Clinicopathological Characteristics of Patients with Non-Small-Cell Lung Cancer Who Harbor EML4-ALK Fusion Gene: A Meta-Analysis

BackgroundA novel fusion gene of echinoderm microtubule-associated protein-like 4 (EML4) and anaplastic lymphoma kinase (ALK) has been recently identified in non-small-cell lung cancers (NSCLCs). Patients with the EML4-ALK fusion gene demonstrate unique clinicopathological and physiological characteristics. Here we present a meta-analysis of large-scale studies to evaluate the clinicopathological characteristics of NSCLC patients harboring the EML4-ALK fusion gene.MethodsBoth English and Chinese databases were systematically used to search the materials of the clinicopathological characteristics of patients with NSCLC harboring the EML4-ALK fusion gene. Pooled relative risk (RR) estimates and the 95% confidence intervals (95% CI) were calculated with the fixed or random effect model. Publication bias and chi-square test were also calculated.Results27 retrospective studies were included in our meta-analysis. These studies included a total of 6950 patients. The incidence rate of EML4-ALK fusion in NSCLC patients was found to be 6.8% (472/6950). The correlation of the EML4-ALK fusion gene and clinicopathological characteristics of NSCLC patients demonstrated a significant difference in smoking status, histological types, stage, and ethnic characteristics. The positive rate of the EML4-ALK fusion gene expression in females were slightly higher than that in males, but not significantly (P = 0.52). In addition, the EML4-ALK fusion gene was mutually exclusive of the EGFR and KRAS mutation genes (P = 0.00).ConclusionOur pooled analysis revealed that the EML4-ALK fusion gene was observed predominantly in adenocarcinoma, non-smoking and NSCLC patients, especially those diagnosed in the advanced clinical stage of NSCLC. Additionally, the EML4-ALK fusion gene was exclusive of the EGFR and KRAS mutation genes. We surmise that IHC assay is a valuable tool for the prescreening of patients with ALK fusion gene in clinical practice, and FISH assay can be performed as a confirmation method. These insights might be helpful in guiding the appropriate molecular target therapy for NSCLC.     

Anaplastic Lymphoma Kinase Rearrangement in Digestive Tract Cancer: Implication for Targeted Therapy in Chinese Population

Background

Anaplastic lymphoma kinase (ALK) rearrangements define a subgroup of lung cancer which is eligible to targeted kinase inhibition. The aim of this study is to observe the incidence rate of ALK fusion in a large cohort of Chinese digestive tract cancer patients.

Patients and Methods

Tissue microarray (TMA) was constructed from 808 digestive tract cancer cases, including 169 esophageal squamous cell carcinoma, 182 gastric cancer and 457 colorectal cancer (CRC) cases. We tested all cases for ALK expression via a fully automated immunohistochemistry (IHC) assay. The IHC-positive cases were subjected to fluorescence in situ hybridization (FISH), real-time polymerase chain reaction (qRT-PCR), target gene enrichment and sequencing for confirmation of ALK gene rearrangement and discovery of novel fusion partner.

Results

Among the tested cases, 2 (0.44%) CRC cases showed positive both by IHC and FISH. By qRT-PCR, EML4–ALK fusion was found in one IHC-positive CRC case. In another IHC-positive CRC case, target gene enrichment and sequencing revealed ALK was fused to a novel partner, spectrin beta non-erythrocytic 1 (SPTBN1). One gastric cancer case showed partially positive IHC result, but no fusion was found by FISH and gene sequencing.

Conclusions

The incidence rate of ALK gene fusion in Chinese CRC patients was 0.44%,but not detectable in gastric and esophageal cancers. The novel SPTBN1 -ALK fusion, together with other ALK fusion genes, may become a potential target for anti-ALK therapy.     

