ALK and NSCLC: Targeted therapy with ALK inhibitors

ALK F1174S mutation impairs ALK kinase activity in EML4-ALK variant 1 and sensitizes EML4-ALK variant 3 to crizotinib

Objective

To assess the influence of F1174S mutation on kinase activity and drug sensitivity of the echinoderm microtubule-associated protein-like 4 (EML4) and anaplastic lymphoma kinase (ALK) fusion (EML4-ALK) variants 1 and 3.

Methods

We constructed mammalian expression plasmids of both wildtype and F1174 mutant EML4-ALK variants 1 and 3, and then characterized them with cell models by performing immunoblotting, neurite outgrowth assay, focus formation assay as well as protein stability assay. Drug sensitivity to ALK tyrosine kinase inhibitors was also compared between wildtype and F1174 mutant EML4-ALK fusions. In addition, we characterized the effect of different F1174 kinase domain mutations in the context of EML4-ALK fusions.

Results

In contrast to the oncogenic ALK-F1174S mutation that has been reported to be activating in the context of full-length ALK in neuroblastoma, EML4-ALK (F1174S) variant 1 exhibits impaired kinase activity leading to loss of oncogenicity. Furthermore, unlike the previously reported F1174C/L/V mutations, mutation of F1174 to S sensitizes EML4-ALK variants 3a and 3b to crizotinib.

Conclusion

These findings highlight the complexity of drug selection when treating patients harboring resistance mutations and suggest that the F1174S mutation in EML4-ALK variant 1 is likely not a potent oncogenic driver. Additional oncogenic driver or other resistance mechanisms should be considered in the case of EML4-ALK variant 1 with F1174S mutation.

Understanding the feasibility of chemotherapeutic and immunotherapeutic targets against non-small cell lung cancers: an update of resistant responses and recent combinatorial therapies

Despite consistent progress in prompt diagnosis and curative therapies in the last decade, lung cancer (LC) continues to threaten mankind, accounting for nearly twice the casualties compared to prostate, breast, and other cancers. Statistics associate ~25% of 2021 cancer-related deaths with LC, more than 80% of which are explicitly caused by tobacco smoking. Prevailing as small and non-small cell pathologies, with respective occurring frequency of nearly 15% and 80-85%, non-small cell LCs (NSCLCs) are prominently distinguished into lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC), subtypes. Since the first use of epidermal growth factor receptor (EGFR) inhibitor gefitinib for NSCLC treatment in 2002, immense progress has been made for targeted therapies with the next generation of drugs spanning across the chronological generations of small molecule inhibitors. The last two years have overseen the clinical approval of more than 10 therapeutic agents as first-line NSCLC medications. However, uncertain mutational aberrations as well as systemic resistant responses, and abysmal overall survival curtail the combating efficacies. Of late, immune checkpoint inhibitors (ICIs) against various molecules including programmed cell death-1 (PD-1) and its ligand (PD-L1) have been demonstrated as reliable LC treatment targets. Keeping these aspects in mind, this review article discusses the success of NSCLC chemo and immunotherapies with their characteristic effectiveness and future perspectives.

Cost‑Effectiveness of Lorlatinib in First-Line Treatment of Adult Patients with Anaplastic Lymphoma Kinase (ALK)‑Positive Non‑Small‑Cell Lung Cancer in Sweden

BACKGROUND

We aimed to investigate the cost effectiveness of lorlatinib, a third-generation anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor (TKI), used first-line in Sweden to treat patients with ALK-positive (ALK+) non-small cell lung cancer (NSCLC). In January 2022, the European Medicines Agency (EMA) extended its approval of lorlatinib to include adult patients with ALK+ NSCLC not previously treated with an ALK inhibitor. Extended first-line approval was based on results from CROWN, a phase III randomized trial that enlisted 296 patients randomized 1:1 to receive lorlatinib or crizotinib. Our analysis compared lorlatinib against the first-generation ALK-TKI crizotinib, and second-generation ALK TKIs alectinib and brigatinib.

METHODS

A partitioned survival model with four health states [pre-progression, non-intracranial (non-central nervous system [CNS]) progression, CNS progression, and death] was constructed. The progressed disease state (which is typically modelled in cost-effectiveness analyses of oncology treatments) was explicitly separated into non-CNS and CNS progression as brain metastases, which are common in NSCLC, and can have a large impact on patient prognosis and health-related quality of life. Treatment effectiveness estimates in the lorlatinib and crizotinib arms of the model were derived from CROWN data, while indirect relative effectiveness estimates for alectinib and brigatinib were informed using network meta-analysis (NMA). Utility data were derived from the CROWN study in the base case, and cost-effectiveness results were compared when applying UK and Swedish value sets. Costs were obtained from Swedish national data. Deterministic and probabilistic sensitivity analyses were conducted to test model robustness.

