Journal of Cancer Therapy, 2013, 4, 54-58 Published Online September 2013 (
Better Selection Model for EML4-ALK Fusion Gene Test
in Patients with Non-Small-Cell Lung Cancer*
Dekel Shlomi1, Amir Onn1, Maya Gottfried2, Jair Bar1, Haim Biran1, Maya Ilouze1, Addie Dvir3,
Hovav Nechushtan4, Lior Soussan-Gutman3, Nir Peled1#
1Pulmonary-Oncology Unit, Chaim Sheba Medical Center, Tel Hashomer, Israel; 2Oncology Department, Meir Medical Center, Kfar
Saba, Israel; 3Oncotest-TEVA, Teva Pharmaceutical Industries LTD., Shoham, Israel; 4Sharett Institute of Oncology, Hadassah He-
brew University Medical Center, Jerusalem, Israel.
Received July 5th, 2013; revised August 6th, 2013; accepted August 14th, 2013
Copyright © 2013 Dekel Shlomi et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background: In the last decade, the search for gene mutations in lung cancer has been constantly growing. EGFR,
KRAS mutations and, recently, the EML4-ALK fusion can guide the selection of treatment for patients who carry a
specific mutation. Methods: During 2010-2011, EML4-ALK fusion test has been performed in Israel, mostly for wild
type EGFR non-squamous NSCLC patients based on fluorescent in-situ hybridization (FISH) technique to detect
EML4-ALK rearrangements. Results: Between January 2010 and December 2011, 3341 patients were diagnosed with
lung cancer in Israel. Of the 2997 patients with NSCLC 687 had squamous cell carcinoma and 2310 had non-squamous
NSCLC. This study focused on available 125 non-squamous NSCLC cases in which analysis for EML4-ALK rear-
rangement was available. All were negative for EGFR mutation. Nineteen (15.2%) were found positive for the fusion, a
figure 2 - 10 times higher compared with previously reported findings. The EML4-ALK fusion was significantly more
prevalent in younger male patients (52.1 vs. 61.3 years, p = 0.049), in whom every additional year reduced the chance
to find the fusion by 7% [CI = 0.93 (0.88 - 0.99), p = 0.03]. Conclusions: A stepwise approach based on histology and
prior EGFR analysis to detect EML4-ALK fusion is highly efficient with a related increased yield of detection. We
recommend testing patients with non-squamous cell lung carcinoma after ruling out an EGFR mutation. The chance to
find the ALK fusion is significantly greater in young er men.
Keywords: Lung Cancer; EML4-ALK; Gene Mutation; EGFR; Histology
1. Introduction
In the past few years, a novel therapeutic approach to
lung cancer treatment has been integrated into clinical
practice. The epid ermal growth factor receptor 1 (HER1/
EGFR) inhibitors, such as Erlotinib (Tarceva, Genentech,
USA) and Gefitinib (Iressa, AstraZeneca, UK), were the
first two oral drugs to demonstrate efficacy in patients
who harbored an activating mutation in the EGFR gene
[1,2]. Searching for other gene mutations as possible
therapeutic targets, Soda et al. identified, in 2007, a
unique rearrangement of the anaplastic lymphoma kinase
(ALK) gene in 6.7% (5/75) Japanese patients with non-
small-cell lung cancer (NSCLC) who were negative for
the EGFR mutation [3]. In this study, the ALK rear-
rangement was described as a small inversion within
chromosome 2p, resulting in the formation of a fusion
gene comprising portions of the echinoderm microtubule-
associated protein-like 4 (EML4) gene and the ALK gene.
The ALK gene is a target for research and has been tar-
geted in anaplastic large cell lymphoma [4] and inflam-
matory myofibroblastic tumor (IMT) [4,5]. In lung can-
cer, the EML4-ALK fusion gene was found almost ex-
clusively in wild-type EGFR and KRAS adenocarcino-
mas [6-10]. Similar results were reported by Wong et al.,
although two out of the 13 ALK positive tumors were
described as comprised of mixed squamous and glandu-
lar components [8]. The discovery of EML4-ALK fusion
as a therapeutic target in lung cancer led to the develop-
*Jair Bar received honoraria and reimbursement for the attendance of a
scientific conference from Pfizer. Hovav Nechushtan participated in
hase IV Sutent study by Pfizer. Lior Soussan-Gutman is an employee
of “Teva Pharmaceutical Industries” LTD. All other authors declared
no conflict of interests.
