Introduction:Lung cancer in never-smokers is a growing, biologically distinct entity lacking non-invasive markers. Established urinary markers-creatine riboside (CR) and N-acetylneuraminic acid (NANA)-report tumor-intrinsic metabolism, not carcinogen processing. We investigated 27-nor-5β-cholestane-3α,7α,12α,24R,25S-pentol glucuronide (CPG), a bile-acid glucuronide linked to aryl-hydrocarbon-receptor (AhR)/CYP xenobiotic metabolism. Methods:Urinary CPG was quantified by UPLC-tandem mass spectrometry in an exploratory (NCI-Maryland; n=846) and validation (Colorado; n=505) cohort of non-small-cell lung cancer cases and frequency-matched controls. Associations with case status, smoking stratum, survival, and discrimination were assessed, using tumor RNA sequencing (n=83) and gene-set enrichment analysis (GSEA). Results:Urinary CPG was higher in cases than controls in both cohorts (P<0.0001). In never-smokers, cases exceeded smoking-matched controls (P<0.001 and P<0.0001), indicating elevation independent of tobacco exposure. After mutual adjustment for CR and NANA, CPG remained independently associated with case status (exploratory OR 1.58, 95% CI 1.15-2.16; validation OR 3.92, 95% CI 2.47- 6.29), with a modest gain in discrimination. High CPG identified never-smokers with worse survival in both cohorts (P<0.001 and P=0.04), remaining significant after multivariable adjustment only in the exploratory cohort. GSEA showed AhR/CYP xenobiotic and Nrf2 oxidative-stress enrichment in high-CPG tumors; the CPG aglycone carried disease-specific 24R,25S stereochemistry. Conclusions:Urinary CPG was associated with NSCLC in two retrospective case-control cohorts, including in a smoking-matched never-smoker comparison. High CPG also identified never-smokers with worse survival, remaining independently prognostic after adjustment in the exploratory cohort. Tumor expression does not establish tissue of origin. Prospective validation against CR and NANA is required.

Abstract Background: HER2 mutations drive 1-2% of non-small cell lung cancers (NSCLCs), and recent HER2-directed antibody-drug conjugates and tyrosine kinase inhibitors (TKIs) such as trastuzumab-deruxtecan and zongertinib have significantly improved outcomes. However, these approaches remain non-curative, and nearly all patients develop progressive disease. Novel strategies capable of eliminating minimal residual disease (MRD) are urgently needed. Generating cell-surface-directed therapies that recognize cell membrane proteins present or upregulated upon TKI adaptation remain underdeveloped in the HER2 space due to lack of cell surface dynamic characterization. Methods: HER2-mutant NSCLC cell lines were treated with zongertinib at varying doses to establish sensitivity values (CellTiter-Glo). A HER2-mutant, zongertinib-insensitive small cell lung cancer line (H446) served as a negative control. Total and cell surface expression of targetable receptors and markers amplified in lung cancers were quantified by western blot and flow cytometry in both, TKI-naïve and TKI-tolerant states (IC50 and IC90 zongertinib exposure). HER2-driven (TKI sensitive and resistant) and control lines were then treated with cell-surface-directed therapies for 24 hours and evaluated for their toxicity. Results: We demonstrate that HER2-mutant NSCLC cell lines retained demonstrated dynamic changes in cell surface protein expression in treatment-naïve versus zongertinib-induced MRD states. TKI-sensitive and TKI-resistant HER2-driven lines demonstrated high sensitivity to therapies targeting surface proteins, which correlated with their level of expression. Conclusions: HER2-driven NSCLC cell lines present dynamic changes in cell surface proteins when undergoing TKI treatment. These proteins can be successfully targeted to eradicate residual NSCLC after TKI treatment, supporting this avenue as a rational therapeutic strategy for eradicating MRD and preventing relapse in HER2-mutant NSCLC. Ongoing studies will inform advancement toward early-phase clinical trials with curative intent. Citation Format: Manale El Kharbili, Daniel Wilkinson, Lauren Giesy, Sharon R. Pine, Peter Fecci, Kyle Concannon. TKI adaptive resistance in HER2-driven non-small cell lung cancer at minimal residual disease stage can be targeted using cell surface-directed therapies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 3166.