Genomic Aberrations in Crizotinib Resistant Lung Adenocarcinoma Samples Identified by Transcriptome Sequencing

ALK-break positive non-small cell lung cancer (NSCLC) patients initially respond to crizotinib, but resistance occurs inevitably. In this study we aimed to identify fusion genes in crizotinib resistant tumor samples. Re-biopsies of three patients were subjected to paired-end RNA sequencing to identify fusion genes using deFuse and EricScript. The IGV browser was used to determine presence of known resistance-associated mutations. Sanger sequencing was used to validate fusion genes and digital droplet PCR to validate mutations. ALK fusion genes were detected in all three patients with EML4 being the fusion partner. One patient had no additional fusion genes. Another patient had one additional fusion gene, but without a predicted open reading frame (ORF). The third patient had three additional fusion genes, of which two were derived from the same chromosomal region as the EML4-ALK. A predicted ORF was identified only in the CLIP4-VSNL1 fusion product. The fusion genes validated in the post-treatment sample were also present in the biopsy before crizotinib. ALK mutations (p.C1156Y and p.G1269A) detected in the re-biopsies of two patients, were not detected in pre-treatment biopsies. In conclusion, fusion genes identified in our study are unlikely to be involved in crizotinib resistance based on presence in pre-treatment biopsies. The detection of ALK mutations in post-treatment tumor samples of two patients underlines their role in crizotinib resistance.     

Identification of Five Driver Gene Mutations in Patients with Treatment-Na?ve Lung Adenocarcinoma in Taiwan

Background

It is important to select appropriate targeted therapies for subgroups of patients with lung adenocarcinoma who have specific gene alterations.

Methods

This prospective study was a multicenter project conducted in Taiwan for assessment of lung adenocarcinoma genetic tests. Five oncogenic drivers, including EGFR, KRAS, BRAF, HER2 and EML4-ALK fusion mutations, were tested. EGFR, KRAS, BRAF and HER2 mutations were assessed by MALDI-TOF MS (Cohort 1). EML4-ALK translocation was tested by Ventana method in EGFR-wild type patients (Cohort 2).

Results

From August 2011 to November 2013, a total of 1772 patients with lung adenocarcinoma were enrolled. In Cohort 1 analysis, EGFR, KRAS, HER2 and BRAF mutations were identified in 987 (55.7%), 93 (5.2%), 36 (2.0%) and 12 (0.7%) patients, respectively. Most of these mutations were mutually exclusive, except for co-mutations in seven patients (3 with EGFR + KRAS, 3 with EGFR + HER2 and 1 with KRAS + BRAF). In Cohort 2 analysis, 29 of 295 EGFR-wild type patients (9.8%) were positive for EML4-ALK translocation. EGFR mutations were more common in female patients and non-smokers and KRAS mutations were more common in male patients and smokers. Gender and smoking status were not correlated significantly with HER2, BRAF and EML4-ALK mutations. EML4-ALK translocation was more common in patients with younger age.

Conclusion

This was the first study in Taiwan to explore the incidence of five oncogenic drivers in patients with lung adenocarcinoma and the results could be valuable for physicians in consideration of targeted therapy and inclusion of clinical trials.     

Will the clinical development of 4th-generation “double mutant active” ALK TKIs (TPX-0131 and NVL-655) change the future treatment paradigm of ALK+ NSCLC?

Our current treatment paradigm of advanced anaplastic lymphoma kinase fusion (ALK+) non-small cell lung cancer (NSCLC) classifies the six currently approved ALK tyrosine kinase inhibitors (TKIs) into three generations. The 2nd-generation (2G) and 3rd-generation (3G) ALK TKIs are all “single mutant active” with varying potencies across a wide spectrum of acquired single ALK resistance mutations. There is a vigorous debate among clinicians which is the best upfront ALK TKI is for the first-line (1L) treatment of ALK+ NSCLC and the subsequent sequencing strategies whether it should be based on the presence of specific on-target ALK resistance mutations or not. Regardless, sequential use of “single mutant active” ALK TKIs will eventually lead to double ALK resistance mutations in cis. This has led to the creation of fourth generation (4G) “double mutant active” ALK TKIs such as TPX-0131 and NVL-655. We discuss the critical properties 4G ALK TKIs must possess to be clinically successful. We proposed conceptual first-line, second-line, and molecularly-based third-line registrational randomized clinical trials designed for these 4G ALK TKIs. How these 4G ALK TKIs would be used in the future will depend on which line of treatment the clinical trial design(s) is adopted provided the trial is positive. If approved, 4G ALK TKIs may usher in a new treatment paradigm for advanced ALK+ NSCLC that is based on classifying ALK TKIs based on the intrinsic functional capabilities (“singe mutant active” versus “double mutant active”) rather than the loosely-defined “generational” (first-, second-,third-,fourth-) classification and avoid the current clinical approaches of seemingly random sequential use of 2G and 3G ALK TKIs.     

