Emergence of Preexisting MET Y1230C Mutation as a Resistance Mechanism to Crizotinib in NSCLC with MET Exon 14 Skipping

IntroductionMET proto-oncogene, receptor tyrosine kinase gene exon 14 skipping (METex14) alterations represent a unique subset of oncogenic drivers in NSCLC. Preliminary clinical activity of crizotinib against METex14-positive NSCLC has been reported. The full spectrum of resistance mechanisms to crizotinib in METex14-positive NSCLC remains to be identified.MethodsHybrid capture–based comprehensive genomic profiling performed on a tumor specimen obtained at diagnosis, and a hybrid capture–based assay of circulating tumor DNA (ctDNA) at the time of progression during crizotinib treatment was assessed in a pairwise fashion.ResultsA METex14 alteration (D1010H) was detected in the pretreatment tumor biopsy specimen, as was MET proto-oncogene, receptor tyrosine kinase (MET) Y1230C, retrospectively, at very low frequency (0.3%). After a confirmed response during crizotinib treatment for 13 months followed by progression, both MET proto-oncogene, receptor tyrosine kinase gene Y1230C and D1010H were detected prospectively in the ctDNA.ConclusionEmergence of the preexisting MET Y1230C likely confers resistance to crizotinib in this case of METex14-positive NSCLC. Existence of pretreatment MET Y1230C may eventually modulate the response of METex14-positive NSCLC to type I MET tyrosine kinase inhibitors. Noninvasive plasma-based ctDNA assays can provide a convenient method to detect resistance mutations in patients with previously known driver mutations.     

A Phase 2 Study of Capmatinib in Patients With MET-Altered Lung Cancer Previously Treated With a MET Inhibitor

IntroductionCapmatinib is approved for MET exon 14–altered NSCLC on the basis of activity in targeted therapy–naive patients. We conducted a phase 2 study to assess the efficacy of capmatinib in patients previously treated with a MET inhibitor.MethodsPatients with advanced NSCLC harboring MET amplification or MET exon 14 skipping alterations received capmatinib 400 mg twice daily. The primary end point was the objective response rate. Secondary end points included progression-free survival, disease control rate (DCR), intracranial response rate, and overall survival. Circulating tumor DNA was analyzed to identify capmatinib resistance mechanisms.ResultsA total of 20 patients were enrolled between May 2016 and November 2019, including 15 patients with MET skipping alterations and five patients with MET amplification. All patients had received crizotinib; three had also received other MET-directed therapies. The median interval between crizotinib and capmatinib was 22 days (range: 4–374). Two patients (10%) achieved an objective response to capmatinib and 14 had stable disease, yielding a DCR of 80%. Among five patients who discontinued crizotinib for intolerance, the DCR was 83%, including two patients with the best tumor shrinkage of −25% and −28%. Intracranial DCR among four patients with measurable brain metastases was 100%, with no observed intracranial objective responses. Overall, the median progression-free survival and overall survival were 5.5 (95% confidence interval: 1.3–11.0) and 11.3 (95% confidence interval: 5.5–not reached) months, respectively. MET D1228 and Y1230 mutations and MAPK alterations were recurrently detected in postcrizotinib, precapmatinib plasma. New and persistent MET mutations and MAPK pathway alterations were detected in plasma at progression on capmatinib.ConclusionsCapmatinib has modest activity in crizotinib-pretreated MET-altered NSCLC, potentially owing to overlapping resistance mechanisms.     

Crizotinib for the Treatment of ALK‐Rearranged Non‐Small Cell Lung Cancer: A Success Story to Usher in the Second Decade of Molecular Targeted Therapy in Oncology

