Anaplastic lymphoma kinase rearrangement in lung Cancer: Its biological and clinical significance

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]

Contents lists available at ScienceDirect

Respiratory Investigation journal homepage: www.elsevier.com/locate/resinv

Review

Anaplastic lymphoma kinase rearrangement in lung Cancer: Its biological and clinical significance Gouji Toyokawa, MD, PhD, Takashi Seto, MD, PhDn Department of Thoracic Oncology, National Kyushu Cancer Center, 3-1-1 Notame, Minami-ku, Fukuoka 811-1395, Japan

art i cle i nfo

ab st rac t

Article history:

Anaplastic lymphoma kinase (ALK) has been found to fuse with other partners, such as

Received 17 April 2014

echinoderm microtubule-associated protein-like 4 (EML4), leading to potent malignant transfor-

Received in revised form

mation in lung cancer, specifically non-small-cell lung cancer (NSCLC). The frequency of

4 June 2014

the ALK rearrangement in patients with NSCLC is reported to be 4–7%, and the rearrange-

Accepted 25 June 2014

ment is frequently observed in relatively younger patients, non- or light smokers and those with adenocarcinoma histology without other genetic disorders, such as mutations of the epidermal growth factor receptor gene. Crizotinib, which is a first-in-class ALK tyrosine kinase

Keywords: Non-small cell lung cancer Oncogenic drivers Anaplastic lymphoma kinase ALK inhibitors

inhibitor (TKI), was shown to be effective and well tolerated in ALK-positive NSCLC patients by a single-arm phase I study. Furthermore, a phase III randomized study demonstrated the superiority of crizotinib to standard chemotherapy (pemetrexed or docetaxel) in the treatment of NSCLC patients harboring the ALK rearrangement who had received one prior platinum-based chemotherapy. However, the mechanisms of resistance to crizotinib are major concerns when administering crizotinib to ALK-positive NSCLC patients, and they include second mutations and a gain in the copy number of the ALK gene, activation of other oncogenes, etc. Treatment strategies to overcome these mechanisms of resistance have been developed, including the use of second-generation ALK inhibitors, such as alectinib and ceritinib, heat shock protein 90 inhibitors and so on. In this article, we review the pre-clinical and clinical data regarding the biologal and clinical significance of the ALK rearrangement in lung cancer. & 2014 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

Abbreviations: ALK, EML4,

anaplastic lymphoma kinase; NSCLC,

non-small cell lung cancer; EGFR, epidermal growth factor receptor;

echinoderm microtubule-associated protein-like 4; CI,

survival; AEs,

adverse events; TKI,

confidence interval; PFS,

tyrosine kinase inhibitor; CNG,

progression-free survival; OS,

copy number gain; CNS,

rat sarcoma viral oncogene homolog; KIT, v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog; MET, oncogene; IGF1R,

insulin-like growth factor 1 receptor; HSP90,

heat shock protein 90; FISH,

overall

central nervous system; KRAS,

Kirsten

met proto-

fluorescence in-situ hybridization;

IHC, immunohistochemistry; RT-PCR, reverse transcriptase-polymerase chain reaction; IC50, half maximal inhibitory concentration n Corresponding author. Tel.: þ81 92 541 3231; fax: þ81 92 551 4585. E-mail address: [email protected] (T. Seto). http://dx.doi.org/10.1016/j.resinv.2014.06.005 2212-5345/& 2014 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

Please cite this article as: Toyokawa G, Seto T. Anaplastic lymphoma kinase rearrangement in lung Cancer: Its biological and clinical significance. Respiratory Investigation (2014), http://dx.doi.org/10.1016/j.resinv.2014.06.005

2

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]

Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Characteristics of the ALK gene. . . . . . . . . . . . 3. Pathological roles of the ALK gene in cancer . 4. Clinical characteristics of ALK-positive NSCLC 5. ALK testing . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. Crizotinib . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Second-generation ALK inhibitors . . . . . . . . . . 8. Mechanisms of resistance to ALK inhibitors . . 9. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conflict of interest . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

Introduction

Lung cancer remains the leading cause of cancer-related deaths and a serious social problem worldwide, including Japan [1]. Although the treatment outcomes of lung cancer still have room for improvement, the aggressive investigation of diagnostic and treatment options has led to the earlier detection and improved treatment outcomes of patients with lung cancer. In particular, the genetic insights into the pathogenesis of lung cancer have paved the way for a new era in the treatment of lung cancer. Oncogenic drivers have been identified to play essential roles in the tumorigenesis, survival and proliferation in lung cancer, especially adenocarcinoma [2]. Mutations of the EGFR gene are representative, and a lot of evidence has been established for the significance of EGFR mutations at both the basic research and clinical levels [3]. Several randomized phase III studies revealed that patients with NSCLC harboring the sensitive EGFR mutations benefit more from EGFR-TKIs compared with cytotoxic chemotherapeutic regimens, the PFS between the patients treated with EGFR-TKIs and chemotherapy were 9.5–13.7 and 4.6–6.9, respectively [4–9]. Despite the remarkable efficacy of EGFR-TKIs for EGFR-mutated NSCLC, the occurrence of resistance, such as that resulting from the T790M mutation, amplification of the MET gene, transformation to small cell cancer, etc. is inevitable [10]. Treatment strategies to overcome these mechanisms of resistance have also been developed and applied in the clinical setting. In 2007, Prof. Mano's group reported that the chromosomal rearrangement involving the ALK and EML4 genes showed potent transforming activity in NSCLC, and that clinically, the EML4–ALK fusion transcript was detected in 6.7% (5/75) of the NSCLC patients examined [11]. Importantly, a chemical inhibitor of ALK markedly inhibited the growth of BA/F3 cells expressing EML4–ALK, thus suggesting that the aberrant ALK rearrangement might be a potential therapeutic target. Clinically, a single-arm study showed that a first-in-class ALK TKI, crizotinib (PF-02341066), showed excellent anti-tumor activity and good tolerability for patients with ALK-rearranged NSCLC [12,13], and based on those results, crizotinib was approved as the first licensed ALK inhibitor for ALKþ NSCLC in not only Japan, but also in the U.S. Furthermore, a phase III study comparing crizotinib with standard chemotherapy (pemetrexed or docetaxel) showed the significant superiority of

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

. . . . . . . . . . . .

