This study investigates the function of Mitotic Arrest Deficient 2 Like 1 (MAD2L1) and its role in facilitating NANOG nuclear localization, contributing to chemoresistance in lung cancer. Using both in vivo and in vitro models, we examined MAD2L1 expression in Carboplatin-resistant lung cancer cell lines. The study utilized gene knockdown and overexpression techniques to assess MAD2L1's role in chemoresistance and cell stemness, alongside co-expression analysis and fluorescence staining and CO-IP to explore MAD2L1 and NANOG interactions. Results showed a marked increase in MAD2L1 expression in resistant lung cancer cells, correlating with enhanced cell stemness. MAD2L1 knockdown heightened sensitivity to Carboplatin and reduced NANOG expression, while MAD2L1 overexpression led to increased resistance and stemness. Mechanistically, MAD2L1 facilitated NANOG's nuclear localization, with their co-expression linked to increased cell resistance and metastasis in vivo. These findings suggest that MAD2L1 enhances chemoresistance by promoting NANOG localization, offering insights into potential therapeutic targets for overcoming lung cancer chemoresistance.

The advent of personalised and precision medicine has radically modified the management and the clinical outcome of cancer patients. However, the expanding number of predictive, prognostic, and diagnostic biomarkers has raised the need for simple, noninvasive, quicker, but equally efficient tests for molecular profiling. In this complex scenario, the adoption of liquid biopsy, particularly circulating tumour DNA (ctDNA), has been a real godsend for many cancer patients who would otherwise have been denied the benefits of targeted treatments. Undeniably, ctDNA analysis has several advantages over conventional tissue-based analysis. One advantage is that it can guide treatment decision making, especially when tissue samples are scarce or totally unavailable. Indeed, a simple blood test can inform clinicians on patients' response or resistance to targeted therapies, help them monitor minimal residual disease (MRD) after surgical resections, and facilitate them with early cancer detection and interception. Finally, an equally important advantage is that ctDNA analysis can help decipher temporal and spatial tumour heterogeneity, a mechanism highly responsible for therapeutic resistance. In this review, we gathered and analysed current evidence on the clinical usefulness of ctDNA analysis in solid tumours.

The prognosis of advanced lung large-cell neuroendocrine carcinoma is poor, and the efficacy of targeted therapy is still being explored. A case of RET fusion mutation combined with ALK rearrangement positive advanced lung complex large cell neuroendocrine carcinoma was reported. The patient developed intrapulmonary and bone metastases 8 months after chemotherapy after lung cancer surgery, RET fusion mutations were detected by genetic testing, and intracranial progression occurred 1 year after pilatinib was applied. The comutation of RET and ALK was detected by genetic testing, and the pulmonary progression occurred 2 months after the application of aletinib, after being treated with pilatinib and aletinib, he progressed again in 9 months. We point out that large cell neuroendocrine carcinoma complex patients with RET gene mutation can benefit from targeted therapy, and when drug resistance is accompanied by ALK comutation, the patient can benefit from the treatment of the aletinib combined with pilatinib targeted therapy and the side effect is slight. At the same time, we further explore the resistance mechanism of targeted therapy in lung cancer.

Neuroendocrine transformation in non-small-cell lung cancer (NSCLC) is an uncommon but clinically significant resistance mechanism to targeted therapy, immunotherapy, and chemotherapy. This phenomenon, primarily observed in adenocarcinoma (ADC) with EGFR mutations under tyrosine kinase inhibitor (TKI) treatment, leads to histological transformation into small-cell lung cancer (SCLC), commonly associated with an aggressive clinical course and poor prognosis. Standard platinum-etoposide chemotherapy provides only transient disease control, highlighting the urgent need for improved therapeutic strategies. Early identification of transformation through biopsy, liquid biopsy, or biomarkers like neuron-specific enolase (NSE) and pro-gastrin-releasing peptide (pro-GRP) may allow for early intervention. As targeted therapies continue to develop, understanding the molecular drivers of neuroendocrine transformation is crucial for optimizing treatment. Further research into novel treatment approaches, including combination therapies with TKIs, chemotherapy, immunotherapy, and epigenetic modulators, is required to improve outcomes for these patients.

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor accounting for less than 5% of all thyroid cancers. An estimated 25% of cases are familial secondary to a germline mutation on the rearranged during transfection proto-oncogene (RET); this gene can be present as a somatic mutation in approximately 40%-60% of sporadic MTC tumors. There is an existing genotype-phenotype correlation in the clinical behavior of MTC, with the RET M918T variant associated with aggressive disease. The current systemic treatment profile for progressive metastatic MTC involves antiangiogenics multikinase inhibitors (MKI), specifically cabozantinib and vandetanib, and high-specific RET inhibitor therapy. Decisions on the timing of systemic therapy initiation in this population should involve multidisciplinary care and individualization on a case-by-case scenario; a comprehensive evaluation of performance status, tumor burden, progression rate, medical comorbidities, possible medication interactions, and goals of care must be considered in a patient-centered approach. This review summarizes the evidence on the safety, efficacy, and limitations of systemic therapies for MTC; the aim is to empower clinicians with the knowledge to optimally manage patients with advanced, progressive, or metastatic MTC.

BackgroundSince the publication of the original work in 2014, significant progress has been made in the characterization of genomic alterations that drive oncogenic addiction of nonsmall cell lung cancer (NSCLC) and how the immune system can leverage non-oncogenic pathways to modulate therapeutic outcomes. This update evaluates and validates the recent and emerging data for prognostic and predictive biomarkers with therapeutic targets in NSCLC.Data sourcesWe performed a literature search from January 2015 to October 2023 using the keywords non-small cell lung cancer, clinical practice guidelines, gene mutations, genomic assay, immune cancer therapy, circulating tumor DNA, predictive and prognostic biomarkers, and targeted therapies.Study selection and data extractionWe identified, reviewed, and evaluated relevant clinical trials, meta-analyses, seminal articles, and published clinical practice guidelines in the English language.Data synthesisRegulatory-approved targeted therapies include those somatic gene alterations of EGFR ("classic" mutations, exon 20 insertion, and rare EGFR mutations), ALK, ROS1, BRAF V600, RET, MET, NTRK, HER2, and KRAS G12C. Data for immunotherapy and circulating tumor DNA in next-generation sequencing are considered emerging, whereas the predictive role for PIK3CA gene mutation is insufficient.ConclusionsAdvances in sequencing and other genomic technologies have led to identifying novel oncogenic drivers, novel resistance mechanisms, and co-occurring mutations that characterize NSCLC, creating further therapeutic opportunities. The benefits associated with immunotherapy in the perioperative setting hold initial promise, with their long-term results awaiting.