Crizotinib, an ALK/MET/ROS1 inhibitor, was approved by the U.S. Food and Drug Administration for the treatment of anaplastic lymphoma kinase (ALK)‐rearranged non‐small cell lung cancer (NSCLC) in August 2011, merely 4 years after the first publication of ALK‐rearranged NSCLC. The crizotinib approval was accompanied by the simultaneous approval of an ALK companion diagnostic fluorescent in situ hybridization assay for the detection of ALK‐rearranged NSCLC. Crizotinib continued to be developed as an ALK and MET inhibitor in other tumor types driven by alteration in ALK and MET. Crizotinib has recently been shown to be an effective ROS1 inhibitor in ROS1‐rearranged NSCLC, with potential future clinical applications in ROS1‐rearranged tumors. Here we summarize the heterogeneity within the ALK‐ and ROS1‐rearranged molecular subtypes of NSCLC. We review the past and future clinical development of crizotinib for ALK‐rearranged NSCLC and the diagnostic assays to detect ALK‐rearranged NSCLC. We highlight how the success of crizotinib has changed the paradigm of future drug development for targeted therapies by targeting a molecular‐defined subtype of NSCLC despite its rarity and affected the practice of personalized medicine in oncology, emphasizing close collaboration between clinical oncologists, pathologists, and translational scientists.     

ALK Inhibitors: What Is the Best Way to Treat Patients With ALK+ Non–Small-Cell Lung Cancer?

Genetic insight into the pathogenesis of lung cancer has paved the way for a new era in its treatment. Recently, anaplastic lymphoma kinase (ALK) has been identified as exerting a potent transforming effect through genetic rearrangement in patients with lung cancer. Preclinical and single-arm phase I studies have shown that patients with ALK-rearranged non–small cell lung cancer (NSCLC) can be successfully treated with crizotinib. Furthermore, a phase III randomized study indicated that crizotinib is superior to standard chemotherapy in the treatment of patients with NSCLC harboring the ALK rearrangement who had received 1 previous platinum-based chemotherapy. Despite the excellent efficacy of crizotinib in patients with ALK-positive (ALK⁺) lung cancer, resistance mechanisms—such as secondary mutations in the ALK gene, the activation of other oncogenes, and so on—have been identified as conferring resistance to crizotinib. Second-generation ALK inhibitors, such as alectinib and ceritinib, have been shown to be effective not only in crizotinib-naive patients but also in those resistant to crizotinib. Therefore, although some agents specifically targeting ALK have been developed and their efficacy has been documented, how ALK inhibitors should be administered in the setting of ALK-rearranged NSCLC remains to be fully elucidated. Can second-generation ALK inhibitors replace crizotinib? Is crizotinib just a first-generation ALK inhibitor? Is the sequential use of crizotinib and second-generation ALK inhibitors the best method? In this article, we review the preclinical and clinical results regarding crizotinib and second-generation ALK inhibitors, as well as the resistance mechanisms, and discuss the best methods for treating patients with ALK⁺ NSCLC.     

Crizotinib in Patients With MET-Amplified NSCLC

IntroductionMET amplification is a rare, potentially actionable, primary oncogenic driver in patients with NSCLC.MethodsThe influence of MET amplification on the clinical activity of the ALK, ROS1, and MET inhibitor, crizotinib (250 mg twice daily), was examined in patients with NSCLC (NCT00585195) who were enrolled into high (≥4 MET-to-CEP7 ratio), medium (>2.2 to <4 MET-to-CEP7 ratio), or low (≥1.8 to ≤2.2 MET-to-CEP7 ratio) amplification categories. Retrospective next-generation sequencing profiling was performed on archival tumor tissue. End points included objective response rate (ORR), duration of response, and progression-free survival.ResultsA total of 38 patients with a MET-to-CEP7 ratio greater than or equal to 1.8 by local fluorescence in situ hybridization testing received crizotinib. All patients were response-assessable, among whom 21, 14, and 3 had high, medium, and low MET amplification, respectively. ORRs of 8 of 21 (38.1%), 2 of 14 (14.3%), and 1 of 3 (33.3%), median duration of response of 5.2, 3.8, and 12.2 months, and median progression-free survival values of 6.7, 1.9, and 1.8 months were observed for those with high, medium, and low MET amplification, respectively. MET amplification gene copy number greater than or equal to 6 was detected by next-generation sequencing in 15 of 19 (78.9%) analyzable patients. Of these 15 patients, objective responses were observed in six (40%), two of whom had concurrent MET exon 14 alterations. No responses were observed among five patients with concurrent KRAS, BRAF, or EGFR mutations.ConclusionsPatients with high-level, MET-amplified NSCLC responded to crizotinib with the highest ORR. Use of combined diagnostics for MET and other oncogenes may potentially identify patients most likely to respond to crizotinib.     