2 2 2 3 3 4 5 7 7 7 7 7

crizotinib to standard chemotherapy in the setting of advanced NSCLC associated with the ALK rearrangement in patients previously treated with platinum-based chemotherapy [14]. As in the resistance to EGFR–TKIs, some resistance mechanisms, such as gatekeeper mutations or a gain in the copy number of the ALK gene and activation of other oncogenes, have been identified to confer intrinsic or acquired resistance to crizotinib, and treatment strategies to overcome these mechanisms of resistance have been developed, including the use of second-generation ALK inhibitors, such as alectinib and ceritinib, and HSP90 inhibitors [15,16]. Thus, although the basic and clinical studies have gradually clarified some of the concerns associated with the ALK rearrangement in lung cancer, there exist unresolved concerns, including the best method for treating patients with ALK-positive NSCLC. We herein review the pre-clinical and clinical data regarding the biologal and clinical significance of the ALK rearrangement in lung cancer.

2.

Characteristics of the ALK gene

ALK, which encodes a trans-membrane receptor tyrosine kinase that is a member of the insulin receptor superfamily, is located on chromosome 2p23. Native ALK expression can be observed only in the small intestine, testes and the nervous system of adult human tissues [17,18]. However, the endogenous roles of ALK in humans remain poorly understood. In particular, although ALK appears to play an important role in the development of the nervous system, mice deficient in ALK are viable and exhibit no apparent developmental or tissue abnormalities [19]. Like other transmembrane tyrosine kinases, dimerization considered to promote the normal activation of the receptor [20].

3.

Pathological roles of the ALK gene in cancer

A fusion gene comprising chromosomes 2 and 5 was the firstreported ALK rearrangement in anaplastic large-cell lymphomas [18,21], and later, the ALK rearrangement was identified in several types of cancer, such as NSCLC, inflammatory myofibroblastic tumors, renal cell carcinoma, colorectal cancer and breast cancer [11,22–25]. In addition to the

Please cite this article as: Toyokawa G, Seto T. Anaplastic lymphoma kinase rearrangement in lung Cancer: Its biological and clinical significance. Respiratory Investigation (2014), http://dx.doi.org/10.1016/j.resinv.2014.06.005

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]

rearrangement, activating mutations of the ALK gene were observed in pediatric neuroblastoma and anaplastic thyroid cancer [26,27]. With regard to the ALK rearrangement in NSCLC, Soda et al. reported that the ALK gene fuses with EML4, resulting in a potent transformation activity in NSCLC, and that mice transduced with NIH3T3 cells expressing the EML4–ALK fusion gene can be successfully treated with the inhibition of ALK [11]. A retroviral cDNA expression library from a patient-derived adenocarcinoma specimen showed that cDNAs comprising 3926 base pairs and containing an open reading frame for a protein of 1059 amino acids were amplified. The aminoterminal portion of the predicted protein was identical to that of human EML4 with the carboxy-terminal portion being identical to the intracellular domain of human ALK, indicating that the cDNA was composed of a fusion product of EML4 and ALK. The transforming potential of the EML4–ALK fusion gene was also confirmed by the transduction of mouse 3T3 fibroblasts with the fusion gene, with the cells transduced with either each gene or a kinase dead fusion gene showing no increase in the cell proliferation. The growth-stimulating effect of the EML4–ALK fusion was shown to depend on the EML4–ALK dimerization through the basic domain of EML4. In concrete terms, EML4–ALK oligomerizes constitutively in cells through the coiled coil domain present within the EML4 region, and becomes activated to exert potent oncogenicity via the aberrant activation of downstream signaling pathways, such as the Ras/MAPK, PI3K/AKT and JAK/STAT pathways [28,29]. The growth of BA/F3 cells expressing EML4–ALK was markedly suppressed by WHI-P154, a chemical inhibitor of ALK, suggesting that the fusion gene might be a potential therapeutic target. Different truncations of EML4 are known to result in the different variant forms of the EML4–ALK fusion gene, and variants 1 (33%), 2 (9%) and 3a/b (22%) are the major variants detected [30]. Preclinical data reported by Heuchman et al. showed that variant 2 is more sensitive to ALK inhibitors than variants 1 and 3a/b, which was considered to be due to the differential protein stability among the variants; however, it remains unclear whether the type of variant can predict the response to treatment with ALK inhibitors in ALK-rearranged patients [12,31]. Other partners, such as the kinesin family member 5B (KIF5B), TRK-fused gene (TFG) and huntingtin interacting protein 1 (HIP1) genes, have also been identified to fuse with the ALK gene in patients with lung cancer, thus resulting in oncogenic transformation [32–34].

4. Clinical characteristics of ALK-positive NSCLC The clinicopathological analyses have demonstrated that the frequency of patients with NSCLC harboring the EML4–ALK fusion gene is approximately 5%, and that this fusion gene is frequently observed in relatively younger patients, non- or light smokers and those with an adenocarcinoma histology without other genetic disorders, while a definite racial difference in the frequency is not observed [35–37]. Regarding the histological characteristics, the adenocarcinomas associated with the fusion gene often exhibit a mucinous cribriform

3

pattern or signet-ring cell subtype [38]. With regard to other histologies, several reports showed the presence of the ALK rearrangement in squamous cell carcinoma and small-cell lung cancer [39–41]; however, its significance and targetable potential in these histologies remain to be elucidated.

5.

