Spectrum of Mechanisms of Resistance to Crizotinib and Lorlatinib in ROS1 Fusion-Positive Lung Cancer

MET gene amplification is a mechanism of resistance to entrectinib in ROS1+ NSCLC

BACKGROUND

ROS1 tyrosine kinase inhibitors (TKIs) have demonstrated significant clinical benefit for ROS1+ NSCLC patients. However, TKI resistance inevitably develops through ROS1 kinase domain (KD) modification or another kinase driving bypass signaling. While multiple TKIs have been designed to target ROS1 KD mutations, less is known about bypass signaling in TKI-resistant ROS1+ lung cancers.

METHODS

Utilizing a primary, patient-derived TPM3-ROS1 cell line (CUTO28), we derived an entrectinib-resistant line (CUTO28-ER). We evaluated proliferation and signaling responses to TKIs, and utilized RNA sequencing, whole exome sequencing, and fluorescence in situ hybridization to detect transcriptional, mutational, and copy number alterations, respectively. We substantiated in vitro findings using a CD74-ROS1 NSCLC patient's tumor samples. Last, we analyzed circulating tumor DNA (ctDNA) from ROS1+ NSCLC patients in the STARTRK-2 entrectinib trial to determine the prevalence of MET amplification.

RESULTS

CUTO28-ER cells did not exhibit ROS1 KD mutations. MET TKIs inhibited proliferation and downstream signaling and MET transcription was elevated in CUTO28-ER cells. CUTO28-ER cells displayed extrachromosomal (ecDNA) MET amplification without MET activating mutations, exon 14 skipping, or fusions. The CD74-ROS1 patient samples illustrated MET amplification while receiving ROS1 TKI. Finally, two of 105 (1.9%) entrectinib-resistant ROS1+ NSCLC STARTRK-2 patients with ctDNA analysis at enrollment and disease progression displayed MET amplification.

CONCLUSIONS

Treatment with ROS1-selective inhibitors may lead to MET-mediated resistance. The discovery of ecDNA MET amplification is noteworthy, as ecDNA is associated with more aggressive cancers. Following progression on ROS1-selective inhibitors, MET gene testing and treatments targeting MET should be explored to overcome MET-driven resistance.

Refining patient selection of MET-activated non-small cell lung cancer through biomarker precision

Dysregulated MET signaling plays an important role in lung oncogenesis, tumor growth and invasiveness. It may occur through various mechanisms, such as MET overexpression or gene amplification or mutation, all of which can be detected by specific methods. The utility of MET overexpression as a biomarker remains unclear due to discrepancies in its occurrence and non-standardized cut-off thresholds. MET exon 14 skipping mutation (METex14) was established as a strong predictor of response to selective MET tyrosine kinase inhibitors (TKIs), and clinical trial results in patients with non-small cell lung cancer (NSCLC) harboring METex14 led to the approval of capmatinib and tepotinib by regulatory agencies worldwide. MET amplification is an emerging biomarker, with clinical data indicating an association between MET gene copy number and response to MET-TKIs. Additionally, MET amplification represents an important mechanism of resistance to TKIs in oncogene-driven NSCLC. The identification of molecular alterations for which targeted therapies are available is important, and high-throughput next-generation sequencing techniques can provide information on multiple genes at the same time, helping to provide valuable predictive information for oncogene-driven cancers. This review summarizes the current methods used for the detection of METex14, MET amplification and MET overexpression, and discusses the evidence for the use of MET-TKIs in patients with NSCLC with MET dysregulation. We discuss the practical challenges that impact the use of METex14 in the clinic and the evidence gaps that need to be addressed to validate additional genomic markers for MET-dependent cancers.

MET alterations in NSCLC—Current Perspectives and Future Challenges

Targeted therapies have revolutionized the treatment and improved the outcome for oncogene-driven NSCLC and an increasing number of oncogenic driver therapies have become available. For MET-dysregulated NSCLC (especially MET exon 14 skipping mutations and MET-amplifications, which is one of the most common bypass mechanisms of resistance in oncogene-addicted NSCLC), several anti-MET-targeted therapies have been approved recently (MET exon 14 skipping mutation) and multiple others are in development. In this narrative review, we summarize the role of MET as an oncogenic driver in NSCLC, discuss the different testing methods for exon 14 skipping mutations, gene amplification, and protein overexpression, and review the existing data and ongoing clinical trials regarding targeted therapies in MET-altered NSCLC. As immunotherapy with or without chemotherapy has become the standard of care for advanced NSCLC, immunotherapy data for MET-dysregulated NSCLC are put into perspective. Finally, we discuss future challenges in this rapidly evolving landscape.

