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Bronchial dysplasia (BD), a presumed precursor of pulmonary squamous cell carcinoma (SCC), rarely progresses to invasive cancer. A high-risk cohort at the University of Colorado provided an opportunity to directly sample airway epithelium at mapped sites on successive bronchoscopies. We have hypothesized that persistent dysplastic lesions showing a similar or higher level of dysplasia on follow-up biopsy, are associated with increased risk for the development of SCC. Endoscopic biopsies from 188 high-risk subjects were histologically classified according to the current WHO classification for BD using a numeric histology score ranging from 1 to 8 representing normal bronchial mucosa through invasive lung cancer. Differences in follow-up histology scores were compared between sites classified by clinical, histologic, and immunohistochemical variables. Subjects with a higher frequency of sites that persist or progress to high-grade dysplasia (≥37.5% persist/progress, N = 35 versus N = 114) show a significant association with development of incident invasive SCC (adjusted HR, 7.84; 95% confidence interval, 1.56–39.39), and those with incident lung SCC have adjusted mean follow-up histology scores 1.55 U higher than in subjects without lung cancer. Current smoking, elevated Ki67 growth fraction, histologic features of angiogenic squamous dysplasia (ASD) and higher histology score in baseline biopsies are significantly associated with increased follow-up histology scores. These results show that persistent BD is associated with the development of invasive SCC. Furthermore, increased expression of Ki67, the presence of angiogenic change and degree of baseline atypia are associated with persistence of BD. Cancer Prev Res; 9(1); 96–104. ©2015 AACR.

EphB3 knockdown does not affect cell viability but enhances cell migration in LY2 cell line.

Supplemental figure S2. Univariable analysis comparing frequency of SCC in cases grouped by highest baseline (BL) histology score (HS) or mean baseline histology score using a cutoff of HS > 5 (moderate dysplasia).

SUPPLEMENTAL TABLE S1. BIOPSY AND CLINCAL CHARACTERISTICS. SUPPLEMENTAL TABLE S2. BASELINE HISTOLOGY AND OUTCOME.

EphB3 and PI3 Kinase p110α are variably expressed in human HNSCC cells.

Eph proteins have emerged as critical drivers affecting tumor growth and progression in human malignancies. Our The Cancer Genome Atlas (TCGA) data analysis showed that EphB3, a receptor tyrosine kinase, is frequently coamplified with PIK3CA in head and neck squamous cell carcinoma (HNSCC). We therefore hypothesized that EphB3 amplification plays a protumorigenic role in HNSCC and that EphB3 and PIK3CA are cooperating oncogenes that contribute toward its pathogenesis. This hypothesis was not experimentally supported, because EphB3 knockdown failed to alter HNSCC tumor cell growth in vitro or in vivo with an orthotopic model. However, responsiveness of EphB3 knockdown tumors to the PI3K inhibitor, BKM120, was significantly decreased in terms of both tumor growth delay and survival. This is correlated with an increase in prosurvival proteins, S6 and BcL-XL, in the EphB3 shRNA tumors treated with BKM120 compared with controls. We further observed that EphB3 knockdown resulted in increased migration in vitro and increased EMT gene signature in vivo. To explain these results, we examined EphB3 phosphorylation levels in HNSCC at baseline. Although total EphB3 levels were high, we found low phospho-EphB3 levels in HNSCCs. Forced EphB3 phosphorylation with an ephrin-B2–Fc fusion protein resulted in decreased HNSCC migration and cell growth, and enhanced response to BKM120 in vitro. These data collectively indicate that progression of HNSCC selects for low/inhibited EphB3 activity to enhance their survival and migratory abilities and decrease response to PI3K signaling. Therefore, strategies focused on activating EphB3 might be helpful to inhibit tumor growth and enhance sensitivity to PI3K inhibitors in HNSCC. Mol Cancer Ther; 17(9); 2049–59. ©2018 AACR.

