Overcoming crizotinib resistance in ALK-rearranged NSCLC with the second-generation ALK-inhibitor ceritinib

In up to 5% of non-small cell lung cancer (NSCLC) patients, the EML4-ALK translocation drives tumor progression. Treatment with the ALK inhibitor crizotinib is more effective than standard chemotherapy. However, resistance to crizotinib occurs after approximately 8 months. Ceritinib is the first second-generation ALK inhibitor approved for treatment of crizotinib-resistant NSCLC. Ceritinib inhibits two of the most common ALK-mutants that confer resistance to crizotinib: L1196 M and G1269A. Cells with ALK expression are more sensitive to ceritinib than crizotinib (IC₅₀ 25 nM vs. 150 nM, respectively). Alternative second-generation ALK inhibitors such as Alectinib, Brigatinib and PF-06463922 are currently in development, each affecting different crizotinib-resistant ALK target mutations. Genetic identification of crizotinib-resistant mutants is essential for selecting the optimal treatment strategy in NSCLC patients to overcome resistance and to increase progression-free survival.     

Targeted therapies in non-small cell lung cancer: a focus on ALK/ROS1 tyrosine kinase inhibitors

Introduction: Anaplastic lymphoma kinase (ALK) and ROS1 rearrangements define important molecular subgroups of advanced non-small cell lung cancer (NSCLC). The identification of these genetic driver alterations created new potential for highly active therapeutic interventions. After discovery of ALK rearrangements in NSCLC, it was recognized that these confer sensitivity to ALK inhibition.

Areas covered: Crizotinib, the first-in-class ALK/ROS1/MET inhibitor, was initially approved as second-line treatment of ALK-positive advanced NSCLC but after this, it was firmly established as the standard first-line therapy for advanced ALK-positive NSCLC. After initial response to crizotinib, tumors inevitably relapse. Next-generation ALK inhibitors, more potent and brain-penetrable than crizotinib, may be effective in re-inducing remissions when cancers are still addicted to ALK. Ceritinib and alectinib are approved for metastatic ALK positive NSCLC patients, while brigatinib received granted accelerated approval by the United States Food and Drug Administration. Regarding ROS1 rearrangement, to date crizotinib is the only ALK-tyrosine kinase inhibitor receiving indication as treatment of ROS1 positive advanced NSCLC.

Expert commentary: Although novel ALK-inhibitors are under clinical investigation compared to crizotinib as front-line treatment for ALK-positive NSCLC, nowadays the current standard first-line therapy for these patients is crizotinib. Further research will clarify the best management of ALK-positive NSCLC, above all who progress on first-line crizotinib.     

The accelerated path of ceritinib: Translating pre-clinical development into clinical efficacy

The discovery of anaplastic lymphoma kinase (ALK)-rearranged non–small-cell lung cancer (NSCLC) in 2007 led to the development and subsequent approval of the ALK inhibitor crizotinib in 2011. However, despite its clinical efficacy, resistance to crizotinib invariably develops. There is now a next generation of ALK inhibitors, including two that have been approved—ceritinib and alectinib—and others that are in development—brigatinib, lorlatinib and X-396. Ceritinib and the other next-generation ALK inhibitors are more potent than crizotinib and can overcome tumor cell resistance mechanisms. Ceritinib gained US Food and Drug Administration approval in 2014 following accelerated review for the treatment of patients with ALK-positive (ALK+) metastatic NSCLC who have progressed on or are intolerant to crizotinib. In pre-clinical studies, it demonstrated more potent inhibition of ALK than crizotinib in enzymatic assays, more durable responses in xenograft models and the ability to potently overcome crizotinib resistance mutations in vitro (including the gatekeeper mutation). There is also evidence for ceritinib penetration across the blood-brain barrier. In clinical trials, ceritinib has demonstrated durable responses and progression-free survival in ALK-inhibitor–pre-treated and –naïve NSCLC patients, including high overall and intracranial response rates in those with central nervous system metastases. Selective gastrointestinal toxicity of ceritinib, such as diarrhea, nausea and vomiting is generally manageable with prophylactic medication and prompt dose reduction or interruption. Future progress in treating ALK+ NSCLC will focus on determining the optimal sequencing of therapies and strategies to overcome acquired resistance, an ongoing challenge in treating ALK-mutation–driven tumors.     