Will the clinical development of 4th-generation “double mutant active” ALK TKIs (TPX-0131 and NVL-655) change the future treatment paradigm of ALK+ NSCLC?

Our current treatment paradigm of advanced anaplastic lymphoma kinase fusion (ALK+) non-small cell lung cancer (NSCLC) classifies the six currently approved ALK tyrosine kinase inhibitors (TKIs) into three generations. The 2nd-generation (2G) and 3rd-generation (3G) ALK TKIs are all “single mutant active” with varying potencies across a wide spectrum of acquired single ALK resistance mutations. There is a vigorous debate among clinicians which is the best upfront ALK TKI is for the first-line (1L) treatment of ALK+ NSCLC and the subsequent sequencing strategies whether it should be based on the presence of specific on-target ALK resistance mutations or not. Regardless, sequential use of “single mutant active” ALK TKIs will eventually lead to double ALK resistance mutations in cis. This has led to the creation of fourth generation (4G) “double mutant active” ALK TKIs such as TPX-0131 and NVL-655. We discuss the critical properties 4G ALK TKIs must possess to be clinically successful. We proposed conceptual first-line, second-line, and molecularly-based third-line registrational randomized clinical trials designed for these 4G ALK TKIs. How these 4G ALK TKIs would be used in the future will depend on which line of treatment the clinical trial design(s) is adopted provided the trial is positive. If approved, 4G ALK TKIs may usher in a new treatment paradigm for advanced ALK+ NSCLC that is based on classifying ALK TKIs based on the intrinsic functional capabilities (“singe mutant active” versus “double mutant active”) rather than the loosely-defined “generational” (first-, second-,third-,fourth-) classification and avoid the current clinical approaches of seemingly random sequential use of 2G and 3G ALK TKIs.     

Mixed responses to first-line alectinib in non-small cell lung cancer patients with rare ALK gene fusions: A case series and literature review

Anaplastic lymphoma kinase (ALK) fusion is a well-defined biomarker for ALK tyrosine kinase inhibitors (TKIs) treatment in non-small cell lung cancer (NSCLC). Alectinib, a second-generation ALK-TKI, has been shown to have significantly longer progression-free survival (PFS) than first-generation ALK inhibitors in untreated ALK-rearranged NSCLC patients. However, its clinical efficacy on rare ALK fusions remains unclear. Herein, two advanced NSCLC patients received first-line alectinib treatment, given their positive ALK fusion status as determined by immunohistochemistry (IHC) testing results. Patients showed limited clinical response (PFS: 4 months) and primary resistance to alectinib respectively. Molecular profiling using next-generation sequencing (NGS) further revealed a striatin (STRN)-ALK fusion in the first patient accompanied by MET amplification, and a LIM domain only protein 7 (LMO7)-ALK fusion in another patient without any other known oncogenic alterations. Both patients demonstrated improved survival after they switched to second-line crizotinib (PFS: 11 months) and ensartinib (PFS: 18 months), respectively, up till the last follow-up assessment. In conclusion, the clinical efficacy of ALK-TKIs including alectinib for lung cancer with uncommon ALK gene fusions is still under evaluation. This study and literature review results showed mixed responses to alectinib in NSCLC patients who harboured rare ALK fusions. Comprehensive molecular profiling of tumour is thus strongly warranted for precise treatment strategies.     

Analysis of Driver Mutations in Female Non-Smoker Asian Patients with Pulmonary Adenocarcinoma

Previous studies have revealed that EGFR mutation and/or EML4?CALK gene fusion rate was higher in the non-smoker Asian females with pulmonary adenocarcinoma. The aim of this study is to determine the distribution of known oncogenic driver mutations in the female non-smoker Asian patients with pulmonary adenocarcinoma. 104 consecutively resected lung adenocarcinomas from 396 non-smoker females (less than 100 cigarettes in a lifetime) at a single institution (Tongji University, Shanghai, China) were analyzed for mutations in EGFR, EML4?ALK, KRAS, HER2, BRAF, and PIK3CA. 73 (70.2?%) tumors harbored EGFR mutations; among these, 28 were deletions in exon 19, 44 were L858R missense changes, and eight were T790M mutations. 10 (9.6?%) harbored EML4?ALK fusions, two harbored KRAS mutations, two harbored BRAF mutations, and two harbored PI3K mutations. A majority of the mutations were mutually exclusive, except two with EGFR mutation and BRAF mutation, one with EML4?ALK fusions and PI3K mutation. Thus, 82.7?% (86 of 104; 95?% CI, 75.4?C90.0?%) of lung adenocarcinomas from non-smoker females were found to harbor the well-known oncogenic mutations in five genes. Lung cancer in non-smoking Asian females is a distinct entity, with majority of this subgroup being developed by the oncogenic mutations. The prospective mutation examination in this population will be helpful for devising a targeted therapy for a majority of the patients.     

