AXL confers intrinsic resistance to osimertinib and advances the emergence of tolerant cells

HDAC5, an early osimertinib-responsive gene, is a novel therapeutic target for the drug resistance in EGFR-mutant lung adenocarcinoma cells

Aberrant epigenetic regulation is closely associated with drug tolerance, an early step in the acquisition of drug resistance. We previously reported that a pioneer transcriptional factor (also called an epigenetic initiator) rapidly induced by osimertinib, a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, plays a pivotal role in promoting the formation of osimertinib-tolerant cells. In this study, to identify novel epigenetic factors associated with osimertinib-tolerance, we performed a comprehensive screening of epigenetic factors whose expression is rapidly induced by osimertinib. Our results revealed that HDAC5, a class IIa histone deacetylase (HDAC), is a prominently induced epigenetic regulator in several EGFR-mutant non-small cell lung cancer (NSCLC) cell lines during the early response to osimertinib. Knockdown of HDAC5 significantly reduced the emergence of osimertinib-resistant cells. Furthermore, treatment with LMK235, a selective HDAC5 inhibitor, significantly increased global histone acetylation and enhanced osimertinib-induced apoptosis. These findings highlight the potential of HDAC5 as a novel therapeutic target to overcome osimertinib-resistance and suggest LMK235 as a promising compound to provide therapeutic benefit to EGFR-mutant NSCLC patients receiving osimertinib treatment.

Drugging the Undruggable and beyond: Emerging precision oncology approaches to target acquired resistance to KRAS G12C and KRAS G12D inhibitors

Development of mutant specific KRAS inhibitors validated KRAS as a 'druggable' target. However, excellent initial efficacy was eventually overshadowed by failure to exhibit sustained clinical response, primarily due to acquired resistance. Some targeted therapies like SOS1, SHP2, and MEK inhibitors, in combination with mutant KRAS G12C inhibitors (G12Ci), are currently under clinical investigation with evidences of improving efficacy. However, a deep understanding of the underlying molecular pathways behind the acquired resistance is still at a nascent stage. Recent preclinical studies have uncovered a role of novel proteins and pathways responsible for resistance and their inhibition demonstrated a robust anticancer efficacy in combination. Plethora of combination therapy approaches are now being proposed with emergence of AXL, ULK1, Tissue factor, farnesyltransferase, etc. as targets to counter G12Ci resistance. This review summarizes in a comprehensive manner, some of the novel combination modalities to overcome G12Ci resistance, based on current understanding and with great potential to hit clinical success. Along with G12C, KRAS G12D (G12D) was also considered a formidable foe, until the discovery of selective inhibitors. However, eventual clinical resistance can eclipse the early success and requires an in-depth understanding of resistance mechanisms. Evidences of G12Ci resistance can be exploited as probable combination strategies to tackle ensuing resistance to G12D inhibitors (G12Di), and can translate in superior clinical efficacy. Early preclinical studies of G12Di in combination with ERBB, SOS1, AKT and immune-checkpoints inhibitors indicate encouraging response. This review further describes some of the early affirmations on combination strategies with G12Di. We postulate to go beyond 'Drugging the Undruggable' with advanced combination approaches mitigating G12C and G12D inhibitor resistance.

Basal-shift transformation leads to EGFR therapy-resistance in human lung adenocarcinoma

Although EGFR tyrosine kinase inhibitors (EGFR-TKIs) are effective for EGFR-mutant lung adenocarcinoma (LUAD), resistance inevitably develops through diverse mechanisms, including secondary genetic mutations, amplifications and as-yet undefined processes. To comprehensively unravel the mechanisms of EGFR-TKI resistance, we establish a biobank of patient-derived EGFR-mutant lung cancer organoids, encompassing cases previously treated with EGFR-TKIs. Through comprehensive molecular profiling including single-cell analysis, here we identify a subgroup of EGFR-TKI-resistant LUAD organoids that lacks known resistance-related genetic lesions and instead exhibits a basal-shift phenotype characterized by the hybrid expression of LUAD- and squamous cell carcinoma-related genes. Prospective gene engineering demonstrates that NKX2-1 knockout induces the basal-shift transformation along with EGFR-target therapy resistance. Basal-shift LUADs frequently harbor CDKN2A/B loss and are sensitive to CDK4/6 inhibitors. Our EGFR-mutant lung cancer organoid library not only offers a valuable resource for lung cancer research but also provides insights into molecular underpinnings of EGFR-TKI resistance, facilitating the development of therapeutic strategies.

AXL promotes inflammatory breast cancer progression by regulating immunosuppressive macrophage polarization

BACKGROUND

Tumor-associated macrophages (TAMs) are key promoters of inflammatory breast cancer (IBC), the most aggressive form of breast cancer. The receptor tyrosine kinase AXL is highly expressed in various cancer types, including IBC, but its role in TAMs remains unexplored.

METHODS

We examined the effects of AXL inhibitor TP-0903 on tumor growth and tumor microenvironment (TME) component M2 macrophages (CD206+) in IBC and triple-negative breast cancer mouse models using flow cytometry and immunohistochemical staining. Additionally, we knocked out AXL expression in human THP-1 monocytes and evaluated the effect of AXL signaling on immunosuppressive M2 macrophage polarization and IBC cell growth and migration. We then investigated the underlying mechanisms through RNA sequencing analysis. Last, we performed CIBERSORT deconvolution to analyze the association between AXL expression and tumor-infiltrating immune cell types in tumor samples from the Inflammatory Breast Cancer International Consortium.

RESULTS

We found that inhibiting the AXL pathway significantly reduced IBC tumor growth and decreased CD206+ macrophage populations within tumors. Mechanistically, our in vitro data showed that AXL promoted M2 macrophage polarization and enhanced the secretion of immunosuppressive chemokines, including CCL20, CCL26, and epiregulin, via the transcription factor STAT6 and thereby accelerated IBC cell growth and migration. RNA sequencing analysis further indicated that AXL signaling in immunosuppressive M2 macrophages regulated the expression of molecules and cytokines, contributing to an immunosuppressive TME in IBC. Moreover, high AXL expression was correlated with larger populations of immunosuppressive immune cells but smaller populations of immunoactive immune cells in tissues from patients with IBC.

CONCLUSIONS

AXL signaling promotes IBC growth by inducing M2 macrophage polarization and driving the secretion of immunosuppressive molecules and cytokines via STAT6 signaling, thereby contributing to an immunosuppressive TME. Collectively, these findings highlight the potential of targeting AXL signaling as a novel therapeutic approach for IBC that warrants further investigation in clinical trials.

Benzaldehyde suppresses epithelial-mesenchymal plasticity and overcomes treatment resistance in cancer by targeting the interaction of 14-3-3ζ with H3S28ph

BACKGROUND

Benzaldehyde (BA) is an aromatic aldehyde found in fruits that has been studied as a potential anticancer agent on the basis of its ability to inhibit transformation in mouse embryo cells and to suppress metastasis in mice.

METHODS

We investigated the cytotoxic effects of BA on cancer cells, and probed its effects on intracellular signaling pathways. The anticancer effects of BA in vivo were studied by using a mouse orthotopic transplantation model of pancreatic cancer.

RESULTS

BA inhibited the growth of osimertinib- or radiation-resistant cancer cells as well as the interaction between 14-3-3ζ and its client proteins. The interaction of 14-3-3ζ with the Ser28-phosphorylated form of histone H3 (H3S28ph) was implicated in treatment resistance and the transcriptional regulation of genes related to epithelial-mesenchymal transition and stemness, including E2F2, SRSF1, and ID1. Treatment of mice with a BA derivative inhibited pancreatic tumor growth and lung metastasis, as well as suppressed a state of epithelial-mesenchymal plasticity (EMP) of tumor cells.

CONCLUSION

The interaction between 14-3-3ζ and H3S28ph plays a key role in EMP and treatment resistance in cancer. The ability of BA to inhibit this and other interactions of 14-3-3ζ offers the potential to overcome treatment resistance and to suppress metastasis.

Strategies Beyond 3rd EGFR-TKI Acquired Resistance: Opportunities and Challenges

The seminal identification of epidermal growth factor receptor (EGFR) mutations as pivotal oncogenic drivers in non-small cell lung cancer (NSCLC) has catalyzed the evolution of biomarker-guided therapeutic paradigms for advanced disease. Currently, third-generation EGFR tyrosine kinase inhibitors (EGFR-TKI) have revolutionized first-line treatment for advanced EGFR-mutated NSCLC, yet acquired resistance remains an inevitable and formidable clinical challenge. This review systematically summarizes molecular mechanisms underlying treatment resistance, with a focus on clinical challenges associated with central nervous system (CNS) metastases. Therapeutic resistance mechanisms are categorized into EGFR-dependent (on-target) pathways, typified by acquired kinase domain mutations (e.g., C797S), and EGFR-independent (off-target) pathways, involving compensatory activation of parallel signaling effectors (e.g., MET amplification, HER2 activation) or phenotypic transformation. We further evaluated contemporary diagnostic modalities for identifying resistance drivers and appraised emerging therapeutic strategies, including fourth-generation EGFR-TKI, various combination therapies, and antibody-drug conjugates (ADCs), and so forth, with emphasis on ongoing clinical trials that may transform the existing treatment paradigm. By synthesizing preclinical and clinical insights, this review aims to advance mechanistic understanding and propose therapeutic strategies to overcome acquired resistance to third-generation EGFR-TKI in first-line treatment.

