10 of 28 (36%) demonstrated LOH: 2 of 6 (33%) chromophobe RCCs, 5 of 6 (83%) papillary RCCs, 3 of 12 (25%) clear cell RCCs, but 0 of 4 renal oncocytomas. BHD promoter methylation status was examined by a methylation-specific PCR assay of all of the tumors. Methylation was detected in 11 of 39 (28%) sporadic renal tumors: 2 of 7 (29%) renal oncocytomas, 1 of 9 (11%) chromophobe RCCs, 4 of 11 (36%) papillary RCCs, and 4 of 12 (33%) clear cell RCCs. Five tumors with methylation also exhibited LOH. Mutation and methylation were absent in 9 kidney cancer cell lines. Our results showed that somatic BHD mutations are rare in sporadic renal tumors. The alternatives, LOH and BHD promoter methylation, are the two possible inactivating mechanisms involved. In conclusion, unlike other hereditary kidney cancer-related genes (i.e., VHL and MET), which are cell type-specific, BHD is involved in the entire spectrum of histological types of renal tumors, suggesting its major role in kidney cancer tumorigenesis.     

Comparative analyses of overall survival in patients with anaplastic lymphoma kinase-positive and matched wild-type advanced nonsmall cell lung cancer

BACKGROUND:

The purpose of this study was to investigate the overall survival (OS) of patients with advanced ALK‐positive nonsmall cell lung cancer (NSCLC) who were managed in the pre‐ALK inhibitor era and to compare their survival with that of a matched case cohort of ALK wild‐type (WT) patients.

METHODS:

Data from 1166 patients who had stage IIIB/IV NSCLC with nonsquamous histology were collected from the NSCLC database of Seoul National University Hospital between 2003 and 2009. ALK fluorescence in situ hybridization (FISH) was used to analyze 262 patients who either had the WT epidermal growth factor receptor (EGFR) or were nonresponders to previous EGFR tyrosine kinase inhibitor (TKI) therapy. Overall survival (OS) was compared between 3 groups: 1) ALK‐positive patients, 2) EGFR mutation‐positive patients, and 3) ALK‐WT/EGFR‐WT patients. Progression‐free survival (PFS) after first‐line chemotherapy and EGFR TKIs also was analyzed.

RESULTS:

Twenty‐three patients were ALK‐positive according to FISH analysis and did not receive ALK inhibitors during follow‐up. The median OS for ALK‐positive patients, EGFR mutation‐positive patients, and WT/WT patients was 12.2 months, 29.6 months, and 19.3 months, respectively (vs EGFR mutation‐positive patients, P = .001; vs WT/WT, P = .127). The PFS after first‐line chemotherapy for the 3 groups was not different. However, the PFS for patients who received EGFR TKIs was shorter in ALK‐positive patients compared with the other 2 groups (vs EGFR mutation‐positive patients, P < .001; vs WT/WT, P < .021).

CONCLUSIONS:

In the pre‐ALK inhibitor era, ALK‐positive patients experienced the shortest survival, although it did not differ statistically from that of WT/WT patients. Although their responses to platinum‐based chemotherapy were not different from comparator groups, ALK‐positive patients were even more resistant to EGFR TKI treatment than WT/WT patients. Cancer 2012;3579–3586. © 2011 American Cancer Society.     

Sequential Use of Anaplastic Lymphoma Kinase Inhibitors in Japanese Patients With ALK-Rearranged Non–Small-Cell Lung Cancer: A Retrospective Analysis

Background

Second-generation anaplastic lymphoma kinase (ALK) inhibitors, such as alectinib and ceritinib, have recently been approved for treatment of ALK-rearranged non–small-cell lung cancer (NSCLC). An optimal strategy for using 2 or more ALK inhibitors has not been established. We sought to investigate the clinical impact of sequential use of ALK inhibitors on these tumors in clinical practice.

In vivo imaging models of bone and brain metastases and pleural carcinomatosis with a novel human EML4‐ALK lung cancer cell line

EML4‐ALK lung cancer accounts for approximately 3–7% of non‐small‐cell lung cancer cases. To investigate the molecular mechanism underlying tumor progression and targeted drug sensitivity/resistance in EML4‐ALK lung cancer, clinically relevant animal models are indispensable. In this study, we found that the lung adenocarcinoma cell line A925L expresses an EML4‐ALK gene fusion (variant 5a, E2:A20) and is sensitive to the ALK inhibitors crizotinib and alectinib. We further established highly tumorigenic A925LPE3 cells, which also have the EML4‐ALK gene fusion (variant 5a) and are sensitive to ALK inhibitors. By using A925LPE3 cells with luciferase gene transfection, we established in vivo imaging models for pleural carcinomatosis, bone metastasis, and brain metastasis, all of which are significant clinical concerns of advanced EML4‐ALK lung cancer. Interestingly, crizotinib caused tumors to shrink in the pleural carcinomatosis model, but not in bone and brain metastasis models, whereas alectinib showed remarkable efficacy in all three models, indicative of the clinical efficacy of these ALK inhibitors. Our in vivo imaging models of multiple organ sites may provide useful resources to analyze further the pathogenesis of EML4‐ALK lung cancer and its response and resistance to ALK inhibitors in various organ microenvironments.