#Corresponding author.
Copyright © 2013 SciRes. JCT
Better Selection Model for EML4-ALK Fusion Gene Test in Patients with Non-Small-Cell Lung Cancer 55
ment of an ALK tyrosine-kinase inhibitor (TKI) Crizo-
tinib (Xalkori, Pfizer, USA), for advanced NSCLC pa-
tients who harbor this mutation [11].
This article summarizes our experience in identifying
EML4-ALK fusion in NSCLC patients, in the Israeli
population during the period 2010-2011.
2. Materials and Methods
This study summarized our experience with EML4-ALK
analysis performed from Januar y 2010 to December 2011.
The study was approved by an inter-institutional review
board. The analysis has been performed mostly to wild
type EGFR NSCLC patients with non-squamous cell
histology. Patients with insufficient tissue for genetic
testing, or for whom EML4-ALK fluorescent in-situ hy-
bridization (FISH) was inconclusive, were excluded.
When the tumor area had been determined on the hema-
toxylin and eosin (H&E) slide from a formalin-fixed
paraffin-embedded (FFPE) patient specimen, an ALK
gene rearrangement was assessed utilizing the Vysis
ALK break-apart FISH kit (Abbott Molecular). Identifi-
cation probes for LSI ALK 5’ probe (Spectrum Green)
and LSI ALK 3’ p robes (Spectrum Orange) we re a pplied,
hybridized, and assessed along with standard controls. At
least 50 non-overlapping nuclei were analyzed, and the
localization of the LSI ALK 5’ probe (green) and LSI
ALK 3’ probe (orange) signals were recorded and inter-
preted accordin g to manuf acturer’s guid elines. A positive
result for a ALK rearrangement were considered if 15%
of cells or more had split 3’ ALK and 5’ ALK signals
apart by >2 times the signal size or a single 3’ ALK sig-
nal (Figure 1).
Statistical analysis: Student’s t-test and chi-square test
were used to examine associations between the ALK
gene rearrangement and independent covariates. Uncon-
ditional logistic regression was used to assess the odd s of
having an ALK gene rearrangement with respect to risk
factors (such as sex and age) and risks were expressed in
terms of odds ratios and respective 95% confidence in-
3. Results
Between January 2010 and December 2011 lung cancer
was diagnosed in 3341 patients in Israel. Among them,
344 patients had SCLC and 2997 had NSCLC. In the
NSCLC group 687 had squamous cell carcinoma and
2310 had non-squamous NSCLC. In this study we fo-
cused on 125 NSCLC patients whom their EML4-ALK
analysis was available (Table 1 ). EML4 -ALK fu sion was
detected in 19 patients (15.2%), of whom 10 were men
and 9 women. The average age of the ALK positive
group was 56.4 years, non-significantly lower than the
average age of 61.3 years of the ALK negative patients
(p = 0.14). However, whe n age was strati fied accordin g to
Figure 1. FISH assay in NSCLC patient positive for EML4-
ALK fusion. Result were considered positive if more than
15% of cells had split 3’ ALK (Spectrum Orange) and 5’
ALK (Spectrum Green) signals apart by >2 times signal size
or single 3’ ALK signal (arrow) in at least 50 non-overlap-
ping nuclei.
Table 1. Clinical characteristic of patients with EML4-ALK
fusion test in non-squamous, EGFR negative, NSCLC pa-
tients in Israel, during 2010-2011.
p-valueALK– ALK+ ALLCharacteristic
106 (84.8%)19 (15.2%) 125
No. of patients
50 (47.2%) 10 (52.6%) 60 Male
0.66 56 (52.8%) 9 (47.4%) 65 Female
0.14 61.3 ± 11.9 56.4 ± 12.9
Age (yrs)
Mean ± SD
0.049 61.96 ± 12.152.1 ± 13.2 Male
0.9 60.7 ± 11.8 61.2 ± 11.4 Female
Ever smoked
27 (40.3%) 6 (66.7%) No
0.13 40 (59.7%) 3 (33.3%) Yes
39 10 Unknown
EGFR: epidermal growth factor receptor.