Emerging importance of HER3 in tumorigenesis and cancer therapy

HER3 is a member of the HER/ErbB family of receptor tyrosine kinases, together with EGFR (HER1), HER2 and HER4. Despite having only weak intrinsic kinase activity, HER3 can contribute to oncogenic signalling via ligand-induced heterodimerization with other HER family members. Evidence indicates that HER3 is altered or aberrantly expressed across a variety of tumour types and can be associated with poor clinical outcomes. Whereas anticancer agents targeting EGFR and HER2 have been approved for decades, no drug targeting HER3 had been approved until very recently. Initial targeting of HER3 with monoclonal antibodies as single agents or in combination with other therapeutics produced disappointing clinical results. Subsequently, efforts have been made to target HER3 with novel agents such as antibody-drug conjugates and bispecific antibodies, with promising efficacy observed in several trials encompassing various tumour types. In December 2024, the HER3 × HER2 bispecific antibody zenocutuzumab was granted FDA Accelerated Approval for the treatment of non-small-cell lung cancers or pancreatic cancers harbouring fusions involving NRG1, the gene encoding the high-affinity HER3 ligand neuregulin 1. In this Review, we provide an essential guide to HER3 signalling and oncogenesis, HER3 expression in cancer and its prognostic implications, oncogenic HER3 somatic mutations as well as rare NRG1 fusions that might depend on HER3 signalling, and the roles of HER3 in resistance to cancer therapies. We also highlight efforts to target HER3 with diverse therapeutic strategies and the potential interplay between HER3 and the antitumour immune response.

Recent advances in TAM mechanisms in lung diseases

TYRO3, MERTK, and AXL receptor tyrosine kinases, collectively known as TAM receptors, play a vital role in maintaining lung tissue homeostasis by regulating integrity and self-renewal. These receptors activate signalling pathways that inhibit apoptosis, promote cell proliferation and differentiation, mediate cell adhesion and migration, and perform other essential biological functions. Additionally, TAM receptors are implicated in mechanisms that suppress anti-tumor immunity and confer resistance to immune checkpoint inhibitors. Disruption of the homeostatic balances can lead to pathological conditions such as lung inflammation, fibrosis, or tumors. Recent studies highlight their significant role in COVID-19-induced lung injury. However, the exact mechanisms by which TAM receptors contribute to lung diseases remain unclear. This article reviews the potential mechanisms of TAM receptor involvement in disease progression, focusing on lung inflammation, fibrosis, cancer, and COVID-19-induced lung injury. It also explores future research aspects and the therapeutic potentials of targeting TAM receptors, providing a theoretical foundation for understanding lung disease mechanisms and identifying treatment targets.

Self-Assembled Multilayered Concentric Supraparticle Architecture

Supraparticles (SPs) with unique properties are emerging as versatile platforms for applications in catalysis, photonics, and medicine. However, the synthesis of novel SPs with complex internal structures remains a challenge. Self-Assembled Multilayered Supraparticles (SAMS) presented here are composed of concentric lamellar spherical structures made from metallic nanoparticles, formed from a synergistic three-way interaction phenomenon between gold nanoparticles, lipidoid, and gelatin, exhibiting interlayer spacing of 3.5  ± 0.2 nm within a self-limited 156.8  ± 56.6 nm diameter. The formation is critically influenced by both physical (including nanoparticle size, lipidoid chain length) and chemical factors (including elemental composition, nanoparticle cap, and organic material), which collectively modulate the surface chemistry and hydrophobicity, affecting interparticle interactions. SAMS can efficiently deliver labile payloads such as siRNA, achieving dose-dependent silencing in vivo, while also showing potential for complex payloads such as mRNA. This work not only advances the field of SP design by introducing a new structure and interaction phenomenon but also demonstrates its potential in nanomedicine.

Multieffect Specific Nanovesicles for Homing Resistant Tumors and Overcoming Osimertinib-Acquired Resistance in NSCLC

Acquired resistance to osimertinib (Osi) remains a major obstacle in the treatment of patients with EGFR-mutant non-small cell lung cancer (NSCLC). AXL elevation is a known key mechanism of Osi-resistance, and therapeutic strategies remain scarce. Emerging evidence reveals that an increased intracellular glutathione (GSH) level induces Osi resistance. In this study, a new mechanism is identified by which GSH regulates AXL expression via glutathione peroxidase 4 (GPX4) in Osi-resistant cells. A multifunctional covalent organic framework (COF) nanoplatform for GSH consumption, AXL inhibition, and co-delivery of the AXL inhibitor (Brigatinib) and Osi is creatively constructed to confirm whether Osi sensitivity improves by simultaneously targeting GSH-AXL resistance mechanisms. Furthermore, it is coated, for the first time, the COF carrier system with specific vesicles to precisely home it into resistant tumors, where CDH2 adhesion molecules play a crucial role. The engineered multifunctional antiresistance-specific nanovesicles effectively inhibited the GSH-AXL axis, induced apoptosis in Osi-resistant cells both in vitro and in vivo, and delayed the progression of Osi-resistant tumors. Overall, these findings provide a novel strategy to overcome the Osi-acquired resistance caused by high AXL levels in NSCLC.

A novel mesenchymal epithelial transition (MET) inhibitor, CB538, relieves acquired resistance in EGFR-mutated MET-amplified non-small cell lung cancer

Background

Osimertinib, a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), is the first-line standard therapy for metastatic EGFR-mutated non-small cell lung cancer (NSCLC). Although osimertinib is effective, it's durable response is invariably limited by the emergence of acquired resistance. Mesenchymal epithelial transition (MET) amplification is a frequent mechanism in patients with EGFR-mutated NSCLC who are resistant to EGFR-TKIs. Consequently, combined treatment with EGFR-TKIs and MET-TKIs has been explored as a strategy for overcoming this resistance. The current study aimed to explore the single and combination inhibition effect of CB538, a novel MET inhibitor in MET-activated, EGFR-mutant NSCLC cells.

Methods

The cellular inhibitory effects of single and co-treatment of CB538 with EGFR-TKIs were evaluated in the established EGFR-TKI-resistant cells [PC9/ER (erlotinib resistance), HCC827/OR (osimertinib resistance)]. The preclinical activities of CB538 were investigated by evaluating in vitro kinase activity, cell growth, and Western blotting of phosphorylated MET and downstream signaling molecules in MET-activated, EGFR-TKI-resistant cells. Cell viability was examined by MTT and colony formation. The inhibition of migration was determined by wound-healing assay. A xenograft tumor model was employed to investigate in vivo HCC827/OR cell growth in BALB/c nude mice.

Results

We confirmed that activated MET/Axl signaling pathways and EMT-related proteins were inhibited by CB538 in established EGFR-TKI-resistant NSCLC cells. CB538, a novel c-MET inhibitor, decreased the growth, migration, and invasive properties of these EGFR-TKI-resistant NSCLC cells. CB538 also inhibited tumor growth and expression of activated proteins (MET and Axl) in in vivo HCC827/OR xenograft model.

Conclusions

Additional treatment with CB538 enhanced sensitivity to EGFR-TKIs in two EGFR-TKI-resistant NSCLC cells by inhibiting EGFR/MET/Axl pathway axis. Overall, the treatment effects of CB538 were confirmed to relieve EGFR-TKI-driven resistance in EGFR-mutant NSCLC cells.

Strategies to Overcome Resistance to Osimertinib in EGFR-Mutated Lung Cancer

Non-small-cell lung cancer (NSCLC) represents the most common type of lung cancer. The majority of patients with lung cancer characterized by activating mutations in the epidermal growth factor receptor (EGFR), benefit from therapies entailing tyrosine kinase inhibitors (TKIs). In this regard, osimertinib, a third-generation EGFR TKI, has greatly improved the outcome for patients with EGFR-mutated lung cancer. The AURA and FLAURA trials displayed the superiority of the third-generation TKI in both first- and second-line settings, making it the drug of choice for treating patients with EGFR-mutated lung cancer. Unfortunately, the onset of resistance is almost inevitable. On-target mechanisms of resistance include new mutations (e.g., C797S) in the kinase domain of EGFR, while among the off-target mechanisms, amplification of MET or HER2, mutations in downstream signaling molecules, oncogenic fusions, and phenotypic changes (e.g., EMT) have been described. This review focuses on the strategies that are currently being investigated, in preclinical and clinical settings, to overcome resistance to osimertinib, including the use of fourth-generation TKIs, PROTACs, bispecific antibodies, and ADCs, as monotherapy and as part of combination therapies.

