Pulmonary Histoplasmosis Complicated by Nonvalvular Right Ventricular Wall Histoplasma capsulatum Endocarditis

Histoplasmosis is commonly a self-limited fungal disease that primarily affects the lung and reticuloendothelial system. Cardiac involvement by histoplasmosis is uncommon. In this report, we provide a detailed description of severe pulmonary histoplasmosis complicated by the disease involvement of the free wall of the right ventricle. A 55-year-old female presented with cough, fevers, dyspnea, and 30-pound unintentional weight loss in 6 months. Her past medical history was significant for supraventricular tachycardia with permanent pacemaker implantation. Imaging studies revealed an intracardiac mass accompanied by mediastinal lymphadenopathy and bilateral lung nodules. Endobronchial ultrasound-guided transbronchial needle aspiration of station 4R lymph nodes revealed numerous yeast forms, morphologically consistent with Histoplasma capsulatum. The diagnosis was further corroborated by the elevated titers of serum antibodies against Histoplasma capsulatum. The right ventricular mass debulking with biopsy showed necrotizing granulomatous inflammation involving nonvalvular endocardium and myocardium of the free wall of the right ventricle. The report documents an unusual presentation of pulmonary histoplasmosis accompanied by nonvalvular endocarditis and suggests a possible association between the site of the cardiac infection and the presence of a permanent intravascular pacer device.

Large Mediastinal Mass as a Rare Presentation of Schistosomiasis

A 39-year-old woman originally from Northeast Africa sought medical attention for positional dyspnea. Computed tomography of the chest revealed an 8.5 cm hypodense anterior mediastinal mass with peripheral calcifications that raised a wide differential diagnosis including infectious and neoplastic lesions. Following surgical resection, a large cavitary necrotizing and calcified granuloma involving the thymus was identified on histopathological examination. The changes were associated with parasitic eggs that based on their morphology suggested infection due to trematode species. The diagnosis was further corroborated by identification of the increased IgG titers for Schistosoma species (ELISA Kit, NovaTec). The patient's symptoms improved following surgery and praziquantel therapy. This unique presentation emphasizes an unusual manifestation of schistosomiasis that can pose a diagnostic challenge, especially in non-endemic regions. It suggests that mediastinal involvement by schistosomiasis is likely due to an ectopic deposition of the parasitic eggs within a definitive host. Suspicion for schistosomiasis should be heightened based on patient demographics and travel to endemic areas.

A PI3K gene expression signature predicts for recurrence in early-stage non-small cell lung cancer treated with stereotactic body radiation therapy

INTRODUCTION

Increasingly, early-stage non-small cell lung cancer (NSCLC) is treated with stereotactic body radiation therapy (SBRT). Although treatment is generally effective, a small subset of tumors will recur because of radioresistance. Preclinical studies suggested PI3K-AKT-mTOR activation mediates radioresistance. This study sought to validate this finding in tumor samples from patients who underwent SBRT for NSCLC.

METHODS

Patients with T1-3N0 NSCLC treated with SBRT at our institution were included. Total RNA of formalin-fixed paraffin-embedded tumor biopsy specimens (pretherapy) was isolated and analyzed using the Clariom D assay. Risk scores from a PI3K activity signature and four published NSCLC signatures were generated and dichotomized by the median. Kaplan-Meier curves and Cox regressions were used to analyze their association with recurrence and overall survival (OS). The PI3K signature was also tested in a data set of resected NSCLC for additional validation.

RESULTS

A total of 92 patients were included, with a median follow-up of 18.3 months for living patients. There was no association of any of the four published gene expression signatures with recurrence or OS. However, high PI3K risk score was associated with higher local recurrence (hazard ratio [HR], 11.72; 95% CI, 1.40-98.0; p = .023) and worse disease-free survival (DFS) (HR, 3.98; 95% CI, 1.57-10.09; p = .0035), but not OS (p = .49), regional recurrence (p = .15), or distant recurrence (p = .85). In the resected NSCLC data set (n = 361), high PI3K risk score was associated with decreased OS (log-rank p = .013) but not DFS (p = 0.54).

CONCLUSIONS

This study validates that higher PI3K activity, measured by gene expression, is associated with local recurrence and worse DFS in early-stage NSCLC patients treated with SBRT. This may be useful in prognostication and/or tailoring treatment, and merits further validation.

A Case of Mediastinal Carcinosarcoma With Beta-HCG Production and KRAS Mutation

Carcinosarcomas of mediastinum are rare and only few well-documented cases are available in the literature. We report a detailed description of mediastinal carcinosarcoma with unique clinical manifestations and immunohistochemical and molecular profiles. A 44-year-old female with an enlarging anterior mediastinal mass was found to have a positive pregnancy test. Thoracoscopic biopsy revealed that the mass represented a carcinosarcoma with adenocarcinoma and chondrosarcoma components. The tumor focally expressed beta-HCG by immunohistochemistry and had KRAS G12A missense mutation by next generation sequencing. The case documents a rare presentation of carcinosarcoma within the mediastinum with uncommon paraneoplastic syndrome and genetic profile. Awareness of these unusual clinical and pathological manifestations of the tumor will help in reaching correct diagnosis and proper management of such patients.

Comparison of four different displays for identification of select pathologic features extracted from whole slide images of surgical pathology cases

BACKGROUND

The establishment of minimum standards for display selection for the whole slide image (WSI) interpretation has not been fully defined. Recently, pathologists have increasingly preferred using remote displays for clinical diagnostics. Our study aims to assess and compare the performance of three fixed work displays and one remote personal display in accurately identifying ten selected pathologic features integrated into WSIs.

DESIGN

Hematoxylin and eosin-stained glass slides were digitized using Philips scanners. Seven practicing pathologists and three residents reviewed ninety WSIs to identify ten pathologic features using the LG, Dell, and Samsung and an optional consumer-grade display. Ten pathologic features included eosinophils, neutrophils, plasma cells, granulomas, necrosis, mucin, hemosiderin, crystals, nucleoli, and mitoses.

RESULTS

The accuracy of the identification of ten features on different types of displays did not significantly differ among the three types of "fixed" workplace displays. The highest accuracy was observed for the identification of neutrophils, eosinophils, plasma cells, granuloma, and mucin. On the other hand, a lower accuracy was observed for the identification of crystals, mitoses, necrosis, hemosiderin, and nucleoli. Participant pathologists and residents preferred the use of larger displays (>30″) with a higher pixel count, resolution, and luminance.

CONCLUSION

Most features can be identified using any display. However, certain features posed more challenges across the three fixed display types. Furthermore, the use of a remote personal consumer-grade display chosen according to the pathologists' preference showed similar feature identification accuracy. Several factors of display characteristics seemed to influence pathologists' display preferences such as the display size, color, contrast ratio, pixel count, and luminance calibration. This study supports the use of standard "unlocked" vendor-agnostic displays for clinical digital pathology workflow rather than purchasing "locked" and more expensive displays that are part of a digital pathology system.

Prognostic Value of Hypoxia Gene Expression Signature in Early-Stage Non-Small Cell Lung Cancer Patients Treated with Stereotactic Body Radiation Therapy

PURPOSE/OBJECTIVE(S)

Stereotactic body radiation therapy (SBRT) is an effective alternative to surgery in the treatment of early-stage non-small cell lung cancer (NSCLC). However, disease recurrence occurs in approximately 20-30% of patients. Hypoxia is a well-known factor promoting solid tumor progression, radiation resistance, and immune evasion. In this study, we utilize a previously published hypoxia gene expression signature (Buffa) and measure its association with clinical outcomes in patients with NSCLC treated with SBRT.

MATERIALS/METHODS

Our study focused on patients with localized, node-negative NSCLC treated with SBRT, and we identified 92 patients treated at our institution between 2008 and 2018 with available gene expression data. Total RNA from formalin-fixed paraffin-embedded archival biopsy specimens (pre-therapy) was isolated and mRNA expression was analyzed using an assay for human samples. For each gene in the Buffa signature, the top 50% of mRNA abundance values were given a score of +1, and the bottom 50% were given a score of -1 to generate a tumor hypoxia score. High scores suggest a hypoxic tumor and low scores imply normoxia. Kaplan-Meier curves were used to assess overall survival, disease-free survival, local recurrence, regional nodal recurrence, and distant recurrence. Cox proportional hazards were performed to account for confounding due to age, T stage, ECOG performance status, biologically effective dose, patient sex, and histology (squamous vs non-squamous).