Microarray analysis showing EphB3 levels in different tumor cell lines

Purpose: Radiotherapy (RT) can transform the immune landscape and render poorly immunogenic tumors sensitive to PD-L1 inhibition. Here, we established that the response to combined RT and PD-L1 inhibition is transient and investigated mechanisms of resistance.Experimental Design: Mechanisms of resistance to RT and PD-L1 blockade were investigated in orthotopic murine head and neck squamous cell carcinoma (HNSCC) tumors using mass cytometry and whole-genome sequencing. Mice were treated with anti–PD-L1 or anti–TIM-3 alone and in combination with and without RT. Tumor growth and survival were assessed. Flow cytometry was used to assess phenotypic and functional changes in intratumoral T-cell populations. Depletion of regulatory T cells (Treg) was performed using anti-CD25 antibody.Results: We show that the immune checkpoint receptor, TIM-3, is upregulated on CD8 T cells and Tregs in tumors treated with RT and PD-L1 blockade. Treatment with anti–TIM-3 concurrently with anti–PD-L1 and RT led to significant tumor growth delay, enhanced T-cell cytotoxicity, decreased Tregs, and improved survival in orthotopic models of HNSCC. Despite this treatment combination, the response was not durable, and analysis of relapsed tumors revealed resurgence of Tregs. Targeted Treg depletion, however, restored antitumor immunity in mice treated with RT and dual immune checkpoint blockade and resulted in tumor rejection and induction of immunologic memory.Conclusions: These data reveal multiple layers of immune regulation that can promote tumorigenesis and the therapeutic potential of sequential targeting to overcome tumor resistance mechanisms. We propose that targeted Treg inhibitors may be critical for achieving durable tumor response with combined radiotherapy and immunotherapy. Clin Cancer Res; 24(21); 5368–80. ©2018 AACR.

Persistent bronchial dysplasia is associated with increased risk of developing invasive squamous cell carcinoma (SCC) of the lung. In this study, we hypothesized that differences in gene expression profiles between persistent and regressive bronchial dysplasia would identify cellular processes that underlie progression to SCC. RNA expression arrays comparing baseline biopsies from 32 bronchial sites that persisted/progressed to 31 regressive sites showed 395 differentially expressed genes [ANOVA, FDR ≤ 0.05). Thirty-one pathways showed significantly altered activity between the two groups, many of which were associated with cell-cycle control and proliferation, inflammation, or epithelial differentiation/cell–cell adhesion. Cultured persistent bronchial dysplasia cells exhibited increased expression of Polo-like kinase 1 (PLK1), which was associated with multiple cell-cycle pathways. Treatment with PLK1 inhibitor induced apoptosis and G2–M arrest and decreased proliferation compared with untreated cells; these effects were not seen in normal or regressive bronchial dysplasia cultures. Inflammatory pathway activity was decreased in persistent bronchial dysplasia, and the presence of an inflammatory infiltrate was more common in regressive bronchial dysplasia. Regressive bronchial dysplasia was also associated with trends toward overall increases in macrophages and T lymphocytes and altered polarization of these inflammatory cell subsets. Increased desmoglein 3 and plakoglobin expression was associated with higher grade and persistence of bronchial dysplasia. These results identify alterations in the persistent subset of bronchial dysplasia that are associated with high risk for progression to invasive SCC. These alterations may serve as strong markers of risk and as effective targets for lung cancer prevention.Significance: Gene expression profiling of high-risk persistent bronchial dysplasia reveals changes in cell-cycle control, inflammatory activity, and epithelial differentiation/cell–cell adhesion that may underlie progression to invasive SCC. Cancer Res; 78(17); 4971–83. ©2018 AACR.

Blockade of EphB4-ephrin-B2 enhances response to EGFR inhibitor (cetuximab) and RT resulting in significant delay in tumor growth and enhanced survival in HNSCC PDX models. Tumor growth volumes are displayed in CUHN013 (A) and CUHN004 (B) tumors including cisplatin-RT treated groups in the absence and presence of sEphB4-HSA. Cisplatin-RT treated groups did not show any significant changes in tumor growth in the absence and presence of sEphB4-HSA in CUHN013 tumors. Survival graphs are shown for CUHN013 (C) and CUHN004 (D) tumors.