YAP Regulates HER3 Signaling-Driven Adaptive Resistance to RET Inhibitors in RET-Aberrant Cancers

PURPOSE

Rearranged during transfection (RET) aberrations represent a targetable oncogene in several tumor types, with RET inhibitors displaying marked efficacy. However, some patients with RET-aberrant cancer are insensitive to RET tyrosine kinase inhibitors (TKI). Recently, drug-tolerant mechanisms have attracted attention as targets for initial therapies to overcome drug resistance. The underlying mechanisms of drug-tolerant cell emergence treated with RET-TKIs derived from RET-aberrant cancer cells remain unknown. This study investigated the role of YAP-mediated HER3 signaling in the underlying mechanisms of adaptive resistance to RET-TKIs in RET-aberrant cancer cells.

EXPERIMENTAL DESIGN

Four RET-aberrant cancer cell lines were used to assess sensitivity to the RET-TKIs selpercatinib and pralsetinib and to elucidate the molecular mechanisms underlying adaptive resistance using RNA sequencing, phospho-receptor tyrosine kinase antibody arrays, chromatin immunoprecipitation assay, and luciferase reporter assays. Clinical specimens from patients with RET fusion-positive lung cancer were analyzed for pretreatment YAP expression and correlated with treatment outcomes.

RESULTS

In high YAP-expressing RET-aberrant cancer cells, YAP-mediated HER3 signaling activation maintained cell survival and induced the emergence of cells tolerant to the RET-TKIs selpercatinib and pralsetinib. The pan-ErBB inhibitor afatinib and YAP/tea domain inhibitors verteporfin and K-975 sensitized YAP-expressing RET-aberrant cancer cells to the RET-TKIs selpercatinib and pralsetinib. Pretreatment YAP expression in clinical specimens obtained from patients with RET fusion-positive lung cancer was associated with poor RET-TKI treatment outcomes.

CONCLUSIONS

The YAP-HER3 axis is crucial for the survival and adaptive resistance of high YAP-expressing RET-aberrant cancer cells treated with RET-TKIs. Combining YAP/HER3 inhibition with RET-TKIs represents a highly potent strategy for initial treatment. See related commentary by Ortiz-Cuaran and Leonce, p. 958.

Identification of functional non-coding variants associated with orofacial cleft

Oral facial cleft (OFC) is a multifactorial disorder that can present as a cleft lip with or without cleft palate (CL/P) or a cleft palate only. Genome wide association studies (GWAS) of isolated OFC have identified common single nucleotide polymorphisms (SNPs) at the 1q32/ IRF6 locus and many other loci where, like IRF6 , the presumed OFC-relevant gene is expressed in embryonic oral epithelium. To identify the functional subset of SNPs at eight such loci we conducted a massively parallel reporter assay in a cell line derived from fetal oral epithelium, revealing SNPs with allele-specific effects on enhancer activity. We filtered these against chromatin-mark evidence of enhancers in relevant cell types or tissues, and then tested a subset in traditional reporter assays, yielding six candidates for functional SNPs in five loci (1q32/ IRF6 , 3q28/ TP63 , 6p24.3/ TFAP2A , 20q12/ MAFB , and 9q22.33/ FOXE1 ). We further tested two SNPs near IRF6 and one near FOXE1 by engineering the genome of induced pluripotent stem cells, differentiating the cells into embryonic oral epithelium, and measuring expression of IRF6 or FOXE1 and binding of transcription factors; the results strongly supported their candidacy. Conditional analyses of a meta-analysis of GWAS suggest that the two functional SNPs near IRF6 account for the majority of risk for CL/P associated with variation at this locus. This study connects genetic variation associated with orofacial cleft to mechanisms of pathogenesis.

Phosphatidylserine as a tumor target for CAR-T cell therapy

BACKGROUND

Phosphatidylserine (PS) exposed on apoptotic cells promotes immune clearance of dead cells without inducing inflammation. Conversely, PS exposure on live tumor cells promotes an immunosuppressive tumor microenvironment that hinders antitumor immune responses. After confirming elevated PS levels in various tumor cell lines and cancer tissues, we aimed to investigate its potential as a target antigen for chimeric antigen receptor T cell (CAR-T) therapy.

METHODS

We used two different approaches to target PS. First, we employed the adaptor proteins, EDAnnexin or BCMAnnexin comprising annexin V and EDA (extra domain A of fibronectin) or B-cell maturation antigen (BCMA) antigens, to redirect the lytic activity of EDA CAR-T or BCMA CAR-T cells toward PS-expressing tumor cells. In a second approach, we developed an annexin V-based CAR (Anxa CAR-T) to directly recognize PS-positive tumor cells.

RESULTS

The adaptors proteins EDAnnexin and BCMAnnexin successfully redirected EDA CAR-T or BCMA CAR-T cell activity, leading to an efficient recognition of PS+ tumor cells in vitro. However, the established immunological synapse differs significantly from that observed when CAR-T cells recognize the tumor cells directly. In vivo administration of the adaptor proteins, combined with the corresponding CAR-T cells, displayed antitumor activity in mice bearing PS+ tumors. Regarding the second approach, Anxa CAR-T cells effectively recognized and killed PS+ tumor cells in vitro. Nonetheless, PS exposure on T-cell membranes during T-cell activation impeded efficient Anxa CAR-T cell manufacturing due to fratricide. By optimizing retroviral dose to reduce Anxa CAR expression on the cell membrane, or by using the multikinase inhibitor dasatinib, the fratricide effect was mitigated, enabling successful Anxa CARLow-T cell production. Remarkably, Anxa CARLow-T cells demonstrated antitumor activity in in vivo murine models of PS+ hepatocarcinoma and teratocarcinoma. No signs of toxicity were observed after Anxa CAR-T cell administration.

CONCLUSIONS

PS holds promise as a target antigen for CAR-T cell therapy, underscoring the need to address fratricide as a key challenge in the development of PS-targeting CAR-T cells.

Osimertinib in the Treatment of Epidermal Growth Factor Receptor-Mutant Early and Locally Advanced Stages of Non-Small-Cell Lung Cancer: Current Evidence and Future Perspectives

The treatment of epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancer (NSCLC) patients was dramatically revolutionized by the introduction of EGFR tyrosine kinase inhibitors in clinical practice, both in advanced and locally advanced/early stages. The present work focuses on osimertinib use in locally advanced and early NSCLC stages. Phase 3 clinical trials have supported the use of osimertinib as the new standard of care, both in the adjuvant setting and in locally advanced disease. The ADAURA study reported an overall survival (OS) advantage for adjuvant osimertinib in completely resected stage II-IIIA EGFR-mutant tumors, while the LAURA study proved a statistically significant benefit in progression-free survival (PFS) and a delay of central nervous system metastasis development in EGFR-mutant patients treated with osimertinib maintenance after concurrent chemoradiotherapy for locally advanced disease. In the neoadjuvant setting, data on osimertinib's efficacy are conflicting; therefore, the Neo-ADAURA study is evaluating the efficacy and safety of neoadjuvant osimertinib alone or in combination with chemotherapy in patients with stage II-IIIB NSCLC and common EGFR mutations. We discuss several issues that need to be clarified, such as the efficacy of the drug on uncommon mutations, the long-term impact on survival, and the management of resistance mechanisms. Moreover, we report the studies that are trying to identify potential biomarkers of response, such as the circulating tumor DNA (ctDNA), with the aim of selecting patients who will benefit most from osimertinib.

AXL signaling in cancer: from molecular insights to targeted therapies

AXL, a member of the TAM receptor family, has emerged as a potential target for advanced-stage human malignancies. It is frequently overexpressed in different cancers and plays a significant role in various tumor-promoting pathways, including cancer cell proliferation, invasion, metastasis, epithelial-mesenchymal transition (EMT), angiogenesis, stemness, DNA damage response, acquired therapeutic resistance, immunosuppression, and inflammatory responses. Beyond oncology, AXL also facilitates viral infections, including SARS-CoV-2 and Zika highlighting its importance in both cancer and virology. In preclinical models, small-molecule kinase inhibitors targeting AXL have shown promising anti-tumorigenic potential. This review primarily focuses on the induction, regulation and biological functions of AXL in mediating these tumor-promoting pathways. We discuss a range of therapeutic strategies, including recently developed small-molecule tyrosine kinase inhibitors (TKIs), monoclonal antibodies, and antibody-drug conjugates (ADCs), anti-AXL-CAR, and combination therapies. These interventions are being examined in both preclinical and clinical studies, offering the potential for improved drug sensitivity and therapeutic efficacy. We further discuss the mechanisms of acquired therapeutic resistance, particularly the crosstalk between AXL and other critical receptor tyrosine kinases (RTKs) such as c-MET, EGFR, HER2/HER3, VEGFR, PDGFR, and FLT3. Finally, we highlight key research areas that require further exploration to enhance AXL-mediated therapeutic approaches for improved clinical outcomes.