Aberrant activation of the RET oncogene by mutations or gene fusions drives various malignancies, including 1%-2% of all non-small cell lung cancers (NSCLCs) that harbor RET gene fusions. Initial attempts to target RET fusion-positive NSCLC with poorly selective multikinase RET inhibitors were associated with significant toxicities and limited efficacy. Two highly potent and selective RET small-molecule inhibitors, selpercatinib and pralsetinib, were granted accelerated approval for advanced RET fusion-positive NSCLC by the US Food and Drug Administration, and have been shown to be highly effective both in treatment-naive and previously treated patients with NSCLC. Selpercatinib has shown superiority over chemotherapy in a phase 3 study (LIBRETTO-431) in previously untreated patients with RET fusion-positive NSCLC, which established its place as the standard of care in this patient population. This review discusses the biology and clinical characteristics of RET-rearranged NSCLC and summarizes the evolution of treatment strategies, current understanding of mechanisms of resistance, and development of new-generation agents to overcome resistance.

RET is a well-recognized drug target for cancer treatment. Despite the promising efficacy of selective second-generation RET inhibitors Selpercatinib and Pralsetinib, the clinical benefits have been compromised due to the quickly developed resistance to these drugs. RET G810 mutations at the solvent front site have been identified as the major on-target mutations contributing to resistance against Selpercatinib and Pralsetinib. Therefore, there is an urgent need for the development of next-generation RET inhibitors to overcome acquired solvent-front resistance mutations. In this study, a series of (E)-1-(4-(2-(1H-pyrazol-5-yl)vinyl)phenyl) derivatives have been identified as selective next-generation RET inhibitors. The representative compound, CQ1373 exhibits potent cellular potency with IC50 values of 13.0, 25.7 and 28.4 nM against BaF3 cells expressing CCDC6-RET, CCDC6-RET-G810C and CCDC6-RET-G810R, respectively. A comprehensive selectivity profile across 89 kinases reveals that CQ1373 demonstrates good selectivity toward wild-type RET and solvent front mutants G810C/R with IC50 values of 4.2, 7.1 and 32.4 nM, respectively. Furthermore, western blot analysis reveals that CQ1373 effectively inhibits RET phosphorylation and downstream signaling through SHC. It also induces apoptosis and cell cycle arrest in a dose-dependent manner in BaF3 cells harboring CCDC6-RET, CCDC6-RET-G810C and CCDC6-RET-G810R fusions. More significantly, CQ1373 exhibits promising in vivo anti-tumor efficacy in a CCDC6-RET-G810R mice xenograft model, highlighting its potentials for RET-driven cancers treatment.

The enhanced comprehension of the molecular pathways underpinning oncogenesis in non-small cell lung cancer (NSCLC) has led to the advancement of personalized treatment for individuals with actionable mutations using targeted therapies. The rearranged during transfection (RET) proto-oncogene, is critical in the embryonic development of various tissues, including renal, neural, and neuroendocrine tissue. RET fusions have been observed in approximately 1-2% of NSCLC cases. Targeted therapies for NSCLC with RET alterations have progressed significantly over the past decade. While multikinase inhibitors (MKIs) faced limitations in efficacy and tolerability, the introduction of selective RET inhibitors (SRIs) such as selpercatininb and pralsetinib has transformed patient outcomes, resulting in deep and durable responses. Ongoing clinical trials are exploring their potential benefits in the neoadjuvant and adjuvant setting. Early phase clinical trials endeavor to demonstrate next-generation selective RET inhibitors can effectively overcome SRI resistance mechanisms, offer improved safety profiles, and enhance patient outcomes.

Non-small cell lung cancer (NSCLC) transforming to small cell lung cancer (SCLC) is one of the mechanisms of resistance to tyrosine kinase inhibitors (TKIs). Cases of NSCLC transforming into SCLC have been discovered. However, we lack concentrated data on the characteristics of this population and the transformed SCLC to aid our insight of the biology and clinical value of NSCLC transforming with positive.

We systematically reviewed the published literatures and summarized the pathological and clinical characteristics, and the prognosis, of published cases.

140 patients with lung adenocarcinoma (LUAD) were included in this study, with a median age of 56.8 years. The median time from the first diagnosis of LUAD transforming to SCLC (ttSCLC) was 20.0 months. The median overall survival (mOS) after the diagnosis of SCLC was 11.0 months (95% CI, 7.41 to 14.59 months). In the univariate analysis, ever smoking (either former or current) was a promising predictor of a shorter ttSCLC (HR, 1.73; 95% CI, 1.14 to 2.62; P = 0.010). TKIs therapy administered as a second line and beyond treatment was related to a significant delay in SCLC onset compared to first-line therapy (HR, 0.62; 95% CI, 0.40 to 0.96; P = 0.031). The median progression-free survival (mPFS) on first-line platinum plus etoposide after the conversion to SCLC was 3.0 months. Female appeared to be related to worse outcomes after transformation of SCLC.

Transformed SCLC exhibited poor response to primary SCLC classic chemotherapy and immunotherapy. It carries a worse prognosis. Exploring novel therapeutic strategies for transformed SCLC is imperative.

The association between RET and multiple endocrine neoplasia type 2 was established in 1993 and remains one of the very few oncogenes for which distinct phenotypes (medullary thyroid cancer or pheochromocytoma) are associated with the same hot-spot variants occurring in either germline or somatic DNA. Somatic RET fusion events have also been described in several cancers, including papillary thyroid cancer, non-small-cell lung cancer, breast cancer, salivary gland cancer and pancreatic cancer. Highly selective RET inhibitors have improved outcomes in RET-altered cancers and have been well-tolerated. Nevertheless, primary and acquired drug resistance has been observed, arising from distinct genomic alterations either in RET (on-target resistance) or via alternate oncogenic pathways (bypass resistance). The same mechanisms of resistance have been observed across multiple cancer types, which implies RET-altered cancers evolve away from RET addiction via stochastic subclonal events. Understanding these mechanisms is crucial for identifying therapeutic opportunities to overcome resistance. Successful treatment targeting bypass oncogenes has been reported in several instances, at least for short-term outcomes; in contrast, although several compounds have been reported to overcome on-target RET alterations, none have yet been translated into routine clinical practice and this remains an area of urgent clinical need.