Supplemental table S1 documents comparability between final groupings of baseline biopsies used for gene expression comparisons between persistent and regressive sites demonstrating comparability in all key histologic and clinical variables with the exception of higher inflammation in the regressive group. Supplemental table S2 describes the number of differentially expressed genes that distinguish the four initial groups of bronchial biopsies including persistent bronchial dysplasia (BD), regressive BD, progressive non-dysplasia (ND) and stable ND. The number of genes differentially expressed between the groups highlight the finding that differences are greater in respect to the outcome of the lesions at a given site versus the degree of dysplasia in the baseline biopsy. Most notably the difference between regressive BD and stable ND, two groups with histologically distinct baseline biopsies show fewer differentially expressed genes than all but one other group comparison including the histologically indistinguishable persistent and regressive BD groups. These findings are consistent with persistent and regressive sites representing biologically distinct lesions. Supplemental table S3 shows airway locations, temporal histologic features of full airways and clinical characteristics associated with each specimen used for gene expression analyses. The table is arranged by persistent versus regressive status and presents specimens in descending order of baseline histologic score within each group. The specimen numbers correspond to those notated in figure 1B of the manuscript. Supplemental figure S1 shows a heat map using differentially expressed genes to demonstrate the rationale for combining groups in the final comparison. The heatmap demonstrates that persistent BD and progressive ND sites, which are combined to represent persistent sites, show similar gene expression profiles, with only cases Group3_051, Group3_086, Group3_113 and Group4_070 showing profiles that demonstrate similarity to the regressive BD/stable ND group. The regressive BD and stable ND, which are combined to represent regressive sites, also show similar gene expression profiles that are opposite to those seen in the persistent site group with only cases Group2_037, Group2_085 and Group2_092 showing profiles that demonstrate similarity to the persistent BD/progressive ND group. Supplemental tables S4 - S6 present full data genelists for genes associated with pathways showing significantly altered activity in comparisons of persistent and regressive BD (supplemental table S3), genes associated with pathways that are altered in relation to increasing histologic score (supplemental table S4) and upstream regulators related to persistence and histologic score (supplemental table S5). Supplemental table S7 shows documents comparability between final groupings of baseline biopsies used for analyses of the composition of inflammatory infiltrates in comparisons between a validational set of persistent and regressive sites. Comparability is demonstrated in all key histologic and clinical variables including mean inflammation score and percent of high inflammation score biopsies between the two groups. A higher mean baseline histologic score was seen in the persistent group. Supplemental figure S2 shows subset analyses of the validational set of persistent and regressive sites with comparison of these groups by tissue compartment (epithelial and stromal) and overall degree of inflammation (supplemental figures S2A and S2B). Supplemental figure S2C shows the changes in expression of genes from the original gene expression array analysis data for those genes associated with polarization of subsets of inflammatory cells. The genes with significant or near significant change provide evidence that the activity of certain subsets of macrophages and T-lymphocytes correlate with persistence or regression of BD. These subsets are further studied in figure 5 of the main text.

Levels of EGFR expression in HNSCC PDX tumors

Purpose: The clinical success of targeted therapies such as cetuximab and radiotherapy (RT) is hampered by the low response rates and development of therapeutic resistance. In the current study, we investigated the involvement of EphB4–ephrin-B2 protumorigenic signaling in mediating resistance to EGFR inhibition and RT in head and neck cancers.Experimental Design: We used patient-derived xenograft (PDX) models of head and neck squamous cell carcinoma (HNSCC) and HNSCC cell lines to test our hypothesis. Tumor tissues were subjected to PhosphoRTK array, and Western blotting to detect changes in EphB4–ephrin-B2 targets. mRNA sequencing and microarray data analysis were performed on PDX tumors and HNSCC cell lines, respectively, to determine differences in gene expression of molecules involved in tumor cell growth, proliferation, and survival pathways. Effects on cell growth were determined by MTT assay on HNSCC cells downregulated for EphB4/ephrin-B2 expression, with and without EGFR inhibitor and radiation.Results: Our data from locally advanced HNSCC patients treated with standard-of-care definitive chemo-RT show elevated EphB4 and ephrin-B2 levels after failure of treatment. We observed significant response toward cetuximab and RT following EphB4–ephrin-B2 inhibition, resulting in improved survival in tumor-bearing mice. Tumor growth inhibition was accompanied by a decrease in the levels of proliferation and prosurvival molecules and increased apoptosis.Conclusions: Our findings underscore the importance of adopting rational drug combinations to enhance therapeutic effect. Our study documenting enhanced response of HNSCC to cetuximab-RT with EphB4–ephrin-B2 blockade has the potential to translate into the clinic to benefit this patient population. Clin Cancer Res; 24(18); 4539–50. ©2018 AACR.