Optimizing Osimertinib for NSCLC: Targeting Resistance and Exploring Combination Therapeutics

Non-small-cell lung cancer (NSCLC) is a leading cause of cancer-related deaths worldwide, with epidermal growth factor receptor (EGFR) mutations present in a substantial proportion of patients. Third-generation EGFR tyrosine kinase inhibitors (EGFR TKI), exemplified by osimertinib, have dramatically improved outcomes by effectively targeting the T790M mutation-a primary driver of acquired resistance to earlier-generation EGFR TKI. Despite these successes, resistance to third-generation EGFR TKIs inevitably emerges. Mechanisms include on-target mutations such as C797S, activation of alternative pathways like MET amplification, histologic transformations, and intricate tumor microenvironment (TME) alterations. These resistance pathways are compounded by challenges in tolerability, adverse events, and tumor heterogeneity. In light of these hurdles, this review examines the evolving landscape of combination therapies designed to enhance or prolong the effectiveness of third-generation EGFR TKIs. We explore key strategies that pair osimertinib with radiotherapy, anti-angiogenic agents, immune checkpoint inhibitors, and other molecularly targeted drugs, and we discuss the biological rationale, preclinical evidence, and clinical trial data supporting these approaches. Emphasis is placed on how these combinations may circumvent diverse resistance mechanisms, improve survival, and maintain a favorable safety profile. By integrating the latest findings, this review aims to guide clinicians and researchers toward more individualized and durable treatment options, ultimately enhancing both survival and quality of life for patients with EGFR-mutated NSCLC.

Expression of extracellular HSP90α in pre- and post-treatment samples of driver-gene-negative non-small cell lung cancer

PURPOSE

This study aimed to explore the significance of the expression of pre- and post-treatment eHSP90α in the treatment response evaluation and prognosis of driver-gene-negative non-small cell lung cancer (NSCLC), as well as the significance of eHSP90α expression in the prognosis of immunotherapy.

METHODS

We collected pre-treatment eHSP90α in 330 driver-gene-negative NSCLC patients and analyzed its relationship with efficacy evaluation and prognosis. Survival curves were used to determine their respective critical values and the relationship between eHSP90α expression and OS and PFS was analyzed. Then, univariable and multivariable Cox regression analyses and LASSO multivariable logistic regression analyses were used to establish the prognostic and efficacy evaluation models.

RESULTS

High expression of pre-treatment eHSP90α in driver-gene-negative NSCLC patients is associated with shorter OS. Pre-treatment eHSP90α, immunotherapy, TTF-1, CA125, and age influence OS in NSCLC patients. In the stratified analysis of immunotherapy, pre-treatment eHSP90α in immunotherapy is an independent influencing factor of OS in NSCLC patients, and pre-treatment eHSP90α, age, CA125, and B lymphocytes in non-immunotherapy are independent influencing factors of OS in NSCLC patients. High expression of pre-treatment eHSP90α in NSCLC patients is associated with shorter PFS. Pre-treatment eHSP90α, M1, Ki-67, and immunotherapy are independent influencing factors of PFS in NSCLC patients. In the stratified analysis of immunotherapy, pre-treatment eHSP90α and CEA in immunotherapy are independent influencing factors of PFS in NSCLC patients, and pre-treatment eHSP90α, M1, Ki-67, CA125, Th/Ts, and age in non-immunotherapy are independent factors affecting PFS in NSCLC patients. Pre-treatment eHSP90α was one of the influencing factors in the efficacy evaluation model.

CONCLUSIONS

The expression of pre-treatment eHSP90α has significant significance for the prognosis and efficacy evaluation of driver-gene-negative NSCLC.

Protocol for modeling acquired resistance to targeted therapeutics in adherent and suspension cancer cell lines via in situ resistance assay

Acquired resistance to oncogene-targeted therapies is the major driver of mortality for patients with cancer. Here, we present a 6-to-16-week assay to model the development of acquired resistance in adherent and suspension cancer cell lines. We describe steps for determining therapeutic dose, assaying acquired resistance, and testing combination therapies. This protocol is a high-throughput, cost-effective, and scalable method to model acquired drug resistance to established and newly developed therapies. For complete details on the use and execution of this protocol, please refer to Sealover et al.1 and Theard et al.2.

PPP3CB overexpression mediates EGFR TKI resistance in lung tumors via calcineurin/MEK/ERK signaling

Despite initial high response rates to first-line EGFR TKI, all non-small-cell lung cancer (NSCLC) with EGFR-activating mutation will ultimately develop resistance to treatment. Identification of resistance mechanisms is critical to adapt treatment and improve patient outcomes. Here, we show that a PPP3CB transcript that encodes full-length catalytic subunit 2B of calcineurin accumulates in EGFR-mutant NSCLC cells with acquired resistance against different EGFR TKIs and in post-progression biopsies of NSCLC patients treated with EGFR TKIs. Neutralization of PPP3CB by siRNA or inactivation of calcineurin by cyclosporin A induces apoptosis in resistant cells treated with EGFR TKIs. Mechanistically, EGFR TKIs increase the cytosolic level of calcium and trigger activation of a calcineurin/MEK/ERK pathway that prevents apoptosis. Combining EGFR, calcineurin, and MEK inhibitors overcomes resistance to EGFR TKI in both in vitro and in vivo models. Our results identify PPP3CB overexpression as a new mechanism of acquired resistance to EGFR TKIs, and provide a promising therapeutic approach for NSCLC patients that progress under TKI treatment.

Research progress on the role of bypass activation mechanisms in resistance to tyrosine kinase inhibitors in non-small cell lung cancer

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.

Comprehensive liquid biopsy analysis for monitoring NSCLC patients under second-line osimertinib treatment

Background

The heterogeneous and complex genetic landscape of NSCLC impacts the clinical outcomes of patients who will eventually develop resistance to osimertinib. Liquid biopsy (LB) analysis as a minimally invasive approach is a key step to efficiently identify resistance mechanisms and adjust to proper subsequent treatments.

Materials and methods

In the present study, we combined plasma-cfDNA and CTC analysis from 30 NSCLC patients in samples collected before treatment and at the progression of disease (PD). We detected molecular alterations at the DNA mutation (EGFR, PIK3CA, KRAS G12C, BRAF V600E), DNA methylation (RASSF1A, BRMS1, FOXA1, SLFN1, SHISA3, RARβ,, WIF-1, RASSF10 and APC), gene expression (CK-19, CK-18, CK-8, AXL, TWIST-1, PD-L1, PIM-1, Vimentin, ALDH-1, and B2M) and chromosomal level (HER2 and MET amplification) as possible resistance mechanisms and druggable targets. We also studied the expression of PD-L1 in single CTCs using immunofluorescence.

Results

In some cases, T790M resistance EGFR mutation was detected at baseline in CTCs but not in the corresponding plasma cfDNA. PIK3CA mutations were detected only in plasma-cfDNA but not in corresponding CTCs. KRAS G12C and BRAF V600E mutations were not detected in the samples analyzed. MET amplification was detected in the CTCs of two patients before treatment whereas HER2 amplification was detected in the CTCs of three patients at baseline and in one patient at PD. DNA methylation analysis revealed low concordance between CTCs and cfDNA, indicating the complementary information obtained through parallel LB analysis. Results from gene expression analysis indicated high rates of vimentin-positive CTCs detected at all time points during osimertinib. Moreover, there was an increased number of NSCLC patients at PD harboring CTCs positive in PD-L1. AXL and PIM-1 expression detected in CTCs during treatment suggesting new possible therapeutic strategies.

Discussion

Our results reveal that comprehensive liquid biopsy analysis can efficiently represent the heterogeneous molecular landscape and provide prominent information on subsequent treatments for NSCLC patients at PD since druggable molecular alterations were detected in CTCs.

