Targeting HDAC6 to treat heart failure with preserved ejection fraction in mice

Heart failure with preserved ejection fraction (HFpEF) poses therapeutic challenges due to the limited treatment options. Building upon our previous research that demonstrates the efficacy of histone deacetylase 6 (HDAC6) inhibition in a genetic cardiomyopathy model, we investigate HDAC6's role in HFpEF due to their shared mechanisms of inflammation and metabolism. Here, we show that inhibiting HDAC6 with TYA-018 effectively reverses established heart failure and its associated symptoms in male HFpEF mouse models. Additionally, in male mice lacking Hdac6 gene, HFpEF progression is delayed and they are resistant to TYA-018's effects. The efficacy of TYA-018 is comparable to a sodium-glucose cotransporter 2 (SGLT2) inhibitor, and the combination shows enhanced effects. Mechanistically, TYA-018 restores gene expression related to hypertrophy, fibrosis, and mitochondrial energy production in HFpEF heart tissues. Furthermore, TYA-018 also inhibits activation of human cardiac fibroblasts and enhances mitochondrial respiratory capacity in cardiomyocytes. In this work, our findings show that HDAC6 impacts on heart pathophysiology and is a promising target for HFpEF treatment.

Abstract A030: Biomarker study of vantictumab plus paclitaxel in HER2- breast cancer patients

Introduction: We have developed a monoclonal antibody, vantictumab, that blocks canonical Wnt/β-catenin signaling through binding of five FZD receptors (1, 2, 5, 7, and 8). This antibody inhibits the growth of several tumor types, including breast. Vantictumab reduces tumor-initiating cell frequency and exhibits synergistic activity with standard-of-care (SOC) agents (Gurney et al., 2012). To confirm the mechanism of action and to potentially target breast cancer patients most likely to respond to vantictumab, we undertook a biomarker study. Methods: We previously identified a 6-gene Wnt pathway-related signature, FBXW2, CCND2, RHOU, CTBP2, WIF1, and DKK1, based on microarray gene expression data from 8 BC patient-derived xenograft (PDX) models with established in vivo response to vantictumab plus SOC. This signature successfully predicted the response of 8 additional and independent PDX breast tumors. We further developed a qPCR Research Use Only (RUO) assay for the 6 genes for use on FFPE human breast tumor samples. This assay was evaluated in the phase 1b study of vantictumab in combination with paclitaxel in locally recurrent or metastatic HER2- breast cancer (NCT01973309) and the signature was refined using a Lasso model with overall survival as the outcome. A repeated 10 fold cross-validation was used to evaluate the performance of the gene signature. The association of the signature with progression-free survival (PFS) and overall survival (OS) was examined (n=40 patients). Furthermore, pharmacodynamic (PD) biomarker analyses were performed on tumor biopsies and hair follicles by comparing gene expression data from post-treatment time points versus baseline data (Affymetrix U133 plus 2 Microarrays). Results: A potential predictive 6-gene Wnt pathway biomarker was identified based on preclinical data and the biomarker was evaluated and refined in a phase 1b study of vantictumab in combination with paclitaxel in HER2- breast cancer. In the phase 1b study, AUC = 75% with repeated 10 fold cross-validation measuring the performance of the gene signature. Based on this analysis, two genes, RHOU and DKK1, were dropped from the preclinical gene signature, which was consistent with the feature ranking in the preclinical qPCR data. The refined 4-gene signature was significantly associated with both PFS and OS at a 50% percentile cut-off. In addition, analysis of PD biomarkers demonstrated that Wnt pathway target genes including AXIN2, LEF1, and CTNNB1 were downregulated while differentiation markers, e.g., KRT19 and Wnt pathway inhibitors, e.g., SFRP1, DKK3 were upregulated by vantictumab plus paclitaxel. Conclusions: We developed a 4-gene signature as a potential predictive biomarker for the response to vantictumab plus paclitaxel in HER2- breast cancer. PD biomarker analysis in tumors and hair follicles confirmed the mechanism of action of vantictumab in patient samples. Preliminary efficacy of vantictumab plus paclitaxel in the phase 1b study was encouraging, particularly in breast cancer patients positive for the 4-gene signature. Updated biomarker and PK/PD data from the phase 1b trial (NCT01973309) will also be presented.