The Biology and Clinical Features of Non–small Cell Lung Cancers with EML4-ALK Translocation

The anaplastic lymphoma kinase (ALK) acts as a dominant oncogenic driver following chromosomal rearrangements in certain cancers including non–small cell lung cancer (NSCLC). NSCLC with ALK translocation occurs in a specific subset of patients and results in unique clinical features. Crizotinib is a small molecule inhibitor of ALK kinase that has recently been approved by the FDA for the treatment of patients with ALK-positive NSCLC. Treatment with crizotinib results in clinical benefit rate of 85%–90% and a median progression-free survival of 9–10 months for this molecular subset of patients. Ongoing studies will define the impact of crizotinib on overall survival and provide insights into the resistance mechanisms and potential activation of alternate pathways. Heat shock protein 90 inhibitors also appear promising in the treatment of ALK-positive NSCLC patients, based on early results. This article reviews the characteristics, treatment, and ongoing research in patients with ALK-positive NSCLC.     

ALK基因抑制剂治疗非小细胞肺癌脑转移的研究进展

间变性淋巴瘤激酶(ALK)重排是非小细胞肺癌(NSCLC)强有力的致癌驱动基因之一,伴ALK重排的NSCLC患者应用第一代ALK抑制剂如克唑替尼的治疗疗效要远远优于化疗.同时越来越多的研究报道了ALK抑制剂在伴有脑转移的NSCLC患者中的颅内有效率.然而尽管第一代ALK抑制剂治疗ALK阳性NSCLC脑转移有初步的临床数据,但在获得性耐药后,肿瘤出现不同程度的复发,给肿瘤患者的后续治疗带来新的挑战.新一代ALK抑制剂如艾乐替尼、色瑞替尼、AP26113和PF-06463922的相继出现解决了这一问题.     

ALK阳性非小细胞肺癌脑转移患者的治疗

背景与目的间变性淋巴瘤激酶（anaplastic lymphoma kinase, ALK）阳性非小细胞肺癌（non-small cell lung cancer, NSCLC）是肺癌的一个重要亚型。ALK阳性NSCLC脑转移患者的治疗尚无标准模式。方法本研究对我院2013年3月-2016年3月期间确诊的ALK阳性NSCLC脑转移患者的临床资料和治疗情况进行回顾性分析,探讨不同治疗模式患者的转归。结果84例晚期ALK阳性NSCLC患者中,22例初诊时有脑转移,剔除3例合并表皮生长因子受体（epidermal growth factor receptor, EGFR）双突变患者,共19例纳入分析。中位颅内疾病进展时间（progression-free survival, PFS）为12.0个月,一线脑部局部治疗（P=0.021）及一线克唑替尼治疗（P=0.030）可延长PFS;一线克唑替尼联合脑部局部治疗的中位颅内PFS为27.0个月,而单纯克唑替尼治疗的PFS仅为4.2个月。结论一线克唑替尼联合脑部局部治疗有助于延长ALK阳性晚期NSCLC患者的颅内PFS,因例数少,尚有待大样本多中心前瞻性临床研究证实。     

Ovarian metastasis from lung adenocarcinoma with ALK-positive rearrangement detected by next generation sequencing: A case report and literatures review

Ovarian metastasis is an exceptionally rare condition in lung adenocarcinoma patients and is often difficult to distinguish from primary ovarian carcinoma. ALK (anaplastic lymphoma kinase) tyrosine kinase inhibitors elicit a significant objective response rate and are well-tolerated in advanced ALK-positive lung cancer. Hence, we report a case of a 41-year-old woman with ovarian metastases from NSCLC. After receiving a 6 course first line chemotherapy and 8 course maintenance therapy, the patient suffered acute abdominal pain, so surgery was performed. ALK rearrangement was detected by next generation sequencing, with a 13% abundance of ALK fusion. Crizotinib was administered, and the disease remained stable after 10 months of crizotinib therapy. Further, we reviewed the literature related to characteristics of metastatic ovarian malignancies that form from lung tumors, the utility of ALK inhibition for treating ALK-positive NSCLC, the molecular diagnosis of ALK rearrangement and the role of next generation sequencing for ALK rearrangement detection.     