ALK testing

Three representative testing modalities exist to detect the ALK rearrangement: FISH, IHC and RT-PCR (Fig. 1), and according to the guidance for ALK gene testing in lung cancer patients published by the Japan Lung Cancer Society, these modalities are associated with various strong and weak points when used to detect the rearrangement. The pros of the FISH assay (Fig. 1A) are that it is capable of detecting unknown fusions, it is an established method used to diagnose lymphoma, it was adopted as a screening method in clinical studies of crizotinib, it is able to evaluate tumors at the cellular level and permits the testing of FFPE samples, while the cons include its cost, relatively long turnaround time, requirement for technical experience and the difficulty in evaluating a translocation on the short arm of chromosome 2. At present, the FISH assay is used as a companion diagnostic modality when deciding whether to administer crizotinib and ceritinib. IHC (Fig. 1B) also has several pros, such as the capability of detecting unknown fusions, the relatively easy technique, the capability of testing FFPE samples, the short turnaround time and being adopted at numerous facilities, while the cons of IHC include the lack of visual confirmation of fusion genes, significant dependence of the results on the clone of the antibody and the detection system used, and false-positivity/ negativity. Several studies reported improved detection using different IHC detection systems and antibodies [42]. The strong points of RT-PCR (Fig. 1C) are its high sensitivity and specificity, while its weak points are the requirement of RNA of good quality (sometimes difficult in FFPE), the requirement for multiplexing and multiple PCRs to cope with numerous patterns of translocation, the incapability of detecting unknown fusions and the inability to confirm the presence of tumor cells. Although several reports showed a high concordance in the ALK testing results between IHC and FISH, and recommended using IHC as the initial test [43–47], the potential for discordance in the results between FISH and IHC still remains a concern when detecting the ALK fusion gene and predicting to response to ALK inhibitors. According to a report by the Japan Lung Cancer Society, among 225 IHCþ patients, FISHþ and FISH results were reported for 213 (94.7%) and 12 (5.3%), respectively, while among 2112 IHC patients, FISHþ and FISH results were reported for 36 (1.7%) and 2076 (98.3%), respectively. Furthermore, Cabillic et al. reported that among 150 ALK-positive NSCLCs out of 3244 total cases, only 80 specimens were classified as ALK positive by both IHC and FISH, and they recommended ALK testing by both FISH and IHC in routine practice [48]. When predicting the response to ALK inhibitors, the discordance appears to be important. For instance, Chihara et al. reported that the response rate of patients whose ALK

Please cite this article as: Toyokawa G, Seto T. Anaplastic lymphoma kinase rearrangement in lung Cancer: Its biological and clinical significance. Respiratory Investigation (2014), http://dx.doi.org/10.1016/j.resinv.2014.06.005

4

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]

Fig. 1 – Representative images of (A) FISH using the Vysis ALK Break-Apart FISH Probe Kit (Abbott Molecular, Inc.), (B) IHC of an adenocarcinoma with an acinar subtype using an antibody that specifically detects ALK (5A4, Nichirei), (C) multiplex RT-PCR using the methods described in Ref. [35] and (D) an electropherogram of variant 1 of the EML4–ALK fusion gene (1, no template control; 2 and 3, patient samples; 4, positive control; and 5, GAPDH).

positivity was confirmed only by FISH was 48%, while patients whose ALK positivity was confirmed by both FISH and IHC or RT-PCR achieved an 81% response rate, and this difference was statistically significant (P ¼0.007) [49]. In the near future, the reasons for the differences should be elucidated in order to help identify ALK-positive patients who are more likely to respond to ALK inhibitors prior to the administration of the agents.

6.

Crizotinib

Crizotinib (PF-02341066) was originally developed as an inhibitor of c-MET, and was proven to show potent inhibitory activities against ALK via the induction of apoptosis and G1–S phase cell cycle arrest [50–52]. ROS1-rearranged lung cancer was also shown to benefit from crizotinib treatment [53,54]. Therefore, crizotinib has recently attracted much attention in the treatment of lung cancer. Table 1 shows a summary of the data from the PROFILE trials. A phase I dose-escalation trial to evaluate crizotinib in patients with advanced cancer and the second part of a phase I study that expanded the cohort of patients with ALK-translocated NSCLC showed a remarkable activity and good tolerability for crizotinib in patients with the ALK fusion

gene (PROFILE 1001) [12,13]. The data for the expanded cohort showed an objective response rate of approximately 60% (95% CI 52.3–68.9) with a median PFS of 9.7 months (95% CI 7.7– 12.8) [13]. The estimated OS at six and 12 months was 87.9% (95% CI 81.3–92.3) and 74.8% (95% CI 66.4–81.5), respectively. The Japanese data from the PROFILE 1001 trial (n¼ 15) were reported by Prof. Mitsudomi in the JLCS2011, which showed that the response rate in the Japanese patients was as high as 93.3%, which was assumed to be due to the accurate confirmation of the ALK fusion by one or more diagnostic modalities (ALK-Lung Cancer Study Group). One-hundred four of the 149 patients (97%) experienced treatment-related AEs, with most reporting gastrointestinal AEs, such as nausea, vomiting, diarrhea and constipation, and visual disorders, which are uncommon in patients treated with other molecular-targeted agents. The grade 3 or 4 AEs were as follows: neutropenia (6.0%), an elevated alanine aminotransferase level (4.0%), hypophosphatemia (4.0%) and lymphopenia (4.0%). The results of the phase I trial led to the approval of crizotinib for use in patients with ALK-rearranged NSCLC in 74 countries or more. A randomized phase III study (PROFILE 1007) was conducted worldwide to compare the efficacy of crizotinib to that of chemotherapy (pemetrexed or docetaxel) in patients with advanced ALK-positive lung cancer who had previously been

Please cite this article as: Toyokawa G, Seto T. Anaplastic lymphoma kinase rearrangement in lung Cancer: Its biological and clinical significance. Respiratory Investigation (2014), http://dx.doi.org/10.1016/j.resinv.2014.06.005

0.1804

0.54

0.821 (0.536–1.255) 0.454 (0.346–0.596) 10.9 m 7.0 m 172 171 2014 PROFILE 1014

Crizotinib PEMþ CBDCA or CDDP

74% 45%

o0.0001

3.0 m (2.6–4.3) 20% (14–26) 174 PEM or DOC

No., number; pts, patients; CI, confidence interval; PEM, pemetrexed; DOC, docetaxel; CBDCA, carboplatin; and CDDP, cisplatin. Estimated OS at six months. b Estimated OS at 12 months. c Interim analysis, not final results.

o0.0001

1.02 (0.68–1.54) o0.001 0.49 (0.37–0.64) o0.001 173 Crizotinib 2013

a

– –

87.9%a and 74.8%b 20.3 m (18.1  not reached)c 22.8 m (18.6  not reached)c Not described Not described –

9.7 m (7.7–12.8) 7.7 m (6.0–8.8) – 143 2012

PROFILE 1001 (expanded cohort) PROFILE 1007

Crizotinib

60.8% (52.3–68.9) 65% (57–72)

Hazard ratio (95% CI) P-value Response rate (95% CI) No. of pts Treatment regimen Year Trial

Table 1 – The PROFILE trials investigating the safety and efficacy of crizotinib.

