Purpose Studies suggest that a subset of patients with triple-negative breast cancer (TNBC) have tumors that express the androgen receptor (AR) and may benefit from an AR inhibitor. This phase II ...study evaluated the antitumor activity and safety of enzalutamide in patients with locally advanced or metastatic AR-positive TNBC. Patients and Methods Tumors were tested for AR with an immunohistochemistry assay optimized for breast cancer; nuclear AR staining > 0% was considered positive. Patients received enzalutamide 160 mg once per day until disease progression. The primary end point was clinical benefit rate (CBR) at 16 weeks. Secondary end points included CBR at 24 weeks, progression-free survival, and safety. End points were analyzed in all enrolled patients (the intent-to-treat ITT population) and in patients with one or more postbaseline assessment whose tumor expressed ≥ 10% nuclear AR (the evaluable subgroup). Results Of 118 patients enrolled, 78 were evaluable. CBR at 16 weeks was 25% (95% CI, 17% to 33%) in the ITT population and 33% (95% CI, 23% to 45%) in the evaluable subgroup. Median progression-free survival was 2.9 months (95% CI, 1.9 to 3.7 months) in the ITT population and 3.3 months (95% CI, 1.9 to 4.1 months) in the evaluable subgroup. Median overall survival was 12.7 months (95% CI, 8.5 months to not yet reached) in the ITT population and 17.6 months (95% CI, 11.6 months to not yet reached) in the evaluable subgroup. Fatigue was the only treatment-related grade 3 or higher adverse event with an incidence of > 2%. Conclusion Enzalutamide demonstrated clinical activity and was well tolerated in patients with advanced AR-positive TNBC. Adverse events related to enzalutamide were consistent with its known safety profile. This study supports additional development of enzalutamide in advanced TNBC.
Direct reprogramming by overexpression of defined transcription factors is a promising new method of deriving useful but rare cell types from readily available ones. While the method presents ...numerous advantages over induced pluripotent stem (iPS) cell approaches, a focus on murine conversions and a reliance on retroviral vectors limit potential human applications. Here we address these concerns by demonstrating direct conversion of human fibroblasts to hepatocyte-like cells via repeated transfection with synthetic modified mRNAs. Hepatic induction was achieved with as little as three transcription factor mRNAs encoding HNF1A plus any two of the factors, FOXA1, FOXA3, or HNF4A in the presence of an optimized hepatic growth medium. We show that the absolute necessity of exogenous HNF1A mRNA delivery is explained both by the factor's inability to be activated by any other factors screened and its simultaneous ability to strongly induce expression of other master hepatic transcription factors. Further analysis of factor interaction showed that a series of robust cross-activations exist between factors that induce a hepatocyte-like state. Transcriptome and small RNA sequencing during conversion toward hepatocyte-like cells revealed global preferential activation of liver genes and miRNAs over those associated with other endodermal tissues, as well as downregulation of fibroblast-associated genes. Induced hepatocyte-like cells also exhibited hepatic morphology and protein expression. Our data provide insight into the process by which direct hepatic reprogramming occurs in human cells. More importantly, by demonstrating that it is possible to achieve direct reprogramming without the use of retroviral gene delivery, our results supply a crucial step toward realizing the potential of direct reprogramming in regenerative medicine.
Colony-stimulating factor 1 (CSF1) and interleukin 34 (IL34) signal
the CSF1 receptor to regulate macrophage differentiation. Studies in IL34- or CSF1-deficient mice have revealed that IL34 function ...is limited to the central nervous system and skin during development. However, the roles of IL34 and CSF1 at homeostasis or in the context of inflammatory diseases or cancer in wild-type mice have not been clarified
. By neutralizing CSF1 and/or IL34 in adult mice, we identified that they play important roles in macrophage differentiation, specifically in steady-state microglia, Langerhans cells, and kidney macrophages. In several inflammatory models, neutralization of both CSF1 and IL34 contributed to maximal disease protection. However, in a myeloid cell-rich tumor model, CSF1 but not IL34 was required for tumor-associated macrophage accumulation and immune homeostasis. Analysis of human inflammatory conditions reveals IL34 upregulation that may account for the protection requirement of IL34 blockade. Furthermore, evaluation of IL34 and CSF1 blockade treatment during
infection reveals no substantial safety concerns. Thus, IL34 and CSF1 play non-redundant roles in macrophage differentiation, and therapeutic intervention targeting IL34 and/or CSF1 may provide an effective treatment in macrophage-driven immune-pathologies.