sex, we found the ALK fusion to be more common in
younger men; 52.1 vs. 62 years of age (p = 0.049). When
unconditional logistic regression was used to assess the
odds of having the ALK fusion with respect to risk fac-
tors, we found that for men, every additional year lessens
the chance to find the fusion by 7% [CI = 0.93 (0.88 -
0.99), p = 0.03]. Smoking information was available for
9 ALK positive patients, in whom 6 (66.7%) were life-
time never smok ers. In the ALK negative patients group,
smoking information was available for 67 patients, in
whom 27 (40.3%) were lifetime never smokers. There
Copyright © 2013 SciRes. JCT
Better Selection Model for EML4-ALK Fusion Gene Test in Patients with Non-Small-Cell Lung Cancer
were no statistical significant differences regarding
smoking habits between the ALK positive and the ALK
negative patients (p = 0.13). When the origin of the bi-
opsy was tested for ALK fusion, we found no correlation
between biopsies that were taken from the lung origin or
the metastasis.
4. Discussion
While EGFR mutation is prevalent in 15% - 20% of
NSCLC patients, being more common in Asian ethnicity,
women and non-smokers [1,12-14], the EML4-ALK fu-
sion is less prevalent, more common in Asian population,
younger and non-smokers or light smokers. To date, no
conclusive data was published regarding sex-depended
Ethnic variation of the EML4-ALK fusion gene shows
a frequency as high as 7.5% (9 of 120) of NSCLC
specimens from Italy and Spain [15],while in US, Koi-
vunen et al. found a frequency of 1.5% (2 of 138 ) in US
Caucasian populatio n [16]. In this study, Korean patients
had a non-significant 3.6% (total population 3%) more
prevalence of the EML4-ALK fusion. In Japan, Soda et
al. [3] detected the EML4-ALK fusion in 6.7% of the
NSCLC patients while Inamura et al. [6] detected ALK
rearrangement in 2.26% (5 of 221) patients with primary
lung cancer. In Chinese population, 4.9% (13/266) were
positive for EML4-ALK fusion, in the study of Wong et
al. of NSCLC pat ie nt s [8].
Histology: In this study, patients were selected to the
EML4-ALK fusion test if they had non-squamous lung
carcinoma and wild type EGFR gene analysis. To the
best of our knowledge, all studies excep t one found ALK
fusion in non-squamous lung carcinomas. Inamura et al.
found EML4-ALK fusion in 11 of 363 in primary lung
cancer, all adenocarcinomas of papillary or acinar type
[7]. Similarly, all of the EML4-ALK fusion-containing
tumors in both Koivunen et al. [16] and Takahashi [10]
studies were adenocarcinomas. In Shaw et al., 18 of 19
EML4-ALK fusion tumors were adenocarcinoma, pre-
dominantly of the signet ring cell subtype, and one was
of the adenosquamous type, however this result could be
due to selection bias [9]. In Chinese population, 11 of the
EML4-ALK fusion were adenocarcinomas, and 2 were
unusual carcinomas with mixed squamous and glandular
components [8]. The most outstanding results were found
in the Martelli et al. study in Italy, in which, of the 9
NCSLC patients with EML4-ALK fusion, 3 were found
to be adenocarcinoma, 2 adenosquamous carcinoma and
4 squamous cell carcinomas [15].
EGFR and KRAS mutations: Several studies found the
EML4-ALK fusion exclusively in wild-type EGFR and
KRAS tumors in NSCLC patients [6-10,17]. Only one of
8 patients with EML4-ALK fusion adenocarcinoma of
the lung, in the Koivunen et al. study, was positive for
EGFR mutation, while all of them were negative for
KRAS mutation [16]. In the Martelli et al. study, all of
the 9 patients with EML4-ALK fusion lung cancer were
negative for EGFR mutation, but KRAS mutation was
detected in one patient with lung adenocarcinoma [15].
