Citations

There is considerable interest in harnessing innate immunity to treat Alzheimer’s disease (AD). Here, we explore whether a decoy receptor strategy using the ectodomain of select TLRs has therapeutic potential in AD. AAV-mediated expression of human TLR5 ectodomain (sTLR5) alone or fused to human IgG4 Fc (sTLR5Fc) results in robust attenuation of amyloid β (Aβ) accumulation in a mouse model of Alzheimer-type Aβ pathology. sTLR5Fc binds to oligomeric and fibrillar Aβ with high affinity, forms complexes with Aβ, and blocks Aβ toxicity. Oligomeric and fibrillar Aβ modulates flagellin-mediated activation of human TLR5 but does not, by itself, activate TLR5 signaling. Genetic analysis shows that rare protein coding variants in human TLR5 may be associated with a reduced risk of AD. Further, transcriptome analysis shows altered TLR gene expression in human AD. Collectively, our data suggest that TLR5 decoy receptor–based biologics represent a novel and safe Aβ-selective class of biotherapy in AD.

Thymidylate synthase (TYMS) is a crucial enzyme for DNA synthesis. TYMS expression is regulated by its antisense mRNA, ENOSF1. Disrupted regulation may promote uncontrolled DNA synthesis and tumor growth. We sought to replicate our previously reported association between rs495139 in the TYMS-ENOSF1 3′ gene region and increased risk of mucinous ovarian carcinoma (MOC) in an independent sample. Genotypes from 24,351 controls to 15,000 women with invasive OC, including 665 MOC, were available. We estimated per-allele odds ratios (OR) and 95% confidence intervals (CI) using unconditional logistic regression, and meta-analysis when combining these data with our previous report. The association between rs495139 and MOC was not significant in the independent sample (OR = 1.09; 95% CI = 0.97–1.22; p = 0.15; N = 665 cases). Meta-analysis suggested a weak association (OR = 1.13; 95% CI = 1.03–1.24; p = 0.01; N = 1019 cases). No significant association with risk of other OC histologic types was observed (p = 0.05 for tumor heterogeneity). In expression quantitative trait locus (eQTL) analysis, the rs495139 allele was positively associated with ENOSF1 mRNA expression in normal tissues of the gastrointestinal system, particularly esophageal mucosa (r = 0.51, p = 1.7 × 10−28), and nonsignificantly in five MOC tumors. The association results, along with inconclusive tumor eQTL findings, suggest that a true effect of rs495139 might be small.

Abstract INTRODUCTION AND OBJECTIVES: Patient responses to cancer immunotherapy such as checkpoint inhibitor drugs vary greatly between patients and there remains no biomarker to predict sensitivity to these drugs. We describe a patient derived xenograft (PDX) avatar system that predicts cancer immunotherapy responses in the context of tumor heterogeneity within 8-10 days. This avatar model preserves the original tumor microenvironment and tumor infiltrating lymphocytes (TILs) at a high tumor take rate for evaluation of various immunotherapy drugs. This prediction model also involves tumor infiltrating lymphocyte isolation and primary cell generation for confirming the immunotherapy response in vitro. This PDX avatar platform generates rapid actionable information and readily identifies patients that would maximally benefit from checkpoint inhibitor therapies in a phenotype-based manner. METHODS: Tissue from patients that underwent a nephrectomy for RCC or metastasectomy were engrafted into the chorioallantoic membrane of avian embryos with a portion used for TIL isolation and primary cell generation. PD-1 and PD-L1 checkpoint inhibitors were intravenously injected and high frequency ultrasound imaging and immunophenotyping was used to quantitate changes in tumor volume, vascularity, and TIL expansion in all treatment groups. Isolated TILs were expanded and co-cultured with respective primary cells to confirm and examine immunotherapy response at a molecular level. RESULTS: Patient PDXs demonstrated heterogeneous responses to immunotherapy that relates to presence and expansion of TILs after checkpoint inhibitor injection. Patient #1 demonstrated the greatest response with a >50% reduction in tumor volume and 4X expansion of T-cells over 8 days of treatment. Patient #2 demonstrated intratumoral heterogeneities in terms of tumor volume change after checkpoint inhibitors treatment despite TIL expansion in all treatment groups. Patient #3 showed no response that correlated to lack of TILs in the PDX. In vitro expansion of TILs and co-culture with primary cell line demonstrated a specific immune response via INF-gamma release and changes in immunomodulatory molecules. CONCLUSIONS: This PDX system preserves TILs and permits rapid large scale prediction of tumor specimens to various systemic therapy agents such as checkpoint inhibitors without the need for humanized models. This avatar system is a useful tool to rapidly predict and examine response to checkpoint inhibitors on a per-patient basis to improve the assignment of cancer immunotherapies to specific RCC patients. Citation Format: Mario Cepeda, Matthew Lowerison, Cindy Liu, Yarolslav Fedyshyn, Vidhu Joshi, Paras Shah, John Cheville, R. Houston Thompson, Boorjian Stephen, Bradley Leibovich, Haidong Dong, Hon S. Leong. Rapid patient derived xenograft avatars that consider tumor heterogeneity for prediction of cancer immunotherapy responses in metastatic renal cell carcinoma patients [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 LB-155.