Safety of MET Tyrosine Kinase Inhibitors in Patients With MET Exon 14 Skipping Non-small Cell Lung Cancer: A Clinical Review

MET exon 14 (METex14) skipping mutations occur in 3% to 4% of non-small cell lung cancer (NSCLC) cases. Currently, four oral MET tyrosine kinase inhibitors (TKIs) are in use for the treatment of patients with METex14 skipping NSCLC (tepotinib, capmatinib, savolitinib, and crizotinib). To support optimal management of METex14 skipping NSCLC in this typically older patient population, the safety profiles of these treatment options are reviewed here. Published safety data from prospective clinical trials with MET TKIs in patients with METex14 skipping NSCLC were reviewed. Treatment-related adverse events (TRAEs) occurring in ≥ 10% of patients were reported where feasible. Guidance on clinical monitoring and management of key MET TKI TRAEs and drug-drug interactions is provided. Across the clinical trials, safety data for MET TKIs were reported for 442 patients with METex14 skipping. Peripheral edema was the most reported TRAE (50%-63% of patients; grade ≥ 3: 1%-11%), followed by nausea (26%-46% of patients; grade ≥ 3: 0%-1%). TRAEs led to dose reductions in 33% to 38% of patients and to discontinuation in 7% to 14% of patients, across the MET TKIs. Considerations on interpreting available safety data are provided, along with insights into monitoring and managing specific MET TKI TRAEs of interest and drug-drug interactions. Overall, MET TKIs are tolerable treatment options for patients with METex14 skipping NSCLC, an older population for whom chemo- or immuno-therapy may not be an effective nor tolerable option. More data regarding the effectiveness of safety interventions and management strategies are needed.     

Targeting ALK: a promising strategy for the treatment of non-small cell lung cancer, non-Hodgkin’s lymphoma, and neuroblastoma

Anaplastic lymphoma kinase (ALK) is a tyrosine kinase receptor that affects a number of biological and biochemical functions through normal ligand-dependent signaling. It has oncogenic functions in a number of tumors including non-small cell lung cancer (NSCLC), anaplastic large cell lymphoma, and neuroblastoma when altered by translocation or amplification or mutation. On August 2011, a small molecule inhibitor against ALK, crizotinib, was approved for therapy against NSCLC with ALK translocations. As we determine the molecular heterogeneity of tumors, the potential of ALK as a relevant therapeutic target in a number of malignancies has become apparent. This review will discuss some of the tumor types with oncogenic ALK alterations. The activity and unique toxicities of crizotinib are described, along with potential mechanisms of resistance and new therapies beyond crizotinib.     

Asian Thoracic Oncology Research Group (ATORG) Expert Consensus Statement on MET Alterations in NSCLC: Diagnostic and Therapeutic Considerations

Non-small cell lung cancer (NSCLC) is a heterogeneous disease, with many oncogenic driver mutations, including de novo mutations in the Mesenchymal Epithelial Transition (MET) gene (specifically in Exon 14 [ex14]), that lead to tumourigenesis. Acquired alterations in the MET gene, specifically MET amplification is also associated with the development of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) resistance in patients with EGFR-mutant NSCLC. Although MET has become an actionable biomarker with the availability of MET-specific inhibitors in selected countries, there is differential accessibility to diagnostic platforms and targeted therapies across countries in Asia-Pacific (APAC).The Asian Thoracic Oncology Research Group (ATORG), an interdisciplinary group of experts from Australia, Hong Kong, Japan, Korea, Mainland China, Malaysia, the Philippines, Singapore, Taiwan, Thailand and Vietnam, discussed testing for MET alterations and considerations for using MET-specific inhibitors at a consensus meeting in January 2022, and in subsequent offline consultation.Consensus recommendations are provided by the ATORG group to address the unmet need for standardised approaches to diagnosing MET alterations in NSCLC and for using these therapies. MET inhibitors may be considered for first-line or second or subsequent lines of treatment for patients with advanced and metastatic NSCLC harbouring MET ex14 skipping mutations; MET ex14 testing is preferred within multi-gene panels for detecting targetable driver mutations in NSCLC. For patients with EGFR-mutant NSCLC and MET amplification leading to EGFR TKI resistance, enrolment in combination trials of EGFR TKIs and MET inhibitors is encouraged.     