RESULTS

Fully incremental analysis identified crizotinib as the least costly and least effective treatment. Brigatinib was extendedly dominated by alectinib and, subsequently, alectinib was extendedly dominated by lorlatinib. Lorlatinib was associated with an incremental cost-effectiveness ratio (ICER) of Swedish Krona (SEK) 613,032 per quality-adjusted life-year (QALY) gained compared with crizotinib. Probabilistic results were generally consistent with deterministic results, and one-way sensitivity identified NMA HRs, alectinib and brigatinib treatment duration, and the CNS-progressed utility multiplier as key model drivers.

CONCLUSIONS

The ICER of SEK613,032 for lorlatinib versus crizotinib falls below the typical willingness-to-pay threshold per QALY gained for high-severity diseases in Sweden (approximately SEK1,000,000). Furthermore, as brigatinib and alectinib were extendedly dominated in the incremental analysis, the results of our study indicate that lorlatinib may be considered a cost-effective treatment option for first-line patients with ALK+ NSCLC in Sweden when compared with crizotinib, alectinib, and brigatinib. Longer-term follow-up data for endpoints informing treatment effectiveness for all first-line treatments would help to reduce uncertainty in the findings.

Matching-Adjusted Indirect Comparisons of Lorlatinib Versus Chemotherapy for Patients With Second-Line or Later Anaplastic Lymphoma Kinase-Positive Non-Small Cell Lung Cancer

OBJECTIVES

This study aimed to compare the relative efficacy of lorlatinib, an anaplastic lymphoma kinase-tyrosine kinase inhibitor, with chemotherapy, for patients with second-line or later advanced anaplastic lymphoma kinase-positive non-small cell lung cancer. The endpoints of interest were overall survival (OS) and progression-free survival (PFS).

METHODS

Evidence for lorlatinib was informed by the single-arm phase I/II trial B7461001. A systematic literature review (SLR) was performed to identify OS and PFS data for chemotherapy. Unanchored matching-adjusted indirect comparisons (MAICs) between lorlatinib and chemotherapy (pemetrexed/docetaxel, platinum-based, or systemic therapy) were performed.

RESULTS

The SLR identified 3 relevant studies reporting PFS. Lorlatinib was associated with a significant decrease in the hazard of progression versus the 2 types of chemotherapy assessed. For PFS, the MAIC of lorlatinib versus the combined treatment arm of docetaxel or pemetrexed resulted in an adjusted hazard ratio (HR) of 0.22 (95% confidence interval [CI] 0.15-0.31). When lorlatinib was compared with platinum-based chemotherapy through an MAIC, the adjusted HR for PFS was 0.40 (95% CI 0.29-0.55). An exploratory comparison was performed for OS with evidence for systemic therapy (assumed equivalent to chemotherapy) not identified in the SLR. Lorlatinib provided a significant decrease in hazard of death (OS) versus systemic therapy, with HRs ranging from 0.12 (95% CI 0.05-0.27) to 0.43 (95% CI 0.27-0.60).

CONCLUSIONS

Lorlatinib demonstrated a significant improvement in PFS compared with chemotherapy, although limitations in the analyses were identified. The evidence informing OS comparisons was highly limited but suggested benefit of lorlatinib compared with systemic therapy.

The Cost-Effectiveness of Lorlatinib Versus Chemotherapy as a Second- or Third-Line Treatment in Anaplastic Lymphoma Kinase (ALK)-Positive Non-small-cell Lung Cancer in Sweden

BACKGROUND

Lorlatinib is a third-generation anaplastic lymphoma kinase (ALK)/c-ros oncogene 1 (ROS1) tyrosine kinase inhibitor (TKI) with efficacy in patients with ALK-rearranged non-small-cell lung cancer (NSCLC) previously treated with a second-generation ALK inhibitor or with first- and second-generation ALK inhibitors. We examined the cost-effectiveness of second- or third-line+ (2L+ or 3L+) lorlatinib in Sweden, versus chemotherapy.