Abstract Malignant pleural mesothelioma is a disease primarily associated with exposure to the carcinogen asbestos. Consistent with this carcinogenic exposure, cytogenetic analyses have identified multiple recurrent structural chromosomal abnormalities in this malignancy, but more recent high-throughput sequencing evaluations of point mutations suggest that there is a low mutational burden in mesothelioma. Since tumor mutational burden has been correlated with responses to treatment with immune checkpoint inhibitors such as nivolumab, it was not consistent that patients with mesothelioma and low mutation burdens would have similar response rates in clinical trials with immune checkpoint inhibitors as patients with non-small cell lung cancer which is associated with a high mutation burden. In order to reconcile these differences, and given the potential for an improved understanding of the molecular pathogenesis of mesothelioma to improve therapeutic options, we used mate-pair sequencing (MPseq) and RNA sequencing (RNAseq) to understand how structural variants affect the transcriptome. MPseq differs from standard next generation sequencing approaches by tiling the whole genome with larger fragments (2-5kb) to reliably detect structural variants such as insertions, deletions and rearrangements. Amongst 22 mesothelioma specimens there were 1535 chromosomal rearrangements (median 41, range 3-298 per specimen), that resulted in junctions or novel fusions of non-coding DNA or genes. Six-hundred thirty-seven of these rearrangements (median 22, range 5-103 range per specimen) resulted in novel fusions of genes. Many of these inter- or intra-chromosomal rearrangements were consistent with a pattern of chromoanagesis such as chromoplexy or chromothripsis. Chromosomal rearrangements detected by MPseq were used to guide analysis of RNAseq data and revealed that these chromosomal junctions resulted in the expression of 179 novel amino acid sequences (median 5, 0-51 range per specimen). To determine whether transcription of chromosomal rearrangement-related junctions have neoantigenic potential, we used in silico tools to determine whether any of the expressed junctions contained peptides that could be presented by patient-specific HLA molecules. The top candidate rearrangement-related peptides with neoantigenic potential bound patient-specific HLA molecules nearly as well or as well as a positive control in competitive binding assays. Our findings represent the discovery of potential neoantigen expression driven by structural chromosomal rearrangements. These results may have implications for the development of novel therapeutic strategies, the selection of patients to receive immunotherapy, and blood-based treatment monitoring strategies. Citation Format: Aaron S. Mansfield, Tobias Peikert, James B. Smadbeck, Julia B. Udell, Farhad Kosari, Stephen J. Murphy, Hongzheng Ren, Vishnu V. Serla, Janet L. Schaefer Klein, Giannoula Karagouga, Faye R. Harris, Carlos Sosa, Sarah H. Johnson, Wendy Nevala, Svetomir N. Markovic, Aaron O. Bungum, Eric S. Edell, Haidong Dong, John C. Cheville, Marie Christine Aubry, Jin Jen, George Vasmatzis. Rearrangement-related peptides with neoantigenic potential in malignant pleural mesothelioma [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 5726.