–

Hazard ratio (95% CI) Median (m) Median (95% CI)

P-value

OS PFS

P value

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]

5

treated with platinum-based chemotherapy (Table 1) [14]. Crizotinib and chemotherapy achieved objective response rates of 65% (95% CI 58–72) and 20% (95% CI 14–26), respectively, and crizotinib achieved a significantly longer PFS (primary endpoint) than chemotherapy (7.7 versus 3.0 months, respectively). Furthermore, the overall quality of life reported by the enrolled patients was significantly better in the crizotinib arm than in the chemotherapy arm. Various factors, such as the small number of events noted during the follow-up period and the cross-over in patients treated with chemotherapy to crizotinib as part of a separate study, appeared to result in no significant differences in the OS (crizotinib, 20.3 versus chemotherapy, 22.8 months, respectively; hazard ratio for death in the crizotinib group, 1.02; 95% CI 0.68–1.54; P¼ 0.54). Although two patients in the crizotinib arm died of interstitial lung disease, the toxicity profile was acceptable. Therefore, crizotinib is thought to be useful as a standard regimen for second-line or beyond therapy in patients with ALK-positive lung cancer. Furthermore, a phase III study (PROFILE 1014) comparing crizotinib (n¼ 172) with platinum-based chemotherapy with pemetrexed plus carboplatin or cisplatin (n¼ 171) in the first-line setting showed a superior PFS for crizotinib over standard chemotherapy in the chemotherapy-naïve patients with ALK-rearranged NSCLC, as shown in Table 1 (median 10.9 versus 7.0 months, respectively; hazard ratio for death in the crizotinib group, 0.454; 95% CI 0.346–0.596; Po0.0001). In addition, a significantly higher objective response rate was observed in the crizotinib group (74% versus 45%, Po0.0001). No statistically significant improvement in the OS was demonstrated (hazard ratio, 0.821; 95% CI 0.536–1.255; P¼ 0.1804), which might have been partly due to the cross-over of 109 out of 171 patients receiving standard chemotherapy by the time of the data cut-off. With regard to toxicities, XALKORIs (crizotinib) Indication and Important Safety Information summarized the toxic profile of crizotinib across clinical trials (n ¼1255), and showed that the serious and fatal toxicities included druginduced hepatotoxicity (fatal outcome: 0.2%), interstitial lung disease/pneumonitis (any grade: 2.5%; grade 3/4: 0.9%, fatal: 0.5%), QT interval prolongation (2.7%), bradycardia with a heart rate less than 50 beats per minute (11%) and embryofetal toxicity. These data are therefore considered to be useful when deciding whether to administer crizotinib.

7.

Second-generation ALK inhibitors

Many second-generation ALK inhibitors, such as alectinib, ceritinib and AP26133, have been developed and are currently under evaluation in clinical trials (Table 2). Most of these inhibitors have lower IC50 values for inhibiting ALK than crizotinib, and importantly, show some degree of blocking activity against crizotinib-resistance [16]. In this section, we describe the data regarding representative second-generation ALK inhibitors. Alectinib is a potent, relatively selective and orally available inhibitor of ALK with ten-fold greater potency than crizotinib, and was also shown to effectively inhibit ALK harboring the gatekeeper mutation (L1196M) [55]. The agent

Please cite this article as: Toyokawa G, Seto T. Anaplastic lymphoma kinase rearrangement in lung Cancer: Its biological and clinical significance. Respiratory Investigation (2014), http://dx.doi.org/10.1016/j.resinv.2014.06.005

6

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]

Table 2 – Representative ALK inhibitors currently being used in the clinic or under development. Compound

Company

Representative targets

Reached phase

PF02341066 (crizotinib) LDK378 (ceritinib) CH/RO5424802 (alectinib) AP26113 ASP3026 X-396

Pfizer Novartis Chugai/Roche Ariad Astellas Xcovery

ALK52, ALK59, ALK55, ALK63, ALK65 ALK66

Approved Approved Phase III Phase I/II Phase I Phase I

c-MET52, ROS153, NTRK154 IGF-1R59 GAK55, LTK55 EGFR63

Table 3 – Mechanisms of resistance to ALK inhibitors. ALK dominant

ALK non-dominant Partially ALK-dependent

ALK-independent

was also shown to effectively inhibit cyclin G associated kinase (GAK) and leukocyte receptor tyrosine kinase (LTK) [55]. A single-arm, open-label, phase I/II trial conducted in Japan demonstrated the excellent efficacy of alectinib for treating ALK-rearranged NSCLC patients whose ALKpositivity was confirmed by both FISH and IHC or RT-PCR analyses [56]. In the phase I portion of the study, 24 patients were treated at doses of 20–300 mg twice daily, and no doselimiting toxicities were observed up to the highest dose, leading to the recommendation of a dose of 300 mg twice daily in the phase 2 trial. Forty-six patients were treated at that dose, and the objective response rate was as high as 93.5% (95% CI 82.1–98.6). Strikingly, no progression of CNS lesions was observed in 15 patients proven to harbor brain metastases by the time of data cutoff. With regard to treatment-related AEs, the most common included dysgeusia (30%), increased AST (28%), increase blood bilirubin (28%), increased blood creatinine (26%), rash (26%), constipation (24%) and increased ALT (22%). Twelve (26%) of the 46 patients experienced AEs of grade 3, such as a decreased neutrophil count and increased blood creatinine phosphokinase level, while no grade 4 AEs or deaths were reported. Serious AEs were observed in five patients, which included interstitial lung disease, brain edema, tumor hemorrhage and sclerosing cholangitis, and the AEs other than brain edema were considered to be related to the agent. The PFS at oneyear was 83% (95% CI 68–92), although the median was not reached [57]. The clinical activity for crizotinib-resistant ALKpositive NSCLC was under evaluation, and preliminary data suggested that alectinib achieved an overall response rate of 54.5% in those patients [58]. Orally available ceritinib also potently inhibits ALK in a relatively selective manner, with a low IC50 of 0.00015 mM, and it also inhibits IGF1R (Table 2) [59]. The results of a phase I trial of ceritinib in ALK-rearranged NSCLC were reported in

Secondary mutations in the ALK gene ALK CNG CNS resistance

Increased autophosphorylation of EGFR Amplification of KIT Transformation to sarcomatoid carcinoma Amplification of MET KRAS mutations EGFR mutations Autophagy