NPS-1034 Exerts Therapeutic Efficacy in Renal Cell Carcinoma Through Multiple Targets of MET, AXL, and TNFRSF1A Signaling in a Metastatic Model

Renal cell carcinoma (RCC) has diverse pathological subtypes, most of which have a poor prognosis. Patients with advanced RCC require systemic therapies for disease control. Although targeted therapies and immune checkpoint inhibitors have shown therapeutic efficacy, patients eventually succumb to disease progression. Therefore, additional therapies targeting different pathways are needed to provide more therapeutic options for sequential treatment. Our study explored the biological mechanisms and therapeutic outcomes for NPS-1034, a dual MET/AXL inhibitor, in RCC, both in vivo and in vitro. Our results showed that NPS-1034 can significantly inhibit tumor proliferation and induce cancer cell apoptosis. Besides MET and AXL, known targets of NPS-1034, we identified TNFRSF1A as another target gene inhibited by NPS-1034 via antibody arrays. This was further supported by next-generation sequencing, showing that the TNF signaling pathway is one of the most significant NPS-1034-regulated pathways. Furthermore, one of the identified target genes, GADD45A, responsible for NPS-1034 anticancer properties, was significantly associated with patient survival in RCC. GADD45A expression was significantly upregulated via NPS-1034 and downregulated via TNFRSF1A overexpression. Finally, its therapeutic efficacy was demonstrated in vivo, showing that NPS-1034 significantly alleviated the tumor burden and inhibited cell proliferation in a lung metastatic animal model. In conclusion, we explored the therapeutic mechanism of NPS-1034 and found that it targets not only MET and AXL but also TNFRSF1A. In a lung metastatic animal model, we confirmed that NPS-1034 is a potential candidate for systemic therapy in RCC.

Cancer drug-tolerant persister cells: from biological questions to clinical opportunities

The emergence of drug resistance is the most substantial challenge to the effectiveness of anticancer therapies. Orthogonal approaches have revealed that a subset of cells, known as drug-tolerant 'persister' (DTP) cells, have a prominent role in drug resistance. Although long recognized in bacterial populations which have acquired resistance to antibiotics, the presence of DTPs in various cancer types has come to light only in the past two decades, yet several aspects of their biology remain enigmatic. Here, we delve into the biological characteristics of DTPs and explore potential strategies for tracking and targeting them. Recent findings suggest that DTPs exhibit remarkable plasticity, being capable of transitioning between different cellular states, resulting in distinct DTP phenotypes within a single tumour. However, defining the biological features of DTPs has been challenging, partly due to the complex interplay between clonal dynamics and tissue-specific factors influencing their phenotype. Moreover, the interactions between DTPs and the tumour microenvironment, including their potential to evade immune surveillance, remain to be discovered. Finally, the mechanisms underlying DTP-derived drug resistance and their correlation with clinical outcomes remain poorly understood. This Roadmap aims to provide a comprehensive overview of the field of DTPs, encompassing past achievements and current endeavours in elucidating their biology. We also discuss the prospect of future advancements in technologies in helping to unveil the features of DTPs and propose novel therapeutic strategies that could lead to their eradication.

Initial AXL and MCL-1 inhibition contributes to abolishing lazertinib tolerance in EGFR-mutant lung cancer cells

Lazertinib, a novel third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), demonstrates marked efficacy in EGFR-mutant lung cancer. However, resistance commonly develops, prompting consideration of therapeutic strategies to overcome initial drug resistance mechanisms. This study aimed to elucidate the adaptive resistance to lazertinib and advocate novel combination treatments that demonstrate efficacy in preventing resistance as a first-line treatment for EGFR mutation-positive NSCLC. We found that AXL knockdown significantly inhibited lung cancer cell viability in the presence of lazertinib, indicating that AXL activation contributes to lazertinib resistance. However, long-term culture with a combination of lazertinib and AXL inhibitors led to residual cell proliferation and increased the MCL-1 expression level, which was mediated by the nuclear translocation of the transcription factor YAP. Triple therapy with an MCL-1 or YAP inhibitor in combination with lazertinib and an AXL inhibitor significantly reduced cell viability and increased the apoptosis rate. These results demonstrate that AXL and YAP/MCL-1 signals contribute to adaptive lazertinib resistance in EGFR-mutant lung cancer cells, suggesting that the initial dual inhibition of AXL and YAP/MCL-1 might be a highly effective strategy in eliminating lazertinib-resistant cells.

Identification of C-mannosylation in a receptor tyrosine kinase AXL

C-mannosylation is a unique type of glycosylation in which a mannose is added to tryptophan in a protein. However, the biological function of C-mannosylation is still largely unknown. AXL is a receptor tyrosine kinase, and its overexpression contributes to tumor malignancy. The role of AXL in cancer cells is broad, including invasion, drug resistance, and vasculogenic mimicry formation. Although Trp320 of AXL was predicted to be C-mannosylated, it has not been confirmed. Here, we demonstrated that Trp320 of AXL is C-mannosylated, measured by mass spectrometry of recombinant AXL purified from various cancer cells. Furthermore, re-expression of C-mannosylation-deficient AXL in human breast cancer MDA-MB-231 cells lacking AXL by the CRISPR/Cas9 system resulted in reduction of vasculogenic mimicry formation. Interestingly, phosphorylation levels of AKT in C-mannosylation-deficient AXL re-expressing cells were comparable to those of parental and wild-type AXL re-expressing cells. These results represent the first discovery of C-mannosylation in a receptor tyrosine kinase and the possibility that C-mannosylation may affect AXL function, distinct from its downstream signaling in cancer cells.

A bispecific antibody targeting EGFR and AXL delays resistance to osimertinib

Activating EGFR (epidermal growth factor receptor) mutations can be inhibited by specific tyrosine kinase inhibitors (TKIs), which have changed the landscape of lung cancer therapy. However, due to secondary mutations and bypass receptors, such as AXL (AXL receptor tyrosine kinase), drug resistance eventually emerges in most patients treated with the first-, second-, or third-generation TKIs (e.g., osimertinib). To inhibit AXL and resistance to osimertinib, we compare two anti-AXL drugs, an antibody (mAb654) and a TKI (bemcentinib). While no pair of osimertinib and an anti-AXL drug is able to prevent relapses, triplets combining osimertinib, cetuximab (an anti-EGFR antibody), and either anti-AXL drug are initially effective. However, longer monitoring uncovers superiority of the mAb654-containing triplet, possibly due to induction of receptor endocytosis, activation of immune mechanisms, or disabling intrinsic mutators. Hence, we constructed a bispecific antibody that engages both AXL and EGFR. When combined with osimertinib, the bispecific antibody consistently inhibits tumor relapses, which warrants clinical trials.

Precision therapy targeting CAMK2 to overcome resistance to EGFR inhibitors in FAT1-mutated oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a prevalent type of cancer with a high mortality rate in its late stages. One of the major challenges in OSCC treatment is the resistance to epidermal growth factor receptor (EGFR) inhibitors. Therefore, it is imperative to elucidate the mechanism underlying drug resistance and develop appropriate precision therapy strategies to enhance clinical efficacy.

METHODS

To evaluate the efficacy of the combination of the Ca2+/calmodulin-dependent protein kinase II (CAMK2) inhibitor KN93 and EGFR inhibitors, we performed in vitro and in vivo experiments using two FAT atypical cadherin 1 (FAT1)-deficient (SCC9 and SCC25) and two FAT1 wild-type (SCC47 and HN12) OSCC cell lines. We assessed the effects of EGFR inhibitors (afatinib or cetuximab), KN93, or their combination on the malignant phenotype of OSCC in vivo and in vitro. The alterations in protein expression levels of members of the EGFR signaling pathway and SRY-box transcription factor 2 (SOX2) were analyzed. Changes in the yes-associated protein 1 (YAP1) protein were characterized. Moreover, we analyzed mitochondrial dysfunction. Besides, the effects of combination therapy on mitochondrial dynamics were also evaluated.

RESULTS

OSCC with FAT1 mutations exhibited resistance to EGFR inhibitors treatment. The combination of KN93 and EGFR inhibitors significantly inhibited the proliferation, survival, and migration of FAT1-mutated OSCC cells and suppressed tumor growth in vivo. Mechanistically, combination therapy enhanced the therapeutic sensitivity of FAT1-mutated OSCC cells to EGFR inhibitors by modulating the EGFR pathway and downregulated tumor stemness-related proteins. Furthermore, combination therapy induced reactive oxygen species (ROS)-mediated mitochondrial dysfunction and disrupted mitochondrial dynamics, ultimately resulting in tumor suppression.

CONCLUSION

Combination therapy with EGFR inhibitors and KN93 could be a novel precision therapeutic strategy and a potential clinical solution for EGFR-resistant OSCC patients with FAT1 mutations.