Crizotinib in the Treatment of Non–Small-Cell Lung Cancer

An anaplastic lymphoma kinase (ALK) translocation giving rise to activated ALK tyrosine kinase is present in approximately 5% of non–small-cell lung cancers (NSCLCs). Crizotinib is an oral tyrosine kinase inhibitor targeting ALK, met proto-oncogene, and c-ros oncogene 1 (ROS1). It was recently approved in several countries for the treatment of patients with advanced, ALK-rearranged NSCLC. In 2012, results from the first phase III trial showing superiority of crizotinib compared with standard chemotherapy in second-line treatment of ALK-positive NSCLC were presented. Furthermore, crizotinib was recently shown to be active in ROS1-rearranged NSCLC. Here, we give an overview of the molecular pathogenesis of ALK-rearranged NSCLC, the pharmacokinetic and pharmacodynamic properties of crizotinib, and clinical trials of crizotinib for ALK-rearranged NSCLC.     

ASCEND-8: A Randomized Phase 1 Study of Ceritinib, 450 mg or 600 mg,Taken with a Low-Fat Meal versus 750 mg in Fasted State in Patients with Anaplastic Lymphoma Kinase (ALK)-Rearranged Metastatic Non–Small Cell Lung Cancer (NSCLC)

IntroductionCeritinib, 750 mg fasted, is approved for treatment of patients with ALK receptor tyrosine kinase gene (ALK)-rearranged (ALK-positive) NSCLC previously treated with crizotinib. Part 1 of the ASCEND-8 study determined whether administering ceritinib, 450 mg or 600 mg, with a low-fat meal may enhance gastrointestinal (GI) tolerability versus 750 mg fasted in patients with ALK-positive NSCLC while maintaining similar exposure.MethodsASCEND-8 is a multicenter, randomized, open-label, phase 1 study. Part 1 investigated the steady-state pharmacokinetics (PK) and safety of ceritinib, 450 mg or 600 mg, taken with a low-fat meal versus 750 mg fasted in patients with advanced ALK-positive NSCLC who were either treatment naive or pretreated with chemotherapy and/or crizotinib. Part 2 will assess efficacy and safety of ceritinib in treatment-naive patients.ResultsAs of June 16, 2016, 137 patients were randomized (450 mg fed [n = 44], 600 mg fed [n = 47], and 750 mg fasted [n = 46]); 135 patients received ceritinib. Median follow-up duration was 4.14 months. At steady state, relative to 750 mg fasted, 450 mg with food demonstrated comparable PK as assessed by maximum (peak) concentration of drug in plasma and area under the plasma concentration–time curve from time zero to 24 hours, whereas 600 mg with food demonstrated approximately 25% higher PK. Relative to 750 mg fasted, 450 mg with food was associated with a lower proportion of patients with GI toxicities, mostly grade 1 (diarrhea [43.2%], nausea [29.5%], and vomiting [18.2%]); there were no grade 3 or 4 events, study drug discontinuations, or serious AEs due to GI toxicities.ConclusionCeritinib, 450 mg with food, had similar exposure and a more favorable GI safety profile than ceritinib, 750 mg in fasted patients with ALK-positive NSCLC.     