RESULTS

The patient's gene expression data were dichotomized based on their median hypoxia score (Table 1). Median follow-up was 23.9 months (95% CI 20.6 - 26.6). A high hypoxia score was associated with squamous histology (p = 0.003). On univariate analysis, a high hypoxia score was significantly associated with local recurrence (hazard ratio [HR] = 5.63; 95% CI 1.03 - 30.78; p = 0.046) and distant recurrence (HR = 1.85; 95% CI 1.14 - 3.02; p = 0.013). There was no significant difference in overall survival (HR = 1.93; 95% CI 0.98 - 3.82; p = 0.058), disease-free survival (HR = 2.13; 95% CI 0.93 - 4.89; p = 0.074), or regional nodal recurrence (HR = 1.45; 95% CI 0.41 - 5.14; p = 0.57). On multivariate analysis, a high hypoxia score was associated with worse overall survival (HR = 2.73; 95% CI 1.23 - 6.07; p = 0.014), local recurrence (HR = 12.85; 95% CI 1.08 - 152.49; p = 0.043) and distant recurrence (HR = 1.91; 95% CI 1.13 - 3.22; p = 0.016).

CONCLUSION

Our findings demonstrate that a hypoxia gene signature is significantly associated with worse survival and increased local and distant recurrence after SBRT for localized NSCLC. This hypoxia signature may be useful in prognostication, selecting patients for surgery versus radiation, or selecting patients for treatment intensification with radiation or other systemic agents, and should be prospectively validated.

Case report: Pulmonary synovial sarcoma in a long-term survivor of childhood Hodgkin lymphoma

Solid organ malignancies have been reported in survivors of Hodgkin lymphoma treated with chemoradiation; however, to the best of our knowledge no cases of pulmonary synovial sarcoma have been documented in the literature in this cohort. We herein provide a detailed description of synovial sarcoma occurring in the lung of a long-term survivor of childhood Hodgkin lymphoma. A 29-year-old female never smoker with past medical history of Hodgkin lymphoma diagnosed at the age of 7 years and treated with chemotherapy and radiation therapy was admitted for management of pneumothorax. Wedge lung resection of an ulcerated subpleural nodule revealed a malignant spindle cell tumor that based on light microscopic and immunohistochemical features was classified as monophasic synovial sarcoma. The diagnosis was further confirmed by identification of SS18 (SYT) rearrangement by fluorescence in situ hybridization and SS18-SSX1 gene fusion by RNA sequencing. The case documents a rare occurrence of synovial sarcoma in a long-term survivor of childhood Hodgkin lymphoma. While comprising a typical genetic profile for synovial sarcoma, the tumor had unusual histological features such as cystic and low-grade morphology. The case suggests that synovial sarcoma falls within an expanding spectrum of secondary malignancies following prior treatment of Hodgkin lymphoma.

Two Thymomas of Different Histological Subtypes Arising in a Giant Thymolipoma: Case Report and Review of the Literature

Thymolipoma is a rare benign tumor of the anterior mediastinum. Only a few reports describing thymoma arising within a thymolipoma have been documented in the literature. We report herein a detailed description of thymolipoma giving rise to 2 thymomas of different histological subtypes. A 74-year-old male with history of metastatic papillary thyroid carcinoma gradually developed 2 soft tissue nodules within a large right hemithorax fatty mass that was present for the past 20 years. Computed tomography (CT)-guided needle biopsy revealed one of the soft tissue nodules to be a thymoma, and the entire mass was surgically resected. Final pathological examination demonstrated the mass to be a thymolipoma containing a micronodular thymoma with lymphoid stroma as well as a WHO type B1 thymoma. No evidence of disease recurrence was seen at the time of his 7-year follow-up. This case documents a rare presentation of thymolipoma harboring 2 thymomas of different histological subtypes and highlights the need for early surgical resection of thymolipomas, as they may harbor malignant nodules.

Abstract CT112: AI-powered and manual assessment of PD-L1 are comparable in predicting response to neoadjuvant atezolizumab in patients (pts) with resectable non-squamous, non-small cell lung cancer (NSCLC)

Background: PD-L1 expression evaluated by immunohistochemistry (IHC) is a well-established predictor of anti-PD-L1/PD-1 cancer immunotherapy (CIT). The Phase II LCMC3 (NCT02927301) study evaluated pre-operative treatment (tx) with atezolizumab (anti-PD-L1) in pts with untreated early stage resectable NSCLC, achieving a 20% major pathologic response (MPR) rate (primary efficacy pts, n=143). A digital PD-L1 scoring method was developed to assess PD-L1 expression as a potential predictive marker for MPR in squamous and non-squamous tumor samples from LCMC3.

Methods: Manual scoring was used to determine PD-L1 status on pre-tx biopsy samples using the tumor proportion score (TPS) with a positive threshold of TPS≥50 (22C3). Binary results were correlated with MPR and stratified by squamous/non-squamous histology. A digital pathology workflow for automated PD-L1 scoring was developed to yield a precise continuous PD-L1 TPS. Deep convolutional neural networks trained using pathologist annotations were used to detect individual cells within the tumor and tumor microenvironment and quantify their PD-L1 expression. These cell type predictions were used to compute a digital PD-L1 TPS. LCMC3 pts with available digital and manual PD-L1 scores were then used to assess the role of PD-L1 expression in predicting MPR.

Results: PD-L1 scores were available for pre-tx biopsies from 108 pts. No significant difference in scores was seen between histological subtypes. At cutoff (Oct 15, 2021), TPS≥50 was seen in 41 (non-squamous, n=26 [39%]; squamous, n=15 [36%]) of 108 pts and was associated with MPR in non-squamous (odds ratio [OR], 28.6; P<0.001; Fisher’s exact test) but not squamous histology (OR, 1.3; P=1.0). Continuous digital PD-L1 scores (range: 0-100) were highly correlated with local manual PD-L1 scores (range: 0-100) for squamous (n=42, Pearson r=0.90, P<0.001) and non-squamous stained histology slides (n=66, Pearson r=0.90, P<0.001). Continuous digital and manual PD-L1 TPS on pre-tx biopsies (n=108) were predictive of MPR (digital: area under the receiver operating curve (AUROC)=0.678, logistic regression [LR] P=0.01; manual: AUROC=0.675, LR P=0.003). Strikingly, when pts were stratified by histology, PD-L1 scores were predictive of MPR from pre-tx biopsies for non-squamous samples (n=66; digital: AUROC=0.821, LR P=0.002; manual: AUROC=0.819, LR P=0.001) but not for squamous samples (n=42; digital: AUROC=0.519, LR P=0.93; manual: AUROC=0.506, LR P=0.90), despite no significant difference in MPR rate between the 2 groups.

Conclusions: These findings support using digitally assessed PD-L1 IHC as a centralized and standardized scoring system and suggest that tumor histological subtype could be an important factor in the utility of PD-L1 as a predictive biomarker for neoadjuvant CIT in early stage NSCLC.

Citation Format: John Abel, Christopher Rivard, Filip Kos, Guillaume Chhor, Yi Liu, Jennifer Giltnane, Sara Hoffman, Murray Resnick, Cyrus Hedvat, Amaro Taylor-Weiner, Farah Khalil, Alan Nicholas, Gregory A. Fishbein, Lynette M. Sholl, Natasha Rekhtman, Stephanie Hennek, Ilan Wapinski, Ann Johnson, Michael Montalto, Katja Schulze, Bruce E. Johnson, David P. Carbone, Konstantin Shilo, Andrew H. Beck, Sanja Dacic, William D. Travis, Ignacio Wistuba. AI-powered and manual assessment of PD-L1 are comparable in predicting response to neoadjuvant atezolizumab in patients (pts) with resectable non-squamous, non-small cell lung cancer (NSCLC) [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 CT112.

Abstract 2557: Slit2 inhibits small cell lung cancer by targeting tumor microenvironment

Small cell lung cancer (SCLC) is the deadliest subtype of lung cancer with a 5-year survival rate of <5% in extensive-state disease and is designated by US Congress as a “recalcitrant cancer”. Recently approved by FDA, immune checkpoint blockade (ICB) immunotherapy showed marginally improved survival and only in a few patients, suggesting an inert immune tumor microenvironment (TME) and the existence of SCLC subtypes. Therefore, there is a significant need to develop more effective therapies for SCLC. In addition to the nearly universal biallelic inactivation of Rb and Tp53 genes in human SCLC tumors, comprehensive genome-wide screening studies have identified major co-occurring mutations in PTEN, CREBBP, EP300, SLIT2, MLL, COBL, and EPHA7 genes. Among them, SLIT2 showed the highest level of genomic abnormalities defined by a pronounced clustering of mutations and frequent genomic loss. However, the role of Slit2 in SCLC has not been defined yet. By using genetically engineered human SCLC cells overexpressing Slit2 or recombinant Slit2 (rSlit2) protein, we show that Slit2 inhibits SCLC cells proliferation, migration, and invasion properties and tumor sphere formation ability of drug-resistant SCLC cells in vitro. The mechanistic studies have identified inhibition of AKT and β-catenin mediated signaling pathways by Slit2 overexpression. Next, we implanted human SCLC cell lines into the immunocompromised NSG mice subcutaneously followed by treatment with rSlit2 or sterile saline. Analysis of tumor volume over the 4 weeks showed that rSlit2 treatment significantly reduced the growth of SCLC tumors. Further analysis of tumors showed that rSlit2 treated tumors harbor less M2-like CD206+ macrophages. Overall, these results suggest that Slit2 possesses tumor suppressive properties and could be developed as a novel therapeutic agent against SCLC.

