Primary NSCLC Research Articles

An immune scoring system predicts prognosis and immune characteristics in lung adenocarcinoma brain metastases by RNA sequencing.

Previous studies have reported that the tumor immune microenvironment (TIME) was associated with the prognosis of lung cancer patients and the efficacy of immunotherapy. However, given the significant challenges in obtaining specimens of brain metastases (BrMs), few studies explored the correlation between the TIME and the prognosis in patients with BrMs from lung adenocarcinoma (LUAD). Transcript profiling of archival formalin-fixed and paraffin-embedded specimens of BrMs from 70 LUAD patients with surgically resected BrMs was carried out using RNA sequencing. An immune scoring system, the green-yellow module score (GYMS), was developed to predict prognosis and immune characteristics in both BrMs and primary LUAD using Weighted Correlation Network analysis (WGCNA) and GSVA analysis. We comprehensively evaluated the immunological role of GYMS based on gene expression profile of LUAD BrMs by systematically correlating GYMS with immunological characteristics and immunotherapy responsiveness in the BrMs. Immunohistochemistry was applied for validation. We found that the high-GYMS group had better clinical prognosis and inflamed immune landscape including high infiltrations of various immune cells, increased immunomodulatory expression, and enriched immune-related pathways by using RNA-seq and immunohistochemical analysis. Low-GYMS group presented a lacked immune infiltration characteristic. Besides, the high-GYMS group had lower TIDE score and higher T-cell inflamed score than low-GYMS group. The GYMS has been validated in independent BrMs cohorts and primary NSCLC cohort treated with anti-PD-1/PD-L1, showing strong reproducibility and stability in both primary LUAD and BrMs. In addition, we construct a GYMS-related risk signature for patients with LUAD BrMs to predict prognosis. We identified two immune-related subtypes which used to estimate prognosis and immune characteristics and developed a reliable GYMS-related risk signature in LUAD BrMs. These results will enhance the understanding of the immune microenvironment in LUAD BrMs and lay the theoretical foundation for the development of personalized therapies for LUAD patients with BrMs.

Combination of circulating tumor cells and 18F-FDG PET/CT for precision diagnosis in patients with non-small cell lung cancer.

To investigate the value of 2-deoxy-18f-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) and circulating tumor cells (CTCs) for the differential diagnosis of patients with benign lung diseases and those with NSCLC. To explore the phenotypic heterogeneity of CTCs and their correlation with FDG uptake in patients with Stage I-IV NSCLC. Blood specimens from patients with benign lung diseases and patients with primary NSCLC were collected for the detection of CTCs and their subtypes (epithelial, mixed, and mesenchymal) and analyzed for 18F-FDG PET/CT tumor metabolic parameters, including the maximum standardized uptake value (SUVmax), standard uptake value (SUL), metabolic tumor volume of primary lesion (MTV), total lesion glycolysis of primary lesion (TLG). Clinical data including age, gender, smoking history, tumor size, TNM stage and pathology type were also collected. The value of the two method alone and in combination for the differential diagnosis of benign and malignant was comparatively analyzed. Finally, the differences in CTC and its subtypes in different stages of NSCLC were compared, and FDG metabolic parameters were correlated with CTC subtypes. There were a total of 65 patients with pulmonary diseases, including 12 patients with benign pulmonary diseases and 53 patients with NSCLC. The mean age was 67 ± 10 (38-89 years), 27 were females and 38 were males. 31 (22 males and 9 females) had a long history of smoking. The mean size of the largest diameter of all single lesions was 36 ± 22 mm with a range of 10-108 mm. Seven out of 12 benign diseases were inflammatory granulomatous lesions and 5 were inflammatory pseudotumours. Twenty-four out of 53 NSCLC were adenocarcinomas and 29 were squamous carcinomas. Twelve out of 53 patients with NSCLC were in Stage I, 10 were in Stage II, 17 were in Stage III and 14 were in Stage IV. SUVmax, SUL, MTV, TLG, total CTCs, epithelial CTCs, and mixed CTCs were all valuable in the differential diagnosis of benign and malignant. TLG combined with mixed CTCs was statistically different from all other diagnostic methods (p < 0.05) and higher than any other diagnostic criteria. In the differential diagnosis of benign and Stage I NSCLC, only total CTC (Z = -2.188 p = 0.039) and mixed CTCs (Z = -3.020 p = 0.014) had certain diagnostic efficacy, and there was no statistical difference between them (p = 0.480). Only mesenchymal CTCs differed in Stage I-IV NSCLC, with a higher number of those who developed distant metastases than those who had non-distant metastases. Epithelial CTCs correlated with SUVmax (r = 0.333, p = 0.015) and SUL (r = 0.374, p = 0.006). Mmesenchymal CTCs correlated with MTV (r = 0.342, p = 0.018) and TLG (r = 0.319, p = 0.02). Further subgroup analyses revealed epithelial CTCs were correlated with SUVmax (r = 0.543, p = 0.009) and SUL (r = 0.552, p = 0.008), and the total CTCs was correlated with SUVmax (r = 0.622, p = 0.003), SUL (r = 0.652, p = 0.003), MTV (r = 0.460, p = 0.031), and TLG (r = 0.472, p = 0.027) in the early group (Stage I-II). Only mesenchymal CTCs was associated with MTV (r = 0.369, p = 0.041), and TLG (r = 0.415, p = 0.02) in the intermediate-late group (Stage III-IV). Both FDG PET metabolic parameters and CTCs demonstrated diagnostic value for NSCLC, and combining TLG with mixed CTCs could enhance their diagnostic efficacy. The total CTCs and mixed CTCs showed greater diagnostic value than FDG PET in distinguishing benign lesions from Stage I NSCLC. In NSCLC patients, the epithelial CTCs exhibited a positive correlation with SUVmax and SUL, while mesenchymal CTCs correlated with MTV, and TLG. Besides, epithelial CTCs showed stronger correlations with SUVmax and SUL, and total CTCs showed stronger correlations with SUVmax, SUL, MTV, and TLG in Stage I-II NSCLC. Only mesenchymal CTCs in Stage III-IV NSCLC showed correlations with MTV and TLG. Stage IV NSCLC cases displayed a higher number of mesenchymal CTCs.