艾乐替尼治疗ALK阳性非小细胞肺癌的研究进展

克唑替尼作为第一代间变性淋巴瘤激酶酪氨酸激酶抑制剂(anaplastic lymphoma kinase-tyrosine kinase inhibitors, ALKTKIs), 在间变性淋巴瘤激酶(ALK)阳性晚期非小细胞肺癌(non-small cell lung cancer, NSCLC)患者的治疗中有着举足轻重的地位, 但其和所有的TKI一样, 也不可避免地遇到了耐药的问题。于是第二代ALK-TKIs (艾乐替尼、色瑞替尼、布加替尼等)应运而生, 本文就其中的研究热点之一艾乐替尼治疗ALK阳性NSCLC的研究进展进行综述。      

Phase II study of ceritinib in alectinib‐pretreated patients with anaplastic lymphoma kinase‐rearranged metastatic non‐small‐cell lung cancer in Japan: ASCEND‐9

Clinical experience of ceritinib in patients who progressed on alectinib is limited. In this prospective phase II study, we evaluated the activity of ceritinib in alectinib‐pretreated patients with anaplastic lymphoma kinase (ALK)‐rearranged metastatic (stage IIIB/IV) non‐small‐cell lung cancer (NSCLC) in Japan. All patients were required to have ≥1 measurable lesion per RECIST, 1.1, and a World Health Organization Performance Status (WHO PS) of 0‐1. Prior crizotinib and/or up to 1 chemotherapy regimen was allowed. Primary endpoint was investigator‐assessed overall response rate (ORR) per RECIST 1.1. Ceritinib was given at a dose of 750 mg/day fasted. A total of 20 patients were enrolled from August 2015 to March 2017. All patients received prior alectinib (100%), 13 (65.0%) patients received prior platinum‐based chemotherapy, and 4 (20%) patients received prior crizotinib. Median duration of exposure and the follow‐up time with ceritinib were 3.7 months (range: 0.4‐15.1) and 11.6 months (range: 4.8‐23.0), respectively. Investigator‐assessed ORR was 25% (95% CI: 8.7‐49.1). Key secondary endpoints, all investigator assessed, included disease control rate (70.0%; 95% CI: 45.7‐88.1), time to response (median, 1.8 months; range: 1.8‐2.0), and duration of response (median, 6.3 months; 95% CI: 3.5‐9.2). Median progression‐free survival was 3.7 months (95% CI: 1.9‐5.3). The most common adverse events reported were diarrhea (85.0%), nausea (80.0%), and vomiting (65.0%). Based on our findings, ceritinib could be considered as one of the treatment options for patients with ALK‐positive NSCLC who progressed on alectinib. (Trial registration no. NCT02450903)     

ALK inhibitors: a new targeted therapy in the treatment of advanced NSCLC

The anaplastic lymphoma kinase (ALK) fusion gene is a key oncogenic driver in a subset of patients with advanced non-small cell lung cancer (NSCLC). Oncogenic fusion genes, including echinoderm microtubule-associated protein-like 4 (EML4) and ALK, have been detected in approximately 2–7 % of NSCLC patients. Fluorescence in situ hybridization (FISH) is the recommended method for detecting ALK gene rearrangement. EML4–ALK fusion genes define a molecular subset of NSCLC with distinct clinical characteristic (lung adenocarcinoma, never or former smoker, usually mutually exclusive with EGFR mutations). Crizotinib (PF-02341066) is an orally bioavailable, ATP-competitive, small molecule inhibitor of both the receptor tyrosine kinases ALK and c-MET (hepatocyte growth factor receptor). Crizotinib has been shown to yield important clinical benefit such as objective response rate, progression-free survival (PFS), and anticipated improvements in quality of life when used in pretreated patients with advanced NSCLC harboring EML4–ALK gene rearrangement. Preliminary phase II data suggested that crizotinib is safe and well tolerated with rapid and robust antitumor activity. A phase III randomized trial in a second-line setting showed response rate and PFS (primary study endpoint) advantage for crizotinib as compared to second-line chemotherapy. Treatment-related adverse events, predominantly restricted to the gastrointestinal and visual systems, are generally self-limiting or easily managed. Crizotinib is a new standard of care for patients with advanced, ALK-positive, NSCLC. In this review, we will discuss the discovery of ALK rearrangements, the clinical epidemiology of lung cancer driven by ALK, the clinical data for ALK-targeted therapy in NSCLC, and ongoing ALK inhibitor-based clinical trials.     