In Vitro Drug Sensitivity Tests to Predict Molecular Target Drug Responses in Surgically Resected Lung Cancer

BackgroundEpidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) and anaplastic lymphoma kinase (ALK) inhibitors have dramatically changed the strategy of medical treatment of lung cancer. Patients should be screened for the presence of the EGFR mutation or echinoderm microtubule-associated protein-like 4 (EML4)-ALK fusion gene prior to chemotherapy to predict their clinical response. The succinate dehydrogenase inhibition (SDI) test and collagen gel droplet embedded culture drug sensitivity test (CD-DST) are established in vitro drug sensitivity tests, which may predict the sensitivity of patients to cytotoxic anticancer drugs. We applied in vitro drug sensitivity tests for cyclopedic prediction of clinical responses to different molecular targeting drugs.MethodsThe growth inhibitory effects of erlotinib and crizotinib were confirmed for lung cancer cell lines using SDI and CD-DST. The sensitivity of 35 cases of surgically resected lung cancer to erlotinib was examined using SDI or CD-DST, and compared with EGFR mutation status.ResultsHCC827 (Exon19: E746-A750 del) and H3122 (EML4-ALK) cells were inhibited by lower concentrations of erlotinib and crizotinib, respectively than A549, H460, and H1975 (L858R+T790M) cells were. The viability of the surgically resected lung cancer was 60.0 ± 9.8 and 86.8 ± 13.9% in EGFR-mutants vs. wild types in the SDI (p = 0.0003). The cell viability was 33.5 ± 21.2 and 79.0 ± 18.6% in EGFR mutants vs. wild-type cases (p = 0.026) in CD-DST.ConclusionsIn vitro drug sensitivity evaluated by either SDI or CD-DST correlated with EGFR gene status. Therefore, SDI and CD-DST may be useful predictors of potential clinical responses to the molecular anticancer drugs, cyclopedically.     

Spectrum of oncogenic driver mutations in lung adenocarcinomas from East Asian never smokers

Purpose

We previously showed that 90% (47 of 52; 95% CI, 0.79 to 0.96) of lung adenocarcinomas from East Asian never-smokers harbored well-known oncogenic mutations in just four genes: EGFR, HER2, ALK, and KRAS. Here, we sought to extend these findings to more samples and identify driver alterations in tumors negative for these mutations.

Experimental Design

We have collected and analyzed 202 resected lung adenocarcinomas from never smokers seen at Fudan University Shanghai Cancer Center. Since mutations were mutually exclusive in the first 52 examined, we determined the status of EGFR, KRAS, HER2, ALK, and BRAF in stepwise fashion as previously described. Samples negative for mutations in these 5 genes were subsequently examined for known ROS1 fusions by RT-PCR and direct sequencing.

Results

152 tumors (75.3%) harbored EGFR mutations, 12 (6%) had HER2 mutations, 10 (5%) had ALK fusions all involving EML4 as the 5′ partner, 4 (2%) had KRAS mutations, and 2 (1%) harbored ROS1 fusions. No BRAF mutation were detected.

Conclusion

The vast majority (176 of 202; 87.1%, 95% CI: 0.82 to 0.91) of lung adenocarcinomas from never smokers harbor mutant kinases sensitive to available TKIs. Interestingly, patients with EGFR mutant patients tend to be older than those without EGFR mutations (58.3 Vs 54.3, P = 0.016) and patient without any known oncogenic driver tend to be diagnosed at a younger age (52.3 Vs 57.9, P = 0.013). Collectively, these data indicate that the majority of never smokers with lung adenocarcinoma could benefit from treatment with a specific tyrosine kinase inhibitor.     