Correlation between gut microbiota characteristics and non-small cell lung cancer based on macrogenomics sequencing

ObjectiveNon-small cell lung cancer (NSCLC) patients undergoing chemotherapy and immunotherapy experience disturbances in the gut microbiota. This study intends to find out the correlation between gut microbiota and clinical indices before and after radiotherapy for NSCLC.MethodsTen patients with primary NSCLC were screened, and plasma and fecal samples were collected before and after radiotherapy, respectively. Inflammatory indices in plasma were detected. Genomic DNA was extracted from fecal specimens and sequenced on on Illumina HiSeq2000 sequencing platform. Thee sequenced data were subjected to Metagenome assembly, gene prediction, species annotation, and gene function analysis to study and analyze gut microbiota and metabolic functions. The correlation between the diversity of gut microbiota and the clinical indicators of NSCLC patients was evaluated, and the changes of gut microbiota before and after radiotherapy were observed.ResultsThe diversity of gut microbiota in NSCLC patients did not correlate with smoking, pathology, and inflammatory markers. The abundance of phylum (p)_Bacteroidetes increased; p_Firmicutes and p_Bacteroidetes accounted for the highest proportion in NSCLC patients, and the abundance of both was dominantly exchanged after radiotherapy. There was a decrease in genus (g)_Bifidobacterium after radiotherapy in NSCLC patients. There was no significant correlation between the diversity of gut microbiota after radiotherapy and radiotherapy sensitivity, and the structural composition and abundance of gut microbiota remained stable.ConclusionThe diversity of gut microbiota is altered after radiotherapy in NSCLC patients, showing an increase in harmful bacteria and a decrease in beneficial bacteria.

Antibiotic Use and Survival in Patients With Late-Stage NSCLC Treated With Chemoimmunotherapy

IntroductionImmunotherapy has improved survival in patients with advanced NSCLC. Efficacy may decrease when patients are treated with antibiotics, possibly due to gut microbiome disruption, but few studies have investigated this using real-world, patient-level populations in the United States. MethodsWe have analyzed antibiotic use in patients with stage IV first, primary NSCLC diagnosed in 2015 and treated with chemotherapy or chemoimmunotherapy, drawn from the Surveillance, Epidemiology, and End Results-Medicare data set. Patients had to have continuous part A, part B, and part D Medicare coverage. Survival was determined through Kaplan-Meier and Cox proportional hazards models. All data analyses were performed using SAS. ResultsThe study included 788 patients, 440 (56%) of whom received antibiotics within 2 months before or after starting systemic treatment. The median follow-up time was 11.64 months. There was a statistically significant difference in survival for patients who received antibiotics (p = 0.007) and who had more than 1 round of antibiotics versus zero or 1 round (p ≤ 0.0001). After adjustment, receipt of antibiotics (hazard ratio [HR]adj: 1.17, 95% confidence interval [CI]: 0.99–1.37) and receipt of multiple rounds of antibiotics (HRadj: 1.35, 95% CI: 1.14–1.60) were statistically significantly associated with worse survival. Among just those receiving chemoimmunotherapy (n = 203; 26%), there was still an increased risk of death for those receiving multiple antibiotic rounds (HRadj: 1.52, 95% CI: 1.09–2.13). ConclusionsAntibiotic use concurrent with chemoimmunotherapy seems to be associated with worse survival. This is more pronounced when more cycles of antibiotics are given. IRB approval numberSTUDY-19-00500.

Evaluating circulating cell-free DNA and DNA integrity index as biomarkers in non-small cell lung cancer

BackgroundAnalysis of free DNA molecules shed from tumour cells in plasma of patients referred as circulating tumour DNA (ctDNA) with reference to physiological circulating cell-free DNA (cfDNA) is nowadays exploited as liquid biopsy and is considered a new emerging promising biomarker for diagnosis, selection of proper treatment, and prognosis of cancer. DNA integrity index (DII) is assessed by calculating the ratio between the concentration of long cfDNA strands released from tumour cells (ALU247) and the short strands released from normal cells (ALU115). The aim of the current study was to evaluate DII as a potential diagnostic and prognostic biomarker of NSCLC.MethodsOur study included 48 NSCLC patients diagnosed as primary NSCLC before starting treatment, 30 COPD patients diagnosed clinically, radiologically, and subjected to chest high-resolution computerized tomography, and 40 healthy controls. cfDNA concentration and DII were measured by quantitative real-time polymerase chain reaction (qPCR).ResultsALU115, ALU247, and DII were significantly higher in NSCLC compared to COPD patients (p < 0.0001) and controls (p < 0.0001) and in COPD patients compared to control subjects (p < 0.0001). DII positively correlated with the stage of tumour (p = 0.01), tumour metastasis (p = 0.004), and with adenocarcinoma compared to other histopathological types (p = 0.02). To evaluate clinical utility of DII in NSCLC, ROC curve analysis demonstrated an AUC of 0.91 at a cut-off value of 0.44 with total accuracy = 85.6%, sensitivity = 90%, specificity = 83%, PPV = 78.1%, and NPV = 92.1%.ConclusioncfDNA and DII represent a promising diagnostic and prognostic tool in NSCLC. This type of noninvasive liquid biopsy revealed its chance in the screening, early diagnosis, and monitoring of NSCLC.

Representativeness of race, ethnicity and social determinants of health in patients with advanced non-small cell lung cancer via linkage of real-world electronic health records, administrative claims, and consumer financial data.