Targeted therapies have changed the treatment landscape of non-small-cell lung cancer and led to improved patient survival across all stages of lung cancer. Newer advances in common and novel oncogenic drivers continue to occur at vigorous speed, making it challenging to stay up to date with the rapidly evolving field. In this article, we review the emerging perspectives in the treatment of actionable targets in lung cancer. We focus on the development of newer KRAS-directed therapies, particularly on non-G12C mutations, pan-RAS inhibitors, and RAS-GTP inhibitors. We also describe the current standard of care for EGFR- and ALK-altered NSCLC and dive into the novel treatments expected to be in the clinic soon. A similar approach is taken toward MET, HER2, RET, ROS1, and FGFR alterations as emerging targets in non-small-cell lung cancer. Finally, we conclude this review with the current body of evidence for targeting TROP-2 as a novel target, potentially of importance in post-targeted therapy scenarios.

Pralsetinib is a RET inhibitor found to have antitumor activity in advanced, metastatic, RET fusion-positive NSCLC.

To assess real-world efficacy of pralsetinib and treatment sequences in patients with RET fusion-positive NSCLC.

Retrospective study of consecutive patients enrolled in the French expanded-access program for pralsetinib from December 1, 2019, to December 31, 2021.

A total of 41 patients with advanced, refractory, RET fusion-positive NSCLC were included. Pralsetinib was administered at a daily dose of 400 mg based on safety and pharmacokinetic outcomes from previous phase 1/2 study.

Pralsetinib was administered as second line in 23 patients (56%) and as third line and beyond in 15 patients (37%). After a median follow-up of 26.3 months, pralsetinib was ongoing in 13 patients. Median real-world progression-free survival was 11.8 (95% confidence interval [CI]: 9.3-15.5) months. Objective response rate was 68% (95% CI: 50%-82%), and disease control rate was 89% (95% CI: 75%-97%). Subsequent line of systemic therapy was initiated in 11 patients. Median overall survival from pralsetinib initiation was 23.8 (95% CI: 16.5-not reached) months.

In this extensive real-world cohort of patients with advanced or metastatic NSCLC harboring RET fusions, we highlight the antitumor efficacy of pralsetinib, particularly when administered in later treatment lines. We also observe the aggressive nature of disease progression, frequent utilization of chemotherapy and antiangiogenic agents as initial subsequent therapies, and limited insight into resistance mechanisms due to infrequent rebiopsy and genomic profiling at progression.

We describe the design, synthesis, and structure-activity relationship (SAR) of heterobifunctional RET ligand-directed degraders (LDDs) derived from three different second-generation RET inhibitors. These LDDs are composed of a target binding motif (TBM) that binds to the RET protein, a linker, and a cereblon binding motif (CBM) as the E3 ligase recognition unit. This led to the identification of a series of pyrazolopyridine-based heterobifunctional LDDs, as exemplified by compound 39. LDD 39 demonstrated high in vitro inhibitory and degradation potency against both RET wild-type and the two representative mutants, V804M and G810R. Importantly, in PK/PD studies, 39 exhibited a differentiated and favorable in vivo profile compared to the corresponding tyrosine kinase inhibitor (TKI), compound 3. Robust and sustained degradation of total-RET (tRET) protein and inhibition of phospho-RET (pRET) signaling were observed in TPC-1 xenograft tumors driven by RET and the RET/G810R mutant following a single dose of LDD 39 at 15 and 75 mg/kg, respectively.

The clinical application of small molecule tyrosine kinase inhibitors (TKIs) has significantly improved the quality of life and prognosis of patients with non-small cell lung cancer (NSCLC) carrying driver genes. However, resistance to TKI treatment is inevitable. Bypass signal activation is one of the important reasons for TKI resistance. Although TKI drugs inhibit downstream signaling pathways of driver genes, key signaling pathways within tumor cells can still be persistently activated through bypass routes such as MET gene amplification, EGFR gene amplification, and AXL activation. This continuous activation maintains tumor cell growth and proliferation, leading to TKI resistance. The fundamental strategy to treat TKI resistance mediated by bypass activation involves simultaneously inhibiting the activated bypass signals and the original driver gene signaling pathways. Some clinical trials based on this combined treatment approach have yielded promising preliminary results, offering more treatment options for NSCLC patients with TKI resistance. Additionally, early identification of resistance mechanisms through liquid biopsy, personalized targeted therapy against these mechanisms, and preemptive targeting of drug-tolerant persistent cells may provide NSCLC patients with more sustained and effective treatment.

Medullary thyroid carcinoma (MTC) is a rare primary neuroendocrine thyroid carcinoma that is distinct from other thyroid or neuroendocrine cancers. Most cases of MTC are sporadic, although MTC exhibits a high degree of heritability as part of the multiple endocrine neoplasia syndromes. REarranged during Transfection (RET) mutations are the primary oncogenic drivers and advances in molecular profiling have revealed that MTC is enriched in druggable alterations. Surgery at an early stage is the only chance for cure, but many patients present with or develop metastases. C-cell-specific calcitonin trajectory and structural doubling times are critical biomarkers to inform prognosis, extent of surgery, likelihood of residual disease, and need for additional therapy. Recent advances in the role of active surveillance, regionally directed therapies for localized disease, and systemic therapy with multi-kinase and RET-specific inhibitors for progressive/metastatic disease have significantly improved outcomes for patients with MTC.

Selpercatinib, a selective RET kinase inhibitor, has demonstrated remarkable efficacy in treating patients with advanced medullary (MTC) and differentiated thyroid cancer with RET alterations. Primary resistance to selpercatinib is a very uncommon situation, and its underlying mechanisms are poorly understood. We report the case of a 42-year-old female with advanced MTC harboring a somatic M918T RET mutation who exhibited a primary resistance to selpercatinib. Despite prompt treatment initiation after the diagnosis of progressive disease, the patient continued experiencing rapid spread of disease, characterized by the appearance of new metastatic lesions and increased tumor burden. Genomic analysis revealed no additional mutations associated with on-target or off-target resistance. This case highlights a rare clinical scenario of primary resistance to selpercatinib in advanced MTC. While secondary resistance mechanisms have been well-documented, primary resistance remains poorly understood. Possible explanations include tumor heterogeneity and activation of alternative signaling pathways that stills need to be elucidated. Emerging therapies targeting resistance mechanisms and next-generation RET inhibitors offer promising avenues for further investigation.