March 2014 [60]. A total of 130 patients with ALK-translocated NSCLC were enrolled in the dose-escalation and expansion phases. Based on the dose-limiting toxicities, such as diarrhea, vomiting, dehydration, elevated aminostransferase levels and hypophosphatemia, the maximum tolerated dose of ceritinib was set as 750 mg per day. Among 114 patients who received over 400 mg per day, the overall response rate was 58% (95% CI 48–67), while the median PFS of these patients was 7.0 months (95% CI 5.6–9.5). Similar to alectinib, ceritinib was also found to be effective against crizotinibresistant disease, i.e., the overall response rate was 56% (95% CI 45–67). This activity of ceritinib against crizotinib-resistant disease was also demonstrated preclinically [61]. The grade 3 or 4 AEs that occurred in more than 5% of the patients included an elevated ALT (21%), elevated AST (11%), diarrhea (7%), elevated lipase level (7%), nausea (5%), fatigue (5%) and vomiting (5%). Similar to crizotinib and alectinib, interstitial lung disease possibly due to ceritinib was observed in four patients, which resolved with the discontinuation of the agent and the standard treatments. Ceritinib has been approved for the use against ALK-positive NSCLC following treatment with crizotinib by U.S. FDA. The efficacy and tolerability of the compound was also confirmed in a Japanese population [62], and phases I, II and III studies are currently ongoing. AP26133 is a novel TKI that potently inhibits mutant activated forms of the ALK and EGFR genes, as well as TKIresistant forms, including L1196M of the ALK gene and T790M of the EGFR gene (Table 2) [16,63]. Preliminary data from an ongoing dose-finding phase I/II study of AP26133 for advanced malignancy refractory to standard treatment showed the efficacy and safety of the compound in NSCLC patients previously treated with ALK inhibitors or EGFR-TKIs [64]. These studies indicated that second-generation ALK inhibitors appear to be well tolerated and are strikingly effective

Please cite this article as: Toyokawa G, Seto T. Anaplastic lymphoma kinase rearrangement in lung Cancer: Its biological and clinical significance. Respiratory Investigation (2014), http://dx.doi.org/10.1016/j.resinv.2014.06.005

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]

in NSCLC patients harboring the ALK rearrangement, even those with resistance to crizotinib. Other ALK inhibitors, such as ASP3026 [65] and X-396 [66], are also currently under clinical evaluation (Table 2). Although it is not clear at present whether crizotinib or second-generation ALK inhibitors will be the superior treatment, a head-to-head study comparing crizotinib with the second-generation ALK inhibitors would clarify this point. In fact, a randomized phase III trial comparing alectinib with crizotinib is currently being performed to address this issue (NCT02075840).

8.

Mechanisms of resistance to ALK inhibitors

Despite the excellent efficacy of crizotinib in the setting of ALK-positive lung cancer, almost all patients eventually develop resistance to crizotinib, and Table 3 shows the various mechanisms conferring intrinsic or acquired resistance to crizotinib [15]. These mechanisms can be divided into two main groups: ALK-dominant or ALK non-dominant. The ALKdominant mechanisms include second mutations in the ALK gene, CNG of the fusion gene and inadequate local drug penetration into the CNS. L1196M and C1156Y in the ALK gene were the first-reported secondary mutations conferring resistance to crizotinib [67]. L1196M, which interferes with the binding of crizotinib as a gatekeeper mutation, corresponds to T315I in the BCR–ABL fusion gene [68] and T790M in the EGFR gene [69]. Other resistance mutations in the ALK gene have been discovered in the clinical setting or in mutagenesis screenings, including L1152R, 1151Tins, G1202R, S1206Y, F1174C, D1203N, G1269A and L1196M [15,70,71]. With regard to CNG of the fusion gene, two of 11 ALK-positive lung cancer patients who acquired resistance to crizotinib were reported to exhibit new onset ALK CNG, which may occur in combination with resistance mutations [72]. The CNS lesions are currently considered to be a ‘sanctuary’ for crizotinib due to the inadequate penetration of the drug into the CNS system [73–76]. The ALK non-dominant mechanisms of resistance to crizotinib include mutations of other oncogenes, such as the EGFR and KRAS genes [72], amplification of the KIT gene [77], increased autophosphorylation of EGFR [77] and transformation to sarcomatoid carcinoma [78]. In vivo analyses showed that imatinib could overcome the resistance occurring via the KIT amplification [77]. In addition, a recent study indicated the involvement of autophagy in the crizotinib resistance in an ALK-rearranged lung cancer cell line, which could be overcome by an inhibitor of autophagy, chloroquine [79]. Various treatment strategies to overcome these mechanisms of resistance have been developed, including second-generation ALK inhibitors and the use of HSP90 inhibitors [80,81]. In addition to the resistance to crizotinib, we previously reported a possible mechanism conferring resistance to alectinib via amplification of the MET gene, which can be overcome with crizotinib therapy [82]. This result suggested that patients acquiring resistance to the second-generation ALK inhibitors through MET amplification might benefit from crizotinib, leading to prolonged survival.

9.

7

Conclusion

We herein described the pre-clinical and clinical data about ALK-rearranged NSCLC and ALK inhibitors. Although the biological and clinical significance of ALK-rearranged NSCLC have been gradually clarified, there still remain concerns that need to be addressed with regard to ALK, such as the role of ALK inhibitors as a first-line treatment, which of the ALK inhibitors is the best, the significance of the sequential use of ALK inhibitors, the control of CNS metastases and the significance of the use of ALK inhibitors as a ‘beyond PD’ therapy. Future basic and clinical studies are warranted to elucidate these concerns, which will lead to improvements in the treatment outcomes in patients with the ALK rearrangement.

Conflict of interest Dr. Seto has received honoraria from Chugai Pharmaceutical Co., Ltd., and Eli Lilly Japan K.K. and received research funding from Chugai Pharmaceutical Co., Ltd., Pfizer Japan Inc., and Novartis Pharma K.K. Dr. Toyokawa declares no conflict of interest.