e13559 Background: Social determinants of health (SDOH) are both drivers of health disparities and barriers to clinical research participation, particularly among historically underserved or marginalized populations. Using real-world data (RWD), diversity plans in cancer clinical trials frequently aim to reduce disparities and improve representation. Our aim was to describe the representativeness of patients with advanced non-small cell lung cancer (aNSCLC) with respect to race, ethnicity and person-level SDOH in a curated electronic health record (EHR) database. Methods: This was a retrospective cohort study of individuals diagnosed with aNSCLC between 2016–2022 in a US-based oncology EHR database (ConcertAI). Information on person-level SDOH was derived from linkage of curated EHR data to administrative claims and consumer financial data. These data were also compared to a sample of patients diagnosed with first primary NSCLC from the Surveillance, Epidemiology, and End Results (SEER) Program and American Community Survey (ACS), where possible. The Kaplan-Meier product limit estimator was used to compare time from advanced diagnosis to treatment initiation. Results: From an overall sample of 17,772 patients with aNSCLC, a total of 10,390 patients had 1 or more SDOH characteristics of interest documented. Compared with patients without linked SDOH data, a higher proportion of patients with linked person-level SDOH data were non-Hispanic (NH) White patients (79% vs 71%) and lower proportions were NH Black (10% vs 13%), NH Asian/Pacific Islander (2% vs 4%) and Hispanic patients (2% vs 4%). Patients with linked SDOH were also more likely to have aNSCLC progressed from an earlier stage and received biomarker testing for targetable alterations. Overall, 54% of patients were married, 38% completed a bachelor’s degree or higher, 14% worked in a blue-collar occupation, and 61% had an individual income of ≤$35,000. All 4 of these SDOH characteristics differed significantly by race/ethnicity. Differences in time-to-treatment initiation were statistically significant by marital status (median of 50 [married] vs 55 [not married] days; P=0.02) and individual income (median of 50 [&gt;$60,000] vs 55 [≤$30,000] days; P=0.04). Patients with aNSCLC in these data differed from patients in SEER and ACS estimates with respect to greater representation of patients who are NH White, have lower levels of education, and lower individual income. Conclusions: This analysis demonstrated the feasibility of measuring person-level SDOH using EHR from patients with aNSCLC treated at oncology clinics across the US. RWD with linked SDOH characteristics should be used cautiously to address the representativeness gap in evidence from oncology trials given their potential inherent selection biases.

Immunotherapy outcomes and profile in lung cancer brain metastases.

8646 Background: Brain metastasis (BM) in NSCLCs have a unique tumor micro-environment (TME) characterized by distinct immune-constituents and the presence of blood-brain barrier, differentiating them from primary NSCLC tumors (PT). Despite the high incidence of BM, earlier trials indicated that less than 15% of BM patients benefit from immune checkpoint inhibitors (ICIs). We characterized the TME of BM to potentially identify a subset of patients who may respond favorably to ICIs. Methods: 36,726 NSCLC samples were analyzed by NGS of DNA (592-gene) and RNA (whole transcriptome) at Caris Life Sciences (Phoenix, AZ). TMB-high was defined as &gt;=10mt/MB, PD-L1 was tested by IHC (22c3), and TME by RNA expression (quanTIseq). Real-world overall survival was obtained from insurance claims data and calculated from treatment start on six common ICIs to last contact (IO-OS), while time-on-treatment (TOT) was from first to last of treatment. Hazard ratios (HRs) were calculated using the Cox proportional hazards model and p values (log-rank test). Fisher’s exact tests and Mann-Whiney U were used and adjusted for multiple comparisons (q&lt;0.05). Results: Samples were comprised of 63.5%, PT 4.9% BM, and 31.6% extracranial metastases. High TMB and loss of heterozygosity (LOH) rates were higher in BM vs. PT (55% vs. 35.7%) and (28.0% vs. 14.3%), q&lt;0.05, respectively, while PD-L1+ rate was similar (53.3% BM vs. 55.6% PT). Significant mutational differences in BM vs. PT included TP53 (77.7% vs 65.1%), KEAP1 (19.4% vs. 12.1%), and STK11 (17.5% vs. 12.0%), q&lt;0.05. Immune deconvolution demonstrated the abundance of neutrophils, Tregs, monocytes, and B cells was higher in PT vs. BM (fold-change: 1.35-1.73, q&lt;0.05), while dendritic cells were higher in BM vs. PT (fold-change: 13, q&lt;0.05). BM had significantly longer IO-OS (24.4 vs. 19.7 mo: HR = 0.83, 95% CI 0.76-0.90, p&lt;0.05) and TOT (7.7 vs. 6.0 mo; HR = 0.83, 95% CI 0.77-0.89, p&lt;0.05) compared to PT. PD-L1+ and TMB High were associated with longer IO-OS in BM vs. PT (HR = 0.71, 95% CI 0.63-0.81, p&lt;0.05) and (HR = 0.83, 95% CI 0.74 – 0.93, p&lt;0.05), respectively. By histology, squamous cell carcinoma (SC) was significantly more prevalent in PT compared to BM (25.9% vs. 8.5%, q&lt;0.05). In adenocarcinoma (AD), BM was associated with longer IO-OS (HR = 0.78, 95% CI 0.70-0.87, p&lt;0.05) compared to PT, while in SC, the survival association was not significant. The longer survival seen in AD was still significant after multivariate analysis with TP53, STK11 and KEAP1 (HR = 0.76, 95% CI 0.68-0.86, q&lt;0.05). In BM, PD-L1+ and TMB High were associated with longer IO-OS in AD and may be considered first line treatment in this population, if asymptomatic. Conclusions: Historically BM have been associated with poor outcomes. We demonstrate that BM has higher TMB, increased infiltration of dendritic cells, and higher LOH than PT. After stratifying patients based on PD-L1 and TMB, patients with BM adenocarcinoma histology had improved post ICI survival.

Abstract 4743: Targeting a novel TWIST1-Hexokinase II pathway to overcome MET TKI resistance in NSCLC