Lung cancers bearing oncogenic EML4-ALK fusions respond to targeted tyrosine kinase inhibitors (TKIs; e.g. alectinib), with variation in the degree of shrinkage and duration of treatment (DOT). However, factors that control this response are not well understood. While the contribution of the immune system in mediating the response to immunotherapy has been extensively investigated, less is known regarding the contribution of immunity to TKI therapeutic responses. We previously demonstrated a positive association of a TKI-induced interferon gamma (IFNγ) transcriptional response with DOT in EGFR-mutant lung cancers. Herein, we used three murine models of EML4-ALK lung cancer to test the role for host immunity in the alectinib therapeutic response. The cell lines (EA1, EA2, EA3) were propagated orthotopically in the lungs of immunocompetent and immunodeficient mice and treated with alectinib. Tumor volumes were serially measured by μCT and immune cell content was measured by flow cytometry and multispectral immunofluorescence. Transcriptional responses to alectinib were assessed by RNAseq and secreted chemokines were measured by ELISA. All cell lines were similarly sensitive to alectinib in vitro and as orthotopic tumors in immunocompetent mice, exhibited durable shrinkage. However, in immunodeficient mice, all tumor models rapidly progressed on TKI therapy. In immunocompetent mice, EA2 tumors exhibited a complete response, whereas EA1 and EA3 tumors retained residual disease that rapidly progressed upon termination of TKI treatment. Prior to treatment, EA2 tumors had greater numbers of CD8+ T cells and fewer neutrophils compared to EA1 tumors. In addition, RNAseq of cancer cells recovered from untreated tumors revealed elevated levels of CXCL9 and 10 in EA2 tumors, and higher levels of CXCL1 and 2 in EA1 tumors. Analysis of pretreatment patient biopsies from ALK+ tumors revealed an association of neutrophil content with shorter time to progression. Combined, these data support a role for adaptive immunity in durability of TKI responses and demonstrate that the immune cell composition of the tumor microenvironment is predictive of response to alectinib therapy.

Patients with lung cancer bearing driver oncogenes such as epidermal growth factor receptor (EGFR) mutations or anaplastic lymphoma kinase (ALK) fusions, often experience long term disease control on targeted therapy. Despite excellent initial responses, ultimately these tumors develop resistance to targeted therapy. While several cancer cell intrinsic mechanisms of targeted therapy resistance are well known, they do not account for all cases of resistance. Based on our previous observations, we hypothesized components of the tumor microenvironment, specifically monocytes and macrophages, also contribute to the development of targeted therapy resistance. We generated bone marrow derived macrophages from C57BL/6 mice and polarized them to an M0, M1, or M2 phenotype over the course of 6 days. At day 7, cells were plated in fresh media and after 2 days, the conditioned media (CM) was collected. Macrophage polarization was verified via qPCR. Murine cell lines, EA-1, EA-2, and EA-3 are unique, murine lung adenocarcinomas bearing an oncogenic ALK fusion derived from C57BL/6 mice. These murine cell lines were then cultured in the macrophage CM prior to exposure to ALK fusion specific tyrosine kinase inhibitors (TKI), alectinib or crizotinib. We observed that culture in M2-CM resulted in at least a 10-fold increase in alectinib resistance across all 3 murine cell lines when compared to the same cell lines cultured in M1 or M0-CM. We next tested for the activity of known, clinically relevant bypass signaling pathways as mediator of M2-CM protection. Aftatinib, an inhibitor of EGFR and human epidermal growth factor receptor 2 (HER2) family of proteins, did not alter M2-CM protection in the presence of alectinib. M2-CM did not impart TKI resistance to the murine cell lines in the presence of crizotinib, a TKI which inhibits ALK fusion activity and MET receptor tyrosine kinase activity, suggesting bypass signaling through MET drives the M2-CM resistance. Ongoing animal model studies demonstrate a clear role for innate immune cells in decreasing tumor responsiveness to TKI. In summary, our work demonstrates TKI therapy may be modulated by the presence of and interaction with specific immune cells within the tumor microenvironment. These data support exploring macrophage targeting therapies to improve TKI responsiveness. Citation Format: Melanie Mandell, Katherine Priest, Anh Le, Lynn Heasley, Raphael Nemenoff, Erin L. Schenk. Macrophage mediated resistance to TKI therapy in ALK fusion positive non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 655.