Citation Format: Dinesh K. Ahirwar, Manish Charan, Swati Misri, Konstantin Shilo, Ramesh Ganju. Slit2 inhibits small cell lung cancer by targeting tumor microenvironment [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 2557.

Slit2 Inhibits Breast Cancer Metastasis by Activating M1-Like Phagocytic and Antifibrotic Macrophages

Tumor-associated macrophages (TAM) are heterogeneous in nature and comprise antitumor M1-like (M1-TAM) or pro-tumor M2-like (M2-TAM) TAMs. M2-TAMs are a major component of stroma in breast tumors and enhance metastasis by reducing their phagocytic ability and increasing tumor fibrosis. However, the molecular mechanisms that regulate phenotypic plasticity of TAMs are not well known. Here we report a novel tumor suppressor Slit2 in breast cancer by regulating TAMs in the tumor microenvironment. Slit2 reduced the in vivo growth and metastasis of spontaneous and syngeneic mammary tumor and xenograft breast tumor models. Slit2 increased recruitment of M1-TAMs to the tumor and enhanced the ability of M1-TAMs to phagocytose tumor cells in vitro and in vivo. This Slit2-mediated increase in M1-TAM phagocytosis occurred via suppression of IL6. Slit2 was also shown to diminish fibrosis in breast cancer mouse models by increasing the expression of matrix metalloproteinase 13 in M1-TAMs. Analysis of patient samples showed high Slit2 expression strongly associated with better patient survival and inversely correlated with the abundance of CD163⁺ TAMs. Overall, these studies define the role of Slit2 in inhibiting metastasis by activating M1-TAMs and depleting tumor fibrosis. Furthermore, these findings suggest that Slit2 can be a promising immunotherapeutic agent to redirect TAMs to serve as tumor killers for aggressive and metastatic breast cancers. In addition, Slit2 expression along with CD163⁺ TAMs could be used as an improved prognostic biomarker in patients with breast cancer. SIGNIFICANCE: This study provides evidence that the antitumor effect of Slit2 in breast cancer occurs by activating the phagocytic activity of M1-like tumor-associated macrophages against tumor cells and diminishing fibrosis.

Predicting ROR1/BCL2 combination targeted therapy of small cell carcinoma of the lung

Small cell lung cancer (SCLC) remains a deadly form of cancer, with a 5-year survival rate of less than 10 percent, necessitating novel therapies. Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is an oncofetal protein that is emerging as a therapeutic target and is co-expressed with BCL2 in multiple tumor types due to microRNA coregulation. We hypothesize that ROR1-targeted therapy is effective in small cell lung cancer and synergizes with therapeutic BCL2 inhibition. Tissue microarrays (TMAs) and formalin-fixed paraffin-embedded (FFPE) SCLC patient samples were utilized to determine the prevalence of ROR1 and BCL2 expression in SCLC. Eight SCLC-derived cell lines were used to determine the antitumor activity of a small molecule ROR1 inhibitor (KAN0441571C) alone and in combination with the BCL2 inhibitor venetoclax. The Chou-Talalay method was utilized to determine synergy with the drug combination. ROR1 and BCL2 protein expression was identified in 93% (52/56) and 86% (48/56) of SCLC patient samples, respectively. Similarly, ROR1 and BCL2 were shown by qRT-PCR to have elevated expression in 79% (22/28) and 100% (28/28) of SCLC patient samples, respectively. KAN0441571C displayed efficacy in 8 SCLC cell lines, with an IC50 of 500 nM or less. Synergy as defined by a combination index of <1 via the Chou-Talalay method between KAN0441571C and venetoclax was demonstrated in 8 SCLC cell lines. We have shown that ROR1 inhibition is synergistic with BCL2 inhibition in SCLC models and shows promise as a novel therapeutic target in SCLC.

Validation of protein arginine methyltransferase 5 (PRMT5) as a candidate therapeutic target in the spontaneous canine model of non-Hodgkin lymphoma

Non-Hodgkin lymphoma (NHL) is a heterogeneous group of blood cancers arising in lymphoid tissues that commonly effects both humans and dogs. Protein arginine methyltransferase 5 (PRMT5), an enzyme that catalyzes the symmetric di-methylation of arginine residues, is frequently overexpressed and dysregulated in both human solid and hematologic malignancies. In human lymphoma, PRMT5 is a known driver of malignant transformation and oncogenesis, however, the expression and role of PRMT5 in canine lymphoma has not been explored. To explore canine lymphoma as a useful comparison to human lymphoma while validating PRMT5 as a rational therapeutic target in both, we characterized expression patterns of PRMT5 in canine lymphoma tissue microarrays, primary lymphoid biopsies, and canine lymphoma-derived cell lines. The inhibition of PRMT5 led to growth suppression and induction of apoptosis, while selectively decreasing global marks of symmetric dimethylarginine (SDMA) and histone H4 arginine 3 symmetric dimethylation. We performed ATAC-sequencing and gene expression microarrays with pathway enrichment analysis to characterize genome-wide changes in chromatin accessibility and whole-transcriptome changes in canine lymphoma cells lines upon PRMT5 inhibition. This work validates PRMT5 as a promising therapeutic target for canine lymphoma and supports the continued use of the spontaneously occurring canine lymphoma model for the preclinical development of PRMT5 inhibitors for the treatment of human NHL.

Diagnosis and management of small pulmonary atypical carcinoid tumor associated with Cushing syndrome

Ectopic adrenocorticotropic hormone (ACTH) syndrome is rare and identification of its source is often challenging. We report the case of an ectopic Cushing syndrome in a young adult male secondary to an occult ACTH producing atypical carcinoid tumor. Extensive biochemical and imaging workup was unrevealing. The diagnosis was aided by Ga-DOTA PET scan demonstrating a suspicious left upper lobe lung nodule. The patient underwent video-assisted thoracoscopic exploration with wedge resection and mediastinal lymphadenectomy of a T2aN2M0 atypical carcinoid, resulting in the normalization of ACTH levels and complete resolution of symptoms. The role of a Ga-DOTA PET scan in diagnosing pulmonary carcinoid tumors and their management are discussed.

Lipid laden macrophages and electronic cigarettes in healthy adults

Background

An outbreak of E-cigarette or Vaping Product Use-Associated Lung Injury (EVALI) with significant morbidity and mortality was reported in 2019. While most patients with EVALI report vaping tetrahydrocannabinol (THC) oils contaminated with vitamin E acetate, a subset report only vaping with nicotine-containing electronic cigarettes (e-cigs). Whether or not e-cigs cause EVALI, the outbreak highlights the need for identifying long term health effects of e-cigs. EVALI pathology includes alveolar damage, pneumonitis and/or organizing pneumonia, often with lipid-laden macrophages (LLM). We assessed LLM in the lungs of healthy smokers, e-cig users, and never-smokers as a potential marker of e-cig toxicity and EVALI.

Methods

A cross-sectional study using bronchoscopy was conducted in healthy smokers, e-cig users, and never-smokers (n = 64). LLM, inflammatory cell counts, and cytokines were determined in bronchial alveolar fluids (BAL). E-cig users included both never-smokers and former light smokers.

Findings

High LLM was found in the lungs of almost all smokers and half of the e-cig users, but not those of never-smokers. LLM were not related to THC exposure or smoking history. LLM were significantly associated with inflammatory cytokines IL-4 and IL-10 in e-cig users, but not smoking-related cytokines.

Interpretation

This is the first report of lung LLM comparing apparently healthy smokers, e-cig users, and never-smokers. LLM are not a specific marker for EVALI given the frequent positivity in smokers; whether LLMs are a marker of lung inflammation in some e-cig users requires further study.