The pregnane X receptor (PXR) was isolated as a xenosensor regulating xenobiotic responses. In this study, we show that PXR plays an endobiotic role by impacting lipid homeostasis. Expression of an ...activated PXR in the livers of transgenic mice resulted in an increased hepatic deposit of triglycerides. This PXR-mediated lipid accumulation was independent of the activation of the lipogenic transcriptional factor SREBP-1c (sterol regulatory element-binding protein 1c) and its primary lipogenic target enzymes, including fatty-acid synthase (FAS) and acetyl-CoA carboxylase 1 (ACC-1). Instead, the lipid accumulation in transgenic mice was associated with an increased expression of the free fatty acid transporter CD36 and several accessory lipogenic enzymes, such as stearoyl-CoA desaturase-1 (SCD-1) and long chain free fatty acid elongase. Studies using transgenic and knock-out mice showed that PXR is both necessary and sufficient for Cd36 activation. Promoter analyses revealed a DR-3-type of PXR-response element in the mouse Cd36 promoter, establishing Cd36 as a direct transcriptional target of PXR. The hepatic lipid accumulation and Cd36 induction were also seen in the hPXR “humanized” mice treated with the hPXR agonist rifampicin. The activation of PXR was also associated with an inhibition of pro-β-oxidative genes, such as peroxisome proliferator-activated receptor α (PPARα) and thiolase, and an up-regulation of PPARγ, a positive regulator of CD36. The cross-regulation of CD36 by PXR and PPARγ suggests that this fatty acid transporter may function as a common target of orphan nuclear receptors in their regulation of lipid homeostasis.
BackgroundIL-18 is an inflammatory cytokine with immuno-stimulatory activities on both the innate and adaptive immune systems. However, tumors generate an IL-18 decoy receptor (IL-18 BP), which ...inactivates both endogenous and exogenously administered IL-18. A decoy-resistant variant of IL-18 (ST-067) has been developed which binds to IL-18Ra but not IL-18 BP. In murine colorectal and melanoma syngeneic tumor models, ST-067 monotherapy and in combination with an anti-PD1 antibody demonstrated significant tumor regression and prolonged survival with an acceptable safety profile. These preclinical data provide the rationale for the current study which will determine the tolerability of both monotherapy and combination therapy in patients with solid tumor malignancies who have disease progression following the standard of care therapy which will include prior immunotherapy (NCT04787042).MethodsThis Phase 1 study is a multi-center, multi-dose dose-escalation trial to determine the maximum tolerated dose (MTD) and recommended Phase 2 dose (R2PD) of ST-067 monotherapy and combination therapy with pembrolizumab in subjects with advanced, solid tumor malignancies. Secondary endpoints of the trial include safety, characterization of pharmacokinetics, and immunogenicity. The dose-escalation phase will use a modified toxicity probability interval method to determine R2PD of ST-067 monotherapy and combination therapy with pembrolizumab. All subjects will receive ST-067 by the subcutaneous route once every 7 days. The RP2D for all ST-067 treatment arms will be based on the safety, tolerability, PK, and available preliminary anti-tumor activity. Key eligibility requirements include advanced, pre-treated solid tumor malignancy with adequate end-organ function and a PS of 0–1. All subjects will have pre- and on-treatment tumor biopsies which will be analyzed for PD biomarkers potentially predictive of response to therapy. Subjects will receive treatment until disease progression or unacceptable toxicity. Tumor assessments will be performed every 8 weeks and interpreted according to RECIST v1.1. Recruitment is ongoing in the US.AcknowledgementsCharlotte Halley, Erica Heaton, Lidia Zayas, Ashley Drokin, Tara Foote , Janine Miller, Kayla Pham, Brian Bengyak, Barbara Johnson for study coordination and patient careEthics ApprovalThis study was approved by either centralized or local institutional review board committees. All enrolled subjects gave signed informed consent prior to taking part of this study.ConsentWritten informed consent was obtained from the patient for publication of this abstract and any accompanying images. A copy of the informed consent is available for review by the editor if this journal.