The return of RET GateKeeper mutations? an in-silico exploratory analysis of potential resistance mechanisms to novel RET macrocyclic inhibitor TPX-0046

TPX-0046 is designed to overcome resistance to FDA approved RET inhibitors Selpercatinib and Pralsetinib. Early prediction of resistance mechanisms to investigational drugs may facilitate subsequent drug and trial designs. This study aims to predict potential mutations inducing resistance to TPX-0046. We conducted an in-silico analysis of TPX-0046 macrocyclic structure and predicted the binding mode on RET. We used as reference literary examples of resistance mechanisms to other macrocyclic inhibitors (Lorlatinib on ALK/ROS1) to construct RET secondary resistance mutations. We conducted docking simulations to evaluate impact of mutations on TPX-0046 binding. TPX-0046 binding mode on RET appears to not be influenced by Solventfront G810X mutation presence. Bulky Gatekeeper V804X mutations affect predicted TPX-0046 binding mode. Mutations in Beta 7 strand region L881F and xDFG S891L impair TPX-0046 docking. Our findings suggest that development of second generation RET inhibitors focused mainly on Solventfront G810X mutations granting resistance to selective RET inhibitors Selpercatinib and Pralsetinib. If these findings are confirmed by identification of Gatekeeper V804X mutations in patients progressing to TPX-0046, explanation of acquired resistance and loss of benefit will be easier These findings might accelerate development of third generation RET inhibitors, as well as clinical trial design in precision oncology settings.

Protein tyrosine kinase inhibitor resistance in malignant tumors: molecular mechanisms and future perspective

Protein tyrosine kinases (PTKs) are a class of proteins with tyrosine kinase activity that phosphorylate tyrosine residues of critical molecules in signaling pathways. Their basal function is essential for maintaining normal cell growth and differentiation. However, aberrant activation of PTKs caused by various factors can deviate cell function from the expected trajectory to an abnormal growth state, leading to carcinogenesis. Inhibiting the aberrant PTK function could inhibit tumor growth. Therefore, tyrosine kinase inhibitors (TKIs), target-specific inhibitors of PTKs, have been used in treating malignant tumors and play a significant role in targeted therapy of cancer. Currently, drug resistance is the main reason for limiting TKIs efficacy of cancer. The increasing studies indicated that tumor microenvironment, cell death resistance, tumor metabolism, epigenetic modification and abnormal metabolism of TKIs were deeply involved in tumor development and TKI resistance, besides the abnormal activation of PTK-related signaling pathways involved in gene mutations. Accordingly, it is of great significance to study the underlying mechanisms of TKIs resistance and find solutions to reverse TKIs resistance for improving TKIs efficacy of cancer. Herein, we reviewed the drug resistance mechanisms of TKIs and the potential approaches to overcome TKI resistance, aiming to provide a theoretical basis for improving the efficacy of TKIs.

Acquired G2032R Resistance Mutation in ROS1 to Lorlatinib Therapy Detected with Liquid Biopsy

Lorlatinib, a third-generation anaplastic lymphoma kinase (ALK)/receptor tyrosine kinase inhibitor (ROS1), demonstrated efficacy in ROS1 positive (ROS1+) non-small cell lung cancer (NSCLC), although approval is currently limited to the treatment of ALK+ patients. However, lorlatinib-induced resistance mechanisms, and its efficacy against the resistance mutation G2032R in ROS1, respectively, have not yet been fully understood. Furthermore, concomitant tumor suppressor gene p53 (TP53) mutations occur in driver alteration positive NSCLC, but their prognostic contribution in the context of ROS1 inhibition remains unclear. Here we report a ROS1+ NSCLC patient who developed an on target G2032R resistance mutation during second-line lorlatinib treatment, indicating the lack of activity of lorlatinib against ROS1 G2032R. The resistance mutation was detected in plasma-derived ctDNA, signifying the clinical utility of liquid biopsies.