Triple combination therapy comprising osimertinib, an AXL inhibitor, and an FGFR inhibitor improves the efficacy of EGFR-mutated non-small cell lung cancer

We previously reported that combined therapy with epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) osimertinib and AXL inhibitor ONO-7475 is effective in preventing the survival of drug-tolerant cells in high-AXL-expressing EGFR-mutated non-small cell lung cancer (NSCLC) cells. Nevertheless, certain residual cells are anticipated to eventually develop acquired resistance to this combination therapy. In this study, we attempted to establish a multidrug combination therapy from the first-line setting to overcome resistance to this combination therapy in high-AXL-expressing EGFR-mutated NSCLC. siRNA screening assay showed that fibroblast growth factor receptor 1 (FGFR1) knockdown induced pronounced inhibition of cell viability in the presence of the osimertinib-ONO-7475 combination, which activates FGFR1 by upregulating FGF2 via the c-Myc pathway. Cell-based assays showed that triple therapy with osimertinib, ONO-7475, and the FGFR inhibitor BGJ398 significantly increased apoptosis by increasing expression of proapoptotic factor Bim and reduced cell viability compared with that observed for the osimertinib-ONO-7475 therapy. Xenograft models showed that triple therapy considerably suppressed tumor regrowth. A novel therapeutic strategy of additional initial FGFR1 inhibition may be highly effective in suppressing the emergence of osimertinib- and ONO-7475-resistant cells.

Drug tolerant persister cell plasticity in cancer: A revolutionary strategy for more effective anticancer therapies

Non-genetic mechanisms have recently emerged as important drivers of anticancer drug resistance. Among these, the drug tolerant persister (DTP) cell phenotype is attracting more and more attention and giving a predominant non-genetic role in cancer therapy resistance. The DTP phenotype is characterized by a quiescent or slow-cell-cycle reversible state of the cancer cell subpopulation and inert specialization to stimuli, which tolerates anticancer drug exposure to some extent through the interaction of multiple underlying mechanisms and recovering growth and proliferation after drug withdrawal, ultimately leading to treatment resistance and cancer recurrence. Therefore, targeting DTP cells is anticipated to provide new treatment opportunities for cancer patients, although our current knowledge of these DTP cells in treatment resistance remains limited. In this review, we provide a comprehensive overview of the formation characteristics and underlying drug tolerant mechanisms of DTP cells, investigate the potential drugs for DTP (including preclinical drugs, novel use for old drugs, and natural products) based on different medicine models, and discuss the necessity and feasibility of anti-DTP therapy, related application forms, and future issues that will need to be addressed to advance this emerging field towards clinical applications. Nonetheless, understanding the novel functions of DTP cells may enable us to develop new more effective anticancer therapy and improve clinical outcomes for cancer patients.

NRG1 Gene Fusions-What Promise Remains Behind These Rare Genetic Alterations? A Comprehensive Review of Biology, Diagnostic Approaches, and Clinical Implications

Non-small cell lung cancer (NSCLC) presents a variety of druggable genetic alterations that revolutionized the treatment approaches. However, identifying new alterations may broaden the group of patients benefitting from such novel treatment options. Recently, the interest focused on the neuregulin-1 gene (NRG1), whose fusions may have become a potential predictive factor. To date, the occurrence of NRG1 fusions has been considered a negative prognostic marker in NSCLC treatment; however, many premises remain behind the targetability of signaling pathways affected by the NRG1 gene. The role of NRG1 fusions in ErbB-mediated cell proliferation especially seems to be considered as a main target of treatment. Hence, NSCLC patients harboring NRG1 fusions may benefit from targeted therapies such as pan-HER family inhibitors, which have shown efficacy in previous studies in various cancers, and anti-HER monoclonal antibodies. Considering the increased interest in the NRG1 gene as a potential clinical target, in the following review, we highlight its biology, as well as the potential clinical implications that were evaluated in clinics or remained under consideration in clinical trials.

Targeting of drug-tolerant persister cells as an approach to counter drug resistance in non-small cell lung cancer

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.

Novel therapeutic strategies targeting bypass pathways and mitochondrial dysfunction to combat resistance to RET inhibitors in NSCLC

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.

Farnesyltransferase inhibition overcomes oncogene-addicted non-small cell lung cancer adaptive resistance to targeted therapies

Drug-tolerance has emerged as one of the major non-genetic adaptive processes driving resistance to targeted therapy (TT) in non-small cell lung cancer (NSCLC). However, the kinetics and sequence of molecular events governing this adaptive response remain poorly understood. Here, we combine real-time monitoring of the cell-cycle dynamics and single-cell RNA sequencing in a broad panel of oncogenic addiction such as EGFR-, ALK-, BRAF- and KRAS-mutant NSCLC, treated with their corresponding TT. We identify a common path of drug adaptation, which invariably involves alveolar type 1 (AT1) differentiation and Rho-associated protein kinase (ROCK)-mediated cytoskeletal remodeling. We also isolate and characterize a rare population of early escapers, which represent the earliest resistance-initiating cells that emerge in the first hours of treatment from the AT1-like population. A phenotypic drug screen identify farnesyltransferase inhibitors (FTI) such as tipifarnib as the most effective drugs in preventing relapse to TT in vitro and in vivo in several models of oncogenic addiction, which is confirmed by genetic depletion of the farnesyltransferase. These findings pave the way for the development of treatments combining TT and FTI to effectively prevent tumor relapse in oncogene-addicted NSCLC patients.

The Therapeutic Role of NPS-1034 in Pancreatic Ductal Adenocarcinoma as Monotherapy and in Combination with Chemotherapy

Pancreatic ductal adenocarcinoma (PDAC) poses a significant challenge in terms of diagnosis and treatment, with limited therapeutic options and a poor prognosis. This study explored the potential therapeutic role of NPS-1034, a kinase inhibitor targeting MET and AXL, in PDAC. The investigation included monotherapy with NPS-1034 and its combination with the commonly prescribed chemotherapy agents, fluorouracil and oxaliplatin. Our study revealed that NPS-1034 induces cell death and reduces the viability and clonogenicity of PDAC cells in a dose-dependent manner. Furthermore, NPS-1034 inhibits the migration of PDAC cells by suppressing MET/PI3K/AKT axis-induced epithelial-to-mesenchymal transition (EMT). The combination of NPS-1034 with fluorouracil or oxaliplatin demonstrated a synergistic effect, significantly reducing cell viability and inducing tumor cell apoptosis compared to monotherapies. Mechanistic insights provided by next-generation sequencing indicated that NPS-1034 modulates immune responses by inducing type I interferon and tumor necrosis factor production in PDAC cells. This suggests a broader role for NPS-1034 beyond MET and AXL inhibition, positioning it as a potential immunity modulator. Overall, these findings highlight the anticancer potential of NPS-1034 in PDAC treatment in vitro, both as a monotherapy and in combination with traditional chemotherapy, offering a promising avenue for further in vivo investigation before clinical exploration.

EGFRvIII Confers Sensitivity to Saracatinib in a STAT5-Dependent Manner in Glioblastoma

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults, with few effective treatments. EGFR alterations, including expression of the truncated variant EGFRvIII, are among the most frequent genomic changes in these tumors. EGFRvIII is known to preferentially signal through STAT5 for oncogenic activation in GBM, yet targeting EGFRvIII has yielded limited clinical success to date. In this study, we employed patient-derived xenograft (PDX) models expressing EGFRvIII to determine the key points of therapeutic vulnerability within the EGFRvIII-STAT5 signaling axis in GBM. Our findings reveal that exogenous expression of paralogs STAT5A and STAT5B augments cell proliferation and that inhibition of STAT5 phosphorylation in vivo improves overall survival in combination with temozolomide (TMZ). STAT5 phosphorylation is independent of JAK1 and JAK2 signaling, instead requiring Src family kinase (SFK) activity. Saracatinib, an SFK inhibitor, attenuates phosphorylation of STAT5 and preferentially sensitizes EGFRvIII+ GBM cells to undergo apoptotic cell death relative to wild-type EGFR. Constitutively active STAT5A or STAT5B mitigates saracatinib sensitivity in EGFRvIII+ cells. In vivo, saracatinib treatment decreased survival in mice bearing EGFR WT tumors compared to the control, yet in EGFRvIII+ tumors, treatment with saracatinib in combination with TMZ preferentially improves survival.

Comparison of the efficacy of first‑/second‑generation EGFR‑tyrosine kinase inhibitors and osimertinib for EGFR‑mutant lung cancer with negative or low PD‑L1 expression

In epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) with negative or low programmed death ligand-1 (PD-L1) expression, the acquisition rate of the T790M mutation is higher after treatment with first-/second-generation EGFR-tyrosine kinase inhibitors (TKIs) and the progression-free survival (PFS) is longer in patients treated with osimertinib. The present study compared the clinical course after the initiation of each EGFR-TKI monotherapy in patients with EGFR-mutant NSCLC with negative or low PD-L1 expression. Data of patients with EGFR-mutant NSCLC with negative or low PD-L1 expression who were treated with EGFR-TKI monotherapy were retrieved and retrospectively analyzed. Between June 2013 and November 2023, 26 and 29 patients were treated with first-/second-generation EGFR-TKIs and osimertinib, respectively. The PFS time was longer in patients treated with osimertinib (median, 22.5 months) than in those treated with first-/second-generation EGFR-TKIs (median, 12.9 months). However, the EGFR-TKI treatment duration, defined as the PFS for osimertinib, or the sum of the PFS for first-/second-generation EGFR-TKIs and sequential osimertinib therapy after the acquisition of the T790M mutation, was similar between patients treated with first-/second-generation EGFR-TKIs (median, 23.0 months) and osimertinib (median, 22.5 months). The Cox proportional hazard model suggested that there was no significant difference in the EGFR-TKI treatment duration between patients treated with first-/second-generation EGFR-TKIs and patients treated with osimertinib (hazard ratio, 1.31, 95% CI, 0.55-3.13). In conclusion, first-/second-generation EGFR-TKIs and osimertinib were associated with a similar EGFR-TKI treatment duration in patients with EGFR-mutant NSCLC with negative or low PD-L1 expression. The findings suggested that both treatments are promising for this population.