Estrogen plays an important role in normal physiology. It is also a risk factor for breast cancer, and antiestrogen therapies have been shown to be effective in the treatment and prevention of breast ...cancers. The liver is important for estrogen metabolism, and a compromised liver function has been linked to hyperestrogenism in patients. In this report, we showed that the liver X receptor (LXR) controls estrogen homeostasis by regulating the basal and inducible hepatic expression of estrogen sulfotransferase (Est, or Sult1e1), an enzyme critical for metabolic estrogen deactivation. Genetic or pharmacological activation of LXR resulted in Est induction, which in turn inhibited estrogen-dependent uterine epithelial cell proliferation and gene expression, as well as breast cancer growth in a nude mouse model of tumorigenicity. We further established that Est is a transcriptional target of LXR, and deletion of the Est gene in mice abolished the LXR effect on estrogen deprivation. Interestingly, Est regulation by LXR appeared to be liver specific, further underscoring the role of liver in estrogen metabolism. Activation of LXR failed to induce other major estrogen-metabolizing enzymes, suggesting that the LXR effect on estrogen metabolism is Est specific. In summary, our results have revealed a novel mechanism controlling estrogen homeostasis in vivo and may have implications for drug development in the treatment of breast cancer and other estrogen-related cancerous endocrine disorders.
Cytosolic sulfotransferase (SULT)-mediated sulfation plays an essential role in the detoxification of bile acids and is necessary to avoid pathological conditions, such as cholestasis, liver damage, ...and colon cancer. In this study, using transgenic mice bearing conditional expression of the activated constitutive androstane receptor (CAR), we demonstrate that activation of CAR is both necessary and sufficient to confer resistance to the hepatotoxicity of lithocholic acid (LCA). Surprisingly, the CAR-mediated protection is not attributable to the expected and previously characterized CYP3A pathway; rather, it is associated with a robust induction of SULT gene expression and increased LCA sulfation. We have also provided direct evidence that CAR regulates SULT expression by binding to the CAR response elements found within the SULT gene promoters. Interestingly, activation of CAR was also associated with an increased expression of the 3'-phosphoadenosine 5'-phosphosulfate synthetase 2 (PAPSS2), an enzyme responsible for generating the sulfate donor 3'-phosphoadenosine-5'-phosphosulfate. Analysis of gene knockout mice revealed that CAR is also indispensable for ligand-dependent activation of SULT and PAPSS2 in vivo. Therefore, we establish an essential and unique role of CAR in controlling the mammalian sulfation system and its implication in the detoxification of bile acids.