Crizotinib-Resistant ROS1 G2101A Mutation Associated With Sensitivity to Lorlatinib in ROS1-Rearranged NSCLC: Case Report

gene rearrangements occur in 1% to 2% of NSCLC. Acquired “on-target” mutations within the ROS1 kinase domain are a known resistance mechanism to the first-line ROS1 inhibitor crizotinib. Here, we report the first case of a patient with an acquired ROS1 G2101A resistance mutation after first-line crizotinib, who responded to lorlatinib. The response was dramatic but short in duration.

[Research Progress of Acquired Resistance Mediated by MET Amplification in Advanced Non-small Cell Lung Cancer]

Mesenchymal-epithelial transition factor (MET) amplification is an important driver of resistance in epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC), and the combination of MET proto-oncogene (MET) and EGFR-tyrosine kinase inhibitors (TKIs) has shown promise in overcoming this molecularly defined acquired resistance. Emerging data also demonstrate MET amplification as a resistance driver to TKIs-treated anaplastic lymphoma kinase (ALK)-, RET-, and ROS1-fusion NSCLC. Here, we review the literature on recent research progress of MET amplification as a resistance driver to targeted therapy in oncogene-driven NSCLC and summarize the progress of clinical strategies to overcome the resistance mechanism.
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A Phase 2 Study of Lorlatinib in Patients With ROS1-Rearranged Lung Cancer With Brain-Only Progression on Crizotinib

Introduction

The central nervous system (CNS) is a common site of progression among patients with ROS1-rearranged lung cancer receiving crizotinib. We conducted a phase 2 study to evaluate the intracranial efficacy of lorlatinib in patients with ROS1-rearranged lung cancer who developed CNS-only progression on crizotinib.

Methods

Patients with metastatic ROS1-rearranged lung cancer with CNS-only progression on crizotinib received lorlatinib 100 mg daily. The primary end point was intracranial disease control rate at 12 weeks per modified Response Evaluation Criteria in Solid Tumors version 1.1. Secondary end points included intracranial and extracranial progression-free survival, intracranial objective response rate, and safety/tolerability.

Results

A total of 16 patients were enrolled between November 2016 and January 2019. Nine patients (56%) had received prior CNS radiation, with a median of 10.9 months between radiation and lorlatinib. At 12 weeks, the intracranial disease control rate was 100% and intracranial objective response rate was 87%. While on study, the complee intracranial response rate was 60%. With median follow-up of 22 months, seven patients experienced disease progression, including five patients with CNS relapse. The median intracranial and extracranial progression-free survivals were 38.8 months (95% confidence interval: 16.9-not reported) and 41.1 months (95% confidence interval: 17.6-not reported), respectively. Molecular analysis of plasma or tissue from patients with extracranial progression on lorlatinib revealed ROS1 G2032R (n = 1), ROS1 L2086F (n = 1), and CCDC6-RET fusion plus ROS1 G2032R (n = 1). The safety profile of lorlatinib was consistent with prior studies. There were 11 patients (69%) who required dose reduction, including one patient who discontinued treatment for grade 3 edema. No grade greater than or equal to 4 adverse events were observed.

Conclusions

Lorlatinib induced durable intracranial responses in patients with ROS1-rearranged NSCLC and prior isolated CNS progression on crizotinib.

ROS1-positive non-small cell lung cancer (NSCLC): Biology, Diagnostics, Therapeutics and Resistance