Anaplastic lymphoma kinase as a new target for the treatment of non-small-cell lung cancer

The anaplastic lymphoma kinase (ALK) gene rearrangement identifies a distinct molecular subset in non-small-cell lung cancer (NSCLC) populations susceptible to targeted inhibition. It consists of a small inversion in the short arm of chromosome 2 between exon 20 of the ALK gene and different exons of the echinoderm microtubule-associated protein-like (EML4) gene. This translocation leads to a chimeric protein with constitutive activation of ALK that possesses an oncogenic activity demonstrated both in vitro and in vivo. Other rare translocation partners for ALK other than EML4 may be found in lung cancers, including TRK-fused gene (TFG) and kinesin family member 5B (KIF5B). ALK-positive patients represent 5-6% of all NSCLCs and they seem to have particular clinicopathological and molecular features. Recently, Phase I-II trial results of crizotinib, a potent dual c-MET and ALK inhibitor, demonstrated its dramatic efficacy in ALK-positive patients with advanced NSCLC. This article will present knowledge on the characteristics of ALK-positive patients, discuss the different methods of ALK rearrangement detection and focus on clinical results of crizotinib.     

Ceritinib Alone for Crizotinib-naive Versus Crizotinib-pretreated for Management of Anaplastic Lymphoma Kinase-rearrangement Non–Small-cell Lung Cancer: A Systematic Review

Ceritinib shows a promising efficacy in patients with anaplastic lymphoma kinase (ALK)-rearrangement non–small-cell lung cancer (NSCLC). The present systematic review determined the whole body and intracranial effectiveness and safety of ceritinib in crizotinib-naive versus crizotinib-pretreated regimens in ALK-rearrangement NSCLC. A comprehensive search of databases, including PubMed, EMBASE, Ovid, Web of Science, and COCHRANE, was performed to identify clinical trials in English-language journals. We estimated the pooled progression-free survival (PFS) and overall response rate (ORR) for ceritinib in whole body and intracranial responses to find differences between crizotinib-naive and crizotinib-pretreated regimens. The intracranial disease control rate in both crizotinib-naive and crizotinib-pretreated regimens was also estimated. The pooled efficacy parameters were as follows: ORR, 56.9% (95% confidence interval [CI], 53.6%-60.1%); PFS, 8.26 months (95% CI, 6.18-11.07 months); intracranial ORR, 41.3% (95% CI, 35.3%-47.6%); and intracranial disease control rate, 79.8% (95% CI, 73.8%-84.7%). The pooled ceritinib for crizotinib-naive showed a trend toward greater ORR and longer PFS compared with ceritinib for crizotinib-pretreated (68.9% and 14.62 months vs. 48.2% and 6.32 months, respectively). The intracranial ORR for ceritinib as the initial regimen was 50.6% compared with 33.6% for crizotinib-pretreated. The discontinuation and dose reduction rates were 3.1% and 38.4%, respectively. The most common grade 3/4 adverse effects were increased alanine aminotransferase (25.5%), increased γ-glutamyltransferase (12.6%), and increased aspartate aminotransferase (11.1%). Ceritinib is an effective agent for both crizotinib-naive and crizotinib-pretreated patients with locally advanced or metastatic ALK-rearranged NSCLC. Ceritinib has significant activity in crizotinib-naive patients with brain metastases.     