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.     

Sequential Therapy with Crizotinib and Alectinib in ALK-Rearranged Non–Small Cell Lung Cancer—A Multicenter Retrospective Study

IntroductionAlectinib and crizotinib have been approved for the therapy of NSCLC caused by anaplastic lymphoma kinase gene (ALK) rearrangement. The effect of alectinib or crizotinib on overall survival (OS) in patients with ALK-rearranged NSCLC remains unknown.MethodsA multicenter retrospective study was conducted to compare OS between patients receiving alectinib and crizotinib and between patients treated with alectinib and those treated sequentially with crizotinib and then alectinib after crizotinib failure. The time to treatment failure (TTF), progression-free survival (PFS), and OS were compared.ResultsSixty-one patients with ALK-rearranged NSCLC were enrolled. Forty-six patients were treated with anaplastic lymphoma kinase (ALK) inhibitors (31 with crizotinib, 28 with alectinib, and 13 with both ALK inhibitors). The response rate was 66.7% for the crizotinib-treated group and 80.8% for the alectinib-treated group. Among all patients, TTF and PFS were significantly prolonged in the alectinib-treated group compared with in the crizotinib-treated group. Subgroup analyses revealed significantly prolonged TTF for alectinib compared with crizotinib therapy in the ALK inhibitor–naive population. OS was significantly longer in the alectinib-treated group than in the crizotinib-treated group. The TTF and OS of patients treated sequentially with crizotinib and then with alectinib after crizotinib failure tended to be longer than those of patients treated with alectinib alone.ConclusionsTherapy with alectinib alone was significantly superior to therapy with crizotinib alone in terms of TTF, PFS, and OS, and sequential therapy with crizotinib and alectinib after crizotinib failure tended to provide a better OS benefit than did therapy with alectinib alone in patients with ALK-positive NSCLC. However, large-scale prospective studies are needed to confirm these observations.     

Dual ALK and EGFR inhibition targets a mechanism of acquired resistance to the tyrosine kinase inhibitor crizotinib in ALK rearranged lung cancer

Introduction

The multitargeted tyrosine kinase inhibitor (TKI) crizotinib is active against ALK translocated non-small-cell lung cancer (NSCLC); however acquired resistance invariably develops over time. ALK mutations have previously been implicated in only a third of resistant tumors. We sought to evaluate alternative mechanisms of resistance and preclinical strategies to overcome these in a cell line driven by EML4-ALK.

Methods

We selected the NSCLC cell line NCI-H3122 (H3122: EML4-ALK E13;A20) and derived resistant variants that were able to grow in the presence of 1 μM crizotinib. These were analyzed for ALK mutations, sensitivity to crizotinib in combination with other TKIs, and for activation of alternative tyrosine kinases.

Results

All H3122 crizotinib resistant (CR) clones lacked amplification or mutations in the kinase domain of ALK. To evaluate if possible alternative kinases functioned as “bypass” tracks for downstream signaling activation in these resistance cells, we performed of phosho-receptor tyrosine kinase array that demonstrated that CR clones had higher phospho-EGFR signals than H3122 cells before and after exposure to crizotinib. A functional approach of dual ALK TKI (with crizotinib) with combinatory TKI inhibition was used as a secondary screen for possible targets. Crizotinib + erlotinib (reversible EGFR TKI) and crizotinib + afatinib (irreversible EGFR/ERBB2 TKI) were able to inhibit the growth of H3122 CR clones, confirming EGFR activation as a mechanism of resistance. The removal of crizotinib from the culture media re-sensitized CR cells to crizotinib.