Funding

The National Cancer Institute, the National Heart, Lung, and Blood Institute, the Food and Drug Administration Center for Tobacco Products, the National Center For Advancing Translational Sciences, and Pelotonia Intramural Research Funds

Abstract LB-159: The association of alveolar lipid laden macrophages with inflammatory cytokines in electronic cigarette users

Introduction: Lipid laden macrophages (LLM) from lung bronchoscopies have been identified as characteristic for some patients with e-cigarette (e-cig) or vaping product use associated lung injury (EVALI). While vaping with THC oils containing vitamin E acetate is thought to have caused the outbreak, there is a subset of the EVALI cases who reported vaping only with nicotine-containing e-cigs. A recent animal study showed that propylene glycol (PG) and vegetable glycerin altered lipid homeostasis and induced LLM. In addition to the associations with EVALI, understanding the health effects of vaping with e-cigs in general needs additional investigation. Objective: We examined alterations in alveolar lipid homeostasis comparing e-cig users to cigarette smokers and never-smokers. Further, we determined the association of LLM with inflammatory cytokines. Methods: LLMs, inflammatory cell counts, and cytokines were determined in bronchial alveolar fluids (BAL) from a cross-sectional study of 62 volunteer subjects, age 21-45. Participants who were e-cig users were either never-smokers or former smokers. Cigarette smoking and e-cig use were confirmed by biomarkers of exposure, including lung and urine cotinine and 3-hydroxycotinine and urine anatabine, nicotelline, and PG. Results: High LLM counts were found in the lungs of almost all smokers and about half of the e-cig users, but not in any never-smokers (P&lt;0.001). LLMs were significantly correlated with the inflammatory cytokines IL-4 and IL-10 in e-cig users (P=0.01). Smoking history, including cigarettes per day and biomarkers of exposure, e-cig use history, and gender were not associated with LLMs (all P&gt;0.05). LLMs were not related to THC exposure. Discussion: This is the first report comparing LLMs in the lungs of e-cig users with smokers and never-smokers. LLMs were found in lungs of both smokers and a portion of e-cig users. Given their presence among smokers, they are not likely to be useful as a marker identifying those with EVALI. However, LLMs may be one of the markers for specific disease risks associated with e-cig usage, but not smoking.

Citation Format: Min-Ae Song, Peter G. Shields, Jo L. Freudenheim, Theodore M. Brasky, Joseph P. McElroy, Joseph P. McElroy, Sarah A. Reisinger, Daniel Y. Weng, Rongqin Ren, Thomas Eissenberg, Mark D. Wewers, Konstantin Shilo. The association of alveolar lipid laden macrophages with inflammatory cytokines in electronic cigarette users [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-159.

Idiopathic pulmonary arterial hypertension in a pot-bellied pig (Sus scrofa domesticus) with right-sided congestive heart failure

Idiopathic pulmonary arterial hypertension is a rare disease reported in humans and dogs diagnosed as persistent elevation of pulmonary arterial blood pressure without predisposing or associated diseases. A four-month-old pot-bellied pig (Sus scrofa domesticus) was presented for decreased appetite, lethargy, respiratory distress, and occasional syncope. On physical examination, the pig was tachypneic with labored breathing, with a distended abdomen and a bilateral grade 4-5/6 parasternal systolic heart murmur. Systolic pulmonary arterial pressure was estimated at 95 mmHg by Doppler echocardiography, consistent with severe pulmonary hypertension. At autopsy, there was dilation of the main pulmonary artery and right ventricle. The lungs were diffusely rubbery, and there was tricavitary effusion. Microscopically, there was severe widespread pulmonary arterial concentric medial hypertrophy with rare plexiform lesions. The clinical history and gross and microscopic findings supported a diagnosis of idiopathic pulmonary arterial hypertension with subsequent right-sided congestive heart failure. Primary (idiopathic) pulmonary arterial hypertension should be considered as a differential diagnosis in young pigs with right-sided congestive heart failure.

Circulating MicroRNAs and Extracellular Vesicle-Containing MicroRNAs as Response Biomarkers of Anti-programmed Cell Death Protein 1 or Programmed Death-Ligand 1 Therapy in NSCLC

INTRODUCTION

Anti-programmed cell death protein 1 (PD-1) or programmed death-ligand 1 (PD-L1) antibody therapy is a standard treatment for advanced NSCLC, and PD-L1 immunohistochemistry is used as a predictive biomarker for therapeutic response. However, because not all patients with NSCLC with high PD-L1 respond, and some patients with low PD-L1 expression exhibit durable benefit, more accurate predictive biomarkers are needed. Circulating microRNA (miRNA) and miRNA packaged in extracellular vesicles (EVs) are believed to play a role in intercellular communication among immune cells and between immune cells and tumor cells and may represent a good source of mechanism-related biomarkers.

METHODS

Pretreatment plasma of patients with advanced NSCLC treated with single-agent anti-PD-1 or anti-PD-L1 antibody was used in this study. Plasma EVs were isolated using size-exclusion chromatography. Whole plasma and EV-containing RNAs were extracted. The miRNA profile was analyzed with a next-generation sequencing platform.

RESULTS

Samples from 14 responders (patients who exhibited partial response or stable disease ≥6 mo) and 15 nonresponders (patients who exhibited progressive disease as per Response Evaluation Criteria in Solid Tumors) were analyzed. In total, 32 miRNAs (p = 0.0030-0.0495) from whole plasma and seven EV-associated miRNAs (p = 0.041-0.0457) exhibited significant concentration differences between responders and nonresponders. The results of some of these circulating miRNAs were validated in a separate cohort with eight responders and 13 nonresponders. The tumor PD-L1 level was also assessed using immunohistochemistry for patients involved in both cohorts.

CONCLUSIONS

Specific circulating miRNAs in whole plasma and plasma EVs are differentially expressed between responders and nonresponders and have potential as predictive biomarkers for anti-PD-1/PD-L1 treatment response.

An EWSR1-CREB3L1 Fusion Gene in Extraskeletal Undifferentiated Round Cell Sarcoma Expands the Spectrum of Genetic Landscape in the "Ewing-Like" Undifferentiated Round Cell Sarcomas

The molecular findings in Ewing sarcoma have greatly expanded in recent years. Furthermore, this is particularly true for the subset termed "Ewing-like" undifferentiated round cell sarcomas in which new translocations have been reported since the fourth edition of the WHO Classification of Tumours of Soft Tissue and Bone. Amid this expanding genetic landscape, we report a case of extraskeletal undifferentiated round cell "Ewing-like" sarcoma in a 27-year-old female. The patient presented with a large lung mass accompanied on staging imaging by deposits suspicious for metastatic disease in the humerus, calvarium, and lymph nodes of the neck and chest. Biopsy of the lung mass revealed a densely packed monotonous proliferation of round, uniform neoplastic cells with scant cytoplasm. By immunohistochemistry, the tumor cells were diffusely positive for CD99, synaptophysin, TLE1, EMA, and MUC4 and negative for FLI1, PAX7, AE1/3, S100, SOX10, WT1, p63, desmin, and HMB45. Fluorescence in situ hybridization demonstrated rearrangement of the EWSR1 gene. Next-generation sequencing based assay revealed an EWSR1-CREB3L1 fusion. Taken together, the histomorphologic and molecular findings were considered consistent with an undifferentiated round cell sarcoma with an EWSR1-CREB3L1 fusion. Although described in entities such as sclerosing epithelioid fibrosarcoma, low-grade fibromyxoid sarcoma, and small cell osteosarcoma, this has not been previously described in undifferentiated round cell ("Ewing-like") sarcoma. This finding adds to the growing list of undifferentiated round cell sarcomas with Ewing-like morphologic phenotype-associated fusion genes and may contribute to further defining and characterizing the different subset of tumors in the Ewing family of tumors.

Nodular pulmonary deposition disease in a patient with the acquired immunodeficiency syndrome: a case report

Background

Pulmonary nodules are a common cause for concern in patients with human immunodeficiency virus and acquired immunodeficiency syndrome. Most commonly, they are the result of an infection, given the patients’ immunocompromised state; however, in some cases, pulmonary nodules in patients with human immunodeficiency virus and patients with acquired immunodeficiency syndrome can result from cellular or protein deposits. We report a rare case of nodular pulmonary light chain deposition disease in a patient with acquired immunodeficiency syndrome and monoclonal gammopathy of undetermined significance.

Case presentation

A 53-year-old African American woman with acquired immunodeficiency syndrome had pulmonary nodules detected incidentally by imaging of her lungs. Pulmonary tuberculosis was high on the differential diagnosis, but she had a negative test result for pulmonary tuberculosis. Imaging also revealed multiple lucent bone lesions, and earlier in the year, serum protein electrophoresis had shown an immunoglobulin G-kappa monoclonal protein (M spike). She was mildly anemic, so there was concern for progression to myeloma; however, the result of her bone marrow biopsy was unremarkable. Lung biopsy revealed finely granular eosinophilic material with negative Congo red staining, consistent with light chain deposition disease.

Conclusions

The extent of this patient’s light chain deposition disease was thought to be caused by a combination of acquired immunodeficiency syndrome and monoclonal gammopathy of undetermined significance, and the interval decrease in lung nodule size after restarting antiretroviral therapy confirms this hypothesis and also highlights a potentially unique contribution of the hypergammaglobulinemia to this disease process in patients with human immunodeficiency virus and patients with acquired immunodeficiency syndrome .