Abstract Non-small cell lung cancer (NSCLC) is the most common primary tumor to metastasize to the brain, with up to 40% of NSCLC patients developing brain metastases (BM). These BM portend a poor prognosis, even when extracranial disease is well-controlled. While targeted therapy and immunotherapy have improved lung cancer survival, there are no therapies specifically targeting NSCLC BM. Our lab identified a significant enrichment of MET amplification in lung adenocarcinoma (LUAD) BM (16%) compared to primary NSCLC (3%) and liver metastases (5%). MET, a receptor tyrosine kinase, and its ligand, hepatocyte growth factor (HGF), promote proliferation, epithelial-mesenchymal transition (EMT), angiogenesis, and metastasis. Although MET tyrosine kinase inhibitors (TKIs) are approved for use in METaltered NSCLC, half of patients with MET alterations fail to respond or inevitably acquire TKI resistance. We have found that MET pathway activation by MET alterations leads to increased expression of TWIST1, an EMT transcription factor required for tumorigenesis in MET-dependent NSCLC. Together, the HGF/MET/TWIST1 axis promotes cancer survival and metastasis. We found that MET amplified BM had distinct transcriptional signatures reflecting increased glycolysis. A similar shift toward glycolysis was observed in the MET amplified metastatic LUAD cell line (H1993) compared to the MET wild type primary LUAD line (H2073) derived from the same patient. Furthermore, LUAD cell lines with high MET expression demonstrated increased expression and activity of glycolytic enzymes, as well as increased susceptibility to glucose deprivation and glycolytic inhibitors (2DG, PFK158, AT-101, V-9302). Conversely, treatment of MET amplified cells with MET TKI, capmatinib, reduced glycolysis and oxidation phosphorylation to the levels observed in MET wild type LUAD lines. Activation of the MET pathway with HGF or TWIST1 overexpression specifically increased the mRNA and protein expression of the key glycolytic enzyme, Hexokinase II (HK2), compared to other glycolytic pathway proteins. Conversely, inhibition of the MET pathway with capmatinib or the TWIST1 inhibitor, harmine, decreased HK2 protein expression through a MYC-independent pathway. However, TWIST1 was required for MET-dependent transcriptional upregulation of HK2. Remarkably, in two novel MET altered models (cell line and patient derived xenograft) of acquired MET TKI resistance, TWIST1 and HK2 expression were increased at the time of resistance. Both models remained sensitive to pharmacologic inhibition of either TWIST1 or glycolysis at the time of acquired resistance to MET TKIs. These findings suggest that continued upregulation of the TWIST1-HK2 axis is required for acquired MET TKI resistance. In summary, these studies suggest a targetable, metabolic reprogramming in MET altered LUAD BM mediated through a novel TWIST1-HK2 pathway. Citation Format: Purva H. Rumde, Kasey R. Cargill, Vinod Kumar, Princey Devadassan, Jason Chen, Leviticus McGraw-Sapp, Xiaxuan Wu, Sanja Dacic, Riyue Bao, Bharathri Sivakama, Eric S. Goetzman, Sameer Agnihotri, Steven J. Mullett, Stacey G. Wendell, Laura P. Stabile, Timothy F. Burns. Targeting a novel TWIST1-Hexokinase II pathway to overcome MET TKI resistance in NSCLC [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 4743.

Abstract 2968: TWIST1-induced suppression of oncogene-induced senescence in non-small cell lung cancer requires the transactivation domain of TWIST1

Abstract Non-small cell lung carcinoma (NSCLC) is a major cause of cancer mortality. High expression of the epithelial-to-mesenchymal transition transcription factor TWIST1 is strongly associated with metastatic cancers and treatment resistance. Additionally, TWIST1 can upregulate O-GlcNAcylation which (1) is required to suppress fail-safe programs such as oncogene (KRasG12D)-induced senescence (OIS) to accelerate tumorigenesis in primary NSCLC tumors, and (2) is a potential modulator of DNA repair/radiation response. To decipher the domains and transcriptional targets required for tumorigenicity and radioresistance, we created a novel genetically engineered mouse model (GEMM) allowing tetracycline-inducible expression in the lung epithelium (via lung specific CCSP-reverse tetracycline transactivator (C)) of KRasG12D (R) with Twist1wt (T) or with Twist1F191G transactivation-null mutant (F). CRT mice had shorter tumor-free survival and more aggressive tumors compared to CR/CRF mice indicating that the Twist1 transactivation domain is required for Twist1-dependent tumorigenesis acceleration. Also, Twist1wt expression promoted radioresistance in cell lines and GEMMs. Contrary to CRT, CRF showed a progressive loss of Twist1F191G expression over time suggesting no functionality/no selective advantage. CRT lung tumors had higher proliferation (Ki67) and lower cell-cycle arrest (p16) compared to CR/CRF suggesting that the transactivation domain of Twist1 is important for the suppression of OIS. Supporting these data, we observed in non-cancer Human Bronchial Epithelial Cell (HBEC) that the co-expression of human TWIST1wt (HBEC-TWIST1wt) could suppress HRasG12V-induced senescence while the transactivation-null TWIST1F187G mutant (HBEC-TWIST1F187G) could not. Additionally, HBEC expressing HRasG12V-TWIST1wt had enhanced tumorigenic/invasive programs. Interestingly, we observed that the inhibition of O-GlcNAcylation rescued OIS in HBEC-HRasG12V-TWIST1wt while the stimulation of O-GlcNAcylation in HBEC-HRasG12V-TWIST1F187G suppressed OIS. Furthermore, TWIST1wt expression with HRasG12V modulated MYC downstream targets and the inhibition of MYC activity using the novel MYC inhibitor MYCi975 in HBEC-HRasG12V-TWIST1wt also rescued OIS induction. Altogether, these results suggest that TWIST1 may suppress OIS via MYC signaling and nominate MYCi975 as a means to activate latent OIS programs. In this context, MYC inhibiting strategies could serve as a therapeutic sensitizer for TWIST1-positive NSCLC. This work and our future studies on TWIST1 toward the control of OIS, O-GlcNAcylation and of mechanisms of radioresistance may help to identify new potential NSCLC therapeutic strategies. Citation Format: Audrey M. Lafargue, Hailun Wang, Sivarajan T. Chettiar, Rajendra P. Gajula, Amol C. Shetty, Yang Song, Brian W. Simons, Triet Nguyen, Christine Lam, Francesca A. Carrieri, Caleb Smack, Nick Connis, Dipanwita Dutta Chowdhury, Jinhee Chang, Danielle Council, Katriana Nugent, Ismaeel Siddiqui, Kekoa Taparra, Mohammad Rezaee, Natasha Zachara, Zachary S. Morris, Christopher McFarland, Sarki Abba Abdulkadir, Christine L. Hann, Phuoc T. Tran. TWIST1-induced suppression of oncogene-induced senescence in non-small cell lung cancer requires the transactivation domain of TWIST1 [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 2968.