ROS1 is a proto-oncogene encoding a receptor tyrosine protein kinase (RTK), homologous to the v - Ros sequence of University of Manchester tumours virus 2(UR2) sarcoma virus, whose ligands are still being investigated. ROS1 fusion genes have been identified in various types of tumours. As an oncoprotein, it promotes cell proliferation, activation and cell cycle progression by activating downstream signalling pathways, accelerating the development and progression of non-small cell lung cancer (NSCLC). Studies have demonstrated that ROS1 inhibitors are effective in patients with ROS1-positive NSCLC and are used for first-line clinical treatment. These small molecule inhibitors provide a rational therapeutic option for the treatment of ROS1-positive patients. Inevitably, ROS1 inhibitor resistance mutations occur, leading to tumours recurrence or progression. Here, we comprehensively review the identified biological properties and Differential subcellular localization of ROS1 fusion oncoprotein promotes tumours progression. We summarize recently completed and ongoing clinical trials of the classic and new ROS1 inhibitors. More importantly, we classify the complex evolving tumours cell resistance mechanisms. This review contributes to our understanding of the biological properties of ROS1 and current therapeutic advances and resistant tumours cells, and the future directions to develop ROS1 inhibitors with durable effects.

2021 global lung cancer therapy landscape

BACKGROUND

The lung cancer treatment landscape has significantly evolved over the past decade. However, a systematic analysis of the current global drug development landscape has not been conducted.

METHODS

We curated and analyzed a comprehensive list of therapeutic entities (TEs) in preclinical development and in clinical trials for lung cancer.

RESULTS

Based on our analysis of 707 therapeutic entities, we found a consistent forward trajectory in the development pipeline for both non-small cell and small cell lung cancer. Most of the TEs were in advanced stages of clinical trials. Targeted therapies continue to dominate in the non-immuno-oncology space. Immuno-oncology targets are expanding beyond inhibitors of the PD-L1 axis.

IMPLICATIONS

Our analysis highlights a robust portfolio of both preclinical and clinical TEs and suggests that lung cancer treatment is going to become even more biomarker-driven.

Culture and multiomic analysis of lung cancer patient-derived pleural effusions revealed distinct druggable molecular types

Malignant pleural effusion (MPE) is an independent determinant of poor prognostic factor of non-small cell lung cancer (NSCLC). The course of anchorage independent growth within the pleural cavity likely reforms the innate molecular characteristics of malignant cells, which largely accounts for resistance to chemotherapy and poor prognosis after the surgical resection. Nevertheless, the genetic and transcriptomic features with respect to various drug responses of MPE-complicated NSCLC remain poorly understood. To obtain a clearer overview of the MPE-complicated NSCLC, we established 28 MPE-derived lung cancer cell lines which were subjected to genomic, transcriptomic and pharmacological analysis. Our results demonstrated MPE-derived NSCLC cell lines recapitulated representative driver mutations generally found in the primary NSCLC. It also exhibited the presence of distinct translational subtypes in accordance with the mutational profiles. The drug responses of several targeted chemotherapies accords with both genomic and transcriptomic characteristics of MPE-derived NSCLC cell lines. Our data also suggest that the impending drawback of mutation-based clinical diagnosis in evaluating MPE-complicated NSCLS patient responses. As a potential solution, our work showed the importance of comprehending transcriptomic characteristics in order to defy potential drug resistance caused by MPE.

Lorlatinib for advanced ROS1+ non-small-cell lung cancer: results of the IFCT-1803 LORLATU study

Introduction

ROS1-rearranged (ROS1+) non-small-cell lung cancer (NSCLC) is a rare lung cancer with limited treatment options. Phase I-II studies with ROS1-tyrosine kinase inhibitors (TKIs) included small numbers of patients and real-world data are lacking. We investigate the efficacy and safety of lorlatinib, a third-generation TKI targeting ALK and ROS1, in patients with ROS1+ NSCLC treated through an expanded access program.

Methods

Consecutive patients with advanced ROS1+ NSCLC treated with lorlatinib between October 2015 and June 2019 were included. Data were collected from medical records. The primary endpoint was progression-free survival.

Results

Out of the 80 patients included, 47(59%) were female, 49(62%) never smokers (less than 100 cigarettes over the lifetime), and 68(85%) had stage IV NSCLC at diagnosis. Most frequent histology was adenocarcinoma (95%) and median age was 58.2 years. At the time of lorlatinib initiation, 51(64%) patients had brain metastases and 55(81%) were PS 0-1. Lorlatinib was administered as second/third/fourth/fifth+ line in 29%/28%/18%/26% of patients. All patients previously received at least one ROS1 TKI, and 55(69%) previously received chemotherapy. Median follow-up from lorlatinib initiation was 22.2 months. Median progression-free survival and overall survival from lorlatinib initiation were 7.1 months [95% confidence interval (CI) 5.0-9.9 months] and 19.6 months (95% CI 12.3-27.5 months). Median duration of treatment with lorlatinib was 7.4 months (95% CI 6.5-13.1 months). Overall response and disease control rates were 45% and 82%, respectively. The central nervous system response rate was 72%. Treatment was stopped due to toxicity in 10 patients (13%). The safety profile was consistent with previously published data.