Abstract P5-04-14: Recombinant Slit2 suppresses breast cancer metastasis by activating anti-tumor macrophages

Metastasis is a major cause of mortality in breast cancer patients in part due to the lack of clinically established targeted therapies. Approximately 5%-20% of patients with Stage II, and ~50% of patients with stage III will recur distally and are likely to die from their disease. Metastatic, or stage IV breast cancers, have a 5-year relative survival rate of about 22%. The expression of a tumor suppressor protein, Slit2 has been shown to be downregulated in various types of tumors including breast cancer. The Slit2 acts through Roundabout Homolog1 (Robo1) receptor. Previously it has been shown that ectopic expression of Slit2 inhibits human MCF-7 breast cancer cell line xenograft tumor growth in mice. However, its role in breast cancer metastasis, tumor microenvironment (TME) and anti-tumor immunity has not been studied before. By using genetically engineered human breast cancer cells, spontaneous mammary tumor and pre-clinical mouse models, we evaluated the role of Slit2 in inhibiting breast cancer growth, metastasis by activating anti-tumor immune response. To study the role of Slit2 in breast cancer, we implanted Slit2 overexpressing human breast cancer cell line MDA-MB-231 (231-Slit2) or vector control cells (231-Vec) to the mammary fat-pads of NOD/SCID/gamma (NSG) mice and observed that 231-Slit2 had significantly reduced tumor growth and metastasis to the lungs compared to 231-Vec. To further confirm the anti-metastatic role of Slit2, we treated mouse mammary tumor virus- Polyoma Middle T antigen (MMTV-PyMT) mammary tumor model and MVT-1 orthotopic tumor bearing FVB/J wildtype mice with recombinant Slit2 (rSlit2) that resulted in significantly reduced tumor growth and metastasis to the lungs in both the models compared to PBS treated mice. The ex-vivo immunofluorescence and flow cytometry studies revealed that Slit2 treated tumors possess a very high number of tumor phagocytic macrophages compared to PBS. In-vitro analysis also showed that rSlit2 treated mouse macrophages (RAW264.7) has higher bacterial particle phagocytic ability. Further analysis of tumors elucidated that Slit2 treated tumors recruited higher number of CD4+ and CD8+ T-cells. In addition, The CD8+ cells were also positive for Granzyme-b showing higher number of effector T-cells in the Slit2 tumors compared to PBS. By using human breast cancer tissue microarray (TMA), we have found that Slit2 expression significantly correlates with better overall survival. These observations highlight the ability of Slit2 to enhance tumor phagocytic macrophages and anti-tumor CD8+/Granzyme-b+ T-cells, thereby restricting tumor growth and lung metastasis. These studies suggest that Slit2 could be used as a novel immunomodulatory therapeutic agent metastatic breast cancer.

Citation Format: Dinesh Kumar Ahirwar, Ramesh Kumar Ganju, Sanjay Mishra, Konstantin Shilo, Kirti Kaul. Recombinant Slit2 suppresses breast cancer metastasis by activating anti-tumor macrophages [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-04-14.

Programmed cell death ligand 1 expression in cytologic and surgical non-small cell lung carcinoma specimens from a single institution: Association with clinicopathologic features and molecular alterations

BACKGROUND

Programmed cell death ligand 1 (PD-L1) expression by the 22C3 pharmDx companion assay has been validated in surgical specimens to support pembrolizumab treatment decisions for patients with non-small cell lung carcinoma (NSCLC). The aims of this study were 1) to assess the adequacy of cytologic specimens for PD-L1 evaluation and 2) to explore correlations of PD-L1 expression with clinicopathologic and molecular features.

METHODS

The study cohort included 100 cytology specimens (fluid [n = 28] and fine-needle aspiration [n = 72]) and 165 surgical specimens (biopsy [n = 138] and resection [n = 27]). The PD-L1 immunohistochemistry 22C3 assay and staining assessment were performed according to the manufacturer's instructions. PD-L1 expression was correlated with patients' demographics, pathologic characteristics, and molecular alterations.

RESULTS

One hundred forty-two specimens (53.6%) were positive for PD-L1 expression (≥1%). No statistically significant difference in PD-L1 expression was identified between cytologic (56.0%) and surgical specimens (52.1%). Seventy-four of 190 tested cases (38.9%) had genetic alterations. PD-L1 positivity was significantly more prevalent in cases with genetic alterations than in cases without genetic alterations. Furthermore, both PD-L1 positivity and high PD-L1 expression (≥50%) had statistically significant associations with Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations. PD-L1 expression had no significant association with histologic phenotypes or other clinicopathologic features.

CONCLUSIONS

The data indicate that cytologic specimens are comparable to surgical specimens for PD-L1 evaluation. The association of PD-L1 expression with KRAS mutations may have clinical relevance in selecting patients with NSCLC for immunotherapy.

Type of TP53 mutation influences oncogenic potential and spectrum of associated K-ras mutations in lung-specific transgenic mice

TP53 and K-ras mutations are two of the major genetic alterations in human nonsmall cell lung cancers. The association between these two genes during lung tumorigenesis is unknown. We evaluated the potential of two common Type I (273H, contact) and Type II (175H, conformational) TP53 mutations to induce lung tumors in transgenic mice, as well as K-ras status, and other driver mutations in these tumors. Among 516 (138 nontransgenic, 207 SPC-TP53-273H, 171 SPC-TP53-175H) mice analyzed, 91 tumors, all adenocarcinomas, were observed. Type II mutants developed tumors more frequently (as compared to nontransgenics, p = 0.0003; and Type I, p = 0.010), and had an earlier tumor onset compared to Type I (p = 0.012). K-ras mutations occurred in 21 of 50 (42%) of murine lung tumors sequenced. For both the nontransgenic and the SPC-TP53-273H transgenics, tumor K-ras codon 12-13 mutations occurred after 13 months with a peak incidence at 16-18 months. However, for the SPC-TP53-175H transgenics, K-ras codon 12-13 mutations were observed as early as 6 months, with a peak incidence between the ages of 10-12 months. Codons 12-13 transversion mutations were the predominant changes in the SPC-TP53-175H transgenics, whereas codon 61 transition mutations were more common in the SPC-TP53-273H transgenics. The observation of accelerated tumor onset, early appearance and high frequency of K-ras codon 12-13 mutations in the Type II TP53-175H mice suggests an enhanced oncogenic function of conformational TP53 mutations, and gains in early genetic instability for tumors containing these mutations compared to contact mutations.

Abstract P5-07-09: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Ahirwar DK, Nasser MW, Shukla RK, Shilo K, Ganju RK. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-07-09.

Notch3-dependent β-catenin signaling mediates EGFR TKI drug persistence in EGFR mutant NSCLC

EGFR tyrosine kinase inhibitors cause dramatic responses in EGFR-mutant lung cancer, but resistance universally develops. The involvement of β-catenin in EGFR TKI resistance has been previously reported, however, the precise mechanism by which β-catenin activation contributes to EGFR TKI resistance is not clear. Here, we show that EGFR inhibition results in the activation of β-catenin signaling in a Notch3-dependent manner, which facilitates the survival of a subset of cells that we call "adaptive persisters". We previously reported that EGFR-TKI treatment rapidly activates Notch3, and here we describe the physical association of Notch3 with β-catenin, leading to increased stability and activation of β-catenin. We demonstrate that the combination of EGFR-TKI and a β-catenin inhibitor inhibits the development of these adaptive persisters, decreases tumor burden, improves recurrence free survival, and overall survival in xenograft models. These results supports combined EGFR-TKI and β-catenin inhibition in patients with EGFR mutant lung cancer.

Abstract 2839: Notch3-dependent beta-catenin signaling mediates EGFR TKI drug persistence in EGFR mutant NSCLC

EGFR tyrosine kinase inhibitors (EGFR-TKIs) usually cause dramatic responses in EGFR-mutant lung cancer, but different patients with identical drivers have widely different progression-free intervals, and resistance universally develops. In those cases without pre-existing resistant clones, even though every cell expresses the driver, some tumor clonogens survive in order to acquire target reactivation or bypass resistance mechanisms. The involvement of β-catenin in EGFR TKI resistance has been previously reported however the precise mechanism by which β-catenin activation contributes to EGFR TKI resistance is not clear. Our transcriptome analysis identified that EGFR inhibition results in the activation of β-catenin signaling in a Notch3-dependent manner, which facilitates the survival of a subset of cells that we call “adaptive persisters”. We have previously reported that EGFR-TKI treatment rapidly activates Notch3, and here our co-immunoprecipitation studies identified a physical association of Notch3 with β-catenin, which in turn leads to increased stability and activation of β-catenin. In vitro pulmosphere formation assays and in vivo limiting dilution assays reveled that adaptive persisters display characteristics of stem-like cells. Furthermore, tumor xenograft studies using HCC827 and HCC4006 demonstrate that the combination of EGFR-TKI and the β-catenin inhibitor, ICG-001 inhibits the development of these adaptive persisters, decreases tumor burden, improves recurrence free survival, and overall survival. Overall, Notch3 plays a pivotal role in the maintenance of lung cancer stem cells (CSCs) and the induction of EGFR TKI mediated drug persisters with cancer stem cell like characteristics, but is difficult to selectively target. Our study finds that this effect is driven by the Notch3-dependent activation of β-catenin signaling in a non-canonical fashion. A combination of EGFR TKI and β-catenin inhibitors decreases tumor take, delays tumor recurrence and increases overall survival in EGFR mutant models. Thus, our findings provide novel insights on role of drug persistence early after EGFR TKI therapy and presents a rationale for clinical testing of EGFR TKIs with β-catenin inhibitors for the treatment of EGFR mutant NSCLC.