Medullary thyroid carcinoma (MTC) is a rare type of thyroid malignancy that accounts for approximately 1-2% of all thyroid cancers (TCs). MTC include hereditary and sporadic cases, the former derived from a germline mutation of rearrangement during transfection (RET) proto-oncogene, whereas somatic RET mutations are frequently present in the latter. Surgery is the standard treatment for early stage MTC, and the 10-year survival rate of early MTC is over 80%. While for metastatic MTC, chemotherapy showing low response rate, and there was a lack of effective systemic therapies in the past. Due to the high risk (ca. 15-20%) of distant metastasis and limited systemic therapies, the 10-year survival rate of patients with advanced MTC was only 10-40% from the time of first metastasis. Over the past decade, targeted therapy for RET has developed rapidly, bringing hopes to patients with advanced and progressive MTC. Two multi-kinase inhibitors (MKIs) including Cabozantinib and Vandetanib have been shown to increase progression-free survival (PFS) for patients with metastatic MTC and have been approved as choices of first-line treatment. However, these MKIs have not prolonged overall survival (OS) and their utility is limited due to high rates of off-target toxicities. Recently, new generation TKIs, including Selpercatinib and Pralsetinib, have demonstrated highly selective efficacy against RET and more favorable side effect profiles, and gained approval as second-line treatment options. Despite the ongoing development of RET inhibitors, the management of advanced and progressive MTC remains challenging, drug resistance remains the main reason for treatment failure, and the mechanisms are still unclear. Besides, new promising therapeutic approaches, such as novel drug combinations and next generation RET inhibitors are under development. Herein, we overview the pathogenesis, molecular genetics and current management approaches of MTC, and focus on the recent advances of RET inhibitors, summarize the current situation and unmet needs of these RET inhibitors in MTC, and provide an overview of novel strategies for optimizing therapeutic effects.

Despite targeted therapies like epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), non-small cell lung cancer (NSCLC) remains a clinical challenge due to drug resistance hampering their efficacy. Here, we designed an "AND" logic gate-based supramolecular therapeutic platform (HA-BPY-GEF-NPs) for the treatment of EGFR-TKI resistant NSCLC. This system integrates both internal and external stimuli-responsive mechanisms that need to be activated in a preset sequence, enabling it to precisely control drug release behavior for enhancing therapeutic precision. By programming the system to respond to sequential near-infrared (NIR) irradiation and enzyme (cathepsin B) inputs, the release of gefitinib is effectively confined to the tumor region. Moreover, the NIR irradiation induces reactive oxygen species production, suppressing tumor growth and inhibiting bypass signaling pathways. The designed drug delivery system offers a highly controlled and targeted therapeutic approach, effectively inhibiting tumor growth, suppressing bypass signaling pathways, and overcoming EGFR-TKI resistance, thus offering a potential solution for maximizing therapeutic benefits.

RET fusions were discovered in non-small cell lung cancer (NSCLC), and the efficacy of RET-targeted treatment in these patients has been previously established. However, patients with required resistance to RET-TKIs have limited treatment options. Herein, we describe a case of critical and advanced lung adenocarcinoma harboring RET fusion. Despite a significant response to Prasetinib previously, the patient developed refractory malignant pleural effusion after 24 months of treatment. He was treated simultaneously with intrapleural plus systemic Tislelizumab injection combined chemotherapy, thereby achieving an excellent clinical benefit maintaining control of pleural effusion for over 6 months. Hence, we would like to discuss intrapleural immunotherapy as an additional treatment method in refractory malignant pleural effusion while demonstrating good treatment tolerance.

Actionable mutations of RET kinase have been identified as oncogenic drivers of solid tumors, including thyroid cancer, metastatic colorectal cancer, and nonsmall cell lung cancer. Although multikinase inhibitors and RET selective inhibitors are used to treat patients with RET alterations, there is insufficient research addressing certain issues: which actionable mutations arise from these therapies, how to improve the clinical response rate to RET inhibitors, and how to design new inhibitors to overcome drug resistance. Therefore, the development of sophisticated tool compounds is required to investigate the molecular mechanisms of actionable mutations and to develop breakthrough therapeutics for different RET alterations. Herein, we present our investigation into the side chains of imidazopyridazine hinge binders that are capable of inducing protein-ligand interaction patterns from the gatekeeper to the waterfront regions. Extending the substituents at the second and sixth positions enhanced the IC50 up to < 0.5 nM for diverse RET alterations.

While activating RET fusions are identified in various cancers, lung cancer represents the most common RET fusion-positive tumor. The clinical drug development of RET inhibitors in RET fusion-positive lung cancers naturally began after RET fusions were first identified in patient tumor samples in 2011, and thereafter paralleled drug development in RET fusion-positive thyroid cancers. Multikinase inhibitors were initially tested with limited efficacy and substantial toxicity. RET inhibitors were then designed with improved selectivity, central nervous system penetrance, and activity against RET fusions and most RET mutations, including resistance mutations. Owing their success to these rationally designed features, the first-generation selective RET tyrosine kinase inhibitors (TKIs) had higher response rates, more durable disease control, and an improved safety profile compared to the multikinase inhibitors. This led to lung and thyroid cancer, and later tumor-agnostic regulatory approvals. While next-generation RET TKIs were designed to abrogate uncommon on-target (e.g., solvent front mutation) resistance to selpercatinib and pralsetinib, many of these drugs lacked the selectivity of the first-generation TKIs, raising the question of what the future holds for drug development in RET-dependent cancers.

Tyrosine kinase inhibitor (TKI)-targeted therapy has revolutionized cancer treatment by selectively blocking specific signaling pathways crucial for tumor growth, offering improved outcomes with fewer side effects compared with conventional chemotherapy. However, despite their initial effectiveness, resistance to TKIs remains a significant challenge in clinical practice. Understanding the mechanisms underlying TKI resistance is paramount for improving patient outcomes and developing more effective treatment strategies. In this review, we explored various mechanisms contributing to TKI resistance, including on-target mechanisms and off-target mechanisms, as well as changes in the tumor histology and tumor microenvironment (intrinsic mechanisms). Additionally, we summarized current therapeutic approaches aiming at circumventing TKI resistance, including the development of next-generation TKIs and combination therapies. We also discussed emerging strategies such as the use of dual-targeted antibodies and PROteolysis Targeting Chimeras. Furthermore, we explored future directions in TKI-targeted therapy, including the methods for detecting and monitoring drug resistance during treatment, identification of novel targets, exploration of dual-acting kinase inhibitors, application of nanotechnologies in targeted therapy, and so on. Overall, this review provides a comprehensive overview of the challenges and opportunities in TKI-targeted therapy, aiming to advance our understanding of resistance mechanisms and guide the development of more effective therapeutic approaches in cancer treatment.