Conclusions

Lorlatinib is a major treatment option for advanced refractory ROS1+ NSCLC in treatment strategy.

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Data are lacking on lorlatinib efficacy in advanced refractory ROS1+ NSCLC.

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Lorlatinib median progression-free survival and objective response rate were 7.1 months and 45%, respectively.

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Lorlatinib represents a major treatment option for patients with a ROS1+ NSCLC.

Disease progression patterns and molecular resistance mechanisms to crizotinib of lung adenocarcinoma harboring ROS1 rearrangements

This retrospective study investigated the association between the pattern of disease progression and molecular mechanism of acquired resistance in a large cohort of 49 patients with ROS1-rearranged advanced non-small-cell lung cancer treated with first-line crizotinib. We found that treatment-emergent ROS1 point mutations were the major molecular mechanism of crizotinib resistance, particularly for patients who developed extracranial-only disease progression. Our findings highlight the importance of rebiopsy and gene testing for subsequent-line therapeutic management.

Licochalcone A Promotes the Ubiquitination of c-Met to Abrogate Gefitinib Resistance

Met proto-oncogene (MET) amplification and tyrosine-protein kinase Met (c-Met) overexpression confer gefitinib resistance in non-small cell lung cancer (NSCLC). The natural product Licochalcone A (Lico A) exhibits a broad range of inhibitory effects against various tumors. However, the effects of Lico A on c-Met signaling and gefitinib resistance in NSCLC remain unclear. In the present study, Lico A efficiently overcame gefitinib-acquired resistance in NSCLC cells by suppressing c-Met signaling. Lico A decreased cell viability and colony formation dose-dependently and impaired in vivo tumorigenesis of gefitinib-resistant HCC827 and PC-9 cells. Furthermore, Lico A induced intrinsic apoptosis and upregulated the protein expression levels of cleaved poly (ADP-ribose) polymerase and cleaved caspase 3. Lico A promoted the interaction between c-Met and E3 ligase c-Casitas B-lineage lymphoma (Cbl), which enhanced c-Cbl-mediated c-Met ubiquitination and degradation. Depletion of c-Cbl compromised Lico A-induced c-Met ubiquitination and its inhibitory efficacy in gefitinib-resistant NSCLC cells. Taken together, the results suggest that Lico A is a promising antitumor agent that might be used to overcome c-Met overexpression-mediated gefitinib resistance in NSCLC cells.

MYC promotes tyrosine kinase inhibitor resistance in ROS1 fusion-positive lung cancer

Targeted therapy of ROS1 fusion-driven non-small cell lung cancer (NSCLC) has achieved notable clinical success. Despite this, resistance to therapy inevitably poses a significant challenge. MYC amplification was present in ~19% of lorlatinib-resistant ROS1-driven NSCLC. We hypothesized that MYC overexpression drives ROS1-TKI resistance. Using complementary approaches in multiple models, including a MYC-amplified patient-derived cell line and xenograft (LUAD-0006), we established that MYC overexpression induces broad ROS1 TKI resistance. Pharmacological inhibition of ROS1 combined with MYC knockdown were essential to completely suppress LUAD-0006 cell proliferation compared to either treatment alone. We interrogated cellular signaling in ROS1-TKI resistant LUAD-0006 and discovered significant differential regulation of targets associated with cell cycle, apoptosis, and mitochondrial function. Combinatorial treatment of mitochondrial inhibitors with crizotinib revealed inhibitory synergism, suggesting increased reliance on glutamine metabolism and fatty-acid synthesis in chronic ROS1-TKI treated LUAD-0006 cells. In vitro experiments further revealed that CDK4/6 and BET bromodomain inhibitors effectively mitigate ROS1 TKI resistance in MYC-overexpressing cells. Notably, in vivo studies demonstrate that tumor control may be regained by combining ROS1 TKI and CDK4/6 inhibition. Our results contribute to the broader understanding of ROS1-TKI resistance in NSCLC. Implications: This study functionally characterizes MYC overexpression as a novel form of therapeutic resistance to ROS1 tyrosine kinase inhibitors in non-small-cell lung cancer and proposes rational combination treatment strategies.