Acknowledgments We thank Brian Quinn for providing critical comments on the manuscript.

r e f e r e nc e s

[1] Sawabata N, Asamura H, Goya T, et al. Japanese Lung Cancer Registry Study: first prospective enrollment of a large number of surgical and nonsurgical cases in 2002. J Thorac Oncol 2010;5:1369–75. [2] Reck M, Heigener DF, Mok T, et al. Management of nonsmall-cell lung cancer: recent developments. Lancet 2013;382:709–19. [3] Mitsudomi T, Yatabe Y. Epidermal growth factor receptor in relation to tumor development: EGFR gene and cancer. FEBS J 2010;277:301–8. [4] Mok TS, Wu YL, Thongprasert S, et al. Gefitinib or carboplatin-paclitaxel in pulmonary adenocarcinoma. N Engl J Med 2009;361:947–57. [5] Mitsudomi T, Morita S, Yatabe Y, et al. Gefitinib versus cisplatin plus docetaxel in patients with non-small-cell lung cancer harbouring mutations of the epidermal growth factor receptor (WJTOG3405): an open label, randomized phase 3 trial. Lancet Oncol 2010;11:121–8. [6] Maemondo M, Inoue A, Kobayashi K, et al. Gefitinib or chemotherapy for non-small-cell lung cancer with mutated EGFR. N Engl J Med 2010;362:2380–8. [7] Zhou C, Wu YL, Chen G, et al. Erlotinib versus chemotherapy as first-line treatment for patients with advanced EGFR mutation-positive non-small-cell lung cancer (OPTIMAL, CTONG-0802): a multicenter, open-label, randomised, phase 3 study. Lancet Oncol 2011;12:735–42. [8] Sequist LV, Yang JC, Yamamoto N, et al. Phase III study of afatinib or cisplatin plus pemetrexed in patients with metastatic lung adenocarcinoma with EGFR mutations. J Clin Oncol 2013;31:3327–34.

Please cite this article as: Toyokawa G, Seto T. Anaplastic lymphoma kinase rearrangement in lung Cancer: Its biological and clinical significance. Respiratory Investigation (2014), http://dx.doi.org/10.1016/j.resinv.2014.06.005

8

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]

[9] Wu YL, Zhou C, Hu CP, et al. Afatinib versus cisplatin plus gemcitabine for first-line treatment of Asian patients with advanced non-small-cell lung cancer harbouring EGFR mutations (LUX-Lung 6): an open-label, randomized phase 3 trial. Lancet Oncol 2014;15:213–22. [10] Suda K, Mizuuchi H, Maehara Y, et al. Acquired resistance mechanisms to tyrosine kinase inhibitors in lung cancer with activating epidermal growth factor receptor mutation—diversity, ductility, and destiny. Cancer Metastasis Rev 2012;31:807–14. [11] Soda M, Choi YL, Enomoto M, et al. Identification of the transforming EML4–ALK fusion gene in non-small-cell lung cancer. Nature 2007;448:561–6. [12] Kwak EL, Bang YJ, Camidge DR, et al. Anaplastic lymphoma kinase inhibition in non-small-cell lung cancer. N Engl J Med 2010;363:1693–703. [13] Camidge DR, Bang YJ, Kwak EL, et al. Activity and safety of crizotinib in patients with ALK-positive non-small-cell lung cancer: updated results from a phase 1 study. Lancet Oncol 2012;13:1011–9. [14] Shaw AT, Kim DW, Nakagawa K, et al. Crizotinib versus chemotherapy in advanced ALK-positive lung cancer. N Engl J Med 2013;368:2385–94. [15] Camidge DR, Doebele RC. Treating ALK-positive lung cancer —early success and future challenges. Nat Rev Clin Oncol 2012;9:268–77. [16] Solomon B, Wilner KD, Shaw AT. Current status of targeted therapy for anaplastic lymphoma kinase-rearranged nonsmall cell lung cancer. Clin Phamacol Ther 2013;95:15–23. [17] Iwahara T, Fujimoto J, Wen D, et al. Molecular characterization of ALK, a receptor tyrosine kinase expressed specifically in the nervous system. Oncogene 1997;14:439–49. [18] Morris SW, Kirstein MN, Valentine MB, et al. Fusion of a kinase gene, ALK, to a nucleolar protein gene, NPM, in nonHodgkin’s lymphoma. Science 1994;263:1281–4. [19] Bilsland JG, Wheeldon A, Mead A, et al. Behavioral and neurochemical alterations in mice deficient in anaplastic lymphoma kinase suggest therapeutic potential for psychiatric indications. Neuropsychopharmacology 2008;33:685–700. [20] Souttou B, Carvalho NB, Raulais D, et al. Activation of anaplastic lymphoma kinase receptor tyrosine kinase induces neuronal differentiation through the mitogeneactivated protein kinase pathway. J Biol Chem 2001;276:9526–31. [21] Le Beau MM, Bitter MA, Larson RA, et al. The t(2;5)(p23;q35): a recurring chromosomal abnormality in Ki-1-positive anaplastic large cell lymphoma. Leukemia 1989;3:866–70. [22] Griffin CA, Hawkins ALK, Dvorak C, et al. Recurrent involvement of 2p23 in inflammatory myofibroblastic tumors. Cancer Res 1999;59:2776–80. [23] Debelenko LV, Raimondi SC, Daw N, et al. Renal cell carcinoma with novel VCL–ALK fusion: new representative of ALK-associated tumor spectrum. Mod Pathol 2011;24:430–42. [24] Lipson D, Capelletti M, Yelensky R, et al. Identification of new ALK and RET gene fusions from colorectal and lung cancer biopsies. Nat Med 2012;18:382–4. [25] Lin E, Li L, Guan Y, et al. Exon array profiling detects EML4– ALK fusion in breast, colorectal, and non-small cell lung cancers. Mol Cancer Res 2009;7:1466–76. [26] Chen Y, Takita J, Choi YL, et al. Oncogenic mutations of ALK kinase in neuroblastoma. Nature 2008;455:971–4. [27] Murugan AK, Xing M. Anaplastic thyroid cancers harbor novel oncogenic mutations of the ALK gene. Cancer Res 2011;71:4403–11. [28] Mano H. Non-solid oncogenes in solid tumors: EML4–ALK fusion genes in lung cancer. Cancer Sci 2008;99:2349–556.