Citation Format: Rajeswara Rao Arasada, Konstantin Shilo, Jianying Zhang, Rashelle Ghanem, Tadaaki Yamada, Seiji Yano, David Carbone. Notch3-dependent beta-catenin signaling mediates EGFR TKI drug persistence in EGFR mutant NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2839.

Abstract 1880: Validation of protein arginine methyltransferase 5 (PRMT5) as a candidate therapeutic target in the canine model of non-Hodgkin lymphoma

Introduction: Lymphoma is a common, aggressive malignancy in dogs. While generally responsive to upfront combination chemotherapy with traditional cytotoxic drugs, remission times are short and cures rare. New treatment strategies are therefore needed. Protein arginine methyltransferase 5 (PRMT5) is a type II protein arginine methyltransferase (PRMT) enzyme whose relevance to cancer biology has become increasingly evident as more studies have shown this enzyme to be involved in the regulation of multiple major signaling pathways affecting cell death, proliferation, and malignant transformation. While the mechanism behind many of these cell-transforming capabilities of PRMT5 remains unknown, knockdown of PRMT5 expression by genetic or pharmacologic means has been shown to modulate the methylation status of target proteins and exert antitumor effects in vitro and in vivo. Consequently, PRMT5 small-molecule inhibitors are in early preclinical development.

Methods: In this study, we characterized patterns of PRMT5 expression and correlated these with histologic subtype using canine lymphoma tissue microarrays (TMAs). We characterized expression of PRMT5 in canine lymphoma tissues and methylation targets in canine B-cell lymphoma cell lines and treated them with different PRMT5 inhibitors to determine effects on PRMT5, target proteins and antitumor activity. We also assessed PRMT5 inhibition ex vivo in patient B-cell lymphomas via flow cytometry and assessment of apoptosis with annexin V/PI staining.

Results: Canine diffuse large B-cell lymphoma showed cytoplasmic staining for PRMT5 (48.8% strong, 50.0% weak, n = 165) compared to negative or weak staining in normal and hyperplastic lymph nodes (n = 40). Lymphoblastic T-cell lymphoma samples showed strong nuclear staining (40%, n= 10). No nuclear staining was appreciated in normal or hyperplastic lymph nodes. Similarly, canine B-cell lines showed high expression of PRMT5. PRMT5 small-molecule inhibitors inhibited growth of CLBL-1 and 17-71 canine lymphoma cell lines. Histone (H3R8 and H4R3) methylation status was suppressed at their respective IC50s. Ex vivo treatment of canine patient tumor cells showed suppression of growth at 24 hours.

Conclusion: We have demonstrated that PRMT5 is expressed in canine lymphomas and that PRMT5 inhibition can suppress the growth of canine lymphoma cells, supporting the continued use of the spontaneous canine lymphoma model for the preclinical development of PRMT5 inhibitors.

Citation Format: Kyle A. Renaldo, Lindsay E. Courtney, Konstantin Shilo, Robert A. Baiocchi, William C. Kisseberth. Validation of protein arginine methyltransferase 5 (PRMT5) as a candidate therapeutic target in the canine model of non-Hodgkin lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1880.

Expression Patterns, Prognostic Value, and Intratumoral Heterogeneity of PD-L1 and PD-1 in Thymoma and Thymic Carcinoma

INTRODUCTION

Thymic epithelial tumors (TETs) including thymoma and thymic carcinoma are rare tumors with little data available to guide treatment. Immunotherapy with checkpoint blockade has shown promising activity, but data regarding the expression patterns and prognostic implications of programmed death 1 (PD-1) and its ligand (PD-L1) in TETs have yielded conflicting results. Intratumoral heterogeneity of PD-1/L1 expression has been shown in other cancers, but has not been described in the TET literature.

METHODS

We performed a retrospective single-center review of 35 patients with resected TET. PD-1/L1 expression was assessed by immunohistochemistry using PD-1 clone: NAT105 and PD-L1 clone: 22C3. Tumor samples from 35 patients were evaluated including 32 patients with thymoma and 3 patients with thymic carcinoma.

RESULTS

PD-L1 expression was detected in 83% (29 of 35) tumor samples, including 100% (3 of 3) of thymic carcinoma patients and 81% (26 of 32) of thymoma patients. PD-1 expression was detected in 77% (27 of 35), including 33% (1 of 3) of thymic carcinoma patients and 81% (26 of 32) thymoma patients. High PD-1 expression was associated with lower grade tumors. Unlike prior studies, PD-L1 expression was not associated with higher grade tumors or higher stage. Neither PD-L1 nor PD-1 expression was significantly associated with survival. Three patients with thymoma had multiple tumor sections evaluated for expression of PD-1/L1, with differing expression patterns of both PD-L1 and PD-1 observed in two patients.

CONCLUSIONS

This study confirms high expression of PD-L1 and PD-1 in TET and shows for the first time intratumoral heterogeneity of PD-L1 and PD-1 in thymoma patients.

Histone Deacetylase Inhibition Enhances the Antitumor Activity of a MEK Inhibitor in Lung Cancer Cells Harboring RAS Mutations

Non-small cell lung cancer (NSCLC) can be identified by precise molecular subsets based on genomic alterations that drive tumorigenesis and include mutations in EGFR, KRAS, and various ALK fusions. However, despite effective treatments for EGFR and ALK, promising therapeutics have not been developed for patients with KRAS mutations. It has been reported that one way the RAS-ERK pathway contributes to tumorigenesis is by affecting stability and localization of FOXO3a protein, an important regulator of cell death and the cell cycle. This is through regulation of apoptotic proteins BIM and FASL and cell-cycle regulators p21^Cip1 and p27^Kip1 We now show that an HDAC inhibitor affects the expression and localization of FOXO proteins and wanted to determine whether the combination of a MEK inhibitor with an HDAC inhibitor would increase the sensitivity of NSCLC with KRAS mutation. Combined treatment with a MEK inhibitor and an HDAC inhibitor showed synergistic effects on cell metabolic activity of RAS-mutated lung cancer cells through activation of FOXOs, with a subsequent increase in BIM and cell-cycle inhibitors. Moreover, in a mouse xenograft model, the combination of belinostat and trametinib significantly decreases tumor formation through FOXOs by increasing BIM and the cell-cycle inhibitors p21^Cip1 and p27^Kip1 These results demonstrate that control of FOXOs localization and expression is critical in RAS-driven lung cancer cells, suggesting that the dual molecular-targeted therapy for MEK and HDACs may be promising as novel therapeutic strategy in NSCLC with specific populations of RAS mutations. Mol Cancer Ther; 17(1); 17-25. ©2017 AACR.

Papillary fibroelastoma arising from the coumadin ridge

Cardiac papillary fibroelastomas (CPF) are rare cardiac tumors, mostly found on the valvular surfaces in the heart. These tumors are frond like in nature and are benign, intracardiac masses, rarely causing any hemodynamic disturbances. However, excision of these masses is indicated due to their propensity to embolize. We present a case report of the tumor found on the coumadin ridge, causing transient ischemic attacks in a patient. We performed complete excision of the tumor via median sternotomy on cardiopulmonary bypass support with cardiac arrest. The diagnosis was confirmed by histological examination. The patient had an uneventful postoperative course and was discharghed on postoperative day 4. She has had complete resolution of her symptoms post excision. The diagnosis of the mass was confirmed on histological examination.

Abstract P6-01-03: N-terminus Slit2 suppresses breast cancer metastasis by inhibiting tumor associated macrophages

This abstract was not presented at the symposium.