Brigatinib: New-generation ALK inhibitor for nonsmall cell lung cancer

Lung cancer, specifically nonsmall cell lung cancer (NSCLC) is the leading cause of death around the world. First-line therapies for metastatic NSCLC such as crizotinib, a tyrosine kinase inhibitor (TKI), have developed resistance due to a rearrangement of the anaplastic lymphoma kinase (ALK) gene. Brigatinib, approved in May 2016, is an ALK inhibitor specifically indicated for ALK-positive metastatic NSCLC in patients who have progressed on or resistant to crizotinib therapy. In several clinical trials, brigatinib has exhibited significant improvement in progression-free survival in patients that have experienced resistance to crizotinib therapy. The optimal dose of brigatinib was found to be 180 mg once daily and demonstrated greater efficacy as compared to its 90 mg once daily dose. Brigatinib was also found to be well tolerated. Although more studies are needed, the current data from these studies indicate brigatinib may be the most favorable therapeutic approach to treat NSCLC ALK-positive patients.     

The potential for crizotinib in non-small cell lung cancer: a perspective review

Tyrosine kinases have a crucial role as key regulators of signaling pathways that influence cell differentiation and growth. Dysregulation of tyrosine kinase-mediated signaling is understood to be an important oncogenic driver. Genetic rearrangements involving the tyrosine kinase anaplastic lymphoma kinase (ALK) gene occur in non-small cell lung cancer (NSCLC), anaplastic large cell lymphomoas, inflammatory myofibroblastic tumors, and other cancers. Cells with abnormal ALK signaling are sensitive to ALK inhibitors such as crizotinib. This review will highlight the discovery of the fusion between echinoderm microtubule-associated protein-like 4 (EML4) and ALK as an oncogenic driver, recognition of other ALK gene rearrangements in NSCLC, and the confirmation that crizotinib is an effective treatment for patients with ALK-positive NSCLC. Work is underway to further define the role for crizotinib in the treatment of ALK-positive lung cancer and other cancers and to investigate the molecular mechanisms for resistance to ALK inhibition with crizotinib.     

The Incidence of Brain Metastases in Stage IV ROS1-Rearranged Non–Small Cell Lung Cancer and Rate of Central Nervous System Progression on Crizotinib

Introduction

Central nervous system (CNS) metastases in lung cancer are a frequent cause of morbidity and mortality. There are conflicting data on the incidence of CNS metastases in stage IV ROS1-positive NSCLC and the rate of CNS progression during crizotinib therapy.

Pemetrexed-based chemotherapy in patients with advanced,ALK-positive non-small cell lung cancer

BackgroundAnaplastic lymphoma kinase (ALK)-positive non-small-cell lung cancer (NSCLC) is highly responsive to crizotinib. To determine whether ALK-positive NSCLC is also sensitive to pemetrexed, we retrospectively evaluated progression-free survival (PFS) of ALK-positive versus ALK-negative patients who had been treated with pemetrexed-based chemotherapy for advanced NSCLC.Patients and methodsWe identified 121 patients with advanced, ALK-positive NSCLC in the USA, Australia, and Italy. For comparison, we evaluated 266 patients with advanced, ALK-negative, epidermal growth factor receptor (EGFR)-wild-type NSCLC, including 79 with KRAS mutations and 187 with wild-type KRAS (WT/WT/WT). We determined PFS on different pemetrexed regimens.ResultsAmong 70 ALK-positive patients treated with a platinum/pemetrexed regimen, the median PFS (mPFS) was 7.3 months (95% confidence interval (CI) 5.5–9.5). The mPFS of 51 ALK-positive patients treated with single-agent pemetrexed or nonplatinum/pemetrexed combinations was 5.5 months (2.8–9.0). For ALK-negative patients, PFS on all pemetrexed-based regimens was similar to that of ALK-positive patients, except in the specific setting of first-line platinum/pemetrexed where the mPFS was only 4.2 and 5.4 months in KRAS and WT/WT/WT patients, respectively. However, among patients with a never/light-smoking history (0–10 pack-year smoking history) treated with first-line platinum/pemetrexed, there was no difference in PFS between ALK-positive and ALK-negative patients.ConclusionsPFS on pemetrexed or nonplatinum/pemetrexed combinations was similar in ALK-positive and ALK-negative patients. PFS on first-line platinum/pemetrexed may be prolonged in never/light-smoking patients regardless of ALK status.     