METHODS

A partitioned survival model with three health states (progression free, progressed, or death) was used. Lorlatinib relative efficacy versus chemotherapy was derived using unanchored matching adjusted indirect treatment comparisons from a phase 2 clinical trial. Utility data were derived from the same trial and published studies. Costs (year 2019) were obtained from Swedish national data. Costs and benefits were discounted at 3% per annum using a societal perspective (base case). Model robustness was evaluated with deterministic and probabilistic sensitivity analyses.

RESULTS

For 2L+, the average discounted total quality-adjusted life year (QALY) gain was 1.29 years. Total incremental costs were Swedish krona (SEK) 731,791, resulting in an incremental cost-effectiveness ratio (ICER) of SEK 566,278 per QALY gained. Non-discounted survival gain amounted to 1.94 years. For 3L+, the average discounted total QALY gain was 1.25 years. Total incremental costs were SEK 754,801, resulting in an ICER of SEK 603,934 per QALY gained. Non-discounted survival gain was 1.88 years. Sensitivity analyses were consistent.

CONCLUSIONS

ICERs ranged from SEK 421,000 to SEK 384,066 less than the boundary for a cost-effective treatment for a high-severity disease in Sweden (SEK 988,000), suggesting 2L+ or 3L+ lorlatinib is a cost-effective treatment for ALK-positive NSCLC versus chemotherapy.

Approving cancer treatments based on endpoints other than overall survival: an analysis of historical data using the PACE Continuous Innovation Indicators™ (CII)

Background

There is an active debate about the role that endpoints other than overall survival (OS) should play in the drug approval process. Yet the term ‘surrogate endpoint’ implies that OS is the only critical metric for regulatory approval of cancer treatments. We systematically analyzed the relationship between U.S. Food and Drug Administration (FDA) approval and publication of OS evidence to understand better the risks and benefits of delaying approval until OS evidence is available.

Scope

Using the PACE Continuous Innovation Indicators (CII) platform, we analyzed the effects of cancer type, treatment goal, and year of approval on the lag time between FDA approval and publication of first significant OS finding for 53 treatments approved between 1952 and 2016 for 10 cancer types (n = 71 approved indications).

Findings

Greater than 59% of treatments were approved before significant OS data for the approved indication were published. Of the drugs in the sample, 31% had lags between approval and first published OS evidence of 4 years or longer. The average number of years between approval and first OS evidence varied by cancer type and did not reliably predict the eventual amount of OS evidence accumulated.

Conclusions

Striking the right balance between early access and minimizing risk is a central challenge for regulators worldwide. We illustrate that endpoints other than OS have long helped to provide timely access to new medicines, including many current standards of care. We found that many critical drugs are approved many years before OS data are published, and that OS may not be the most appropriate endpoint in some treatment contexts. Our examination of approved treatments without significant OS data suggests contexts where OS may not be the most relevant endpoint and highlights the importance of using a wide variety of fit-for-purpose evidence types in the approval process.

Crizotinib-induced antitumour activity in human alveolar rhabdomyosarcoma cells is not solely dependent on ALK and MET inhibition

Background

Rhabdomyosarcoma (RMS) is the most commonly diagnosed malignant soft tissue tumour in children and adolescents. Aberrant expression of Anaplastic Lymphoma Kinase (ALK) and MET gene has been implicated in the malignant progression of RMS, especially in the alveolar subtype. This observation suggests that crizotinib (PF-02341066), a kinase inhibitor against ALK and MET, may have a therapeutic role in RMS, although its antitumour activity in this malignancy has not yet been studied.

Methods

RH4 and RH30 alveolar RMS (ARMS) cell lines were treated with crizotinib and then assessed by using proliferation, viability, migration and colony formation assays. Multiple approaches, including flow cytometry, immunofluorescence, western blotting and siRNA-based knock-down, were used in order to investigate possible molecular mechanisms linked to crizotinib activity.

Results

In vitro treatment with crizotinib inhibited ALK and MET proteins, as well as Insulin-like Growth Factor 1 Receptor (IGF1R), with a concomitant robust dephosphorylation of AKT and ERK, two downstream kinases involved in RMS cell proliferation and survival. Exposure to crizotinib impaired cell growth, and accumulation at G2/M phase was attributed to an altered expression and activation of checkpoint regulators, such as Cyclin B1 and Cdc2. Crizotinib was able to induce apoptosis and autophagy in a dose-dependent manner, as shown by caspase-3 activation/PARP proteolytic cleavage down-regulation and by LC3 activation/p62 down-regulation, respectively. The accumulation of reactive oxygen species (ROS) seemed to contribute to crizotinib effects in RH4 and RH30 cells. Moreover, crizotinib-treated RH4 and RH30 cells exhibited a decreased migratory/invasive capacity and clonogenic potential.