Conclusions

We identified activation of EGFR as a mechanism of resistance to crizotinib in preclinical models of ALK translocated NSCLC. If EGFR activation is confirmed as a predominant mechanism of ALK TKI-induced resistance in patient-derived tumors, the use of ALK plus EGFR TKIs could be explored for this important cohort of NSCLCs.     

Management of Central Nervous System Metastases in Patients With Advanced Anaplastic Lymphoma Kinase-Rearranged Non–Small-Cell Lung Cancer During Crizotinib Treatment

BackgroundCentral nervous system (CNS) progression is a common manifestation of acquired resistance to crizotinib in anaplastic lymphoma kinase (ALK)-rearranged non–small-cell lung cancer (NSCLC). However, an optimal tailored treatment approach has not been established in patients with CNS failure during crizotinib treatment.Patients and MethodsPatients with ALK-rearranged NSCLC with CNS progression during crizotinib treatment between January 2013 and December 2016 were included for analysis. Clinical data for different treatments after CNS failure during crizotinib treatment were retrospectively collected.ResultsAmong the 44 patients who had CNS progression during crizotinib treatment, 19, 15, 8, and 2 patients received crizotinib treatment beyond progressive disease (CBPD), a second ALK tyrosine kinase inhibitor (TKI), chemotherapy, and best supportive care, respectively. Post progression survival offered by treatment with a second ALK TKI was significantly more favorable than that of chemotherapy (P < .001) or CBPD (P = .045). In addition, patients who received sequential treatment with a second ALK TKI had significantly longer intracranial time to progression (IC-TTP) compared with those treated with chemotherapy (P < .01) or CBPD after radiotherapy (P = .003). In the 7 patients who received brigatinib, the median IC-TTP was 21.8 months (95% confidence interval, 11.7-32.0). The additional use of CNS radiotherapy in patients treated with a second ALK TKI showed no significance in terms of IC-TTP (P = .54).ConclusionAlthough CBPD is an option in patients with isolated CNS progression during crizotinib treatment, sequential treatment with a second ALK TKI, particularly brigatinib, might be preferable. The newly approved TKI, brigatinib, showed promise in the control of brain metastases, even without radiotherapy.     

Acquisition of Cabozantinib-Sensitive MET D1228N Mutation During Progression on Crizotinib in MET-Amplified Triple-Negative Breast Cancer

BackgroundTargeting of somatic MET mutations using crizotinib has led to strong clinical responses, most frequently in patients with lung cancer, raising the possibility of adopting similar treatment strategies in patients with MET alterations in other cancer types.Patient and MethodsWe describe a patient with advanced triple-negative breast cancer with a 30-fold amplification of MET. Next-generation sequencing of pre- and postprogression biopsies was performed to identify the resistance mechanism emerging after an initial exceptional response to crizotinib. The response of the resistance mutant to type I and II MET inhibitors was assessed in cultured cells.ResultsAfter progressing on crizotinib, a MET-D1228N mutation was detected, which is located in the crizotinib-binding region of the MET kinase domain. Experimental studies demonstrated that this mutation confers complete resistance to crizotinib yet retains cabozantinib sensitivity. Treatment of the patient with cabozantinib led to a subjective improvement in clinical symptoms, but the patient progressed after 7 weeks.ConclusionAlthough MET mutations are rare in breast cancer, these patients may experience substantial clinical benefit from crizotinib treatment. Nevertheless, drug resistance owing to on-target MET mutations will likely be frequently encountered and comprehensive mechanistic studies to assess sensitivity of these mutants to a series of potential second-line therapies may help guide subsequent treatment for these patients.     