Pralsetinib, a targeted inhibitor of the RET enzyme, plays a critical role in the treatment of adult patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) characterized by RET gene fusion mutations following platinum-based chemotherapy. Nevertheless, impurities resulting from the manufacturing and degradation of pralsetinib have the potential to impact its therapeutic effectiveness and safety profile.

To address this issue, a liquid chromatography method was developed and validated for the specific identification of pralsetinib and its related impurities. The separation of pralsetinib and its related impurities was achieved via a Waters X Bridge C18 column with dimensions of 4.6 mm × 250 mm and a particle size of 5 μm. Mobile phase A was composed of 20 mmol/L potassium dihydrogen phosphate (KH2PO4) and acetonitrile (ACN) at a volume ratio of 19:1, while mobile phase B consisted solely of ACN, utilizing a gradient elution technique. Detection was performed at a wavelength of 260 nm, with an injection volume of 10 μL and a flow rate of 1.0 mL/min.

The chromatographic method established in this study was validated according to the ICH Q2 (R1) guidelines. The method demonstrated excellent linearity over a specific concentration range (imp-A: 0.035-10.21 μg/mL; imp-B: 0.09-10.16 μg/mL; imp-C: 0.15-10.19 μg/mL; pralsetinib: 0.04-10.32 μg/mL). Additionally, the method possesses high sensitivity, with detection limits for impurities A, B, C, and pralsetinib of 0.01, 0.03, 0.015, and 0.013 μg/mL, respectively, and quantification limits of 0.035, 0.09, 0.05, and 0.04 μg/mL, respectively. In terms of specificity, stability, repeatability, accuracy, and robustness, the method met the validation acceptance criteria. Overall, the chromatographic technique established in this study can effectively separate pralsetinib and its impurities, providing reliable assurance for the accurate detection and quantification of impurities.

The chromatographic method developed in this study can be utilized for the detection of pralsetinib and its impurities, offering a crucial reference for research on the quality of pralsetinib.

RET fusions are relatively rare in Non-Small-Cell Lung Cancers (NSCLCs), being around 1-2% of all NSCLCs. They share the same clinical features as the other fusion-driven NSCLC patients, as follows: younger age, adenocarcinoma histology, low exposure to tobacco, and high risk of spreading to the brain. Chemotherapy and immunotherapy have a low impact on the prognosis of these patients. Multitargeted RET inhibitors have shown modest activity jeopardized by high toxicity. New potent and selective RET inhibitors (RET-Is) (pralsetinib and selpercatinib) have achieved a higher efficacy minimizing the known toxicities of the multitargeted agents. This review will describe the sensitivity of immune-checkpoint inhibitors (ICIs) in RET fusion + NSCLC patients, as well their experiences with the 'old' multi-targeted RET inhibitors. This review will focus on the advent of new potent and selective RET-Is. We will describe their efficacy as well as the main mechanisms of resistance to them. We will further proceed to deal with the new drugs and strategies proposed to overcome the resistance to RET-Is. In the last section, we will also focus on the safety profile of RET-Is, dealing with the main toxicities as well as the rare but severe adverse events.

The advent of targeted therapies revolutionized treatments of advanced oncogene-driven non-small cell lung cancer (NSCLC). Nonetheless, despite initial dramatic responses, development of drug resistance is inevitable. Although mechanisms underlying acquired resistance, such as on-target mutations, bypass pathways, or lineage transformation, have been described, overcoming drug resistance remains challenging. Recent evidence suggests that drug-tolerant persister (DTP) cells, which are tumor cells tolerant to initial drug exposure, give rise to cells that acquire drug resistance. Thus, the possibility of eradicating cancer by targeting DTP cells is under investigation, and various strategies are proposed. Here, we review overall features of DTP cells, current efforts to define DTP markers, and potential therapeutic strategies to target and eradicate DTP cells in oncogene-driven NSCLC. We also discuss future challenges in the field.

RET fusion is an oncogenic driver in 1-2 % of patients with non-small cell lung cancer (NSCLC). Although RET-positive tumors have been treated with multikinase inhibitors such as vandetanib or RET-selective inhibitors, ultimately resistance to them develops. Here we established vandetanib resistance (VR) clones from LC-2/ad cells harboring CCDC6-RET fusion and explored the molecular mechanism of the resistance. Each VR clone had a distinct phenotype, implying they had acquired resistance via different mechanisms. Consistently, whole exome-seq and RNA-seq revealed that the VR clones had unique mutational signatures and expression profiles, and shared only a few common remarkable events. AXL and IGF-1R were activated as bypass pathway in different VR clones, and sensitive to a combination of RET and AXL inhibitors or IGF-1R inhibitors, respectively. SMARCA4 loss was also found in a particular VR clone and 55 % of post-TKI lung tumor tissues, being correlated with higher sensitivity to SMARCA4/SMARCA2 dual inhibition and shorter PFS after subsequent treatments. Finally, we detected an increased number of damaged mitochondria in one VR clone, which conferred sensitivity to mitochondrial electron transfer chain inhibitors. Increased mitochondria were also observed in post-TKI biopsy specimens in 13/20 cases of NSCLC, suggesting a potential strategy targeting mitochondria to treat resistant tumors. Our data propose new promising therapeutic options to combat resistance to RET inhibitors in NSCLC.

This case report describes the efficacy of selpercatinib, a selective RET inhibitor, in an unusual case of large-cell neuroendocrine pancreatic carcinoma (LCNEPAC) harboring a CCDC6::RET fusion. A 56-year-old male with a history of multiple lines of systemic therapies exhibited marked clinical amelioration shortly after initiating selpercatinib within the LOXO-RET-17001 study (ClinicalTrials.gov ID: NCT03157128, first posted: 2017-05-17). Data from the patient's smartwatch suggested early efficacy before conventional methods, such as serum tumor markers and CT imaging confirmed the antitumor activity. This case not only underscores the efficacy of selpercatinib in treating RET fusion-positive rare tumors but also highlights the potential of wearable technology in cancer care. In conclusion, the standard readings from commercially available wearable devices can be useful for the monitoring of treatment response to targeted therapy and may serve as digital biomarkers in clinical trials. This approach marks a significant advancement in patient-centric healthcare, leveraging technology to enhance the effectiveness and precision of treatment evaluation.