Conclusions

These results provide a further insight into the molecular mechanisms affected by crizotinib in ARMS cells inferring that it could be a useful therapeutic tool in ARMS cancer treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0228-4) contains supplementary material, which is available to authorized users.

The kinase ALK stimulates the kinase ERK5 to promote the expression of the oncogene MYCN in neuroblastoma

Anaplastic lymphoma kinase (ALK) is an important molecular target in neuroblastoma. Although tyrosine kinase inhibitors abrogating ALK activity are currently in clinical use for the treatment of ALK-positive (ALK(+)) disease, monotherapy with ALK tyrosine kinase inhibitors may not be an adequate solution for ALK(+) neuroblastoma patients. Increased expression of the gene encoding the transcription factor MYCN is common in neuroblastomas and correlates with poor prognosis. We found that the kinase ERK5 [also known as big mitogen-activated protein kinase (MAPK) 1 (BMK1)] is activated by ALK through a pathway mediated by phosphoinositide 3-kinase (PI3K), AKT, MAPK kinase kinase 3 (MEKK3), and MAPK kinase 5 (MEK5). ALK-induced transcription of MYCN and stimulation of cell proliferation required ERK5. Pharmacological or RNA interference-mediated inhibition of ERK5 suppressed the proliferation of neuroblastoma cells in culture and enhanced the antitumor efficacy of the ALK inhibitor crizotinib in both cells and xenograft models. Together, our results indicate that ERK5 mediates ALK-induced transcription of MYCN and proliferation of neuroblastoma, suggesting that targeting both ERK5 and ALK may be beneficial in neuroblastoma patients.

ALK-positive cancer: still a growing entity

 Since the discovery of ALK-positive anaplastic large-cell lymphoma in 1994 many other types of tumors showing ALK expression were disclosed. They form a heterogeneous group, including lung, renal and soft tissue tumors. The biological function of ALK, its role in carcinogenesis and impact exerted on the clinical outcome have been studied by many research groups. New drugs specifically dedicated for ALK inhibition, for example, crizotinib, have been synthesized and have become a viable treatment option for ALK-positive lung adenocarcinoma, and potentially for other ALK-positive cancers. This review summarizes the current state of knowledge concerning ALK-positive neoplasms, focusing on the clinical aspects of the subject.

Mechanistic insight into ALK receptor tyrosine kinase in human cancer biology

The burgeoning field of anaplastic lymphoma kinase (ALK) in cancer encompasses many cancer types, from very rare cancers to the more prevalent non-small-cell lung cancer (NSCLC). The common activation of ALK has led to the use of the ALK tyrosine kinase inhibitor (TKI) crizotinib in a range of patient populations and to the rapid development of second-generation drugs targeting ALK. In this Review, we discuss our current understanding of ALK function in human cancer and the implications for tumour treatment.

Phosphoproteomic analysis of anaplastic lymphoma kinase (ALK) downstream signaling pathways identifies signal transducer and activator of transcription 3 as a functional target of activated ALK in neuroblastoma cells

Activation of the anaplastic lymphoma kinase (ALK) receptor tyrosine kinase is a key oncogenic mechanism in a growing number of tumor types. In the majority of cases, ALK is activated by fusion with a dimerizing partner protein as a result of chromosomal translocation events, most studied in the case of the nucleophosmin–ALK and echinoderm microtubule-associated protein-like 4–ALK oncoproteins. It is now also appreciated that the full-length ALK receptor can be activated by point mutations and by deletions within the extracellular domain, such as those observed in neuroblastoma. Several studies have employed phosphoproteomics approaches to find substrates of ALK fusion proteins. In this study, we used MS-based phosphotyrosine profiling to characterize phosphotyrosine signaling events associated with the full-length ALK receptor. A number of previously identified and novel targets were identified. One of these, signal transducer and activator of transcription 3 (STAT3), has previously been observed to be activated in response to oncogenic ALK signaling, but the significance of this in signaling from the full-length ALK receptor has not been explored further. We show here that activated ALK robustly activates STAT3 on Tyr705 in a number of independent neuroblastoma cell lines. Furthermore, knockdown of STAT3 by RNA interference resulted in a reduction in myelocytomatosis neuroblastom (MYCN) protein levels downstream of ALK signaling. These observations, together with a decreased level of MYCN and inhibition of neuroblastoma cell growth in the presence of STAT3 inhibitors, suggest that activation of STAT3 is important for ALK signaling activity in neuroblastoma.