Citation Format: Chun Zhang, William R. Henner, Min Wang, Fiore Cattaruzza, Pete Yeung, Gilbert O'Young, Yuwang Liu, Gretchen Argast, Lu Xu, Shailaja Uttamsingh, John Lewicki, Ann M. Kapoun. Biomarker study of vantictumab plus paclitaxel in HER2- breast cancer patients [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A030.

Abstract 5621: Prevalence of GITR expression and pharmacodynamic (PD) biomarkers in syngeneic tumor models treated by a GITR agonist (GITRL-Fc)

GITRL (Glucocorticoid-Induced Tumor Necrosis Factor Receptor Ligand, TNFSF18) is a member of the tumor necrosis factor (TNF) ligand superfamily. GITRL binds and activates the co-stimulatory surface receptor GITR, which promotes proliferation and activation of effector T cells (Teff) and inhibits suppressive activity of regulatory T cells (Treg). It is thus hypothesized that co-stimulation of GITR by agonist agents will promote anti-tumor immunity. We generated a novel single-gene GITRL trimer fused to an immunoglobulin Fc domain (GITRL-Fc) that shows robust single agent antitumor efficacy and immune effects in multiple syngeneic mouse models, suggesting its potential benefit in cancer immunotherapy To investigate the prevalence of GITR expression in human tumors, RNA-Seq data analyses of 33 tumor types in TCGA showed GITR is highly expressed in a subset of solid tumors, including head & neck, lung, breast, esophageal, and bladder cancers. In most solid tumors, GITR expression correlated poorly with T cell markers, implying that GITR may not be exclusive to immune cells and may be expressed in tumor cells as well. Similar findings emerged from RNA-Seq data analysis of patient-derived xenograft (PDX) samples from 24 tumor types. The gene expression data was corroborated by immunohistochemistry (IHC) analysis of GITR expression in 17 tumor types which showed that in addition to immune cells, GITR was expressed on tumor cell membranes. A multi-platform approach was taken to investigate GITRL-Fc pharmacodynamic (PD) biomarkers in tumors and in matched whole blood samples from mice bearing CT26 colon, 4T1 breast, and B16F10 melanoma carcinoma models. Global gene expression levels were profiled by microarray on treated and control tissues. We also monitored the changes of immune cell populations and cytokine secretions by flow cytometry, Luminex and IHC. Immune gene changes were more robust in tumors than in blood samples. In tumor samples, GITRL-Fc increased the gene expression associated with T cells, CD8 T cells, cytotoxicity, Th1 cells, interferon gamma (IFN-γ), natural killer cells, Teff cells, and T cell activation markers. These gene changes were validated by quantitative real-time PCR. Similarly, flow cytometry analysis showed that GITRL-Fc promoted activation of CD4+ effector cells, decreased Treg frequency, and increased the ratio of CD8+ T cell/Treg in the tumor. GITRL-Fc also modulated secretion of cytokines in splenocytes, including an increase in IFN-γ. Taken together, the PD biomarker changes in immune-related gene expression, immune cell populations, and cytokine secretions observed in these preclinical tumor models are consistent with GITRL-Fc mechanism of action and demonstrated target engagement of GITRL-Fc. Additional approaches, including in-silico sorting, to monitor rare immune cell populations in tumor samples will be discussed.