Detecting ALK,ROS1 and RET Fusion Genes in Cell Block Samples

Whether Cell block (CB) samples are applicable to detect anaplastic lymphoma kinase (ALK), c-ros oncogene 1 (ROS1) and ret proto-oncogene (RET) fusion genes in lung adenocarcinoma is still unknown. In this study, 108 cytological samples that contained lung adenocarcinoma cells were collected, and made into CB. The CB samples all contained at least 30% lung adenocarcinoma cells. In these patients, 48 harbored EGFR mutation. Among the 50 EGFR wild type patients who detected fusion genes, 14 carried EML4-ALK fusion (28%), 2 had TPM3-ROS1 fusion (4%), and 3 harbored KIF5B-RET fusion (6%). No double fusions were found in one sample. Patients with fusion genes were younger than those without fusion genes (p = 0.032), but no significant difference was found in sex and smoking status (p > 0.05). In the thirty-five patients who received first-line chemotherapy, patients with fusion gene positive had disease control rate (DCR) (72.7% VS 50%, p > 0.05) and objective response rate (ORR) (9.1% VS 4.2%, p > 0.05) compared with those having fusion gene negative. The median progression free survival (mPFS) were 4.0 and 2.7 months in patients harbored fusion mutations and wild type, respectively (p > 0.05). We conclude that CB samples could be used to detect ALK, ROS1 and RET fusions in NSCLC. The frequency distribution of three fusion genes is higher in lung adenocarcinoma with wild-type EGFR, compared with unselected NSCLC patient population. Patients with fusion genes positive are younger than those with fusion gene negative, but they had no significantly different PFS in first-line chemotherapy.     

Platform Comparison for Evaluation of ALK Protein Immunohistochemical Expression,Genomic Copy Number and Hotspot Mutation Status in Neuroblastomas

ALK is an established causative oncogenic driver in neuroblastoma, and is likely to emerge as a routine biomarker in neuroblastoma diagnostics. At present, the optimal strategy for clinical diagnostic evaluation of ALK protein, genomic and hotspot mutation status is not well-studied. We evaluated ALK immunohistochemical (IHC) protein expression using three different antibodies (ALK1, 5A4 and D5F3 clones), ALK genomic status using single-color chromogenic in situ hybridization (CISH), and ALK hotspot mutation status using conventional Sanger sequencing and a next-generation sequencing platform (Ion Torrent Personal Genome Machine (IT-PGM)), in archival formalin-fixed, paraffin-embedded neuroblastoma samples. We found a significant difference in IHC results using the three different antibodies, with the highest percentage of positive cases seen on D5F3 immunohistochemistry. Correlation with ALK genomic and hotspot mutational status revealed that the majority of D5F3 ALK-positive cases did not possess either ALK genomic amplification or hotspot mutations. Comparison of sequencing platforms showed a perfect correlation between conventional Sanger and IT-PGM sequencing. Our findings suggest that D5F3 immunohistochemistry, single-color CISH and IT-PGM sequencing are suitable assays for evaluation of ALK status in future neuroblastoma clinical trials.     

Predictive Value of Somatic Mutations for the Development of Malignancy in Thyroid Nodules by Cytopathology

Objective: The purpose of our prospective longitudinal study was to evaluate the predictive efficacy of genetic testing for malignancies in fine-needle aspiration biopsy samples that are cytologically benign at the time of biopsy.Methods: A total of 779 aspirated cytological samples collected from thyroid nodules of 626 patients were included in a 3-year follow-up study. Consecutive patients with cytologically benign thyroid nodules by the Bethesda System for Reporting Thyroid Cytopathology were enrolled in the study. At enrollment, somatic 1-point nucleotide polymorphisms of BRAF and RAS family genes were tested by melting-point analysis, while RET/PTC and PAX8/PPAR-gamma rearrangements were examined by real-time polymerase chain reaction. The genetic test was considered to be positive if a somatic mutation was found. Malignant cytopathologic diagnoses were confirmed by histopathology.Results: In samples collected from 779 thyroid nodules, there were 39 BRAF, 33 RAS mutations, and 1 RET/PTC rearrangements found at the beginning of the study. No PAX8/PPAR-gamma rearrangement was identified. There were 52 malignant thyroid tumors removed during follow-up, out of which 24 contained a somatic mutation. The specificity of the presence of somatic mutations for malignancies was as high as 93.3%, and sensitivity was 46.2%. The negative predictive value of genetic testing reached 96.0%.Conclusion: Our results show that our set of genetic tests can predict the appearance of malignancy in benign thyroid nodules (at the beginning of follow-up) with high specificity and strong negative predictive value.Abbreviations:BRAF = v-raf murine sarcoma viral oncogene homolog B1FLUS = follicular lesion of undetermined significanceFNAB = fine-needle aspiration biopsyFTC = follicular thyroid carcinomaHRAS = homologous to the oncogene from the Harvey rat sarcoma virusKRAS = homologous to the oncogene from the Kirsten rat sarcoma virusNRAS = first isolated from a human neuroblastoma/neuroblastomaRAS = viral oncogene homologPAX8 = paired box 8PCR = polymerase chain reactionPPAR-gamma = peroxisome proliferator-activated receptor gammaPTC = papillary thyroid carcinomaRAS = rat sarcomaRET = rearranged during transfection tyrosine-kinase proto-oncogeneSM = somatic mutationSNP = single-nucleotide polymorphism     