[29] Chiarle R, Voena C, Ambrogio C, et al. The anaplastic lymphoma kinase in the pathogenesis of cancer. Nat Rev Cancer 2008;8:11–23. [30] Sasaki T, Rodig SJ, Chirieac LR, et al. The biology and treatment of EML4–ALK non-small cell lung cancer. Eur J Cancer 2010;46:1773–80. [31] Heuckmann JM, Balke-Want H, Malchers F, et al. Differential protein stability and ALK inhibitor sensitivity of EML4–ALK fusion variants. Clin Cancer Res 2012;18:4682–90. [32] Takeuchi K, Choi YL, Togashi Y, et al. KIF5B-ALK, a novel fusion oncokinase identified by an immunohistochemistrybased diagnostic system for ALK-positive lung cancer. Clin Cancer Res 2009;15:3143–9. [33] Rikova K, Guo A, Zeng Q, et al. Global survey of phosphotyrosine signaling identifies oncogenic kinases in lung cancer. Cell 2007;131:1190–203. [34] Fang DD, Zhang B, Gu Q, et al. HIP1-ALK, a novel ALK fusion variant that responds to crizotinib. J Thorac Oncol 2014;9:285–94. [35] Soda M, Isobe K, Inoue A, et al. A prospective PCR-based screening for the EML4–ALK oncogene in non-small cell lung cancer. Clin Cancer Res 2012;18:5682–9. [36] Gainor JF, Varghese AM, Ou SH, et al. ALK rearrangements are mutually exclusive with mutations in EGFR or KRAS: an analysis of 1683 patients with non-small cell lung cancer. Clin Cancer Res 2013;19:4273–81. [37] Camidge DR, Kono SA, Flacco A, et al. Optimizing the detection of lung cancer patients harboring anaplastic lymphoma kinase (ALK) gene rearrangements potentially suitable for ALK inhibitor treatment. Clin Cancer Res 2010;16:5581–90. [38] Takeuchi K, Soda M, Togashi Y, et al. RET, ROS1 and ALK fusions in lung cancer. Nat Med 2012;18:378–81. [39] Kim H, Park E, Kim YJ, et al. ALK rearrangement in a pure squamous cell carcinoma: the challenge of detection of ALK rearrangement. Virchows Arch 2013;462:597–9. [40] Toyokawa G, Taguchi K, Ohba T, et al. First case of combined small-cell lung cancer with adenocarcinoma harboring EML4–ALK fusion and an exon 19 EGFR mutation in each histological component. J Thorac Oncol 2012;7:e39–41. [41] Toyokawa G, Takenoyama M, Taguchi K, et al. An extremely rare case of small-cell lung cancer harboring variant 2 of the EML4–ALK fusion gene. Lung Cancer 2013;81:487–90. [42] Iwama E, Okamoto I, Harada T, et al. Development of anaplastic lymphoma kinase (ALK) inhibitors and molecular diagnosis in ALK rearrangement-positive lung cancer. Onco Targets Ther 2014;7:375–85. [43] Minca EC, Portier BP, Wang Z, et al. ALK status testing in nonsmall cell lung carcinoma: correlation between ultrasensitive IHC and FISH. J Mol Diagn 2013;15:341–6. [44] Sholl LM, Weremowica S, Gray SW, et al. Cobined use of ALK immunohistochemistry and FISH for optimal detection of ALK-rearranged lung adenocarcinomas. J Thorac Oncol 2013;8:322–8. ´ , et al. [45] Martinez P, Herna´ndez-Losa J, Montero MA Fluorescence in situ hybridization and immunohistochemistry as diagnostic methods for ALK positive non-small cell lung cancer patients. PLoS One 2013;8:322–8. [46] Conklin CM, Craddock KJ, Have C, et al. Immunohistochemistry is a reliable screening tool for identification of ALK rearrangement in non-small-cell lung carcinoma and is antibody dependent. J Thorac Oncol 2013;8:45–51. [47] Park HS, Lee JK, Kim DW, et al. Immunohistochemical screening for anaplastic lymphoma kinase (ALK) rearrangement in advanced non-small cell lung cancer patients. Lung Cancer 2012;77:288–92.

Please cite this article as: Toyokawa G, Seto T. Anaplastic lymphoma kinase rearrangement in lung Cancer: Its biological and clinical significance. Respiratory Investigation (2014), http://dx.doi.org/10.1016/j.resinv.2014.06.005

respiratory investigation ] (] ] ] ]) ] ] ] –] ] ]

[48] Cabillic F, Gros A, Dugay F, et al. Parallel FISH and immunohistochemical studies of ALK status in 3244 nonsmall-cell lung cancers reveal major discordances. J Thorac Oncol 2014;9:295–306. [49] Chihara D, Suzuki R. More on crizotinib. N Engl J Med 2011;364:776–7. [50] Christensen JG, Zou HY, Arango ME, et al. Cytoreductive antitumor activity of PF-2341066, a novel inhibitor of anaplastic lymphoma kinase and c-Met, in experimental models of anaplastic large-cell lymphoma. Mol Cancer Ther 2007;6:3314–22. [51] McDermott U, Lafrate AJ, Gray NS, et al. Genomic alterations of anaplastic lymphoma kinase may sensitize tumors to anaplastic lymphoma kinase inhibitors. Cancer Res 2008;68:3389–95. [52] Cui JJ, Tran-Dube´ M, Shen H, et al. Structure based drug design of crizotinib (PF-02341066), a potent and selective dual inhibitor of mesenchymal-epithelial transition factor (cMET) kinase and anaplastic lymphoma kinase (ALK). J Med Chem 2011;54:6342–63. [53] Komiya T, Thomas A, Khozin S, et al. Response to crizotinib in ROS1-rearranged non-small-cell lung cancer. J Clin Oncol 2012;30:3425–6. [54] Vaishnavi A, Capelletti M, Le AT, et al. Oncogenic and drugsensitive NTRK1 rearrangements in lung cancer. Nat Med 2013;19:1469–72. [55] Sakamoto H, Tsukaguchi T, Hiroshima S, et al. CH5424802, a selective ALK inhibitor capable of blocking the resistant gatekeeper mutant. Cancer Cell 2011;19:679–90. [56] Seto T, Kiura K, Nishio M, et al. CH5424802 (RO5424802) for patients with ALK-rearranged advanced non-small-cell lung cancer (AF-001JP study): a single-arm, open-label, phase 1-2 study. Lancet Oncol 2013;14:590–8. [57] Inoue A, Nishio M, Kiura K, et al. One-year follow-up of a Phase I/II study of a highly selective ALK inhibitor CH5424802/ RO5424802 in ALK-rearranged advanced non-small cell lung cancer (NSCLC). In: Proceedings of WCLC; 2013. P3.11-034. [58] Gadgeel S, Ou SH, Chiappori AA, et al. A phase 1 dose escalation study of a new ALK inhibitor, CH5424802/ RO5424802, in ALKþ non-small cell lung cancer (NSCLC) patients who have failed crizotinib (AF-002JG/NP28761, NCT01588028). In: Proceedings of WCLC; 2013. Abstract16.06. [59] Marsilje TH, Pei W, Chen B, et al. Synthesis, structure-activity relationships, and in vivo efficacy of the novel potent and selective anaplastic lymphoma kinase (ALK) inhibitor 5Chloro-N2-(2-isopropoxy-5-methyl-4-(piperidin-4-yl) phenyl)-N4-(2-(isopropylsulfonyl)phenyl)pyrimidine-2,4diamine (LDK378) currently in Phase 1 and Phase 2 clinical trials. J Med Chem 2013;56:5675–90. [60] Shaw AT, Kim DW, Mehra R, et al. Ceritinib in ALKrearranged non-small-cell lung cancer. N Engl J Med 2014;370:1189–97. [61] Friboulet L, Li N, Katayama R, et al. The ALK inhibitor ceritinib overcomes crizotinib resistance in non-small cell lung cancer. Cancer Discov 2014;4:662–73. [62] Seto T, Murakami H, Hirai F, et al. Phase I study of the ALK inhibitor LDK378 in Japanes patients with advanced, ALKrearranged NSCLC and other tumors harboring genetic ALK alterations. In: Proceedings of WCLC; 2013. P1.11-007. [63] Rivera VM, Wang F, Anjum R, et al. AP26113 is a dual ALK/ EGFR inhibitor: characterization against EGFR T790M in cell and mouse models of NSCLC. In: Proceedings of the 103rd AACR Annual Meeting, AACR’12. Chicago, USA; 2012. [64] Camidge DR, Bazhenova L, Salgia R, et al. First-in-human dose-finding study of the ALK/EGFR inhibitor AP26113 in patients with advanced malignancies: updated results. J Clin