Abstract Introductory Sentence: This study investigates the therapeutic potential of dual alectinib and everolimus inhibition to prolong the clinical benefit of alectinib in ALK-positive non-small cell lung cancer. Pertinent experimental procedures: ALK-rearranged NSCLC cell lines (CUTO8, CUTO9, CUTO29.1, CUTO39, CUTO41, CUTO43, CUTO46) obtained from the University of Colorado; DFCI032 from Dana-Farber; NCI-H2228 and NCI-H3122 from ATCC; and SNU2292 and SNU2535 from Seoul National University were screened using a high-throughput drug-combination platform to identify synergistic interactions between alectinib and a curated library of 1,600 approved and experimental compounds. Functional validation in NCI-H3122 included colony-formation and Glo-Caspase 3/7 apoptosis assays with therapeutically relevant concentrations of everolimus (Cmax and Caverage) plus 100 nM alectinib, ∼ten-fold lower than reported Cmax/Caverage. Apoptotic activation was further confirmed by Western blot for cleaved PARP, cleaved caspase-3, and the pro-survival protein MCL-1. In parallel, ex vivo screening was conducted on ALK167-T-01, an ALK-positive PDX model harboring the p.Leu1196Met ALK mutation. Summary of new unpublished data: High-throughput screening identified a consistent synergistic response to alectinib combined with multiple mTOR inhibitors across all the ALK-rearranged models tested. Synergy was assessed by the Chou-Talalay method, with Cl <1 in most ALK-positive cell lines tested. In NCI-H3122, the combination significantly reduced clonogenic potential (alectinib alone VS combo Caverage; p<0.01 and alectinib alone VS combo Cmax; p<0.001) and induced apoptosis, evidenced by increased Caspase 3/7 activity (alectinib alone VS combo Caverage; p<0.01 and alectinib alone VS combo Cmax; p<0.001) and significant PARP and caspase-3 cleavage. Ex vivo PDX screening using ALK167-T-01 with Glo-Caspase 3/7 assays at therapeutically relevant everolimus concentrations plus 100 nM alectinib showed higher apoptosis vs single agents (alectinib alone VS combo Caverage; p<0.001 and alectinib alone VS combo Cmax; p<0.0001), confirming synergy is not exclusive to sensitive lines. Statement of the conclusions: Dual ALK and mTOR targeting with alectinib and everolimus produces synergistic antitumor activity in vitro and ex vivo, reflected by significantly increased apoptosis vs single agents. These findings support further investigation in in vivo models, including alectinib-sensitive and -resistant tumors. AI disclosure: AI was used for language editing only; content was verified by the authors. Citation Format: Hamadi Madhi, Habib Serhan, Rachel Mercer, Benjamin Levy, Anna Rottinghaus, Liwei Bao, Xu Cheng, Sharon R. Pine, Ross Camidge, Angel Qin, Nathan M. Merrill, Sofia D. Merajver, Matthew B. Soellner. Preclinical evidence for synergistic activity of alectinib and everolimus in ALK-positive non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6501.