Anaplastic lymphoma kinase (ALK) inhibitors for second-line therapy of non-small cell lung cancer

Targeted therapies are nowadays a treatment option in metastatic non-small cell lung cancer, for which oncogenic drivers have been identified. The epidermal growth factor-receptor tyrosine kinase inhibitors gefitinib and erlotinib, are the standard of care for patients in whom tumors are presenting with an activating epidermal growth factor-receptor mutation, with new active agents like afatinib reaching clinics in the near future. Other genetic abnormalities have been documented in squamous and non-squamous lung cancer. The EML4-ALK gene fusion is a rare event, occurring in around 5% of lung cancer, quite exclusively in adenocarcinoma with a predominance of young non/light smokers. Detection of ALK-positive tumors is challenging, as there is no gold-standard technique. Fluorescence in situ hybridization is the method used in prospective trials assessing the activity of crizotinib and is recommended by the American FDA. Crizotinib is the first orally active inhibitor of receptor tyrosine kinases, including ALK and ROS1, in clinical practice. Impressive results came from a phase I study and are now confirmed in a large phase II study with response rate of 60%, whatever the number of previous lines of chemotherapy. Other ALK inhibitors are currently in the preclinical phase, and some are showing promising results in early phase I/II studies. This review aims to present the current knowledge on the EML4-ALK gene fusion, the pitfalls for the pathologist and the clinician in searching this abnormality, and to review the existing literature on ALK inhibitors under development, focusing their role compared to chemotherapy in non-small cell lung cancer patients.

Cell culture and Drosophila model systems define three classes of anaplastic lymphoma kinase mutations in neuroblastoma

Neuroblastoma is a childhood extracranial solid tumour that is associated with a number of genetic changes. Included in these genetic alterations are mutations in the kinase domain of the anaplastic lymphoma kinase (ALK) receptor tyrosine kinase (RTK), which have been found in both somatic and familial neuroblastoma. In order to treat patients accordingly requires characterisation of these mutations in terms of their response to ALK tyrosine kinase inhibitors (TKIs). Here, we report the identification and characterisation of two novel neuroblastoma ALK mutations (A1099T and R1464STOP), which we have investigated together with several previously reported but uncharacterised ALK mutations (T1087I, D1091N, T1151M, M1166R, F1174I and A1234T). In order to understand the potential role of these ALK mutations in neuroblastoma progression, we have employed cell culture-based systems together with the model organism Drosophila as a readout for ligand-independent activity. Mutation of ALK at position 1174 (F1174I) generates a gain-of-function receptor capable of activating intracellular targets such as ERK (extracellular signal regulated kinase) and STAT3 (signal transducer and activator of transcription 3) in a ligand-independent manner. Analysis of these previously uncharacterised ALK mutants and comparison with ALK^F1174 mutants suggests that ALK mutations observed in neuroblastoma fall into three classes. These classes are: (i) gain-of-function ligand-independent mutations such as ALK^F1174l, (ii) kinase-dead ALK mutants, e.g. ALK^I1250T (Schönherr et al., 2011a) and (iii) ALK mutations that are ligand-dependent in nature. Irrespective of the nature of the observed ALK mutants, in every case the activity of the mutant ALK receptors could be abrogated by the ALK inhibitor crizotinib (Xalkori/PF-02341066), albeit with differing levels of sensitivity.

Anaplastic lymphoma kinase as a therapeutic target

INTRODUCTION

Anaplastic lymphoma kinase (ALK), a tyrosine kinase receptor, has been initially identified through its involvement in chromosomal translocations associated with anaplastic large cell lymphoma. However, recent evidence that aberrant ALK activity is also involved in an expanding number of tumor types, such as other lymphomas, inflammatory myofibroblastic tumor, neuroblastomas and some carcinomas, including non-small cell lung carcinomas, is boosting research progress in ALK-targeted therapies.