Peptides derived from the dependence receptor ALK are proapoptotic for ALK-positive tumors

ALK is a receptor tyrosine kinase with an oncogenic role in various types of human malignancies. Despite constitutive activation of the kinase through gene alterations, such as chromosomal translocation, gene amplification or mutation, treatments with kinase inhibitors invariably lead to the development of resistance. Aiming to develop new tools for ALK targeting, we took advantage of our previous demonstration identifying ALK as a dependence receptor, implying that in the absence of ligand the kinase-inactive ALK triggers or enhances apoptosis. Here, we synthesized peptides mimicking the proapoptotic domain of ALK and investigated their biological effects on tumor cells. We found that an ALK-derived peptide of 36 amino acids (P36) was cytotoxic for ALK-positive anaplastic large-cell lymphoma and neuroblastoma cell lines. In contrast, ALK-negative tumor cells and normal peripheral blood mononuclear cells were insensitive to P36. The cytotoxic effect was due to caspase-dependent apoptosis and required N-myristoylation of the peptide. Two P36-derived shorter peptides as well as a cyclic peptide also induced apoptosis. Surface plasmon resonance and mass spectrometry analysis of P36-interacting proteins from two responsive cell lines, Cost lymphoma and SH-SY5Y neuroblastoma, uncovered partners that could involve p53-dependent signaling and pre-mRNA splicing. Furthermore, siRNA-mediated knockdown of p53 rescued these cells from P36-induced apoptosis. Finally, we observed that a treatment combining P36 with the ALK-specific inhibitor crizotinib resulted in additive cytotoxicity. Therefore, ALK-derived peptides could represent a novel targeted therapy for ALK-positive tumors.Designing targeted therapy for cancer has been a major goal of the last decade. Oncogenic tyrosine kinases have raised early interest, because elucidation of their structure facilitated the development of small-molecule inhibitors with therapeutic efficiency.¹ The pioneer BCR-ABL inhibitor molecule imatinib was approved for therapeutic use as early as 2001 to treat chronic myeloid leukemia and Ph1-positive acute lymphoblastic leukemia.² Later on, inhibitors targeting receptors for epidermal growth factor or vascular endothelial growth factor were approved for treatment of solid tumors, such as lung and breast cancer. To date, many tyrosine kinase inhibitors (TKIs) are used in the clinic.³ However, cancers treated by TKIs invariably become resistant to therapy and relapse. Acquired resistance develops through various mechanisms including secondary mutations of the targeted oncogene or activation of alternative proliferative signaling pathways.⁴ It seems thus necessary to invent new strategies designed to attack the tumor on multiple fronts.ALK (anaplastic lymphoma kinase) is an oncogenic receptor tyrosine kinase associated with many tumor types. ALK was first identified in 1994 as a rearranged gene fusion (NPM–ALK) resulting from the t(2;5)(p23;q35) translocation occurring in 75% human anaplastic large-cell lymphomas (ALCLs).^{5, 6} Other translocations or gene inversions involving ALK were later described in solid tumors including 50–60% inflammatory myofibroblastic tumors, and a small proportion of diffuse large B-cell lymphomas, breast and renal carcinomas.^{7, 8} Recently, 4–8% non-small-cell lung cancer (NSCLC) were found to harbor an echinoderm microtubule-associated protein-like 4 (EML4)–ALK fusion.^{7, 9} Resulting fusion proteins associate the N-terminal portion of a protein partner (containing in most cases a dimerization domain) to the entire intracellular portion of ALK, including its tyrosine kinase domain. Subsequent dimerization of this fusion protein leads to constitutive activation of ALK kinase, resulting in enhanced signaling for cell proliferation, survival and oncogenicity.