Background:Five-year survival from lung cancer exceeds 60% at stage I-II but falls below 10% once metastasis occurs. Low-dose CT (LDCT) screening reduces mortality in heavy smokers but carries a false-positive rate of approximately 29% and is restricted to smoking-based eligibility, leaving most cases undetected. We aimed to develop and independently validate an interpretable machine-learning urinary metabolite risk index (uLCI) for non-invasive lung cancer detection. Methods:Four urinary metabolites-creatine riboside (CR), N-acetylneuraminic acid (NANA), 27-nor-5β-cholestane-3α,7α,12α,24R,25S-pentol (CP), and cortisol sulfate (CS)-and three clinical variables (age, race, smoking) were integrated by Lasso-regularised logistic regression into a uLCI score. The model was developed under 10-fold cross-validation in the NCI-Maryland (NCI-MD) cohort (n=845; 470 controls, 375 cases, stages I-IV) and applied without refitting to the independent Colorado Lung Cancer Cohort (n=488; 211 controls, 277 cases). Analyses were prespecified; reporting followed TRIPOD+AI. Findings:uLCI achieved an area under the curve (AUC) of 0·906 (95% CI 0·887-0·926) in NCI-MD and 0·748 (0·701-0·793) in the independent Colorado cohort. Scores rose monotonically across stages in both cohorts (Spearman ρ=0·69 and 0·45; both p<0·0001). Stage-specific discrimination was preserved from stage I to IV (NCI-MD 0·900-0·927; Colorado 0·722-0·843). Net reclassification improvement over clinical variables was 1·24 (1·14-1·36) and 0·74 (0·56-0·90). uLCI tertiles stratified post-resection survival in stage I-II disease (adjusted hazard ratio 2·03, 1·26-3·27). Interpretation:uLCI is an independently validated, interpretable urinary risk index that detects lung cancer across all stages, with monotonic stage progression and post-resection prognostic value. Its false-positive rate compares favourably with published estimates for LDCT and cell-free-DNA assays, supporting prospective head-to-head evaluation as a non-invasive triage tool, including in screening-ineligible populations.

Lung cancer is one of the most frequently diagnosed cancers in the US. African-American (AA) men are more likely to develop lung cancer with higher incidence and mortality rates than European-American (EA) men. Herein, we report high-confidence alternative splicing (AS) events from high-throughput, high-depth total RNA sequencing of lung tumors and non-tumor adjacent tissues (NATs) in two independent cohorts of patients with adenocarcinoma (LUAD) and squamous cell carcinoma (LUSC). We identified novel AS biomarkers with notable differential percent spliced in (PSI) values between lung tumors and NATs enriched in the AA and EA populations, which were associated with oncogenic signaling pathways. We also uncovered tumor subtype- and population-specific AS events associated with cell surface proteins and cancer driver genes. We highlighted significant AS events in SYNE2 specific to LUAD in both populations, as well as those in CD44 from EAs and TMBIM6 from AAs specific to LUAD. Here, we also present the validation of cancer signatures based on direct high-throughput reverse transcription-PCR. Our large survey of lung tumors presents a rich data resource that may help to understand molecular subtypes of lung tumor between AAs and EAs and reveal new therapeutic vulnerabilities that potentially advance health equity.

Lung cancer is the leading cause of cancer-related deaths in the world, with ∼2.5 million people diagnosed and ∼1.5 million deaths each year. While the last two decades have yielded substantial progress with systemic targeted and immune therapies improving treatment responses in subgroups of patients with advanced and refractory lung cancer, there is still a dire unmet clinical need to develop more effective therapies with durable responses. CD47 receptors are overexpressed on the surface of a variety of malignant tumor cells including lung cancer. Although there has been increasing interest in developing targeting antibodies against CD47 for immunotherapy, they failed clinical trials due to their dose-limiting toxicities, primarily hematopoietic toxicity. Using a unique diphtheria toxin resistant Pichia pastoris yeast expression system, we have developed a diphtheria toxin-based bivalent CD47 immunotoxin (bi-CD47-IT) for targeted therapy of CD47 + non-small cell lung cancer (NSCLC). Bi-CD47-IT demonstrated compelling preclinical efficacy in multiple NSCLC cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) mouse models, including subcutaneous, orthotopic, metastatic and humanized models. This study demonstrates the remarkable preclinical activity of bi-CD47-IT against various lung cancer models, making bi-CD47-IT a novel and promising therapeutic approach for NSCLC.