AXL receptor as an emerging molecular target in colorectal cancer

AXL receptor tyrosine kinase (AXL) is a receptor tyrosine kinase whose aberrant expression has recently been associated with colorectal cancer (CRC), contributing to tumor growth, epithelial-mesenchymal transition (EMT), increased invasiveness, metastatic spreading, and the development of drug resistance. In this review we summarize preclinical data, the majority of which are limited to recent years, convincingly linking the AXL receptor to CRC. These findings support the value of targeting AXL with molecules in drug discovery, offering novel and advanced therapeutic or diagnostic tools for CRC management.

Brigatinib, a newly discovered AXL inhibitor, suppresses AXL-mediated acquired resistance to osimertinib in EGFR-mutated non-small cell lung cancer

In addition to the classical resistance mechanisms, receptor tyrosine-protein kinase AXL is a main mechanism of resistance to third-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) osimertinib in EGFR-mutated non-small cell lung cancer (NSCLC). Developing an effective AXL inhibitor is important to sensitize osimertinib in clinical application. In this study we assessed the efficacy of brigatinib, a second-generation of anaplastic lymphoma kinase (ALK)-TKI, as a novel AXL inhibitor, in overcoming acquired resistance to osimertinib induced by AXL activation. We established an AXL-overexpression NSCLC cell line and conducted high-throughput screening of a small molecule chemical library containing 510 anti-tumor drugs. We found that brigatinib potently inhibited AXL expression, and that brigatinib (0.5 μM) significantly enhanced the anti-tumor efficacy of osimertinib (1 μM) in AXL-mediated osimertinib-resistant NSCLC cell lines in vitro. We demonstrated that brigatinib had a potential ability to bind AXL kinase protein and further inhibit its downstream pathways in NSCLC cell lines. Furthermore, we revealed that brigatinib might decrease AXL expression through increasing K48-linked ubiquitination of AXL and promoting AXL degradation in HCC827OR cells and PC-9OR cells. In AXL-high expression osimertinib-resistant PC-9OR and HCC827OR cells derived xenograft mouse models, administration of osimertinib (10 mg·kg-1·d-1) alone for 3 weeks had no effect, and administration of brigatinib (25 mg·kg-1·d-1) alone caused a minor inhibition on the tumor growth; whereas combination of osimertinib and brigatinib caused marked tumor shrinkages. We concluded that brigatinib may be a promising clinical strategy for enhancing osimertinib efficacy in AXL-mediated osimertinib-resistant NSCLC patients.

Disrupting EGFR-HER2 Transactivation by Pertuzumab in HER2-Positive Cancer: Quantitative Analysis Reveals EGFR Signal Input as Potential Predictor of Therapeutic Outcome

Pertuzumab (Perjeta®), a humanized antibody binding to the dimerization arm of HER2 (Human epidermal growth factor receptor-2), has failed as a monotherapy agent in HER2 overexpressing malignancies. Since the molecular interaction of HER2 with ligand-bound EGFR (epidermal growth factor receptor) has been implied in mitogenic signaling and malignant proliferation, we hypothesized that this interaction, rather than HER2 expression and oligomerization alone, could be a potential molecular target and predictor of the efficacy of pertuzumab treatment. Therefore, we investigated static and dynamic interactions between HER2 and EGFR molecules upon EGF stimulus in the presence and absence of pertuzumab in HER2+ EGFR+ SK-BR-3 breast tumor cells using Förster resonance energy transfer (FRET) microscopy and fluorescence correlation and cross-correlation spectroscopy (FCS/FCCS). The consequential activation of signaling and changes in cell proliferation were measured by Western blotting and MTT assay. The autocorrelation functions of HER2 diffusion were best fitted by a three-component model corrected for triplet formation, and among these components the slowly diffusing membrane component revealed aggregation induced by EGFR ligand binding, as evidenced by photon-counting histograms and co-diffusing fractions. This aggregation has efficiently been prevented by pertuzumab treatment, which also inhibited the post-stimulus interaction of EGFR and HER2, as monitored by changes in FRET efficiency. Overall, the data demonstrated that pertuzumab, by hindering post-stimulus interaction between EGFR and HER2, inhibits EGFR-evoked HER2 aggregation and phosphorylation and leads to a dose-dependent decrease in cell proliferation, particularly when higher amounts of EGF are present. Consequently, we propose that EGFR expression on HER2-positive tumors could be taken into consideration as a potential biomarker when predicting the outcome of pertuzumab treatment.

Pharmacologic Targeting of Histone H3K27 Acetylation/BRD4-dependent Induction of ALDH1A3 for Early-phase Drug Tolerance of Gastric Cancer

Anticancer drug-tolerant persister (DTP) cells at an early phase of chemotherapy reshape refractory tumors. Aldehyde dehydrogenase 1 family member A3 (ALDH1A3) is commonly upregulated by various anticancer drugs in gastric cancer patient-derived cells (PDC) and promotes tumor growth. However, the mechanism underlying the generation of ALDH1A3-positive DTP cells remains elusive. Here, we investigated the mechanism of ALDH1A3 expression and a combination therapy targeting gastric cancer DTP cells. We found that gastric cancer tissues treated with neoadjuvant chemotherapy showed high ALDH1A3 expression. Chromatin immunoprecipitation (ChIP)-PCR and ChIP sequencing analyses revealed that histone H3 lysine 27 acetylation was enriched in the ALDH1A3 promoter in 5-fluorouracil (5-FU)-tolerant persister PDCs. By chemical library screening, we found that the bromodomain and extraterminal (BET) inhibitors OTX015/birabresib and I-BET-762/molibresib suppressed DTP-related ALDH1A3 expression and preferentially inhibited DTP cell growth. In DTP cells, BRD4, but not BRD2/3, was recruited to the ALDH1A3 promoter and BRD4 knockdown decreased drug-induced ALDH1A3 upregulation. Combination therapy with 5-FU and OTX015 significantly suppressed in vivo tumor growth. These observations suggest that BET inhibitors are efficient DTP cell-targeting agents for gastric cancer treatment.

SIGNIFICANCE

Drug resistance hampers the cure of patients with cancer. To prevent stable drug resistance, DTP cancer cells are rational therapeutic targets that emerge during the early phase of chemotherapy. This study proposes that the epigenetic regulation by BET inhibitors may be a rational therapeutic strategy to eliminate DTP cells.

Role of SPRY4 in health and disease

SPRY4 is a protein encoding gene that belongs to the Spry family. It inhibits the mitogen-activated protein kinase (MAPK) signaling pathway and plays a role in various biological functions under normal and pathological conditions. The SPRY4 protein has a specific structure and interacts with other molecules to regulate cellular behavior. It serves as a negative feedback inhibitor of the receptor protein tyrosine kinases (RTK) signaling pathway and interferes with cell proliferation and migration. SPRY4 also influences inflammation, oxidative stress, and cell apoptosis. In different types of tumors, SPRY4 can act as a tumor suppressor or an oncogene. Its dysregulation is associated with the development and progression of various cancers, including colorectal cancer, glioblastoma, hepatocellular carcinoma, perihilar cholangiocarcinoma, gastric cancer, breast cancer, and lung cancer. SPRY4 is also involved in organ development and is associated with ischemic diseases. Further research is ongoing to understand the expression and function of SPRY4 in specific tumor microenvironments and its potential as a therapeutic target.

Development of nanoparticles incorporated with quercetin and ACE2-membrane as a novel therapy for COVID-19

INTRODUCTION

Angiotensin-converting enzyme 2 (ACE2) and AXL tyrosine kinase receptor are known to be involved in the SARS-CoV-2 entry of the host cell. Therefore, targeting ACE2 and AXL should be an effective strategy to inhibit virus entry into cells. However, developing agents that can simultaneously target ACE2 and AXL remains a formidable task. The natural compound quercetin has been shown to inhibit AXL expression.

MATERIALS AND METHODS

In this study, we employed PLGA nanoparticles to prepare nanoparticles encapsulated with quercetin, coated with ACE2-containing cell membranes, or encapsulated with quercetin and then coated with ACE-2-containing cell membranes. These nanoparticles were tested for their abilities to neutralize or inhibit viral infection.