TRPV2 is a novel biomarker and therapeutic target in triple negative breast cancer

Transient receptor potential vanilloid type-2 (TRPV2) is an ion channel that is triggered by agonists like cannabidiol (CBD). Triple negative breast cancer (TNBC) is an aggressive disease with limited therapeutic options. Chemotherapy is still the first line for the treatment of TNBC patients; however, TNBC usually gains rapid resistance and unresponsiveness to chemotherapeutic drugs. In this study, we found that TRPV2 protein is highly up-regulated in TNBC tissues compared to normal breast tissues. We also observed that TNBC and estrogen receptor alpha negative (ERβ-) patients with higher TRPV2 expression have significantly higher recurrence free survival compared to patients with lower TRPV2 expression especially those who were treated with chemotherapy. In addition, we showed that TRPV2 overexpression or activation by CBD significantly increased doxorubicin (DOX) uptake and apoptosis in TNBC cells. The induction of DOX uptake was abrogated by TRPV2 blocking or downregulation. In vivo mouse model studies showed that the TNBC tumors derived from CBD+DOX treated mice have significantly reduced weight and increased apoptosis compared to those treated with CBD or DOX alone. Overall, our studies for the first time revealed that TRPV2 might be a good prognostic marker for TNBC and ERβ- breast cancer patient especially for those who are treated with chemotherapy. In addition, TRPV2 activation could be a novel therapeutic strategy to enhance the uptake and efficacy of chemotherapy in TNBC patients.

Fatty acid binding protein 5 promotes metastatic potential of triple negative breast cancer cells through enhancing epidermal growth factor receptor stability

Fatty acid binding protein 5 (FABP5), an intracellular lipid binding protein, has been shown to play a role in various cancers, including breast cancer. However, FABP5 and its role in triple negative breast cancer (TNBC) have not been studied. We show FABP5 protein expression correlates with TNBC, high grade tumors, and worse disease-free survival in a tissue microarray containing 423 breast cancer patient samples. High FABP5 expression significantly correlates with epidermal growth factor receptor (EGFR) expression in these samples. Decreased tumor growth and lung metastasis were observed in FABP5-/- mice othotopically injected with murine breast cancer cells. FABP5 loss in TNBC tumor cells inhibited motility and invasion. Mechanistic studies revealed that FABP5 knockdown in TNBC cells results in decreased EGFR expression and FABP5 is important for EGF-induced metastatic signaling. Loss of FABP5 leads to proteasomal targeting of EGFR. Our studies show that FABP5 has a role in both host and tumor cell during breast cancer progression. These findings suggest that FABP5 mediates its enhanced effect on TNBC metastasis, in part, through EGFR, by inhibiting EGFR proteasomal degradation. These studies show, for the first time, a correlation between FABP5 and EGFR in enhancing TNBC metastasis through a novel mechanism.

Epidermal growth factor receptor (EGFR) mutations in small cell lung cancers: Two cases and a review of the literature

Activating mutations in the epidermal growth factor receptor (EGFR) gene are exceedingly rare in small cell lung cancer (SCLC). We present two cases of SCLC harboring EGFR mutations, one in an 82 year-old male smoker with a combined SCLC and adenocarcinoma with a novel D855H point mutation in exon 21, and the second in a 68 year-old female never smoker with the L858R point mutation in exon 21. The cases, accompanied by a review of the literature, highlight the importance of integration of clinicopathologic considerations and adherence to recently promulgated Guideline recommendations for molecular testing in lung cancer.

Veliparib Alone or in Combination with Mitomycin C in Patients with Solid Tumors With Functional Deficiency in Homologous Recombination Repair

BACKGROUND

BRCA germline mutations are being targeted for development of PARP inhibitors. BRCA genes collaborate with several others in the Fanconi Anemia (FA) pathway. We screened cancer patients' tumors for FA functional defects then aimed to establish the safety/feasibility of administering PARP inhibitors as monotherapy and combined with a DNA-breaking agent.

METHODS

Patients underwent FA functional screening for the presence (or lack) of tumor FancD2 nuclear foci formation on their archival tumor material, utilizing a newly developed method (Fanconi Anemia triple-stain immunofluorescence [FATSI]), performed in a Clinical Laboratory Improvement Amendments-certified laboratory. FATSI-negative patients were selected for enrollment in a two-arm dose escalation trial of veliparib, or veliparib/mitomycin-C (MMC).

RESULTS

One hundred eighty-five of 643 (28.7%) screened patients were FATSI-negative. Sixty-one received veliparib or veliparib/MMC through 14 dose levels. Moderate/severe toxicities included fatigue (DLT at veliparib 400mg BID), diarrhea, and thrombocytopenia. Recommended doses are 300mg BID veliparib and veliparib 200mg BID for 21 days following 10mg/m(2) MMC every 28 days. Six antitumor responses occurred, five in the combination arm (3 breast, 1 ovarian, 1 endometrial [uterine], and 1 non-small cell lung cancer). Two patients have received 36 and 60 cycles to date. BRCA germline analysis among 51 patients revealed five deleterious mutations while a targeted FA sequencing gene panel showed missense/nonsense mutations in 29 of 49 FATSI-negative tumor specimens.

CONCLUSIONS

FATSI screening showed that a substantial number of patients' tumors have FA functional deficiency, which led to germline alterations in several patients' tumors. Veliparib alone or with MMC was safely administered to these patients and produced clinical benefit in some. However, a better understanding of resistance mechanisms in this setting is needed.

Abstract A47: Chromatin remodeling factor SMARCA4 as a predictive biomarker of cisplatin therapy in non-small cell lung cancer

Adjuvant cisplatin-based chemotherapy is recommended for patients with completely resected non-small cell lung cancer (NSCLC). However, due to limited efficacy of this therapy, studies are required to identify biomarkers to select patients who would derive the most benefit of the therapy. SMARCA4 (also known as BRG1) and SMARCA2 (also known as BRM) are two important mutually exclusive catalytic subunits with ATPase activity of the mammalian chromatin remodeling complex SWItch/Sucrose NonFermentable (SWI/SNF). These subunits are required for mammalian development and are altered in a variety of malignancies including lung, prostate, pancreatic, breast, and colon. Several studies have reported that both SMARCA4 and SMARCA2 are required for the full activation of DNA damage response by ATM-mediated activation of γ-H2AX. As SMARCA4 is frequently deleted in many primary tumors including NSCLC, we hypothesized that the loss of SMARCA4 may enhance the sensitivity of tumor cells to chemotherapeutic agents causing DNA damage and may serve as predictive biomarkers of sensitivity for these agents. To that end, in the present study we evaluated the association between SMARCA4 and/or SMARCA2 alterations and the outcome of DNA-damaging chemotherapeutic cisplatin in NSCLC. We used a gene expression profiling microarray (n=133) from both control and treatment arms of the North American Intergroup phase III trial of adjuvant cisplatin plus vinorelbine (JBR.10). Kaplan-Meier method and log-rank tests were used to estimate and test the differences of probabilities in overall survival and disease-specific survival between expression groups and treatment arms. Multivariate Cox regression models were used while adjusting for other baseline clinical covariates. Improved five-year disease-specific survival was detected only in patients with low SMARCA4 expression when treated with adjuvant cisplatin/vinorelbine compared with the observational arm (HR=0.1, 95% CI: 0.0.0·5, P=0.001 (low); HR 1.1, 95% CI: 0·5-2.4, P=0·76 [high]). The interaction test was statistically significant (P=0.007). In contrast, no significant survival benefits were noted in patients with high SMARCA4 or high SMARCA2 expression. Taken together, these results suggest that decreased expression of chromatin remodeling factors SMARCA4 may serve as putative predictive biomarkers of platinum-based therapy (cisplatin) in NSCLC and requires further validation.

Citation Format: Arup R. Chakraborty, Erica Bell, Mo Xiaokui, Ziyan Liu, Konstantin Shilo, Simon Kirste, Petra Stegmaier, Maureen McNulty, Niki Karachaliou, Rafael Rosell, Gerold Bepler, David P. Carbone, Arnab Chakravarti. Chromatin remodeling factor SMARCA4 as a predictive biomarker of cisplatin therapy in non-small cell lung cancer. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Sep 24-27, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2016;76(2 Suppl):Abstract nr A47.

SMARCA4/BRG1 Is a Novel Prognostic Biomarker Predictive of Cisplatin-Based Chemotherapy Outcomes in Resected Non-Small Cell Lung Cancer

PURPOSE

Identification of predictive biomarkers is critically needed to improve selection of patients who derive the most benefit from platinum-based chemotherapy. We hypothesized that decreased expression of SMARCA4/BRG1, a known regulator of transcription and DNA repair, is a novel predictive biomarker of increased sensitivity to adjuvant platinum-based therapies in non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

The prognostic value was tested using a gene-expression microarray from the Director's Challenge Lung Study (n = 440). The predictive significance of SMARCA4 was determined using a gene-expression microarray (n = 133) from control and treatment arms of the JBR.10 trial of adjuvant cisplatin/vinorelbine. Kaplan-Meier method and log-rank tests were used to estimate and test the differences of probabilities in overall survival (OS) and disease-specific survival (DSS) between expression groups and treatment arms. Multivariate Cox regression models were used while adjusting for other clinical covariates.