Citation Format: Min Wang, Fiore Cattaruzza, Pete Yeung, Alayne Brunner, Erwan LeScolan, Yuwang Liu, Jennifer Cain, Gilbert OYoung, Earth Light Lowe, Belinda Cancilla, Rose Harris, Tim Hoey, Austin Gurney, John Lewicki, Gretchen Argast, Ann M. Kapoun. Prevalence of GITR expression and pharmacodynamic (PD) biomarkers in syngeneic tumor models treated by a GITR agonist (GITRL-Fc) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5621. doi:10.1158/1538-7445.AM2017-5621

Abstract 1727: Circulating Tumor Cells (CTCs) in patients with extensive stage small cell lung cancer and their association with clinical outcome

Background: The NOTCH pathway has been identified as a key therapeutic pathway in SCLC. Tarextumab (TRXT, anti-Notch2/3, OMP-59R5) is a fully human monoclonal antibody that targets the Notch2 and Notch3 receptors. PINNACLE is a Phase 1b/2 trial of TRXT in combination with etoposide and platinum therapy (EP) in patients with untreated extensive stage small cell lung cancer (ES-SCLC). Baseline CTCs and post treatment changes in CTCs have previously been shown to predict the response to chemotherapy in SCLC. CTCs may also serve as pharmacodynamic biomarkers. Here we describe a study of baseline and longitudinal CTCs in ES-SCLC patients from the PINNACLE phase 1b trial (clinicaltrials.gov:NCT01859741).

Materials and methods: CTCs, CTC clusters, apoptotic CTCs and N-Cadherin+ CTCs were identified and enumerated from patient blood samples using Epic Sciences CTC technology. Baseline CTCs from 26 patients were correlated with clinical outcome: progression-free survival (PFS), overall survival (OS) and best overall response, as well as metastatic status. A mixed effects model was used to investigate the post treatment changes in CTCs among the dose groups. Association of CTCs with PFS/OS and best overall response, including CTCs at each time point, as well as temporal changes of CTC status, were studied. Multivariate analysis was performed to identify CTC numbers in a subset of time points to correlate with response to treatment.

Results: CTCs were present in 81% of the patients (21/26). CTC clusters and apoptotic CTCs were detected in 38% and 77% of the patients, respectively. At baseline, CTC counts ≥ 5/mL were significantly associated with poor OS (p=0.04). There was a trend that the presence of CTC clusters was associated with worse OS. With a cut-off of 3.4/mL, apoptotic CTCs showed a trend in association with overall survival. CTC numbers in patients with liver metastasis were significantly higher than in patients without liver metastasis. CTCs were also found to be correlated significantly with the number of metastatic sites. When measuring at Day 7 post dosing, CTC numbers were significantly decreased.

Conclusions: Our findings suggest that CTCs are frequently detectable in patients and are a prognostic factor in ES-SCLC. CTCs decrease with TRXT and platinum-based chemotherapy. Updated results will be presented. CTCs will be further evaluated in the phase 2 portion of the PINNACLE trial.

Citation Format: Chun Zhang, Ryon Graf, Adam Jendrisak, Amanda K. Anderson, Priscilla Ontiveros, Sarah Orr, Anne Chiang, David Spigel, Charles Rudin, Eric Holmgren, Jakob Dupont, Gretchen Argast, Leonardo Faoro, Lei Zhou, John Lewicki, Ann M. Kapoun. Circulating Tumor Cells (CTCs) in patients with extensive stage small cell lung cancer and their association with clinical outcome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1727. doi:10.1158/1538-7445.AM2017-1727

Abstract 3370: The role of epithelial to mesenchymal transition (EMT) in resistance to Erlotinib in EGFR mutant NSCLC cell line models

The EGFR kinase inhibitor erlotinib is approved as a maintenance therapy in 1st line NSCLC as well as for treatment of 2nd/3rd line NSCLC and in combination with Gemcitabine for pancreatic cancer. It has been observed that the most pronounced responses to EGFR tyrosine kinase inhibitors (TKI's) were observed in patients whose tumors expressed a mutated form of the EGFR kinase. These mutations mapped to the kinase domain of the receptor and functionally have been shown to render tumors and cells lines onco-addicted to EGFR signaling. Although patients expressing a mutated EGFR show a dramatic initial response to EGFR TKI's, ∼50% of these patients will progress while on therapy after 1-2 years. The mechanisms that underlie this acquired resistance to EGFR TKI therapy have been intensively studied and include but are not limited to the presence of a second mutation, T790M, or increased HGF-MET signaling.