Abstract 6732: Immunomodulatory and anti-tumor effect of a CCR2-targeted STING agonist iADC in human lung cancer

Abstract Introduction: Antibody drug conjugates (ADCs) targeting cancer-cell antigens can improve therapeutic index and show prominent clinical impact. Limited studies have used ADCs to target antigens present in non-malignant cells in the tumor microenvironment or to deliver immunomodulatory agents. We developed an immune-cell directed antibody drug conjugate (iADC) TAK-500 that selectively activates STING in C-C chemokine receptor type 2 (CCR2) expressing cells to achieve enhanced efficacy over non-targeted STING agonists. Here, we spatially mapped CCR2 protein in human NSCLC and studied the immunomodulatory role and anti-tumor effect of the novel iADC TAK-500 on human lung cancer tumor explants ex vivo. Methods: Using multiplexed quantitative immunofluorescence (mQIF) panels we measured the levels of CCR2 protein, myeloid cell populations and tumor infiltrating lymphocyte (TIL) subsets in 411 primary NSCLC carcinomas from treatment-naïve patients in 2 independent cohorts and determined their clinical significance. In addition, we longitudinally studied CCR2 levels, myeloid cells (DAPI/CCR2/CD68/CD11b), TILs (DAPI/CK/CD4/CD8/CD20), T-cell functional markers (DAPI/CK/CD3/Ki-67/GZMB [Granzyme B]) and cancer-cell death/proliferation markers (DAPI/CK/TFR1/Ki-67/CC3 [Cleaved Caspase 3]) in 314 primary cultured tissue fragments from paired tumor and non-tumor specimens resected from 11 lung cancer patients at Yale New Haven Hospital between 2021-2023 (8 adenocarcinomas, 2 small cell carcinomas, and 1 squamous cell carcinoma). Each biopsy was divided into 4-mm2 fragments, cultured in extracellular matrix for 5 days with or without TAK-500 treatment. Samples were processed into FFPE tissue and stained with mQIF panels using a tissue microarray format. Results: CCR2 protein was detected in 386 of 411 (94%) NSCLCs from 2 independent cohorts predominantly localized in CD11b+ intratumor myeloid cells and CD68+ tumor-associated macrophages (TAMs). Elevated CCR2 was associated with adenocarcinoma histology, increased PD-L1, activating KRAS mutations and longer survival. Treatment with TAK-500 for 5 days reduced CCR2 levels in myeloid cells and CD68+ TAMs, without significant changes in TIL or T-cell GZMB/Ki-67 levels. TAK-500 also significantly reduced tumor proliferation (Ki-67 expression) and increased tumor cell apoptosis (CC3 levels) after 5 days of treatment. Notably, these TAK-500-induced changes were observed only in tumor specimens with high baseline CCR2 levels above the median in retrospective NSCLC cohorts. No significant effect was observed in the paired non-tumor fragments. Conclusion: Our results reveal prominent myeloid CCR2 expression in a subset of human NSCLCs with distinct clinicopathologic/molecular characteristics. Using a novel lung cancer explant ex vivo system, we demonstrate a CCR2-dependent immunomodulatory and anti-tumor effect of TAK-500 iADC. Citation Format: Angelo Porciuncula, Vicky A. Appleman, Alex Parent, Jeff Raizer, Richard C. Gregory, Neil Lineberry, Adnan O. Abu-Yousif, Kurt A. Schalper. Immunomodulatory and anti-tumor effect of a CCR2-targeted STING agonist iADC in human 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 6732.

Spatial and temporal heterogeneity of tumor immune microenvironment between primary tumor and brain metastases in NSCLC

BackgroundBrain metastasis is a common outcome in non-small cell lung cancer, and despite aggressive treatment, its clinical outcome is still frustrating. In recent years, immunotherapy has been developing rapidly, however, its therapeutic outcomes for primary lung cancer and brain metastases are not the same, suggesting that there may be differences in the immune microenvironment of primary lung cancer and brain metastases, however, we currently know little about these differences.MethodsSeventeen paired samples of NSCLC and their brain metastases and 45 other unpaired brain metastases samples were collected for the current study. Immunohistochemical staining was performed on all samples for the following markers: immune checkpoints CTLA-4, PD-1, PD-L1, B7-H3, B7-H4, IDO1, and EphA2; tumor-infiltrating lymphocytes (TILs) CD3, CD4, CD8, and CD20; tumor-associated microglia/macrophages (TAMs) CD68 and CD163; and tumor proliferation index Ki-67. The differences in expression of these markers were compared in 17 paired samples, and the effect of the expression level of these markers on the prognosis of patients was analyzed in lung adenocarcinoma brain metastases samples. Subsequently, multiplex immunofluorescence staining was performed in a typical lung-brain paired sample based on the aforementioned results. The multiplex immunofluorescence staining results revealed the difference in tumor immune microenvironment between primary NSCLC and brain metastases.ResultsIn 17 paired lesions, the infiltration of CTLA-4+ (P = 0.461), PD-1+ (P = 0.106), CD3+ (P = 0.045), CD4+ (P = 0.037), CD8+ (P = 0.008), and CD20+ (P = 0.029) TILs in brain metastases were significantly decreased compared with primary tumors. No statistically significant difference was observed in the CD68 (P = 0.954) and CD163 (P = 0.654) TAM infiltration between primary NSCLC and paired brain metastases. In all the brain metastases lesions, the expression of PD-L1 is related to the time interval of brain metastases in NSCLC. In addition, the Cox proportional hazards regression models showed high expression of B7-H4 (hazard ratio [HR] = 3.276, 95% confidence interval [CI] 1.335–8.041, P = 0.010) and CD68 TAM infiltration (HR = 3.775, 95% CI 1.419–10.044, P = 0.008) were independent prognosis factors for lung adenocarcinoma brain metastases patients.ConclusionsBoth temporal and spatial heterogeneity is present between the primary tumor and brain metastases of NCSLC. Brain metastases lesions exhibit a more immunosuppressive tumor immune microenvironment. B7-H4 and CD68+ TAMs may have potential therapeutic value for lung adenocarcinoma brain metastases patients.

9P Primary NSCLC patient-derived microtumors (PMTs) for clinical-relevant prediction of immunotherapy efficacy

9P Primary NSCLC patient-derived microtumors (PMTs) for clinical-relevant prediction of immunotherapy efficacy

Prospective Cohort Study to Compare Long-Term Lung Cancer-Specific and All-Cause Survival of Clinical Early Stage (T1a–b; ≤20 mm) NSCLC Treated by Stereotactic Body Radiation Therapy and Surgery