Precision medicine against <Emphasis Type="Italic">ALK</Emphasis>-positive non-small cell lung cancer: beyond crizotinib

Anaplastic lymphoma kinase (ALK) rearrangements represent the molecular driver of a subset of non-small cell lung cancers (NSCLCs). Despite the initial response, virtually all ALK-positive patients develop an acquired resistance to the ALK inhibitor crizotinib, usually within 12 months. Several next-generation ALK inhibitors have been developed in order to overcome crizotinib limitation, providing an unprecedented survival for this subset of patients. The aim of this review to summarize the current knowledge on ALK tyrosine kinase inhibitors (TKIs) in the treatment of advanced ALK-positive NSCLC, focusing on the role of novel ALK inhibitors in this setting. In addition, we will discuss their role in the pharmacological management of ALK-positive brain metastasis. Next-generation ALK inhibitors showed an impressive clinical activity in ALK-positive NSCLC, also against the sanctuary site of CNS. Sequential therapy with ALK TKIs appears to be effective in patients who fail a first ALK TKI and translates in clinically meaningful benefit. However, these agents display different activity profiles against crizotinib resistance mutation; therefore re-genotyping the disease at progression in order to administer the right TKI to the right patient is going to be necessary to correctly tailor the treatment. To avoid repeated invasive procedure, noninvasive methods to detect and monitor ALK rearrangement are under clinical investigation.     

Targeting stemness is an effective strategy to control EML4-ALK+ non-small cell lung cancer cells

The fusion between anaplastic lymphoma kinase (ALK) and echinoderm microtubule-associated protein-like 4 (EML4) is a causative factor in a unique subset of patients with non-small cell lung carcinoma (NSCLC). Although the inhibitor crizotinib, as it blocks the kinase activity of the resulting EML4-ALK fusion protein, displays remarkable initial responses, a fraction of NSCLC cases eventually become resistant to crizotinib by acquiring mutations in the ALK domain or activating bypass pathways via EGFR, KIT, or KRAS. Cancer stem cell (CSC) theory provides a plausible explanation for acquisition of tumorigenesis and resistance. However, the question as to whether EML4-ALK-driven tumorigenesis is linked with the stem-like property and whether the stemness is an effective target in controlling EML4-ALK⁺ NSCLC including crizotinib-resistant NSCLC cells has not been addressed. Here, we report that stem-like properties stem from ALK activity in EML4-ALK⁺ NSCLC cells. Notably, treatment with rapamycin, a CSC targeting agent, attenuates stem-like phenotypes of the EML4-ALK⁺ cells, which increased capability of tumor formation and higher expression of stemness-associated molecules such as ALDH, NANOG, and OCT4. Importantly, combinational treatment with rapamycin and crizotinib leads to synergistic anti-tumor effects on EML4-ALK⁺ NSCLC cells as well as on those resistant to crizotinib. Thus, we provide a proof of principle that targeting stemness would be a novel strategy to control intractable EML4-ALK⁺ NSCLC.     

Molecular rationale for the use of PI3K/AKT/mTOR pathway inhibitors in combination with crizotinib in ALK-mutated neuroblastoma

Mutations in the ALK tyrosine kinase receptor gene represent important therapeutic targets in neuroblastoma, yet their clinical translation has been challenging. The ALK^F1174L mutation is sensitive to the ALK inhibitor crizotinib only at high doses and mediates acquired resistance to crizotinib in ALK-translocated cancers. We have shown that the combination of crizotinib and an inhibitor of downstream signaling induces a favorable response in transgenic mice bearing ALK^F1174L/MYCN-positive neuroblastoma. Here, we investigated the molecular basis of this effect and assessed whether a similar strategy would be effective in ALK-mutated tumors lacking MYCN overexpression. We show that in ALK-mutated, MYCN-amplified neuroblastoma cells, crizotinib alone does not affect mTORC1 activity as indicated by persistent RPS6 phosphorylation. Combined treatment with crizotinib and an ATP-competitive mTOR inhibitor abrogated RPS6 phosphorylation, leading to reduced tumor growth and prolonged survival in ALK^F1174L/MYCN-positive models compared to single agent treatment. By contrast, this combination, while inducing mTORC1 downregulation, caused reciprocal upregulation of PI3K activity in ALK-mutated cells expressing wild-type MYCN. Here, an inhibitor with potency against both mTOR and PI3K was more effective in promoting cytotoxicity when combined with crizotinib. Our findings should enable a more precise selection of molecularly targeted agents for patients with ALK-mutated tumors.     