¹⁰The full-length ALK receptor cDNA codes for a transmembrane receptor tyrosine kinase of the insulin receptor superfamily, which is essentially expressed in the developing nervous system.^{11, 12} Some authors proposed the two heparin-binding factors pleiotrophin (PTN) and midkine as ligands for ALK.¹⁰ However, their binding to ALK is controversed and might be indirectly mediated by heparin.¹³ ALK kinase signaling most likely involves co-receptors and/or co-signaling molecules such as the transmembrane receptor tyrosine phosphatase beta/zeta (RPTPb/z), a receptor for PTN and midkine. In the absence of ligand, RPTPb/z dephosphorylates ALK, whereas PTN and midkine direct binding to RPTPb/z inactivates its phosphatase activity.¹⁴ Expression of the full-length ALK receptor was also observed in neuroblastoma, a pediatric tumor derived from the neural crest affecting the peripheral nervous system. The ALK kinase in neuroblastoma is most often constitutively active as a result of gain-of-function mutations or protein overexpression, due to ALK gene amplification or copy number increase.^{10, 15}ALK appears therefore as an interesting therapeutic target to treat ALK-positive tumors. Indeed, since the identification of NPM–ALK and other ALK fusions as oncogenes for ALCL and inflammatory myofibroblastic tumors,^{6, 16, 17} several pharmaceutical companies developed ALK-specific TKIs. In 2010, a TKI targeting ALK and c-MET, crizotinib¹⁸ (also called PF-02341066), was authorized in clinical trials as a second-line therapy for advanced stage NSCLC harboring EML4–ALK. The initial clinical responses were so encouraging that crizotinib is currently tested in a growing number of advanced ALK-positive tumors (clinicaltrials.gov). Nevertheless, the tumors invariably develop resistance to the inhibitor, mostly through mutations of the kinase active site.^{19, 20} Therefore, it appears necessary to design alternate treatments or to associate TKIs with other molecules. One promising strategy would be to impair distinct functions of the oncogenic tyrosine kinase through targeting different sites of the ALK protein.We recently demonstrated that the ALK receptor tyrosine kinase belongs to the functional family of so-called ‘dependence receptors''.^{21, 22} Such dependence receptors function with a dual signaling: in the presence of ligand (or a situation mimicking a ligand, e.g., inducing receptor dimerization and activation), the receptor exerts a prosurvival/antiapoptotic effect on the cell; in contrast, in absence of ligand and when the cell is submitted to environmental or genotoxic stress, a dependence receptor becomes proapoptotic. The proapoptotic effect is mediated by caspase-dependent cleavage of the receptor, either releasing or exposing a proapoptotic domain/sequence (called ‘addiction/dependence domain'' or ADD), thus amplifying the apoptotic process.²³ Molecular analysis of ALK deletion mutants allowed us to map the ADD domain of ALK to a 36-amino-acid (aa) stretch located within the juxtamembrane intracytoplasmic region of ALK. The ADD of ALK lacks homology with any known protein motif implicated in apoptotic processes and is necessary for ALK proapoptotic function.²² The purpose of the present study was to design a novel targeted therapy, taking advantage of the proapoptotic function of ALK.Our hypothesis was that a synthetic peptide could mimic the proapoptotic function of ALK. Therefore, we synthesized several peptides whose sequence reproduced the entire ADD domain (36 aa) of ALK or part of it (12 aa) to assay their effects on various tumor cell lines. We show that several of these ALK-derived peptides are proapoptotic for ALK-expressing, but not ALK-negative, tumor cells. In addition, the ALK-derived 36-aa peptide (P36) enhanced the cytotoxic effect of the ALK kinase inhibitor crizotinib in ALK-positive ALCL and neuroblastoma cell lines. Thus our results uncover a new strategy for targeting ALK-expressing tumors.