Abstract Introduction: Alterations of the HGF-cMET axis, often through MET gene amplification, can act as resistance mechanism to tyrosine kinase inhibitors (TKIs) in patients with ALK and RET rearranged non-small cell lung cancer (NSCLC). The efficacy of targeting the cMET pathway through use of MET tyrosine kinase inhibitors continues to evolve. An unresolved question is whether the HGF-cMET pathway is activated early in cancer cells after ALK and RET TKI exposure. Here, we evaluate novel pre-clinical models to better characterize the onset of MET pathway-mediated resistance using murine cell lines and orthotopic murine models. Methods: Murine Eml4-Alk (EA1 and EA3) and Trim24-Ret (TR.1) cell lines were cultured with increasing doses of alectinib (EA1 and EA3) or pralestinib or selpercatinib (TR.1) until resistance was acquired. A cell line was established from an orthotopic TR.1 tumor that progressed on selpercatinib (TR.1-1092). Passage control cells and the TKI-resistant cultures were submitted to clonogenic growth assays in targeting TKI or crizotinib (MET TKI). Control and TKI-resistant cell lines were submitted to HGF ELISA, MET immunoblotting and RNAseq. Orthotopic TR.1 tumors were established in C57BL/6 mice and after ~2 weeks, daily treatment with selpercatinib was performed for 21 days with weekly mCT to monitor tumor size. At 21 days when the tumors were beginning to progress, half the mice were treated with selpercatinib and crizotinib (a MET TKI) while the other half continued on selpercatinib alone. Results: HGF levels (pg/μg) were significantly higher in alectinib-resistant EA1 cells vs. EA3 cells and was associated with retained sensitivity to crizotinib in alectinib-resistant EA1, but not EA3 cells. MET mRNA (but not gene copy number) and HGF mRNA/protein levels in pralsetinib and selpercatinib resistant TR.1 lines were significantly higher than controls and accompanied by acquired sensitivity to crizotinib. In C57BL/6 mice bearing orthotopic TR.1 tumors, the progression on selpercatinib occurring after 2-3 weeks of treatment was reversed in a durable manner by co-treatment with crizotinib. Conclusions: The HGF-cMET axis is activated early in response to ALK and RET TKI exposure through transcriptional mechanisms without evidence of MET gene amplification. These findings unveil a potential therapeutic window to disrupt the MET bypass pathway in ALK and RET rearranged NSCLC prior to overt clinical progression. Citation Format: Tejas Patil, Trista Hinz, Sharon Pine, Hatim Saabawy, Paul Bunn, Erin L. Schenk, Ross Camidge, Lynn Heasley. Early activation of HGF-cMET serves as a bypass pathway to ALK and RET tyrosine kinase inhibitors in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5867.

Abstract Purpose: Nonsmokers account for 10% to 13% of all lung cancer cases in the United States. Etiology is attributed to multiple risk factors including exposure to secondhand smoking, asbestos, environmental pollution, and radon, but these exposures are not within the current eligibility criteria for early lung cancer screening by low-dose CT (LDCT). Experimental Design: Urine samples were collected from two independent cohorts comprising 846 participants (exploratory cohort) and 505 participants (validation cohort). The cancer urinary biomarkers, creatine riboside (CR) and N-acetylneuraminic acid (NANA), were analyzed and quantified using liquid chromatography–mass spectrometry to determine if nonsmoker cases can be distinguished from sex and age-matched controls in comparison with tobacco smoker cases and controls, potentially leading to more precise eligibility criteria for LDCT screening. Results: Urinary levels of CR and NANA were significantly higher and comparable in nonsmokers and tobacco smoker cases than population controls in both cohorts. Receiver operating characteristic analysis for combined CR and NANA levels in nonsmokers of the exploratory cohort resulted in better predictive performance with the AUC of 0.94, whereas the validation cohort nonsmokers had an AUC of 0.80. Kaplan–Meier survival curves showed that high levels of CR and NANA were associated with increased cancer-specific death in nonsmokers as well as tobacco smoker cases in both cohorts. Conclusions: Measuring CR and NANA in urine liquid biopsies could identify nonsmokers at high risk for lung cancer as candidates for LDCT screening and warrant prospective studies of these biomarkers.