UNUSUAL RESISTANCE MECHANISMS IN A CASE OF ROS1 REARRANGED NSCLC: A Case Report

The unprecedented growth of the high-throughput next-generation sequencing has facilitated the identification of rare oncogene fusions such as ROS1 for NSCLC. ROS1 rearrangement has been observed in only 2% of cases of NSCLC and has been successfully targeted using various tyrosine kinase inhibitors including crizotinib. However, the on-target and off-target mechanisms of the resistance are still vague. Here, we report a case of a patient with ROS1 rearranged NSCLC presenting primary resistance to crizotinib.

ROS-1 Fusions in Non-Small-Cell Lung Cancer: Evidence to Date

The ROS-1 gene plays a major role in the oncogenesis of numerous tumors. ROS-1 rearrangement is found in 0.9–2.6% of non-small-cell lung cancers (NSCLCs), mostly lung adenocarcinomas, with a significantly higher rate of women, non-smokers, and a tendency to a younger age. It has been demonstrated that ROS-1 is a true oncogenic driver, and tyrosine kinase inhibitors (TKIs) targeting ROS-1 can block tumor growth and provide clinical benefit for the patient. Since 2016, crizotinib has been the first-line reference therapy, with two-thirds of the patients’ tumors responding and progression-free survival lasting ~20 months. More recently developed are ROS-1-targeting TKIs that are active against resistance mechanisms appearing under crizotinib and have better brain penetration. This review summarizes current knowledge on ROS-1 rearrangement in NSCLCs, including the mechanisms responsible for ROS-1 oncogenicity, epidemiology of ROS-1-positive tumors, methods for detecting rearrangement, phenotypic, histological, and molecular characteristics, and their therapeutic management. Much of this work is devoted to resistance mechanisms and the development of promising new molecules.

Utility of the Ba/F3 cell system for exploring on-target mechanisms of resistance to targeted therapies for lung cancer

Molecular targeted therapies are the standard of care for front‐line treatment of metastatic non‐small‐cell lung cancers (NSCLCs) harboring driver gene mutations. However, despite the initial dramatic responses, the emergence of acquired resistance is inevitable. Acquisition of secondary mutations in the target gene (on‐target resistance) is one of the major mechanisms of resistance. The mouse pro‐B cell line Ba/F3 is dependent on interleukin‐3 for survival and proliferation. Upon transduction of a driver gene, Ba/F3 cells become independent of interleukin‐3 but dependent on the transduced driver gene. Therefore, the Ba/F3 cell line has been a popular system to generate models with oncogene dependence and vulnerability to specific targeted therapies. These models have been used to estimate oncogenicity of driver mutations or efficacies of molecularly targeted drugs. In addition, Ba/F3 models, together with N‐ethyl‐N‐nitrosourea mutagenesis, have been used to derive acquired resistant cells to investigate on‐target resistance mechanisms. Here, we reviewed studies that used Ba/F3 models with EGFR mutations, ALK/ROS1/NTRK/RET fusions, MET exon 14 skipping mutations, or KRAS G12C mutations to investigate secondary/tertiary drug resistant mutations. We determined that 68% of resistance mutations reproducibly detected in clinical cases were also found in Ba/F3 models. In addition, sensitivity data generated with Ba/F3 models correlated well with clinical responses to each drug. Ba/F3 models are useful to comprehensively identify potential mutations that induce resistance to molecularly targeted drugs and to explore drugs to overcome the resistance.