RESULTS

Our data showed that nanoparticles encapsulated with quercetin and then coated with ACE2-containing cell membrane inhibited the expression of AXL without causing cytotoxic activity. Nanoparticles incorporated with both quercetin and ACE2-containing cell membrane were found to be able to neutralize pseudo virus infection and were more effective than free quercetin and nanoparticles encapsulated with quercetin at inhibition of pseudo virus and SARS-CoV-2 infection.

CONCLUSIONS

We have shown that the biomimetic nanoparticles incorporated with both ACE-2 membrane and quercetin showed the most antiviral activity and may be further explored for clinical application.

Single cell lineage tracing reveals clonal dynamics of anti-EGFR therapy resistance in triple negative breast cancer

BACKGROUND

Most primary Triple Negative Breast Cancers (TNBCs) show amplification of the Epidermal Growth Factor Receptor (EGFR) gene, leading to increased protein expression. However, unlike other EGFR-driven cancers, targeting this receptor in TNBC yields inconsistent therapeutic responses.

METHODS

To elucidate the underlying mechanisms of this variability, we employ cellular barcoding and single-cell transcriptomics to reconstruct the subclonal dynamics of EGFR-amplified TNBC cells in response to afatinib, a tyrosine kinase inhibitor (TKI) that irreversibly inhibits EGFR.

RESULTS

Integrated lineage tracing analysis revealed a rare pre-existing subpopulation of cells with distinct biological signature, including elevated expression levels of Insulin-Like Growth Factor Binding Protein 2 (IGFBP2). We show that IGFBP2 overexpression is sufficient to render TNBC cells tolerant to afatinib treatment by activating the compensatory insulin-like growth factor I receptor (IGF1-R) signalling pathway. Finally, based on reconstructed mechanisms of resistance, we employ deep learning techniques to predict the afatinib sensitivity of TNBC cells.

CONCLUSIONS

Our strategy proved effective in reconstructing the complex signalling network driving EGFR-targeted therapy resistance, offering new insights for the development of individualized treatment strategies in TNBC.

AXL signal mediates adaptive resistance to KRAS G12C inhibitors in KRAS G12C-mutant tumor cells

Recently, novel Kirsten rat sarcoma viral oncogene homolog (KRAS) inhibitors have been clinically developed to treat KRAS G12C-mutated non-small cell lung cancer (NSCLC) patients. However, achieving complete tumor remission is challenging. Therefore, the optimal combined therapeutic intervention with KRAS G12C inhibitors has a potentially crucial role in the clinical outcomes of patients. We investigated the underlying molecular mechanisms of adaptive resistance to KRAS G12C inhibitors in KRAS G12C-mutated NSCLC cells to devise a strategy preventing drug-tolerant cell emergence. We demonstrate that AXL signaling led to the adaptive resistance to KRAS G12C inhibitors in KRAS G12C-mutated NSCLC, activation of which is induced by GAS6 production via YAP. AXL inhibition reduced the viability of AXL-overexpressing KRAS G12C-mutated lung cancer cells by enhancing KRAS G12C inhibition-induced apoptosis. In xenograft models of AXL-overexpressing KRAS G12C-mutated lung cancer treated with KRAS G12C inhibitors, initial combination therapy with AXL inhibitor markedly delayed tumor regrowth compared with KRAS G12C inhibitor alone or with the combination after acquired resistance to KRAS G12C inhibitor. These results indicated pivotal roles for the YAP-GAS6-AXL axis and its inhibition in the intrinsic resistance to KRAS G12C inhibitor.

Tumor-Extrinsic Axl Expression Shapes an Inflammatory Microenvironment Independent of Tumor Cell Promoting Axl Signaling in Hepatocellular Carcinoma

The activation of the receptor tyrosine kinase Axl by Gas6 is a major driver of tumorigenesis. Despite recent insights, tumor cell-intrinsic and -extrinsic Axl functions are poorly understood in hepatocellular carcinoma (HCC). Thus, we analyzed the cell-specific aspects of Axl in liver cancer cells and in the tumor microenvironment. We show that tumor-intrinsic Axl expression decreased the survival of mice and elevated the number of pulmonary metastases in a model of resection-based tumor recurrence. Axl expression increased the invasion of hepatospheres by the activation of Akt signaling and a partial epithelial-to-mesenchymal transition (EMT). However, the liver tumor burden of Axl+/+ mice induced by diethylnitrosamine plus carbon tetrachloride was reduced compared to systemic Axl-/- mice. Tumors of Axl+/+ mice were highly infiltrated with cytotoxic cells, suggesting a key immune-modulatory role of Axl. Interestingly, hepatocyte-specific Axl deficiency did not alter T cell infiltration, indicating that these changes are independent of tumor cell-intrinsic Axl. In this context, we observed an upregulation of multiple chemokines in Axl+/+ compared to Axl-/- tumors, correlating with HCC patient data. In line with this, Axl is associated with a cytotoxic immune signature in HCC patients. Together these data show that tumor-intrinsic Axl expression fosters progression, while tumor-extrinsic Axl expression shapes an inflammatory microenvironment.

Mechanisms of resistance to targeted therapy and immunotherapy in non-small cell lung cancer: promising strategies to overcoming challenges

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.

Combination Therapy with EGFR Tyrosine Kinase Inhibitors and TEAD Inhibitor Increases Tumor Suppression Effects in EGFR Mutation-positive Lung Cancer

EGFR-tyrosine kinase inhibitors (TKI) are the first-line therapies for EGFR mutation-positive lung cancer. EGFR-TKIs have favorable therapeutic effects. However, a large proportion of patients with EGFR mutation-positive lung cancer subsequently relapse. Some cancer cells survive the initial treatment with EGFR-TKIs, and this initial survival may be associated with subsequent recurrence. Therefore, we aimed to overcome the initial survival against EGFR-TKIs. We hypothesized that yes-associated protein 1 (YAP1) is involved in the initial survival against EGFR-TKIs, and we confirmed the combined effect of EGFR-TKIs and a YAP1-TEAD pathway inhibitor. The KTOR27 (EGFR kinase domain duplication) lung cancer cell lines established from a patient with EGFR mutation-positive lung cancer and commercially available PC-9 and HCC827 (EGFR exon 19 deletions) lung cancer cell lines were used. These cells were used to evaluate the in vitro and in vivo effects of VT104, a TEAD inhibitor. In addition, YAP1 involvement was investigated in pathologic specimens. YAP1 was activated by short-term EGFR-TKI treatment in EGFR mutation-positive lung cancer cells. In addition, inhibiting YAP1 function using siRNA increased the sensitivity to EGFR-TKIs. Combination therapy with VT104 and EGFR-TKIs showed better tumor-suppressive effects than EGFR-TKIs alone, in vitro and in vivo. Moreover, the combined effect of VT104 and EGFR-TKIs was observed regardless of the localization status of YAP1 before EGFR-TKI exposure. These results suggest that combination therapy with the TEAD inhibitor and EGFR-TKIs may improve the prognosis of patients with EGFR mutation-positive lung cancer.

Hippo Signaling at the Hallmarks of Cancer and Drug Resistance

Originally identified in Drosophila melanogaster in 1995, the Hippo signaling pathway plays a pivotal role in organ size control and tumor suppression by inhibiting proliferation and promoting apoptosis. Large tumor suppressors 1 and 2 (LATS1/2) directly phosphorylate the Yki orthologs YAP (yes-associated protein) and its paralog TAZ (also known as WW domain-containing transcription regulator 1 [WWTR1]), thereby inhibiting their nuclear localization and pairing with transcriptional coactivators TEAD1-4. Earnest efforts from many research laboratories have established the role of mis-regulated Hippo signaling in tumorigenesis, epithelial mesenchymal transition (EMT), oncogenic stemness, and, more recently, development of drug resistances. Hippo signaling components at the heart of oncogenic adaptations fuel the development of drug resistance in many cancers for targeted therapies including KRAS and EGFR mutants. The first U.S. food and drug administration (US FDA) approval of the imatinib tyrosine kinase inhibitor in 2001 paved the way for nearly 100 small-molecule anti-cancer drugs approved by the US FDA and the national medical products administration (NMPA). However, the low response rate and development of drug resistance have posed a major hurdle to improving the progression-free survival (PFS) and overall survival (OS) of cancer patients. Accumulating evidence has enabled scientists and clinicians to strategize the therapeutic approaches of targeting cancer cells and to navigate the development of drug resistance through the continuous monitoring of tumor evolution and oncogenic adaptations. In this review, we highlight the emerging aspects of Hippo signaling in cross-talk with other oncogenic drivers and how this information can be translated into combination therapy to target a broad range of aggressive tumors and the development of drug resistance.