[65]

[66]

[67]

[68]

[69]

[70]

[71]

[72]

[73]

[74]

[75]

[76]

[77]

[78]

[79]

[80]

[81]

[82]

9

Oncol 2013;31 (suppl; abstr 8031), http://meetinglibrary.asco. org/print/1167681. Kuromitsu S, Mori M, Shimada I, et al. Antitumor activities of ASP3026 against EML4–ALK-dependent tumor models. Mol Cancer Ther 2011;10 (suppl; abstr A227), http://mct. aacrjournals.org/cgi/content/meeting_abstract/10/ 11_MeetingAbstracts/A227. Lovly CM, Heuckmann JM, de Stanchina E, et al. Insights into ALK-driven cancers revealed through development of novel ALK tyrosine kinase inhibitors. Cancer Res 2011;71:4920–31. Choi YL, Soda M, Yamashita Y, et al. EML4–ALK mutations in lung cancer that confer resistance to ALK inhibitors. N Engl J Med 2010;363:1734–9. Gorre ME, Mohammed M, Ellwood K. Clinical resistance to STI-571 cancer therapy caused by BCR-ABL gene mutation or amplification. Science 2001;293:876–80. Pao W, Miller VA, Politi KA, et al. Acquired resistance of lung adenocarcinomas to gefitinib or erlotinib is associated with a second mutation in the EGFR kinase domain. PLoS Med 2005;2:e73. Zhang S, Wang F, Keats J, et al. Crizotinib-resistant mutants of EML4–ALK identified through an accelerated mutagenesis screen. Chem Biol Drug Des 2011;78:999–1005. Gridelli C, Peters S, Sgambato A, et al. ALK inhibitors in the treatment of advanced NSCLC. Cancer Treat Rev 2014;40:300–6. Doebele RC, Pilling AB, Aisner DL, et al. Mechanisms of resistance to crizotinib in patients with ALK gene rearranged non-small cell lung cancer. Clin Cancer Res 2012;18:1472–82. Maillet D, Martel-Lafay I, Arpin D, et al. Ineffectiveness of crizotinib on brain metastases in two cases of lung adenocarcinoma with EML4–ALK rearrangement. J Thorac Oncol 2013;8:e30–1. Kaneda H, Okamoto I, Nakagawa K. Rapid response of brain metastasis to crizotinib in a patient with ALK rearrangement-positive non-small-cell lung cancer. J Thorac Oncol 2013;8:e32–3. Gainor JF, Ou SH, Logan J, et al. The central nervous system as a sanctuary site in ALK-positive non-small cell lung cancer. J Thorac Oncol 2013;8:1570–3. Peled N, Zach L, Liran O, et al. Effective crizotinib schedule for brain metastases in ALK rearrangement metastatic nonsmall-cell lung cancer. J Thorac Oncol 2013;8:e112–3. Katayama R, Shaw AT, Khan TM, et al. Mechanisms of acquired crizotinib resistance in ALK-rearranged lung cancers. Sci Transl Med 2012;4:120ra17. Kobayashi Y, Sakao Y, Ito S, et al. Transformation to sarcomatoid carcinoma in ALK-rearranged adenocarcinoma, which developed acquired resistance to crizotinib and received subsequent chemotherapies. J Thorac Oncol 2013;8:e75–8. Ji C, Zhang L, Cheng Y, et al. Induction of autophagy contributes to crizotinib resistance in ALK-positive lung cancer. Cancer Biol Ther 2014;15:570–7. Katayama R, Khan TM, Benes C, et al. Therapeutic strategies to overcome crizotinib resistance in non-small cell lung cancers harbouring the fusion oncogene EML4–ALK. Proc Natl Acad Sci USA 2011;108:7535–40. Chen Z, Akbay EA, Mikse OR, et al. Co-clinical trials demonstrate superiority of crizotinib to chemotherapy in ALK-rearranged non-small cell lung cancer and predict strategies to overcome resistance. Clin Cancer Res 2014;20:1204–11. Gouji T, Takashi S, Mitsuhiro T, et al. Crizotinib can overcome acquired resistance to CH5424802: is amplification of the MET gene a key factor? J Thorac Oncol 2014;9:e27–8.

Please cite this article as: Toyokawa G, Seto T. Anaplastic lymphoma kinase rearrangement in lung Cancer: Its biological and clinical significance. Respiratory Investigation (2014), http://dx.doi.org/10.1016/j.resinv.2014.06.005