AREAS COVERED

The first aim of this review is to describe current understandings about the ALK tyrosine kinase and its implication in the oncogenesis of human cancers as a fusion protein or through mutations. The second goal is to discuss its interest as a therapeutic target and to provide a review of the literature regarding ALK inhibitors. Mechanisms of acquired resistance are also reviewed.

EXPERT OPINION

Several ALK inhibitors have recently been developed, offering new treatment options in tumors driven by abnormal ALK signaling. However, as observed with other tyrosine kinase inhibitors, resistance has emerged in patients treated with these agents. The complexity of mechanisms of acquired resistance recently described suggests that other therapeutic options, including combination of ALK and other kinases targeted drugs, will be required in the future.

Targeting ALK in neuroblastoma--preclinical and clinical advancements

Despite improvements in cancer therapies in the past 50 years, neuroblastoma remains a devastating clinical problem and a leading cause of childhood cancer deaths. Advances in treatments for children with high-risk neuroblastoma have, until recently, involved addition of cytotoxic therapy to dose-intensive regimens. In this era of targeted therapies, substantial efforts have been made to identify optimal targets for different types of cancer. The discovery of hereditary and somatic activating mutations in the oncogene ALK has now placed neuroblastoma among other cancers, such as melanoma and non-small-cell lung cancer (NSCLC), which benefit from therapies with oncogene-specific small-molecule tyrosine kinase inhibitors. Crizotinib, a small-molecule inhibitor of ALK, has transformed the landscape for the treatment of NSCLC harbouring ALK translocations and has demonstrated activity in preclinical models of ALK-driven neuroblastomas. However, inhibition of mutated ALK is complex when compared with translocated ALK and remains a therapeutic challenge. This Review discusses the biology of ALK in the development of neuroblastoma, preclinical and clinical progress with the use of ALK inhibitors and immunotherapy, challenges associated with resistance to such therapies and the steps being taken to overcome some of these hurdles.

ALK Inhibitors, a Pharmaceutical Perspective

In 2007, the ALK tyrosine kinase was described as a potential therapeutic target for a subset of non-small-cell lung cancer patients. Clinical proof of concept, culminating in the recent approval by the Food and Drug Administration of the Pfizer drug crizotinib followed in record time. The drug was approved together with a companion diagnostic for detection of patients eligible for therapy. This remarkable example of the coming of age of personalized medicine in cancer therapy is hopefully only an auspice of things to come in a rapidly developing field. Perhaps unsurprisingly, however, the appearance of clinical acquired resistance to crizotinib was observed early on in clinical testing, with the identification of several ALK secondary point mutations which diminish drug efficacy and which open the way for development of second-generation inhibitors. It is also emerging that acquired resistance to crizotinib may additionally occur through ALK-independent mechanisms, which still need to be elucidated in detail. Here we discuss the factors that led to such a rapid approval of a targeted agent, and we describe the second-generation compounds currently in development.

Anaplastic Lymphoma Kinase (ALK) regulates initiation of transcription of MYCN in neuroblastoma cells

Neuroblastoma is a neural crest-derived embryonal tumour of the postganglionic sympathetic nervous system and a disease with several different chromosomal gains and losses, which include MYCN-amplified neuroblastoma on chromosome 2, deletions of parts of the chromosomes 1p and 11q, gain of parts of 17q and triploidy. Recently, activating mutations of the ALK (Anaplastic Lymphoma Kinase) RTK (Receptor Tyrosine Kinase) gene have been described in neuroblastoma. A meta-analysis of neuroblastoma cases revealed that ALK mutations (49 of 709 cases) in relation to genomic subtype were most frequently observed in MYCN amplified tumours (8.9%), correlating with a poor clinical outcome. MYCN proteins target proliferation and apoptotic pathways, and have an important role in the progression of neuroblastoma. Here, we show that both wild-type and gain-of-function mutants in ALK are able to stimulate transcription at the MYCN promoter and initiate mRNA transcription of the MYCN gene in both neuronal and neuroblastoma cell lines. Further, this stimulation of MYCN gene transcription and de novo MYCN protein expression is abrogated by specific ALK inhibitors, such as crizotinib (PF-2341066), NVP-TAE684, and by small interfering RNA to ALK resulting in a decrease in proliferation rate. Finally, co-transfection of ALK gain-of-function mutations together with MYCN leads to an increase in transformation potential. Taken together, our results indicate that ALK signalling regulates initiation of transcription of the MYCN gene providing a possible explanation for the poor clinical outcome observed when MYCN is amplified together with activated ALK.