IntroductionWe aimed to compare outcomes of patients with first primary clinical T1a-bN0M0 NSCLC treated with surgery or stereotactic body radiation therapy (SBRT). MethodsWe identified patients with first primary clinical T1a-bN0M0 NSCLCs on last pretreatment computed tomography treated by surgery or SBRT in the following two prospective cohorts: International Early Lung Cancer Action Program (I-ELCAP) and Initiative for Early Lung Cancer Research on Treatment (IELCART). Lung cancer-specific survival and all-cause survival after diagnosis were compared using Kaplan-Meier analysis. Propensity score matching was used to balance baseline demographics and comorbidities and analyzed using Cox proportional hazards regression. ResultsOf 1115 patients with NSCLC, 1003 had surgery and 112 had SBRT; 525 in I-ELCAP in 1992 to 2021 and 590 in IELCART in 2016 to 2021. Median follow-up was 57.6 months. Ten-year lung cancer-specific survival was not significantly different: 90% (95% confidence interval: 87%–92%) for surgery versus 88% (95% confidence interval: 77%–99%) for SBRT, p = 0.55. Cox regression revealed no significant difference in lung cancer-specific survival for the combined cohorts (p = 0.48) or separately for I-ELCAP (p = 1.00) and IELCART (p = 1.00). Although 10-year all-cause survival was significantly different (75% versus 45%, p < 0.0001), after propensity score matching, all-cause survival using Cox regression was no longer different for the combined cohorts (p = 0.74) or separately for I-ELCAP (p = 1.00) and IELCART (p = 0.62). ConclusionsThis first prospectively collected cohort analysis of long-term survival of small, early NSCLCs revealed that lung cancer-specific survival was high for both treatments and not significantly different (p = 0.48) and that all-cause survival after propensity matching was not significantly different (p = 0.74). This supports SBRT as an alternative treatment option for small, early NSCLCs which is especially important with their increasing frequency owing to low-dose computed tomography screening. Furthermore, treatment decisions are influenced by many different factors and should be personalized on the basis of the unique circumstances of each patient.

Local control and toxicity after magnetic resonance imaging (MR)-guided single fraction lung stereotactic ablative radiotherapy

PurposeMagnetic resonance imaging (MR)-guided radiotherapy permits continuous intrafraction visualization and use of automatic triggered beam delivery, with use of smaller planning target volumes (PTV). We report on long-term clinical outcomes following MR-guided single fraction (SF) lung SABR on a 0.35 T linac. Materials and MethodsDetails of patients treated with SF-SABR for lung tumors were accessed from an ethics approved institutional database. A breath-hold 3D MR simulation scan was performed using a true FISP sequence, followed by a breath-hold 3D CT scan. The gross tumor volume (GTV) was first contoured on the breath-hold CT scan, which was then compared with contours on the 3D MR scan, before the GTV was finalized. SABR plans used step-and-shoot IMRT beams to a PTV derived by adding a 5 mm margin to the breath-hold GTV, and a 3 mm gating window was used. SABR was delivered during repeated breath-holds, using automatic beam gating with continuous visualization of the GTV in a sagittal MR plane. ResultsBetween 2018–2022, 50 consecutive patients were treated, and 69% had a primary non-small cell lung cancer. Median PTV was 11.2 cc (range 3.9–53.5); 80% of GTV’s were located ≤2.5 cm from the chest wall. Prescribed doses were 34 Gy (in 58%), 30 Gy (32%), or between 20–28 Gy (10%). After a median follow-up of 18.1 months (95% CI 12.8–23.5), the 2-year survival was 82% (89% for primary NSCLC and 62% for metastases). After a median follow-up of 16.1 months (95% CI 11.2–21.1), local recurrences developed in 2 patients (4%). The 3-year local control rate was 97%, and just 1 patient developed grade ≥3 toxicity (chest wall pain). ConclusionMR-guided SF-SABR delivery to lung tumors on a 0.35 T linac, using repeated breath-holds with automatic beam gating, achieves good tumor control and low toxicity.

Pan-cancer landscape of FOXA1 alterations: Insights and clinical implications.

3090 Background: Forkhead box A1 ( FOXA1) is a pioneer transcription factor that regulates organogenesis and is associated with progression in breast and prostate cancers. To explore its role more broadly in oncogenesis, we characterize FOXA1 genomic alterations and clinical correlates in a large pan-cancer cohort from the American Association for Cancer Research project Genomics, Evidence, Neoplasia, Information, Exchange (AACR-GENIE) database. Methods: Using AACR-GENIE, FOXA1 mutations (in frame insertions/deletions (indel-inframe), frameshift insertions/deletions (indel truncating), point mutations (missense), fusions, and amplifications) were characterized across &gt;30 cancer types for primary and metastatic tumors with patient characteristics and clinical outcomes. FOXA1 alterations were queried in the MSK-MET cohort, a subset of GENIE cohort, allowing the definition of hazard ratios (HRs) and overall survival estimates based on Cox proportional hazard models. Results: Among 120,625 samples queried from the AACR GENIE data, FOXA1 was profiled in 87,706 samples: 30,268 metastases, 49,228 primary tumors, and 8,210 not specified. FOXA1 mutations were present in 1,869 samples (2.1%), mostly in the forkhead DNA-binding domain. Prostate tumors were enriched with indel-inframe alterations whereas breast cancers were enriched with missense mutations. F266, R261, and D226 mutations in the Wing2 region were common in breast and prostate cancers. In the GENIE cohort, FOXA1 copy number profiles were collected for 74,715 samples, with amplification detected in 834 (1.1%) and deletion in 96 samples (0.1%). FOXA1-amplification was most common in non-small cell lung cancer (NSCLC, 3%, n=190, in primary; 6%, n=264, in metastatic), followed by small cell lung cancer (SCLC) (4.1%, n=10, in primary; 3.5%, n=10, in metastatic), breast (2%, n=80 in primary; 1.6%, n=73, in metastatic) and prostate cancers (2.2%, n=49, in primary; 1.6%, n=27 in metastatic). In the MSK-MET cohort, FOXA1 amplifications were associated with poorer outcomes in primary breast (HR: 3.04, 95% CI: 1.89-4.89, p=4e-6), primary NSCLC (HR: 1.45, 95% CI: 1.06-1.99, p=0.02), and prostate cancer (HR: 1.94, 95% CI: 1.03-3.68, p=0.04). FOXA1 amplifications were associated with wide-spread metastases in primary breast, NSCLC, and prostate cancer. Conclusions: In this observational study of pan-cancer FOXA1 mutant specimens from the GENIE database, we found that FOXA1 alterations in prostate cancer (primary and metastatic tumors) were predominantly indels versus missense in other cancers. We also observe a consistent association between FOXA1 amplification and enhanced metastatic potential regardless of tissue of origin. Our findings suggest that FOXA1 amplifications could serve as a potential prognostic and therapeutic target, particularly for breast, prostate, and non-small cell lung cancer.