Based on this data, ALK fusion testing in Israel is fo-
cused on patients with non-squamous lung carcinoma
who were negative for the EGFR mutation. By selecting
NSCLC patients with non-squamous lung carcinoma and
negative EGFR mutation, we could expect a higher
prevalence of the EML4-ALK fusion and were thus hop-
ing to cut on unnecessary high cost tests. Accordingly,
out of the tested population in our study a frequency of
15.2% of EML4-ALK fusion was found, which is 2 - 10
times higher than previously reported [6,8,15,16].
Age: We found a non-significant lower age for patients
in the EML4-ALK fusion group (56.4 vs. 61.3 years, p =
0.14). However, mean age of males with positive results
was 9.86 years younger than males with negative result
(52.1 vs. 61.96 years, p = 0.049). We also found that
among men, every additional year reduced the chance to
find the fusion by 7%, which was statistically sig nificant
[CI = 0.93 (0.88 - 0.99), p = 0.03]. These findings were a
further support to previous studies that indicated a statis-
tically significant prevalence of ALK fusion in younger
patients [7-9,17]. In the Wong et al. study, the ALK
positive group had median age of 59 years, compared
with the ALK negativ e patients, in whom the median age
was 64 (p = 0.018) [8 ]. Inamura et al. found that patients
with EML4-ALK lung cancers were younger (mean age
56 vs. 64 years, p = 0.0062) [7]. Four of 11 pa t ients (36%)
with EML4-ALK-positive lung cancers were below 50
years of age, as compared with 12 of 242 patients ( 5.0%)
with EML4-ALK-negativ e lung cancers (p = 0.00038). In
the Shaw study, patients with EML4-ALK fusion tumors
were of a significantly younger median age of 52 com-
pared with 66 years of age in patients with EGFR muta-
tion and 64 years of age in patients with WT/WT status
[9]. However, in the Martelli et al. study, no age correla-
tion was not e d [15].
Sex: Previous studies found mixed results in regard to
sex differences. However, this study showed no sex
preferences for the EML4-ALK fusion (10 males vs. 9
females, p = 0.66). In Japan, 4 of the 5 patients who were
positive for the EML4-ALK fusion genes were females
[10]. In a combined US and Korean population study, the
frequency of EML4-ALK fusion was non-significantly
higher in females (4%) versus males (2%) [16]. The
study of Shaw et al. in US, mostly of non-Asian popula-
tion, identified a significantly greater prevalence of
EML4-ALK fusion in men (23%) than in women (9%)
[9], while Martelli et al. did not find any correlation with
Copyright © 2013 SciRes. JCT
Better Selection Model for EML4-ALK Fusion Gene Test in Patients with Non-Small-Cell Lung Cancer 57
sex [15].
Smoking: Our data collection was not comprehensive
enough to determine smoking habits differences among
groups. Smoking exposure data was collected from 76 of
125 patients (60.8%), but no statistically significant dif-
ferences were found among the groups. Several studies
showed that the EML4-ALK fusion was more frequent in
never smokers or light smokers [8-10,16-17]. In the
Koivunen et al. study, the EML4-ALK fusion was de-
tected significantly more frequently in patients with lim-
ited smoking history (<10 pack-years) compared with
tumors from smokers [16]. In the Shaw et al. study [9],
patients who were positive for EML4-ALK fusion were
more likely to be never smokers or light smokers, com-
pared with patients in the wild-type cohort (p < 0.001).
Also in the Wong et al. study, the EML4-ALK fusion
was significantly higher in non-smokers [8]. In the Ta-
kahashi et al. study, the EML4-ALK fusion was pre-
dominantly found in non-smokers or light smokers [10].
Other studies found no association between EML4-ALK
fusion and smoking hab i ts [7,15] .
5. Conclusion
EML4-ALK fusion in selected patients in Israel with
non-squamous cell lung carcinoma, in whom the EGFR
mutation test was negative, was found to be more fre-
quent (15.2%) than expected when no selection was in-
troduced. In this group, the ALK fusion was significantly
more prevalent in younger men. Based on this study and
on published literature, in order to avoid unnecessary
ALK fusion tests, we recommend selecting patients with
non-squamous cell lung carcinoma in whom both the
EGFR and the KRAS mutations are negative.
6. Acknowledgements
The authors thank Oncotest-TEVA Pharmaceutical in-
dustries LTD. for their assistance in data management.
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