Gallstone disease is a hepatobiliary disorder due to biochemical imbalances in the gallbladder bile. In this report, we show that activation of nuclear receptor liver X receptor (LXR) sensitized mice ...to lithogenic diet–induced gallbladder cholesterol crystallization, which was associated with dysregulation of several hepatic transporters that efflux cholesterol, phospholipids, and bile salts. The combined effect of increased biliary concentrations of cholesterol and phospholipids and decreased biliary concentrations of bile salts in LXR‐activated mice led to an increased cholesterol saturation index and the formation of cholesterol crystals. Interestingly, the lithogenic effect of LXR was completely abolished in the low‐density lipoprotein receptor (Ldlr) null background or when the mice were treated with Ezetimibe, a cholesterol‐lowering drug that blocks intestinal dietary cholesterol absorption. These results suggest that LDLR‐mediated hepatic cholesterol uptake and intestinal cholesterol absorption play an essential role in LXR‐promoted lithogenesis. Conclusion: The current study has revealed a novel lithogenic role of LXR as well as a functional interplay between LXR and LDLR in gallbladder cholesterol crystallization and possibly cholesterol gallstone disease (CGD). We propose that LXR is a lithogenic factor and that the LXR transgenic mice may offer a convenient CGD model to develop therapeutic interventions for this disease. (HEPATOLOGY 2008.)
Liver X receptors (LXRs) have been identified as sterol sensors that regulate cholesterol and lipid homeostasis and macrophage functions. In this study, we found that LXRs also affect sensitivity to ...bile acid toxicity and cholestasis. Activation of LXRα in transgenic mice confers a female‐specific resistance to lithocholic acid (LCA)–induced hepatotoxicity and bile duct ligation (BDL)–induced cholestasis. This resistance was also seen in wild‐type female mice treated with the synthetic LXR ligand TO1317. In contrast, LXR double knockout (DKO) mice deficient in both the α and β isoforms exhibited heightened cholestatic sensitivity. LCA and BDL resistance in transgenic mice was associated with increased expression of bile acid–detoxifying sulfotransferase 2A (Sult2a) and selected bile acid transporters, whereas basal expression of these gene products was reduced in the LXR DKO mice. Promoter analysis showed that the mouse Sult2a9 gene is a transcriptional target of LXRs. Activation of LXRs also suppresses expression of oxysterol 7α‐hydroxylase (Cyp7b1), which may lead to increased levels of LXR‐activating oxysterols. Conclusion: We propose that LXRs have evolved to have the dual functions of maintaining cholesterol and bile acid homeostasis by increasing cholesterol catabolism and, at the same time, preventing toxicity from bile acid accumulation. (HEPATOLOGY 2007;45:422–432.)
Kinases are heavily pursued pharmaceutical targets because of their mechanistic role in many diseases. Small molecule kinase inhibitors (SMKIs) are a compound class that includes marketed drugs and ...compounds in various stages of drug development. While effective, many SMKIs have been associated with toxicity including chromosomal damage. Screening for kinase-mediated toxicity as early as possible is crucial, as is a better understanding of how off-target kinase inhibition may give rise to chromosomal damage. To that end, we employed a competitive binding assay and an analytical method to predict the toxicity of SMKIs. Specifically, we developed a model based on the binding affinity of SMKIs to a panel of kinases to predict whether a compound tests positive for chromosome damage. As training data, we used the binding affinity of 113 SMKIs against a representative subset of all kinases (290 kinases), yielding a 113x290 data matrix. Additionally, these 113 SMKIs were tested for genotoxicity in an in vitro micronucleus test (MNT). Among a variety of models from our analytical toolbox, we selected using cross-validation a combination of feature selection and pattern recognition techniques: Kolmogorov-Smirnov/T-test hybrid as a univariate filter, followed by Random Forests for feature selection and Support Vector Machines (SVM) for pattern recognition. Feature selection identified 21 kinases predictive of MNT. Using the corresponding binding affinities, the SVM could accurately predict MNT results with 85% accuracy (68% sensitivity, 91% specificity). This indicates that kinase inhibition profiles are predictive of SMKI genotoxicity. While in vitro testing is required for regulatory review, our analysis identified a fast and cost-efficient method for screening out compounds earlier in drug development. Equally important, by identifying a panel of kinases predictive of genotoxicity, we provide medicinal chemists a set of kinases to avoid when designing compounds, thereby providing a basis for rational drug design away from genotoxicity.
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