RESULTS

In the Director's Challenge Study, reduced expression of SMARCA4 was associated with poor OS compared with high and intermediate expression (P < 0.001 and P = 0.009, respectively). In multivariate analysis, compared with low, high SMARCA4 expression predicted a decrease in risk of death [HR, 0.6; 95% confidence interval (CI), 0.4-0.8; P = 0.002]. In the JBR.10 trial, improved 5-year DSS was noted only in patients with low SMARCA4 expression when treated with adjuvant cisplatin/vinorelbine [HR, 0.1; 95% CI, 0.0-0.5, P = 0.002 (low); HR, 1.0; 95% CI, 0.5-2.3, P = 0.92 (high)]. An interaction test was highly significant (P = 0.01).

CONCLUSIONS

Low expression of SMARCA4/BRG1 is significantly associated with worse prognosis; however, it is a novel significant predictive biomarker for increased sensitivity to platinum-based chemotherapy in NSCLC. Clin Cancer Res; 22(10); 2396-404. ©2015 AACR.

TRIM72 modulates caveolar endocytosis in repair of lung cells

Alveolar epithelial and endothelial cell injury is a major feature of the acute respiratory distress syndrome, in particular when in conjunction with ventilation therapies. Previously we showed [Kim SC, Kellett T, Wang S, Nishi M, Nagre N, Zhou B, Flodby P, Shilo K, Ghadiali SN, Takeshima H, Hubmayr RD, Zhao X. Am J Physiol Lung Cell Mol Physiol 307: L449-L459, 2014.] that tripartite motif protein 72 (TRIM72) is essential for amending alveolar epithelial cell injury. Here, we posit that TRIM72 improves cellular integrity through its interaction with caveolin 1 (Cav1). Our data show that, in primary type I alveolar epithelial cells, lack of TRIM72 led to significant reduction of Cav1 at the plasma membrane, accompanied by marked attenuation of caveolar endocytosis. Meanwhile, lentivirus-mediated overexpression of TRIM72 selectively increases caveolar endocytosis in rat lung epithelial cells, suggesting a functional association between these two. Further coimmunoprecipitation assays show that deletion of either functional domain of TRIM72, i.e., RING, B-box, coiled-coil, or PRY-SPRY, abolishes the physical interaction between TRIM72 and Cav1, suggesting that all theoretical domains of TRIM72 are required to forge a strong interaction between these two molecules. Moreover, in vivo studies showed that injurious ventilation-induced lung cell death was significantly increased in knockout (KO) TRIM72(KO) and Cav1(KO) lungs compared with wild-type controls and was particularly pronounced in double KO mutants. Apoptosis was accompanied by accentuation of gross lung injury manifestations in the TRIM72(KO) and Cav1(KO) mice. Our data show that TRIM72 directly and indirectly modulates caveolar endocytosis, an essential process involved in repair of lung epithelial cells through removal of plasma membrane wounds. Given TRIM72's role in endomembrane trafficking and cell repair, we consider this molecule an attractive therapeutic target for patients with injured lungs.

Impact of Pre-Analytical Variables on Cancer Targeted Gene Sequencing Efficiency

Tumor specimens are often preserved as formalin-fixed paraffin-embedded (FFPE) tissue blocks, the most common clinical source for DNA sequencing. Herein, we evaluated the effect of pre-sequencing parameters to guide proper sample selection for targeted gene sequencing. Data from 113 FFPE lung tumor specimens were collected, and targeted gene sequencing was performed. Libraries were constructed using custom probes and were paired-end sequenced on a next generation sequencing platform. A PCR-based quality control (QC) assay was utilized to determine DNA quality, and a ratio was generated in comparison to control DNA. We observed that FFPE storage time, PCR/QC ratio, and DNA input in the library preparation were significantly correlated to most parameters of sequencing efficiency including depth of coverage, alignment rate, insert size, and read quality. A combined score using the three parameters was generated and proved highly accurate to predict sequencing metrics. We also showed wide read count variability within the genome, with worse coverage in regions of low GC content like in KRAS. Sample quality and GC content had independent effects on sequencing depth, and the worst results were observed in regions of low GC content in samples with poor quality. Our data confirm that FFPE samples are a reliable source for targeted gene sequencing in cancer, provided adequate sample quality controls are exercised. Tissue quality should be routinely assessed for pre-analytical factors, and sequencing depth may be limited in genomic regions of low GC content if suboptimal samples are utilized.

PDL1 Regulation by p53 via miR-34

BACKGROUND

Although clinical studies have shown promise for targeting PD1/PDL1 signaling in non-small cell lung cancer (NSCLC), the regulation of PDL1 expression is poorly understood. Here, we show that PDL1 is regulated by p53 via miR-34.

METHODS

p53 wild-type and p53-deficient cell lines (p53(-/-) and p53(+/+) HCT116, p53-inducible H1299, and p53-knockdown H460) were used to determine if p53 regulates PDL1 via miR-34. PDL1 and miR-34a expression were analyzed in samples from patients with NSCLC and mutated p53 vs wild-type p53 tumors from The Cancer Genome Atlas for Lung Adenocarcinoma (TCGA LUAD). We confirmed that PDL1 is a direct target of miR-34 with western blotting and luciferase assays and used a p53(R172HΔ)g/+K-ras(LA1/+) syngeneic mouse model (n = 12) to deliver miR-34a-loaded liposomes (MRX34) plus radiotherapy (XRT) and assessed PDL1 expression and tumor-infiltrating lymphocytes (TILs). A two-sided t test was applied to compare the mean between different treatments.

RESULTS

We found that p53 regulates PDL1 via miR-34, which directly binds to the PDL1 3' untranslated region in models of NSCLC (fold-change luciferase activity to control group, mean for miR-34a = 0.50, SD = 0.2, P < .001; mean for miR-34b = 0.52, SD = 0.2, P = .006; and mean for miR-34c = 0.59, SD = 0.14, and P = .006). Therapeutic delivery of MRX34, currently the subject of a phase I clinical trial, promoted TILs (mean of CD8 expression percentage of control group = 22.5%, SD = 1.9%; mean of CD8 expression percentage of MRX34 = 30.1%, SD = 3.7%, P = .016, n = 4) and reduced CD8(+)PD1(+) cells in vivo (mean of CD8/PD1 expression percentage of control group = 40.2%, SD = 6.2%; mean of CD8/PD1 expression percentage of MRX34 = 20.3%, SD = 5.1%, P = .001, n = 4). Further, MRX34 plus XRT increased CD8(+) cell numbers more than either therapy alone (mean of CD8 expression percentage of MRX34 plus XRT to control group = 44.2%, SD = 8.7%, P = .004, n = 4). Finally, miR-34a delivery reduced the numbers of radiation-induced macrophages (mean of F4-80 expression percentage of control group = 52.4%, SD = 1.7%; mean of F4-80 expression percentage of MRX34 = 40.1%, SD = 3.5%, P = .008, n = 4) and T-regulatory cells.

CONCLUSIONS

We identified a novel mechanism by which tumor immune evasion is regulated by p53/miR-34/PDL1 axis. Our results suggest that delivery of miRNAs with standard therapies, such as XRT, may represent a novel therapeutic approach for lung cancer.

Akt Kinase-Interacting Protein 1 Signals through CREB to Drive Diffuse Malignant Mesothelioma

Diffuse malignant mesothelioma (DMM) is a tumor of serosal membranes with propensity for progressive local disease. Because current treatment options are largely ineffective, novel therapeutic strategies based on molecular mechanisms and the disease characteristics are needed to improve the outcomes of patients with this disease. Akt kinase interacting protein 1 (Aki1; Freud-1/CC2D1A) is a scaffold protein for the PI3K-PDK1-Akt signaling module that helps determine receptor signal selectivity for EGFR. Aki1 has been suggested as a therapeutic target, but its potential has yet to be evaluated in a tumor setting. Here, we report evidence supporting its definition as a therapeutic target in DMM. In cell-based assays, Aki1 silencing decreased cell viability and caused cell-cycle arrest of multiple DMM cell lines via effects on the PKA-CREB1 signaling pathway. Blocking CREB activity phenocopied Aki1 silencing. Clinically, Aki1 was expressed in most human DMM specimens where its expression correlated with phosphorylated CREB1. Notably, Aki1 siRNA potently blocked tumor growth in an orthotopic implantation model of DMM when administered directly into the pleural cavity of tumor-bearing mice. Our findings suggest an important role for the Aki1-CREB axis in DMM pathogenesis and provide a preclinical rationale to target Aki1 by intrathoracic therapy in locally advanced tumors.