Pralsetinib and selpercatinib are two highly potent and selective rearranged during transfection (RET) inhibitors that substantially improved the clinical outcome of patients with RET-rearranged non-small cell lung cancer. Treatment with one RET inhibitor after failure of the other is generally not recommended because of cross-resistance mechanisms. We report the case of a patient affected by metastatic RET-rearranged non-small cell lung cancer who experienced long-lasting disease control with pralsetinib. After 13 months from treatment start, the patient developed recurrent drug-related pneumonitis, requiring temporary interruptions and dose reductions and eventually failing to control the disease. Selpercatinib was then started as an off-label treatment, allowing both clinical and radiological intracranial disease control. Selpercatinib was well-tolerated at full dosage, and no pulmonary event occurred. In our case report, after pralsetinib dose reduction due to pulmonary toxicity, the therapeutic switch to selpercatinib allowed the patient to receive a full-dose treatment, eventually restoring disease control. Our case report and a few literature data suggest that switching from pralsetinib to selpercatinib may represent a therapeutic opportunity, especially for patients with brain metastases.

The molecular pathogenesis of thyroid carcinoma is well studied and of importance for the treatment of advanced stages. Differentiated, poorly differentiated and anaplastic carcinomas originate in the follicular cells, while medullary carcinomas derive from the C‑cells. The prognosis of differentiated thyroid carcinoma is generally very favourable after surgery and radioiodine therapy. Where tumours progress and lose the ability to enrich iodine, curative treatment is usually not possible. A strategy of watchful waiting is often appropriate. Activating mutations in BRAF or gene fusions of RET and NTRK provide opportunities for targeted therapies. These may be applied with the aim of restoring iodine uptake (redifferentiation). In the absence of molecular therapy targets, multityrosine kinase inhibitors (MKI) are the therapy of choice. If anaplastic thyroid carcinoma is suspected, rapid diagnostic workup including molecular pathology is warranted. Surgery where possible and radiochemotherapy are essential components of therapy. In the presence of a BRAF mutation, inhibition of BRAF and MEK is effective, even if it is not approved in Germany. Where molecular targets are lacking, combination therapy with the MKI lenvatinib and immune checkpoint inhibition is highly effective. Mutations in RET are present in the vast majority of cases of medullary thyroid carcinoma. In aggressive advanced disease, selective RET inhibition has recently been approved as first-line therapy and often leads to an objective response and long-lasting disease stabilisation. In summary, thyroid carcinomas are among the tumour entities for which molecularly targeted therapies can be used most frequently. The involvement of specialised centres is advisable.

Lung cancer is a major cause of death worldwide, being often detected at a later stage due to the non-appearance of early symptoms. Therefore, specificity of the treatment is of utmost importance for its effective treatment. Precision medicine is a personalized therapy based on the genomics of the patient to design a suitable drug approach. Genetic mutations render the tumor resistant to specific mutations and the therapy is in vain even though correct medications are prescribed. Therefore, Precision medicine needs to be explored for the treatment of Non-small cell lung cancer (NSCLC). Nanoparticles are widely explored to give personalized interventions to treat lung cancer due to their various advantages like the ability to reach cancer cells, enhanced permeation through tissues, specificity, increased bioavailability, etc. Various nanoparticles (NPs) including gold nanoparticles, carbon nanotubes, aptamer-based NPs etc. were conjugated with biomarkers/diagnostic agents specific to cancer type and were delivered. Various biomarker genes have been identified through precision techniques for the diagnosis and treatment of NSCLC like EGFR, RET, KRAS, ALK, ROS-1, NTRK-1, etc. By incorporating of drug with the nanoparticle through bioconjugation, the specificity of the treatment can be enhanced with this revolutionary treatment. Additionally, integration of theranostic cargos in the nanoparticle would allow diagnosis as well as treatment by targeting the site of disease progression. Therefore, to target NSCLC effectively precision nanomedicine has been adopted in recent times. Here, we present different nanoparticles that are used as precision nanomedicine and their effectiveness against NSCLC disease.

MET amplification/mutations are important targetable oncogenic drivers in NSCLC, however, acquired resistance is inevitable and the majority of patients with targetable MET alterations fail to respond to MET tyrosine kinase inhibitors (TKIs). Furthermore, MET amplification is among the most common mediators of TKI resistance. As such, novel therapies to target MET pathway and overcome MET TKI resistance are clearly needed. Here we show that the epithelial-mesenchymal transition (EMT) transcription factor, TWIST1 is a key downstream mediator of HGF/MET induced resistance through suppression of p27 and targeting TWIST1 can overcome resistance. We found that TWIST1 is overexpressed at the time of TKI resistance in multiple MET-dependent TKI acquired resistance PDX models. We have shown for the first time that MET directly stabilized the TWIST protein leading to TKI resistance and that TWIST1 was required for MET-driven lung tumorigenesis as well as could induce MET TKI resistance when overexpressed. TWIST1 mediated MET TKI resistance through suppression of p27 expression and genetic or pharmacologic inhibition of TWIST1 overcame TKI resistance in vitro and in vivo. Our findings suggest that targeting TWIST1 may be an effective therapeutic strategy to overcome resistance in MET-driven NSCLC as well as in other oncogene driven subtypes in which MET amplification is the resistance mechanism.

Breast cancer is the most common malignancy among women, posing a formidable health challenge worldwide. In this complex landscape, the c-MET (cellular-mesenchymal epithelial transition factor) receptor tyrosine kinase (RTK), also recognized as the hepatocyte growth factor (HGF) receptor (HGFR), emerges as a prominent protagonist, displaying overexpression in nearly 50% of breast cancer cases. Activation of c-MET by its ligand, HGF, secreted by neighboring mesenchymal cells, contributes to a cascade of tumorigenic processes, including cell proliferation, metastasis, angiogenesis, and immunosuppression. While c-MET inhibitors such as crizotinib, capmatinib, tepotinib and cabozantinib have garnered FDA approval for non-small cell lung cancer (NSCLC), their potential within breast cancer therapy is still undetermined. This comprehensive review embarks on a journey through structural biology, multifaceted functions, and intricate signaling pathways orchestrated by c-MET across cancer types. Furthermore, we highlight the pivotal role of c-MET-targeted therapies in breast cancer, offering a clinical perspective on this promising avenue of intervention. In this pursuit, we strive to unravel the potential of c-MET as a beacon of hope in the fight against breast cancer, unveiling new horizons for therapeutic innovation.