Abstract Interactions between tumor intrinsic factors and tumor microenvironment play a vital role in disease progression and treatment response. SOX9, a transcription factor crucial for tissue development and homeostasis, has been linked to the advancement of tumor growth. However, its specific role as a driver in lung adenocarcinoma (LUAD) is not well-defined. Additionally, the impact of SOX9 on the tumor microenvironment has not been previously explored. We here identify SOX9 transcription factor to play a critical role in defining tumor immune microenvironment and driving disease progression. We employed CRISPR/Cas9 and Cre-LoxP gene knockout methods within the Kras G12D-induced mouse model of lung adenocarcinoma (LUAD). Our objective was to investigate the mechanisms through which SOX9 contributes to the development and advancement of lung adenocarcinoma. To substantiate our findings, we conducted immune profiling, gene expression analyses, RT-qPCR, and immunohistochemistry assessments in the Kras G12D-driven murine LUAD. These results were subsequently validated by examining bulk and single-cell gene expression profiles, as well as immunohistochemistry, in human lung adenocarcinoma. Our studies indicated that SOX9 played a very important role by enhancing lung tumor development, burden, and progression, leading to lower overall survival. SOX9. SOX9 consistently facilitated the growth of organoids in vitro. However, the promotion of tumor growth by SOX9 was notably reduced in immunocompromised mice compared to syngeneic mice. SOX9 demonstrated a suppressive effect on immune cell infiltration, particularly affecting the functionality of tumor-associated CD8+ T cells, natural killer cells, and dendritic cells. CD8+ T cells in the SOX9 overexpressing tumors showed upregulation of exhaustion markers. SOX9-mediated tumor growth advantage could not be observed in the CD8 knockout mice model, suggesting a CD8+ T cell-dependent role. In addition, SOX9 significantly upregulated collagen-related gene expression, leading to a substantial increase in collagen fibers possibly affecting the migration of immune cells into the tumor microenvironment. Together, our studies indicate that SOX9 plays a very critical role in modulating tumor microenvironment by controlling immune cell infiltration and CD8+ T cell exhaustion driving Kras G12D- driven lung tumor progression. Citation Format: Dinoop Ravindran Menon, Hua Zhong, Shridar Ganesan, Hatim Sabaawy, Sharon Pine. SOX9-dependent immune microenvironment remodeling drives KRAS-induced lung adenocarcinoma progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5352.