3136 Background: MDM2 is an E3 ubiquitin ligase that plays a critical role in the degradation of the tumor suppressor p53. Milademetan (RAIN-32) is an orally available, small molecule inhibitor of MDM2 that disrupts the MDM2-p53 complex thereby restoring p53 activity. Approximately 50% of tumors harbor wildtype (WT) TP53 and thus may be susceptible to strategies that reactivate p53. The CDKN2A gene is altered in more than 15% of all tumors (TCGA PanCancer Atlas) and encodes two proteins, p14ARF and p16, which are inhibitors of p53 and cyclin dependent kinases, respectively. Given the role of p14ARF in regulating the MDM2-p53 pathway, we investigated the use of CDKN2A loss in the context of WT TP53 as a strategy for selection of patients who might benefit from milademetan. Methods: N/A. Results: We evaluated the sensitivity of 215 cancer cell lines to milademetan treatment (Ishizawa et al., 2018) by CDKN2A and TP53 status. The median IC50 of CDKN2A homozygous (HZ) loss vs. non-HZ loss was 8,620 vs. 10,000 nM. However, when we assessed CDKN2A HZ loss with WT TP53 versus mutant TP53 the median IC50 was 79.5 vs. 10,000 nM demonstrating that the use of both CDKN2A and TP53 was better able to discriminate sensitive vs. resistant cell lines. To validate these in vitro findings, we tested milademetan in 5 xenograft models with CDKN2A HZ loss and WT TP53, all of which demonstrated tumor growth inhibition with milademetan. As suppression of p53 activity by MDM2 amplification (Kato et al. 2017) or CDKN2A loss (Adib et al. 2021) has been associated with resistance to immune checkpoint inhibitors (ICI), we also tested the combination of anti-PD1 with milademetan in the colon-26 syngeneic model ( CDKN2A HZ loss) and observed a significant enhancement in tumor growth inhibition compared to milademetan or anti-PD1 alone. Based on the differential sensitivity to milademetan using both CDKN2A loss and WT TP53 status we evaluated TCGA Pan-Cancer Atlas data to estimate the frequency of these genetic co-alterations. Among solid tumors types the most frequent percentage of these co-alterations included glioblastoma, mesothelioma, melanoma, bladder, sarcoma, pancreatic and NSCLC. Overall, the percentage of all tumors with co-alteration of CDKN2A HZ loss and WT TP53 was 6.2%. Patients with CDKN2A HZ loss had a significantly worse overall survival than those without CDKN2A HZ loss (median OS of 29.7 vs. 97.4 months, p < 0.0001), and this was maintained when accounting for tumor type in multivariate analysis (p < 0.0001). Conclusions: Milademetan showed evidence of preclinical anti-tumor activity across multiple tumor types with CDKN2A loss and WT TP53. In vivo data supported potential synergy of milademetan with an ICI in this genetic subset. A clinical trial evaluating the safety and efficacy of milademetan plus atezolizumab in advanced solid tumors with CDKN2A HZ loss and WT TP53 (MANTRA-4) is planned.

Platelet-derived growth factor (PDGF), which is a potent mitogen for vascular smooth-muscle cells (VSMC), also inhibits the expression of specific smooth-muscle proteins, including smooth-muscle alpha-actin (SM-alpha-actin), in these cells. The goal of this study was to identify signalling pathways mediating these distinct effects. In rat aortic VSMC, PDGF caused a rapid activation of Ras and Raf, leading to the activation of mitogen-activated protein kinases (ERKs). Cells stably transfected with constitutively active Ras (H-Ras) expressed low levels of SM-alpha-actin protein. Arginine vasopressin, which stimulated SM-alpha-actin promoter activity in wild-type cells or controls (Neo; transfected with a plasmid lacking an insert), failed to do so in cells transiently expressing H-Ras. The effects of Ras on suppression of SM-alpha-actin expression were not mediated by the Raf/ERK pathway, since cells stably expressing constitutively active Raf (BxB-Raf) had normal levels of SM-alpha-actin protein, and stimulation of SM-alpha-actin promoter activity by vasopressin was unaffected in cells transiently expressing BxB-Raf. Furthermore a specific inhibitor of ERK activation had no effect on SM-alpha-actin expression. Exposure of wild-type VSMC to PDGF, or stable expression of Ras but not Raf, also resulted in constitutive increases in prostaglandin E2 production and cytosolic phospholipase A2 (cPLA2) activity, which was mediated by an increased expression of cPLA2 protein. Transient expression of cPLA2 in wild-type VSMC inhibited the stimulation of SM-alpha-actin promoter activity by vasopressin. These results suggest that PDGF-induced inhibition of SM-alpha-actin expression is mediated through a Ras-dependent/Raf independent pathway involving the induction of cPLA2 and eicosanoid production.

FGFR1 amplification is a genomic aberration recently identified in various types of cancer. Especially squamous cell carcinomas of the lung and the head and neck show this genetic alteration in high frequencies. In these cancers FGFR1 is not only a therapeutic target but does also serve as a biomarker that correlates with parameters of worse outcome. However, since FGFR1 amplification does not always correlate with high protein expression defining the best predictive biomarker for a FGFR1 targeted therapy is of great importance.