Previously, the role of epithelial to mesenchymal transition (EMT) in resistance to EGFR kinase inhibitors has been described in the context of wild type EGFR. EMT. We were therefore interested in understanding whether EMT could play a role in resistance to EGFR TKIs in the context of an EGFR mutation. Here we show that a panel of NSCLC cell lines, expressing mutant EGFR, can undergo an EMT in response to TGFβ treatment. The cell lines take on a scattered and spindle-like morphology and also down regulate the expression of E-cadherin and up regulate expression of vimentin, classic protein markers of an EMT. Importantly we show that after undergoing EMT, the EGFR mutant line HCC827 has reduced sensitivity to erlotnib treatment which is regained after reversal of the EMT. To further explore whether EMT could play a role in acquired resistance to erlotinib, we generated in vitro cell line models that were resistant to EGFR inhibition through continued culturing in the presence of erlotinib over a 6 month period. Resistant clones generated from parental HCC4006 cells acquired a more scattered and spindle-like morphology consistent with an EMT. These clones had down-regulated E-cadherin and ErbB3 expression and upregulated vimentin, fibronectin and Zeb1 expression and also showed a gene expression pattern consistent with having undergone an EMT. In addition, the resistant H4006 clones were more migratory and invasive than their parental counterpart. Finally we show that the resistant clones are enriched for stem cell markers and have enhanced signaling through the Src family kinases and the JAK-STAT pathway suggesting a mechanistic rationale for their reduced sensitivity to EGFR inhibitors.

Taken together. these data indicate that NSCLC cell lines that express a mutant version of EGFR are able to undergo an EMT which can influence the efficacy of EGFR TKIs, suggesting that this may be an additional mechanism underlying the acquired resistance of NSCLC patients to EGFR therapy in the clinic.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3370. doi:10.1158/1538-7445.AM2011-3370

Functional proteomic analysis of melanoma progression

Functional proteomics provides a powerful approach to screen for alterations in protein expression and posttranslational modifications under conditions of human disease. In this study, we use protein screening to examine markers of melanoma progression, by profiling melanocyte versus melanoma cell lines using two-dimensional electrophoresis and mass spectrometry. Eight candidate markers were identified as differentially regulated in transformed cells. In particular, hepatoma-derived growth factor (HDGF) and nucleophosmin B23 were strongly correlated with melanoma. Nucleophosmin B23 is a nucleolar and centrosome-associated protein, which has been implicated as a target for cyclin E/cyclin-dependent kinase 2 (CDK2) in modulating centrosome duplication and cell cycle control. Western blotting of one-dimensional and two-dimensional gels showed that the form of nucleophosmin B23 that is up-regulated in melanoma represents a posttranslationally modified form, most likely reflecting enhanced phosphorylation in the tumor-derived cells. In contrast, Western analysis of HDGF demonstrated increased expression of all forms in melanoma cell lines compared with melanocytes. Immunohistochemical analysis of human tissue biopsies showed strong expression of HDGF in early and late stage melanomas and low expression in melanocytes and nontumorigenic nevi. Interestingly, biopsies of nevi showed a graded effect in which HDGF immunoreactivity was reduced in nevoid nests penetrating deep into the dermis compared with nests at the epidermal-dermal junction, suggesting that HDGF expression in nevi is dependent on epidermal cell interactions. In contrast, biopsies of melanoma showed strong expression of HDGF throughout the tumor, including cells located deeply within dermis. Thus, expression of this antigen likely reports a reduced dependence of protein expression on epidermal interactions.