Resistance to targeted therapy and immunotherapy in non-small cell lung cancer (NSCLC) is a significant challenge in the treatment of this disease. The mechanisms of resistance are multifactorial and include molecular target alterations and activation of alternative pathways, tumor heterogeneity and tumor microenvironment change, immune evasion, and immunosuppression. Promising strategies for overcoming resistance include the development of combination therapies, understanding the resistance mechanisms to better use novel drug targets, the identification of biomarkers, the modulation of the tumor microenvironment and so on. Ongoing research into the mechanisms of resistance and the development of new therapeutic approaches hold great promise for improving outcomes for patients with NSCLC. Here, we summarize diverse mechanisms driving resistance to targeted therapy and immunotherapy in NSCLC and the latest potential and promising strategies to overcome the resistance to help patients who suffer from NSCLC.

Rearranged during transfection (RET) alterations, which lead to aberrant activation of the RET proto-oncogene, have been identified in various cancers. In non-small cell lung cancer (NSCLC), RET mutations often manifest as RET fusion genes and are observed in 1-2 % of patients with NSCLC. In recent years, selective RET inhibitors such as selpercatinib and pralsetinib, approved by the Food and Drug Administration (FDA) in 2020, have been part of the revolutionary changes in the treatment landscape for non-small cell lung cancer. While first-generation RET inhibitors have become part of the standard of care for RET-fusion positive NSCLC, a new challenge has emerged: acquired resistance to RET inhibitors. RET resistance is a complex phenomenon that can manifest as either on-target or off-target resistance. Numerous studies have been conducted to identify the mechanisms behind this resistance. This review provides an overview of the biology of RET in NSCLC, methods of RET testing, and a comprehensive analysis of the clinical outcomes associated with multikinase and selective RET inhibitors for NSCLC. Additionally, we will explore future perspectives for RET fusion-positive NSCLC, including ongoing trials and the challenges involved in overcoming resistance to RET inhibitors.

RET gain-of-function mutations are the most common drivers in medullary thyroid carcinoma, while RET fusions are identified in 5-10% of papillary thyroid carcinomas. Thus, RET plays a major role in the tumorigenesis of thyroid neoplasia, making it a valuable therapeutic target. Over a decade ago, multikinase inhibitors (MKIs) were first shown to have variable degrees of anti-RET activity. Despite some clinical efficacy in RET-altered thyroid cancers, significant off-target activity of MKIs led to marked toxicities limiting their use. More recently, two potent, highly selective RET inhibitors, selpercatinib and pralsetinib, were shown to have notable efficacy in RET-altered cancers, associated with more tolerable side effect profiles than those of MKIs. However, these treatments are non-curative, and emerging evidence suggests that patients who progress on therapy acquire mutations conferring drug resistance. Thus, the quest for a more definitive treatment for advanced, RET-altered thyroid cancers continues. This year we celebrate the 30th anniversary of the association of germline mutations of the RET proto-oncogene with the multiple endocrine neoplasia (MEN) type 2 syndromes. In this timely review, we summarize the current state-of-the-art treatment strategies for RET-altered thyroid cancers, their limitations, as well as future therapeutic avenues.

Patients treated with RET protein tyrosine kinase inhibitors (TKIs) selpercatinib or pralsetinib develop RET TKI resistance by secondary RET mutations or alterative oncogenes, of which alterative oncogenes pose a greater challenge for disease management because of multiple potential mechanisms and the unclear tolerability of drug combinations. A patient with metastatic medullary thyroid carcinoma (MTC) harboring a RET activation loop D898_E901del mutation was treated with selpercatinib. Molecular alterations were monitored with tissue biopsies and cfDNA during the treatment. The selpercatinib-responsive MTC progressed with an acquired ETV6::NTRK3 fusion, which was controlled by selpercatinib plus the NTRK inhibitor larotrectinib. Subsequently, tumor progressed with an acquired EML4::ALK fusion. Combination of selpercatinib with the dual NTRK/ALK inhibitor entrectinib reduced the tumor burden, which was followed by appearance of NTRK3 solvent-front G623R mutation. Preclinical experiments validated selpercatinib plus larotrectinib or entrectinib inhibited RET/NTRK3 dependent cells, whereas selpercatinib plus entrectinib was necessary to inhibit cells with RET/NTRK3/ALK triple alterations or a mixture of cell population carrying these genetic alterations. Thus, RET-altered MTC adapted to selpercatinib and larotrectinib with acquisition of ETV6::NTRK3 and EML4::ALK oncogenes can be managed by combination of selpercatinib and entrectinib providing proof-of-concept of urgency of incorporating molecular profiling in real-time and personalized N-of-1 care transcending one-size-fits-all approach.

Lung cancer ranks among the most common cancers world-wide and is the first cancer-related cause of death. The classification of lung cancer has evolved tremendously over the past two decades. Today, non-small cell lung cancer (NSCLC), particularly lung adenocarcinoma, comprises a multitude of molecular oncogenic subsets that change both the prognosis and management of disease.Since the first targeted oncogenic alteration identified in 2004, with the epidermal growth factor receptor (EGFR), there has been unprecedented progress in identifying and targeting new molecular alterations. Almost two decades of experience have allowed scientists to elucidate the biological function of oncogenic drivers and understand and often overcome the molecular basis of acquired resistance mechanisms. Today, targetable molecular alterations are identified in approximately 60% of lung adenocarcinoma patients in Western populations and 80% among Asian populations. Oncogenic drivers are largely enriched among non-smokers, east Asians, and younger patients, though each alteration has its own patient phenotype.The current landscape of druggable molecular targets includes EGFR, anaplastic lymphoma kinase (ALK), v-raf murine sarcoma viral oncogene homolog B (BRAF), ROS proto-oncogene 1 (ROS1), Kirstin rat sarcoma virus (KRAS), human epidermal receptor 2 (HER2), c-MET proto-oncogene (MET), neurotrophic receptor tyrosine kinase (NTRK), rearranged during transfection (RET), neuregulin 1 (NRG1). In addition to these known targets, others including Phosphoinositide 3-kinases (PI3K) and fibroblast growth factor receptor (FGFR) have garnered significant attention and are the subject of numerous ongoing trials.In this era of personalized, precision medicine, it is of paramount importance to identify known or potential oncogenic drivers in each patient. The development of targeted therapy is mirrored by diagnostic progress. Next generation sequencing offers high-throughput, speed and breadth to identify molecular alterations in entire genomes or targeted regions of DNA or RNA. It is the basis for the identification of the majority of current druggable alterations and offers a unique window into novel alterations, and de novo and acquired resistance mechanisms.In this review, we discuss the diagnostic approach in advanced NSCLC, focusing on current oncogenic driver alterations, through their pathophysiology, management, and future perspectives. We also explore the shortcomings and hurdles encountered in this rapidly evolving field.