MET Exon 14 Alterations and New Resistance Mutations to Tyrosine Kinase Inhibitors: Risk of Inadequate Detection with Current Amplicon-Based NGS Panels

IntroductionTargeted therapies such as tyrosine kinase inhibitors (TKIs) have dramatically improved the treatment of lung adenocarcinoma, and detection of activating mutations of genes such as EGFR or anaplastic lymphoma kinase gene (ALK) is now mandatory in the clinical setting. However, additional targetable alterations are continuously being described and forcing us to adapt our detection methods. Here we have evaluated the ability of eight amplicon-based next-generation sequencing (NGS) panels to detect the recently described mesenchymal epithelial transition factor (MET) exon 14 (METex14) alterations or new mutations conferring resistance to TKIs.MethodsA total of 191 tumor samples from patients with NSCLC were screened for METex14 mutations by Sanger sequencing, and 62 additional cases were screened by Sanger sequencing and two amplicon-based NGS panels. In silico comparison of eight commercially available targeted NGS panels was also performed for the detection of METex14 alterations or ALK, ROS1, or EGFR resistance mutations.ResultsNGS analysis of the positive METex14 cases revealed a false-negative case because of amplicon design. Moreover, in silico analysis revealed that none of the eight panels considered would be able to detect more than 63% of literature-reported cases of METex14 mutations and similar limitations would be expected with new ALK, ROS1, or EGFR resistance mutations.ConclusionsWe have illustrated major limitations of commercially available amplicon-based DNA NGS panels for detection of METex14 and recently described resistance mutations to TKIs. Documented choice of available panels and their frequent reevaluation are mandatory to deliver the most accurate data to the clinician for therapeutic decisions.     

Detection of Nonreciprocal/Reciprocal ALK Translocation as Poor Predictive Marker in Patients With First-Line Crizotinib-Treated ALK-Rearranged NSCLC

IntroductionDuring nonreciprocal/reciprocal translocation process, 5′-anaplastic lymphoma kinase (ALK) sometimes gets retained in the genome and is detectable by next-generation sequencing; however, no study has investigated its clinical significance. Our study aimed to assess the impact of harboring 5′-ALK on the efficacy of crizotinib.MethodsA total of 150 patients with next-generation sequencing–identified ALK-rearranged NSCLC from March 2014 to July 2018 at the Hunan Cancer Hospital were enrolled in this study. The efficacy of crizotinib as first-line therapy was evaluated in 112 patients according to the retention of 5′-ALK.ResultsAmong the 150 patients with NSCLC, nonreciprocal/reciprocal translocation was detected in 18.7% (28 of 150), and 3′-ALK fusion alone was detected in 81.3% (122 of 150). Among the 112 patients who received first-line crizotinib, 89 had 3′-ALK fusion alone (79 echinoderm microtubule associated protein-like 4 [EML4]-ALK and 10 non–EML4-ALK), and 23 had nonreciprocal/reciprocal ALK translocation. Among the patients with nonreciprocal/reciprocal ALK translocation, three patients harbored dual concurrent 3′-ALK fusions. Patients with nonreciprocal/reciprocal ALK translocation had higher incidence of brain metastasis at baseline than those with 3′-ALK fusion alone (39.1% versus 13.4%, p = 0.028). Crizotinib-treated patients with nonreciprocal/reciprocal ALK translocation had significantly shorter median progression-free survival (PFS) compared with patients carrying 3′-ALK fusion alone (6.1 m versus 12.0 m, p = 0.001) or with EML4-ALK fusion alone (6.1 m versus 12.6 m, p = 0.001). Multivariate analysis revealed that harboring nonreciprocal/reciprocal ALK translocation was an independent predictor of worse PFS for crizotinib-treated ALK-rearranged NSCLC (p = 0.0046).ConclusionsPresence of nonreciprocal/reciprocal ALK translocation was predictive for worse PFS and greater likelihood of baseline brain metastases in patients with ALK-rearranged NSCLC who received first-line crizotinib.