Resistance profile and structural modeling of next-generation ROS1 tyrosine kinase inhibitors

ROS1 fusion proteins resulting from chromosomal rearrangements of the ROS1 gene are targetable oncogenic drivers in diverse cancers. Acquired resistance to targeted inhibitors curtails clinical benefit and response durability. Entrectinib, a NTRK/ROS1/ALK targeted tyrosine kinase inhibitor (TKI), was approved for the treatment of ROS1 fusion-positive NSCLC in 2019. In addition, lorlatinib and repotrectinib are actively being explored in the setting of treatment naïve or crizotinib-resistant ROS1 fusion driven NSCLC. Here, we employ an unbiased forward mutagenesis screen in Ba/F3 CD74-ROS1 and EZR-ROS1 cells to identify resistance liabilities to entrectinib, lorlatinib, and repotrectinib. ROS1^F2004C emerged as a recurrent entrectinib resistant mutation and ROS1^G2032R was discovered in entrectinib and lorlatinib-resistant clones. Cell-based and modeling data show that entrectinib is a dual type I/II mode inhibitor, and thus liable to both types of resistant mutations. Comprehensive profiling of all clinically relevant kinase domain mutations showed that ROS1^L2086F is broadly resistant to all type I inhibitors, but remains sensitive to type II inhibitors. ROS1^F2004C/I/V are resistant to type I inhibitors, entrectinib and crizotinib, and type II inhibitor, cabozantinib, but retain sensitivity to the type I macrocyclic inhibitors. Development of new, more selective type II ROS1 inhibitor(s) or potentially cycling type I and type II inhibitors may be one way to expand durability of ROS1 targeted agents.

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.

Research progress on the drug resistance of ALK kinase inhibitors

BACKGROUND

The fusion and rearrangement of the ALK gene of anaplastic lymphoma kinase is an important cause of a variety of cancers, including non-small cell lung cancer (NSCLC) and anaplastic large cell lymphoma (ALCL). Since crizotinib first came out, many ALK inhibitors have come out one after another, but the fatal flaw in each generation of ALK inhibitors is the body's resistance to drugs. Therefore, how to solve the problem of drug resistance has become an important bottleneck in the application and development of ALK inhibitors. This article briefly introduces the drug resistance of ALK inhibitors and the modified forms of ALK inhibitors, which provide a theoretical basis for solving the drug resistance of ALK inhibitors and the development of a new generation of ALK kinase inhibitors.

METHOD

We use relevant databases to query relevant literature, and then screen and select based on the relevance and cutting edge of the content. We then summarize and analyze appropriate articles, integrate and classify relevant studies, and finally write articles based on topics.

RESULT

This article starts with the problem of ALK resistance, first introduces the composition of ALK kinase, and then introduces the problem of resistance of ALK kinase inhibitors. Later, the structural modification to overcome ALK resistance was introduced, and finally, the method to overcome ALK resistance was introduced.

CONCLUSION

This article summarizes the resistance pathways of ALK kinase inhibitors, and integrates the efforts made to overcome the structural modification of ALK resistance problems, and hopes to provide some inspiration for the development of the next generation of ALK kinase inhibitors.

The evolving paradigm of precision medicine in lung cancer

PURPOSE OF REVIEW

In this review, we report a complete and updated summary of the most recent treatment advances in the fields of oncogene-addicted disease and provide expert perspectives on the evolving paradigm of precision medicine in lung cancer patients.

RECENT FINDINGS

The advent of innovative genome sequencing technologies is rapidly increasing the number of targetable molecular alterations in advanced nonsmall cell lung cancer (NSCLC), leading to the introduction of novel selective inhibitors into the clinical arena, showing unprecedent tumor responses against rare and elusive NSCLC targets. The results of the ADAURA trial suggested that targeting EGFR pathway in the adjuvant setting is a feasible and effective strategy. The routine use of next-generation sequencing (NGS) is currently recommended as new standard approach to profile advanced NSCLC samples while recent findings suggest the potential application of a plasma-based first approach for tumor genotyping. Innovative umbrella trials provide the right infrastructure to investigate the role of precision medicine in advanced NSCLC, but failed to show clinical benefit.

SUMMARY

Implementing NGS-based molecular screening, increasing patients' access to biomarker driven-clinical trials, ensuring equal access to molecular testing and innovative treatments, overcoming disparities and preserve health systems' financial sustainability represents the main challenges of precision medicine worldwide.