Single cell RNA sequencing to reveal immune microenvironment in primary and brain metastatic lesion of non-small cell lung cancer.

e21009 Background: Despite immune checkpoint inhibitors (ICIs) have been proven effective in patients with advanced NSCLC, suboptimal therapeutic responses are seen in brain metastatic lesions. The heterogeneous cellular components in the tumor immune microenvironment (TIME) pose a challenge in understanding the low immune response. A comprehensive understanding of the heterogeneous TIME in primary and brain metastatic NSCLC is currently lacking, but crucial for improving ICI therapeutic responses in NSCLC patients with brain metastasis. Therefore, we use single cell RNA sequencing (scRNA-seq) to reveal distinct immune microenvironment in primary and brain metastatic lesion of NSCLC. Methods: Eight primary and nine brain metastatic NSCLC tumor samples were obtained through surgical resection. Immune cells (CD45+) were enriched through fluorescence-activated cell sorting (FACS) and subjected to scRNA-seq using the 10X Genomics platform. Sequencing reads were normalized and analyzed using R/Seurat package. Cellular components of each sample were determined based on known marker genes. Results: In our study, we observed a significant difference in the immune cell composition between primary and brain metastatic tumor samples. We found brain metastatic tumors are marked by an enrichment of TIMP1+ monocytes and PLTP+ tumor-associated macrophages (TAMs), both of which display heightened anti-inflammatory properties. In contrast, primary tumors exhibit an enrichment of FCN1+ monocytes and MARCO+ TAMs. Further analysis has revealed that the enrichment of TIMP1+ monocytes and PLTP+ TAMs is associated with a worse prognosis in patients receiving immunotherapy. Additionally, our examination of the transcriptome profile of CD8+ T cells showed an upregulation of inhibitory and exhausted signatures in brain metastatic tumor samples. Conclusions: Our study provided a comprehensive understanding of the TIME of primary and brain metastatic NSCLC and to gain deeper insights into the immunological mechanisms involved in the response to ICIs. The results of our study could prove valuable for the development of future immunotherapy strategies for NSCLC patients with brain metastasis.

Chemotherapy induced peripheral neuropathy (CIPN) due to paclitaxel versus docetaxel in patients with early-stage breast cancer receiving taxane therapy: SWOG S1714.

12003 Background: Paclitaxel (Pac) and docetaxel (Doc) are used to treat early-stage breast cancer (BC). CIPN due to taxane therapy can cause sensory and motor deficits. CIPN symptoms caused by Pac versus Doc are not well described. Methods: SWOG S1714 enrolled patients ≥ 18 years with Stage I-III primary NSCLC, BC, or ovarian cancer starting treatment with a taxane-based regimen. CIPN was assessed by the patient-reported EORTC QLQ-CIPN20 (CIPN-20) and clinician-assessed NCI-CTCAE. Assessments occurred at baseline and 4, 8, 12, and 24 weeks after registration. Increase in CIPN-20 sensory subscale score ≥ 8 points was considered clinically meaningful. Chi-square and Fisher tests were used for baseline comparisons; logistic regression was used for multivariable analyses. Results: Among 1336 enrolled patients, 1106 of eligible patients had a diagnosis of BC, with median age 54.8 y (range 23.9-84.2 y), 99.3% female, and 72.3% White/11.3% Black/4.6% Asian/11.1% Hispanic/Latino. Pac was administered to 615 (55.6%) and Doc to 491(44.3%) patients. Between the Pac and Doc cohorts, there were significant baseline differences in median age, diabetes, and performance status. At 24 weeks, the proportion of patients with ≥8 point increase in CIPN-20 sensory score was lower for Doc (40.5%) vs Pac (50.2%) (odds ratio [OR] 0.64, 95% CI 0.50, 0.82; multivariable adjusted p&lt;.001). At nearly every timepoint through 24 weeks, patients treated with Pac had more sensory and motor neuropathy as measured by both the CIPN-20 and NCI-CTCAE (Table). Conclusions: In this diverse cohort of patients with BC, the frequency of CIPN was higher than expected for both Pac and Doc and more severe in patients receiving Pac. These findings based on CIPN-20 can assist in treatment decision-making about taxane therapy. Long term follow up will better characterize the differences in the trajectory of CIPN between Pac and Doc. Funding: NIH/NCI/NCORP grant UG1CA189974. Clinical trial information: NCT03939481. [Table: see text]

Patient characteristics, treatment patterns, and clinical outcomes among patients with de novo advanced or metastatic (stage IIIB–IV) non-small cell lung cancer in a real-world setting.

e21032 Background: In the past decade, therapies targeting EGFR, KRAS, ALK, ROS1, BRAF, NTRK, MET, RET variants , and PD-L1 expression were approved and recommended for use in advanced non-small cell lung cancer (aNSCLC). This study describes real-world patient characteristics, biomarker testing, treatment patterns, and clinical outcomes in patients with de novo stage IIIB–IV aNSCLC in the United States. Methods: This is a retrospective cohort study of patients with aNSCLC using TEMPUS oncology data. Patients were included if they were diagnosed with stage IIIB, IIIC, or IV NSCLC (index date) as their primary NSCLC diagnosis between 1/1/2012 and 12/31/2020, and were &gt;18 years of age at index. Patients with an advanced diagnosis within 90-days of their primary diagnosis were defined as having de novo aNSCLC. Patient demographics and clinical characteristics including biomarker testing for EGFR, KRAS, ALK, ROS1, BRAF, NTRK, MET, RET alterations, and/or PD-L1 expression, as well as treatment patterns, were described. Median progression-free survival (PFS) and median overall survival (OS) were stratified by stage at diagnosis (IIIB/IIIC vs IV) and evaluated by Kaplan–Meier analysis. Results: A total of 7,624 patients met the study criteria. 12.5% (n = 955) were diagnosed at stage IIIB/IIIC versus 87.5% (n = 6,669) diagnosed at stage IV. Of the de novo patients with aNSCLC, 47.6% (n = 3,632) were female, median age (IQR) was 65.3 years (58.1–72.4), 67.4% (n = 5,136) were White, and 62.7% (n = 4,781) had evidence of biomarker testing. Biomarker testing was significantly more common among patients diagnosed at stage IV (64.9%, n = 4,325) than stage IIIB/IIIC (47.7%, n = 456; p &lt; 0.001). At index, 10.3% (n = 785) of patients had evidence of brain metastasis, 49.2% (n = 3,749) were current or former smokers, and 66.7% (n = 5,086) had non-squamous histology. 69.1% (n = 5,269) received first-line treatment with chemotherapy (58.5%, n = 3,083), chemotherapy + immune checkpoint inhibitor (ICI) (20.8%, n = 1,096), ICI monotherapy (9.5%, n = 503), tyrosine kinase inhibitors (10.4%, n = 548), or other treatments (0.7%, n = 39). Among patients with de novo aNSCLC overall at stage IIIB/IIIC and stage IV, median PFS was 5.0 months (mos) (95% CI: 4.8, 5.3), 7.2 mos (95% CI: 6.3, 8.1), and 4.8 mos (95% CI: 4.6, 4.9; p &lt; 0.0001), respectively; median OS was 13.9 mos (95% CI: 13.3, 14.5), 19.4 mos (95% CI: 16.8, 22.0), and 13.2 mos (95% CI: 12.6, 13.8; p &lt; 0.0001), respectively. Conclusions: Among patients with de novo aNSCLC, those diagnosed at stage IIIB/IIIC had significantly longer median PFS and OS than those diagnosed at stage IV. Many real-world patients with aNSCLC were not tested for biomarkers for which there are now approved targeted therapies. Earlier diagnosis and increased biomarker testing may improve clinical outcomes in real-world patients with aNSCLC.