Abstract Lung cancer (LC) is the leading cause of cancer-induced mortality, with 350 patients in the US dying from LC daily, the majority from non-small cell lung cancer (NSCLC). Molecular-targeted therapy such as tyrosine kinase inhibitors (TKI) are effective in first and subsequent lines of therapy against oncogenic drivers (KRAS, EGFR, or ALK fusions, others); however, nearly all treated patients progress eventually and run out of therapeutic options. Key reasons are the lack of predictive biomarkers and LC models that reflect the underlying heterogeneity and different phenotypic cell states among subclones within and between patients. Here, we developed a novel platform for refining the resolution of molecular interrogation to the single cell level, using single cell spatial multiomic (scSpMO), coupled with rational designed drug screens in patient-derived organoids (PDOs) from LC biopsies obtained upon progression. By deriving LC PDOs in epithelial and tumor microenvironment (TME) conditions to faithfully maintain the histological and genetic features of their respective LC tissues, we identified enrichment conditions for LC PDOs guided by tumor mutation variants and activated pathways. PDOs are maintained under the same treatment condition in the clinic (e.g., Lorlatinib) and drug testing is tailored to identify next lines of combined therapy. With six patients enrolled and others in ongoing studies, single cell PDOs (at >80% establishment rate) were used to determine key molecular bypass mechanism for resistance to TKI, including on-target variants, driver bypass, lineage plasticity and acquired resistance. Functional assays for acquired resistance such as PI3K/AKT signaling, Src kinase, BRAF fusion and MET hyperactivity allow the identification of potential novel combined lines of therapy for each patient through the compassionate care program and/or trial participation. Our platform when empowered with datasets of bulk, scRNA-seq and scSpMO signatures of primary human NSCLC, together with PDOs offer the ability to perform analysis of LC phenotypes such as lineage transformation in high-content assays, predict and/or act on resistance to therapy and provides a path for precision medicine-guided immediate impact on patient care. Citation Format: Liqiong Liu, Ann Strange, Schuyler Lee, Bifeng Gao, Daniel Merrick, Tejas Patil, James DeGregori, D Ross Camidge, Sharon R. Pine, Hatim E. Sabaawy. Assessment of tyrosine kinase inhibitor bypass mechanisms in lung cancer using single cell multiomics, patient derived organoids and rationally designed drug screens [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6496.

Advances in artificial intelligence have paved the way for leveraging hematoxylin and eosin-stained tumor slides for precision oncology. We present ENLIGHT-DeepPT, an indirect two-step approach consisting of (1) DeepPT, a deep-learning framework that predicts genome-wide tumor mRNA expression from slides, and (2) ENLIGHT, which predicts response to targeted and immune therapies from the inferred expression values. We show that DeepPT successfully predicts transcriptomics in all 16 The Cancer Genome Atlas cohorts tested and generalizes well to two independent datasets. ENLIGHT-DeepPT successfully predicts true responders in five independent patient cohorts involving four different treatments spanning six cancer types, with an overall odds ratio of 2.28 and a 39.5% increased response rate among predicted responders versus the baseline rate. Notably, its prediction accuracy, obtained without any training on the treatment data, is comparable to that achieved by directly predicting the response from the images, which requires specific training on the treatment evaluation cohorts. Hoang et al. developed a deep-learning framework called ENLIGHT-DeepPT that predicts therapy response based on imputed transcriptomics and shows predictive power across patient cohorts and cancer types.

e20521 Background: Lung cancer (LC) remains the leading cause of cancer-related death in 2024, with most LC diagnoses with non-small cell lung cancer (NSCLC) subtype. Tyrosine kinase inhibitors (TKI) and targeted therapy against oncogenic drivers (KRAS, EGFR, or ALK fusions, others) are effective initial therapies; however, nearly all treated patients eventually develop resistance to therapy. Key reasons are the focus on limited predictive biomarkers and lack of patient derived LC models that reflect the underlying heterogeneity and the various phenotypic cell states among subclones within and between patients. Methods: We report the establishment of a novel platform for personalized LC care by refining the resolution of molecular interrogation of diagnostic and resistance biopsies to the single cell level, and with spatial profiling using single cell spatial multiomic (scSpMO) and coupling these enhanced diagnostic tools with functional validation with rational designed drug screens in patient-derived organoids (PDOs). Results: For deriving LC PDOs in epithelial and tumor microenvironment (TME) conditions to faithfully maintain the histological and genetic features of their respective LC tissues, we developed enrichment conditions for LC PDOs guided by tumor mutation variants and activated pathways. PDOs are maintained under the same treatment condition in the clinic (e.g., Lorlatinib) and drug testing is tailored to identify potentially most effective next lines of therapy. With nine patients enrolled and others in ongoing studies, single cell PDOs (at > 80% establishment rate) were used to determine activated pathways, lineage plasticity and acquired resistance. Functional assays for acquired resistance such as PI3K/AKT signaling, Src kinase, BRAF fusion and MET hyperactivity allow the identification of potentially novel lines of therapy and treatment sequence and/or combinations for each patient, through the compassionate care program and/or trial participation. Conclusions: Our platform when empowered by combining datasets from scRNA-seq and scSpMO signatures, with validated functional drug responses in PDOs, offers the ability to perform high-content assays, predict and/or act on resistance to therapy for each patient, and provides a path for precision medicine-guided impact on patient care.