Src homology 2 domain-containing phosphatase (SHP2) is a non-receptor protein phosphatase that transduces signals from upstream receptor tyrosine kinases (RTKs)/non-RTKs to Ras/MAPK pathway. Accumulating studies indicated that SHP2 is a critical mediator of resistance to current targeted therapies in multiple cancers. Here, we reported a novel SHP2 allosteric inhibitor JC-010a, which was highly selective to SHP2 and bound at the "tunnel" allosteric site of SHP2. The effect of JC-010a on combating RTK/non-RTK or MAPK inhibitors-induced acquired resistance was explored. Our study demonstrated that JC-010a monotherapy significantly inhibited the proliferation of cancer cells with different oncogenic drivers via inhibiting signaling through SHP2. Importantly, JC-010a abolished acquired resistance induced by targeted therapies: in KRAS-mutant cancers, JC-010a abrogated selumetinib-induced adaptive resistance mediated by RTK/SHP2; in BCR-ABL-driven leukemia cells, we demonstrated JC-010a inhibited BCR-ABL T315I mutation-mediated imatinib resistance and proposed a novel mechanism of JC-010a involving the disrupted co-interaction of SHP2, BCR-ABL, and Hsp90; in non-small cell lung cancer (NSCLC) cells, JC-010a inhibited both EGFR T790M/C797S mutation and alternate RTK-driven resistance to gefitinib or osimertinib; importantly, we first proposed a novel potential therapeutic strategy for RET-rearranged cancer, we confirmed that JC-010a monotherapy inhibited cell resistance to BLU-667, and JC-010a/BLU-667 combination prolonged anticancer response both in vivo and in vitro cancer models by inhibiting the alternate MET activation-induced RAS/MAPK reactivation, thereby promoting cancer cell apoptosis. These findings suggested that JC-010a was a novel selective SHP2 allosteric inhibitor, and combing JC-010a with current targeted therapy agents provided a promising therapeutic approach for clinical resistant cancers.

Acquired MET gene amplification, MET exon 14 skip mutations, or MET fusions can emerge as resistance mechanisms to tyrosine kinase inhibitors (TKIs) in patients with lung cancer. The efficacy and safety of combining MET TKIs (such as crizotinib, capmatinib, or tepotinib) with parent TKIs to target acquired MET resistance are not well characterized.

Multi-institutional retrospective chart review identified 83 patients with metastatic oncogene-driven NSCLC that were separated into the following two pairwise matched cohorts: (1) MET cohort (n = 41)-patients with acquired MET resistance continuing their parent TKI with a MET TKI added or (2) Chemotherapy cohort (n = 42)-patients without any actionable resistance continuing their parent TKI with a platinum-pemetrexed added. Clinicopathologic features, radiographic response (by means of Response Evaluation Criteria in Solid Tumors version 1.1), survival outcomes, adverse events (AEs) (by means of Common Terminology Criteria for Adverse Events version 5.0), and genomic data were collected. Survival outcomes were assessed using Kaplan-Meier methods. Multivariate modeling adjusted for lines of therapy, brain metastases, TP53 mutations, and oligometastatic disease.

Within the MET cohort, median age was 56 years (range: 36-83 y). Most patients were never smokers (28 of 41, 68.3%). Baseline brain metastases were common (21 of 41, 51%). The most common oncogenes in the MET cohort were EGFR (30 of 41, 73.2%), ALK (seven of 41, 17.1%), and ROS1 (two of 41, 4.9%). Co-occurring TP53 mutations (32 of 41, 78%) were frequent. Acquired MET alterations included MET gene amplification (37 of 41, 90%), MET exon 14 mutations (two of 41, 5%), and MET gene fusions (two of 41, 5%). After multivariate adjustment, the objective response rate (ORR) was higher in the MET cohort versus the chemotherapy cohort (ORR: 69.2% versus 20%, p < 0.001). Within the MET cohort, MET gene copy number (≥10 versus 6-10) did not affect radiographic response (54.5% versus 68.4%, p = 0.698). There was no difference in ORR on the basis of MET TKI used (F [2, 36] = 0.021, p = 0.978). There was no difference in progression-free survival (5 versus 6 mo; hazard ratio = 0.64; 95% confidence interval: 0.34-1.23, p = 0.18) or overall survival (13 versus 11 mo; hazard ratio = 0.75; 95% confidence interval: 0.42-1.35, p = 0.34) between the MET and chemotherapy cohorts. In the MET cohort, dose reductions for MET TKI-related toxicities were common (17 of 41, 41.4%) but less frequent for parent TKIs (two of 41, 5%). Grade 3 AEs were not significant between crizotinib, capmatinib, and tepotinib (p = 0.3). The discontinuation rate of MET TKIs was 17% with no significant differences between MET TKIs (p = 0.315). Among pre- and post-treatment biopsies (n = 17) in the MET cohort, the most common next-generation sequencing findings were loss of MET gene amplification (15 of 17, 88.2%), MET on-target mutations (seven of 17, 41.2%), new Ras-Raf-MAPK alterations (three of 17, 17.6%), and EGFR gene amplification (two of 17, 11.7%).

The efficacy and safety of combining MET TKIs (crizotinib, capmatinib, or tepotinib) with parent TKIs for acquired MET resistance are efficacious. Radiographic response and AEs did not differ significantly on the basis of the underlying MET TKI used. Loss of MET gene amplification, development of MET on-target mutations, Ras-Raf-MAPK alterations, and EGFR gene amplification were molecular patterns found on progression with dual parent and MET TKI combinations.