Abstract The liver is the most common site of metastasis in pancreatic ductal adenocarcinoma (PDAC). This metastatic tropism is dependent, at least in part, on the formation of a “pro-metastatic” niche that supports tumor cell seeding and colonization in the liver. However, mechanisms that direct the formation of this niche remain poorly understood. We show using the LSL-KrasG12D/+;LSL-Trp53R172H/+;Pdx-1-Cre (KPC) model of PDAC that pancreatic tumor development enhances the susceptibility of the liver to metastatic seeding by inducing recruitment of F4/80+ and Ly6G+ myeloid cells and fibrosis within the liver. 3' mRNA sequencing (QuantSeq) on RNA isolated from the liver of KPC mice versus control PC mice revealed that the liver produces a specific set of myeloid chemoattractants, particularly serum amyloid A1 and A2 (SAA1/2), early during PDAC development. In addition, gene set enrichment analysis (GSEA) on genes upregulated in the liver of KPC mice demonstrated a significant enrichment of the interleukin 6 (IL-6)/Signal Transducer and Activator of Transcription 3 (STAT3) signaling pathway. Consistent with this finding, phosphorylation of STAT3 was detected in 20-30% of F4/80+ myeloid cells and 80-90% of hepatocytes. A requirement for IL-6/STAT3 signaling in the formation of a pro-metastatic niche was determined by comparing the metastatic potential of wild type mice, Il-6 knockout (Il-6-/-) mice, and mice treated with anti-IL-6 receptor (IL-6R) antibody after orthotopic implantation of KPC-derived PDAC cells. Compared to wild type mice, the liver of Il-6-/- mice and mice treated with anti-IL-6R antibody was less susceptible to metastatic seeding and showed significantly less accumulation of myeloid cells, fibrosis, and production of SAA1/2 in the liver. We obtained similar results with mice that lack Stat3 specifically in hepatocytes (Stat3flox/flox Alb-Cre), demonstrating that IL-6/STAT3 signaling in hepatocytes is necessary for the formation of a pro-metastatic niche in the liver. Further, using Saa1/2 double knockout (Saa-/-) mice, we found that SAA1/2 production by hepatocytes was required for formation of the pro-metastatic niche in the liver and increased susceptibility to metastatic seeding. Patients with a history of liver metastasis also showed higher levels of SAA1/2 in the plasma compared to normal donors, and SAA overexpression was detected in hepatocytes in liver biopsy samples collected from PDAC patients. Collectively, our study reveals a novel role for hepatocytes in directing the formation of a pro-metastatic niche in the liver during PDAC development and identifies IL-6/STAT3/SAA1/2 signaling as a promising therapeutic target for prevention of metastasis in PDAC. Citation Format: Jae W. Lee, Stacy K. Thomas, Chad A. Komar, Whitney L. Gladney, Xia Hua, Dong Xin, Abraham Shaked, Mitesh J. Borad, Ramesh K. Ramanathan, Ailing Ji, Nancy R. Webb, Maria C. de Beer, Frederick C. de Beer, Paige M. Porrett, Gregory L. Beatty. IL-6/STAT3 activation in hepatocytes drives pro-metastatic niche formation in the liver [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 1102.

AbstractBackgroundAlthough the prognosis of core‐binding factor (CBF) acute myeloid leukemia (AML) is better than other subtypes of AML, 30% of patients still relapse and may require allogeneic hematopoietic cell transplantation (alloHCT). However, there is no validated widely accepted scoring system to predict patient subsets with higher risk of relapse.MethodsEleven centers in the US and Europe evaluated 247 patients with t(8;21)(q22;q22).ResultsComplete remission (CR) rate was high (92.7%), yet relapse occurred in 27.1% of patients. A total of 24.7% of patients received alloHCT. The median disease‐free (DFS) and overall (OS) survival were 20.8 and 31.2 months, respectively. Age, KIT D816V mutated (11.3%) or nontested (36.4%) compared with KIT D816V wild type (52.5%), high white blood cell counts (WBC), and pseudodiploidy compared with hyper‐ or hypodiploidy were included in a scoring system (named I‐CBFit). DFS rate at 2 years was 76% for patients with a low‐risk I‐CBFit score compared with 36% for those with a high‐risk I‐CBFit score (P < 0.0001). Low‐ vs high‐risk OS at 2 years was 89% vs 51% (P < 0.0001).ConclusionsI‐CBFit composed of readily available risk factors can be useful to tailor the therapy of patients, especially for whom alloHCT is not need in CR1 (ie, patients with a low‐risk I‐CBFit score).

Aims: Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disease thought to be caused by repetitive traumatic brain injury (TBI) and subconcussive injuries. While hyperphosphorylation of tau (p-Tau), which is attributed to astrocytic tangles (ATs) and neurofibrillary tangles, is known to be involved in CTE, there are limited neuropathological or molecular data. By utilizing repetitive mild TBI (rmTBI) mouse models, our aim was to examine the pathological changes of CTE-associated structures, specifically the ATs. Results: Our rmTBI mouse models showed symptoms of depressive behavior and memory deficit, alongside an increased p-Tau expression in their neurons and astrocytes in both the hippocampus and cortex. rmTBI induced oxidative stress in endothelial cells and nitric oxide (NO) generation in astrocytes, which were mediated by hypoxia and increased hypoxia-inducible factor 1-α (HIF1α). There was also correlated decreased regional cerebral tissue perfusion units, mild activation of astrocytes and NFκB phosphorylation, increased expression of inducible nitric oxide synthase (iNOS), increased endothelial nitric oxide synthase (eNOS) uncoupling with decreased tetrahydrobiopterin, and increased expression of nitrotyrosine, NADPH oxidase 2 (Nox2)/nuclear factor (erythroid-derived 2) factor 2 (Nrf2) signaling proteins. Combined, these effects induced peroxynitrite formation and hyperphosphorylation of tau in the hippocampus and cortex toward the formation of ATs. Innovation: Our model features molecular pathogenesis events of CTE with clinically relevant latency periods. In particular, this is the first demonstration of an increased astrocytic iNOS expression in an in vivo model. Conclusion: We propose a novel mechanism of uncoupled eNOS and NO contribution to Tau phosphorylation and AT formation in rmTBI brain, toward an increased molecular understanding of the pathophysiology of human CTE.