Abstract Brain metastases (BM) are a common site of metastasis for both non-small cell (NSCLC) and small cell lung cancer, affecting 20-56% of advanced lung cancer (LC) patients. In breast cancer models, we have shown that astrocytes secrete brain-derived neurotrophic factor (BDNF), which, in a paracrine manner, activates its receptor tropomyosin-related kinase B (TrkB, also called NTRK2) in a subset of cancer cells, promoting BM. Although NTRK gene rearrangements are known to function as primary oncogenic drivers in a subset of NSCLC, wildtype TrkB has been shown to promote lung adenocarcinoma metastases and TrkB expression was associated with worse survival in multiple LC subtypes. Thus, we HYPOTHESIZE that paracrine BDNF/TRKB activation is also a mechanism whereby subsets of non-NTRK rearranged LC cells can colonize the brain. We investigated TrkB expression levels in murine (CMT167) and human (LU65, H358, PC9BR3, H2030BR3) LC cell lines and their ability to form BM in mouse models. TrkB expression varied among cell lines, with brain metastases incidence of 20% (CMT167), 50% (PC9BR3), 64% (H358) and 75% for H2030BR3. While all cells responded to BDNF stimulation activating AKT, ERK and PLCg signaling, H358 and H2030BR3 cells showed faster and stronger TRKB activation. Stimulation with astrocyte-conditioned media (Ast-CM) or coculture with astrocytes, activated TrkB and promoted proliferation and invasion of LC cells. Entrectinib, an FDA-approved drug for NTRK fusion-positive solid tumors, decreased BDNF and Ast-CM-induced TrkB activation and proliferation, particularly in models with increased BDNF-dependency. Importantly, co-culture of a subset of LC cells with astrocytes renders them less sensitive to Entrectinib, suggesting that additional survival mechanisms contribute to LC cell fitness in the brain niche. Ongoing studies interrogate the effectiveness of Entrectinib to decrease early and late brain metastatic progression in LC. These studies suggest that targeting TrkB could impact LC therapy even in tumors lacking NTRK rearrangements