Efficacy and Safety of Brigatinib Compared With Crizotinib in Asian vs. Non-Asian Patients With Locally Advanced or Metastatic ALK–Inhibitor-Naive ALK+ Non–Small Cell Lung Cancer: Final Results From the Phase III ALTA-1L Study

BackgroundBrigatinib is a next-generation anaplastic lymphoma kinase (ALK) inhibitor with demonstrated efficacy in locally advanced and metastatic non–small cell lung cancer (NSCLC) in crizotinib-refractory and ALK inhibitor-naive settings. This analysis assessed brigatinib in Asian vs. non-Asian patients from the first-line ALTA-1L trial.Patients and MethodsThis was a subgroup analysis from the phase III ALTA-1L trial of brigatinib vs. crizotinib in ALK inhibitor–naive ALK+ NSCLC. The primary endpoint was progression-free survival (PFS) as assessed by blinded independent review committee (BIRC). Secondary endpoints included confirmed objective response rate (ORR) and overall survival (OS) in the overall population and BIRC-assessed intracranial ORR and PFS in patients with brain metastases.ResultsOf the 275 randomized patients, 108 were Asian. Brigatinib showed consistent superiority in BIRC-assessed PFS vs. crizotinib in Asian (hazard ratio [HR]: 0.35 [95% CI: 0.20-0.59]; log-rank P = .0001; median 24.0 vs. 11.1 months) and non-Asian (HR: 0.56 [95% CI: 0.38-0.84]; log-rank P = .0041; median 24.7 vs. 9.4 months) patients. Results were consistent with investigator-assessed PFS and BIRC-assessed intracranial PFS. Brigatinib was well tolerated. Toxicity profiles and dose modification rates were similar between Asian and non-Asian patients.ConclusionEfficacy with brigatinib was consistently better than with crizotinib in Asian and non-Asian patients with locally advanced or metastatic ALK inhibitor-naive ALK-+ NSCLC. There were no clinically notable differences in overall safety in Asian vs. non-Asian patients.     

Elucidation of Resistance Mechanisms to Second-Generation ALK Inhibitors Alectinib and Ceritinib in Non–Small Cell Lung Cancer Cells

Crizotinib is the first anaplastic lymphoma kinase (ALK) inhibitor to have been approved for the treatment of non–small cell lung cancer (NSCLC) harboring an ALK fusion gene, but it has been found that, in the clinic, patients develop resistance to it. Alectinib and ceritinib are second-generation ALK inhibitors which show remarkable clinical responses in both crizotinib-naive and crizotinib-resistant NSCLC patients harboring an ALK fusion gene. Despite their impressive activity, clinical resistance to alectinib and ceritinib has also emerged. In the current study, we elucidated the resistance mechanisms to these second-generation ALK inhibitors in the H3122 NSCLC cell line harboring the EML4-ALK variant 1 fusion in vitro. Prolonged treatment of the parental H3122 cells with alectinib and ceritinib led to two cell lines which are 10 times less sensitive to alectinib and ceritinib than the parental H3122 cell line. Although mutations of ALK in its kinase domain are a common resistance mechanism for crizotinib, we did not detect any ALK mutation in these resistant cell lines. Rather, overexpression of phospho-ALK and alternative receptor tyrosine kinases such as phospho-EGFR, phospho-HER3, and phospho-IGFR-1R was observed in both resistant cell lines. Additionally, NRG1, a ligand for HER3, is upregulated and responsible for resistance by activating the EGFR family pathways through the NRG1-HER3-EGFR axis. Combination treatment with EGFR inhibitors, in particular afatinib, was shown to be effective at overcoming resistance. Our study provides new mechanistic insights into adaptive resistance to second-generation ALK inhibitors and suggests a potential clinical strategy to combat resistance to these second-generation ALK inhibitors in NSCLC.