Characteristics of Patients With Second Primary Lung Cancer Following Breast Cancer: A Retrospective Descriptive Study

BackgroundBreast cancer (BC) is the most common noncutaneous malignancy in women and survivors are at an increased risk for secondary malignancy with lung cancer (LC) being the most common. There are few studies that have explored the clinicopathological specifics of LC in BC survivors. MethodsIn this single-institution, retrospective study, we identified BC survivors who subsequently developed LC, examined their breast and LC clinical and pathological characteristics and compared them to the general BC and LC population as published in the literature. ResultsIn our study, we found the following associations that could be meaningful: an association between receiving radiation (RT) and LC (including a statistically significant P = .03 chance of ipsilateral LC after BC treatment with RT), a higher incidence and amount of smoking and LC, high BRCA positivity (78.9%) in the few patients who had germline testing, and a higher incidence of EGFR mutations in NSCLC after BC (60.9%) as well as an earlier stage of NSCLC disease. ConclusionTreatments such as RT, genetic factors such as BRCA mutations, and tobacco use may increase the risk of developing LC amongst BC survivors. Exploring this further can potentially lead to better risk stratification through modified low-dose CT chest screening protocols to catch LCs earlier and ultimately improve outcomes. Past studies have shown that BC survivors who are subsequently diagnosed with NSCLC may have improved OS compared with primary NSCLC and our study showed a high incidence of EGFR mutated NSCLC, which also suggest both improved prognosis and a different molecular profile of NSCLC, which warrants further investigation. Lastly, BC survivors who subsequently are diagnosed with NSCLC had earlier stage disease in our study, perhaps a result of surveillance, highlighting the importance of close monitoring of BC survivors.

Abstract 2444: RAB27B drives a cancer stem cell phenotype in non-small cell lung cancer cells through enhanced extracellular vesicle secretion

Abstract Non-small cell lung cancer (NSCLC), a major subtype of lung cancer, accounts for ~85% of all lung cancer diagnoses. A sub-population of cells within human NSCLC tumors called cancer stem cells (CSCs) have been found to exhibit distinct properties that contribute to factors associated with poor outcomes in NSCLC patients including metastasis, relapse, and therapeutic resistance. We previously performed RNAseq analysis on bulk cancer cells (BCCs) and CSCs from a panel of primary NSCLC tumors and cell lines to identify signaling mechanisms involved in the tumorigenic behavior of NSCLC CSCs. Our analysis revealed that expression of RAB27B, a small GTPase that plays a critical role in extracellular vesicle (EV) formation and secretion, was significantly upregulated in CSCs when compared to BCCs. Interestingly, RAB27B is overexpressed and predicts patient survival in NSCLC. The goal of this study was to assess the role of RAB27B in the tumorigenic behavior of NSCLC CSCs and determine the mechanism by which RAB27B promotes an aggressive stem-cell like phenotype in NSCLC cells an aspect of RAB27B function that has not been investigated in NSCLC. QPCR and immunoblot analysis was used to compare RAB27B mRNA and protein expression in a panel of NSCLC BCCs and CSCs. Two independent shRNA constructs were used to knockdown (KD) RAB27B in NSCLC CSCs. The effects of RAB27B KD on CSC expansion, transformed growth and invasion were analyzed by clonal expansion, soft agar colony formation and Boyden chamber assays, respectively. Xenograft and tail vein mouse models were used to assess the effects of RAB27B KD on CSC tumor growth and lung colonization. EVs were isolated from the conditioned media of BCCs, CSCs and RAB27B KD CSCs using differential ultracentrifugation, and characterized by nanoparticle tracking analysis, transmission electron microscopy and immunoblotting according to MISEV guidelines. Our analysis revealed that RAB27B is significantly upregulated in NSCLC CSCs compared to BCCs. RAB27B KD cells exhibited a significant decrease in clonal expansion, transformed growth and invasion when compared to non-target shRNA control CSCs. In vivo studies demonstrated that RAB27B is important for the tumorigenicity of CSCs and promotes tumor cell proliferation, and angiogenesis. EVs were positive for EV-specific markers and negative for an intracellular vesicle marker. CSCs secrete significantly more EVs when compared to BCCs and KD of RAB27B in CSCs led to a decrease in the levels of EVs secreted. Furthermore, delivery of CSC-derived, but not BCC-derived EVs to BCCs induced spheroid growth, clonal expansion, and invasion in BCCs. Taken together, our results indicate that RAB27B is required for maintenance of a highly tumorigenic, cancer-initiating and invasive stem-like cell population in NSCLC and RAB27B is involved in propagating EV-mediated communication from NSCLC CSCs to BCCs. Citation Format: Kayleah M. Meneses, Jennifer A. Lindemann, Prita Pandya, Dania S. Al-Qasrawi, Ryan Argo, Celeste Weems, Danielle J. Beetler, Irene K. Yan, Joy Wolfram, Tushar C. Patel, Verline Justilien. RAB27B drives a cancer stem cell phenotype in non-small cell lung cancer cells through enhanced extracellular vesicle secretion [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 2444.