Tumor suppressor Liver Kinase B1 (LKB1) activates 5’-adenosine monophosphate protein kinase (AMPK) and maintains energy homeostasis in response to energy crises. LKB1 and KRAS are the third most frequent co-mutations detected in non-small cell lung cancer (NSCLC), causing aggressive tumor growth and metastases. Unfortunately, standard treatment with RAS-RAF-MEK-ERK signaling pathway inhibitors has minimal therapeutic efficacy in LKB1-mutant KRAS-driven NSCLC. Thus, identifying a novel treatment for patients harboring co-mutations in LKB1 and KRAS is urgently needed. Autophagy degrades and recycles the building blocks for cancer cells to survive metabolic challenges. Using genetically engineered mouse models (GEMMs), we have previously demonstrated that autophagy compensates for Lkb1 loss for Kras-driven lung tumorigenesis; loss of an autophagy-essential gene Atg7 dramatically impaired tumor initiation and tumor growth in KrasG12D/+;Lkb1−/− (KL) lung tumors. This is in sharp contrast to Lkb1 wild-type (WT) (KrasG12D/+;p53−/− (KP)) tumors that are less sensitive to autophagy gene ablation. To further value our discoveries in clinical translational ability, we treated mouse lung tumor derived cell lines (TDCLs) with FDA-approved autophagy inhibitor hydroxychloroquine (HCQ) and MEK inhibitor Trametinib and found that the combination treatment displayed synergistic anti-proliferative effects in KL TDCLs compared to KP TDCLs. To elucidate the underlying mechanism of increased sensitivity of KL TDCLs to Trametinib by autophagy ablation, we performed metabolomic profiling of KL TDCLs with Trametinib, HCQ, or combination treatment and found that several glycolytic and TCA cycle intermediates, amino acids, and ATP levels were significantly upregulated upon treatment with Trametinib, which were significantly reduced by the combination treatment. In addition, the combination treatment significantly reduced mitochondrial membrane potential, basal respiration, and ATP production in KL TDCLs. In vivo studies using tumor allografts, genetically engineered mouse models (GEMMs) and patient-derived xenografts (PDXs) showed anti-tumor activity of the combination treatment on KL tumors, but not in KP tumors. Moreover, we found increased lipid peroxidation indicative of ferroptosis in KL TDCLs and KL PDX tumors with the combination treatment compared to the single agent treatments. Finally, treatment with a ferroptosis inhibitor rescued the reduced KL allograft tumor growth caused by the combination treatment. Taken together, our observations indicate that autophagy upregulation in KL tumors causes resistance to Trametinib treatment by maintaining energy homeostasis for cell survival and inhibits ferroptosis. Therefore, a combination of autophagy and MEK inhibition could be a novel therapeutic strategy to specifically treat LKB1-deficient KRAS-driven NSCLC. Citation Format: Vrushank Bhatt, Taijin Lan, Wenping Wang, Jerry Kong, Eduardo Cararo Lopes, Khoosheh Khayati, Jianming Wang, Akash Raju, Michael Rangel, Enrique Lopez, Zhixian Sherrie Hu, Xuefei Luo, Xiaoyang Su, Jyoti Malhotra, Wenwei Hu, Sharon R. Pine, Eileen White, Jessie Yanxiang Guo. Autophagy and MEK inhibition promotes ferroptosis in liver kinase B1 (Lkb1)-deficient Kras-driven lung tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 272.

LKB1 and KRAS are the third most frequent co-mutations detected in non-small cell lung cancer (NSCLC) and cause aggressive tumor growth. Unfortunately, treatment with RAS-RAF-MEK-ERK pathway inhibitors has minimal therapeutic efficacy in LKB1-mutant KRAS-driven NSCLC. Autophagy, an intracellular nutrient scavenging pathway, compensates for Lkb1 loss to support Kras-driven lung tumor growth. Here we preclinically evaluate the possibility of autophagy inhibition together with MEK inhibition as a treatment for Kras-driven lung tumors. We found that the combination of the autophagy inhibitor hydroxychloroquine (HCQ) and the MEK inhibitor Trametinib displays synergistic anti-proliferative activity in KrasG12D/+;Lkb1-/- (KL) lung cancer cells, but not in KrasG12D/+;p53-/- (KP) lung cancer cells. In vivo studies using tumor allografts, genetically engineered mouse models (GEMMs) and patient-derived xenografts (PDXs) showed anti-tumor activity of the combination of HCQ and Trametinib on KL but not KP tumors. We further found that the combination treatment significantly reduced mitochondrial membrane potential, basal respiration, and ATP production, while also increasing lipid peroxidation, indicative of ferroptosis, in KL tumor-derived cell lines (TDCLs) and KL tumors compared to treatment with single agents. Moreover, the reduced tumor growth by the combination treatment was rescued by ferroptosis inhibitor. Taken together, we demonstrate that autophagy upregulation in KL tumors causes resistance to Trametinib by inhibiting ferroptosis. Therefore, a combination of autophagy and MEK inhibition could be a novel therapeutic strategy to specifically treat NSCLC bearing co-mutations of LKB1 and KRAS.

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Supplementary Figure from Inhibition of Mtorc1/2 and DNA-PK via CC-115 Synergizes with Carboplatin and Paclitaxel in Lung Squamous Cell Carcinoma