Axl and Mertk Receptors Cooperate to Promote Breast Cancer Progression by Combined Oncogenic Signaling and Evasion of Host Antitumor Immunity.

Despite the promising clinical benefit of targeted and immune checkpoint blocking therapeutics, current strategies have limited success in breast cancer, indicating that additional inhibitory pathways are required to complement existing therapeutics. TAM receptors (Tyro-3, Axl, and Mertk) are often correlated with poor prognosis because of their capacities to sustain an immunosuppressive environment. Here, we ablate Axl on tumor cells using CRISPR/Cas9 gene editing, and by targeting Mertk in the tumor microenvironment (TME), we observed distinct functions of TAM as oncogenic kinases, as well as inhibitory immune receptors. Depletion of Axl suppressed cell intrinsic oncogenic properties, decreased tumor growth, reduced the incidence of lung metastasis and increased overall survival of mice when injected into mammary fat pad of syngeneic mice, and demonstrated synergy when combined with anti-PD-1 therapy. Blockade of Mertk function on macrophages decreased efferocytosis, altered the cytokine milieu, and resulted in suppressed macrophage gene expression patterns. Mertk-knockout mice or treatment with anti-Mertk-neutralizing mAb also altered the cellular immune profile, resulting in a more inflamed tumor environment with enhanced T-cell infiltration into tumors and T-cell-mediated cytotoxicity. The antitumor activity from Mertk inhibition was abrogated by depletion of cytotoxic CD8α T cells by using anti-CD8α mAb or by transplantation of tumor cells into B6.CB17-Prkdc SCID mice. Our data indicate that targeting Axl expressed on tumor cells and Mertk in the TME is predicted to have a combinatorial benefit to enhance current immunotherapies and that Axl and Mertk have distinct functional activities that impair host antitumor response. SIGNIFICANCE: This study demonstrates how TAM receptors act both as oncogenic tyrosine kinases and as receptors that mediate immune evasion in cancer progression.

Multiple Plasma Biomarkers for Risk Stratification in Patients With Heart Failure and Preserved Ejection Fraction.

BACKGROUND: Better risk stratification strategies are needed to enhance clinical care and trial design in heart failure with preserved ejection fraction (HFpEF). OBJECTIVES: The purpose of this study was to assess the value of a targeted plasma multi-marker approach to enhance our phenotypic characterization and risk prediction in HFpEF. METHODS: In this study, the authors measured 49 plasma biomarkers from TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist) trial participants (n = 379) using a Multiplex assay. The relationship between biomarkers and the risk of all-cause death or heart failure-related hospital admission (DHFA) was assessed. A tree-based pipeline optimizer platform was used to generate a multimarker predictive model for DHFA. We validated the model in an independent cohort of HFpEF patients enrolled in the PHFS (Penn Heart Failure Study) (n = 156). RESULTS: Two large, tightly related dominant biomarker clusters were found, which included biomarkers of fibrosis/tissue remodeling, inflammation, renal injury/dysfunction, and liver fibrosis. Other clusters were composed of neurohormonal regulators of mineral metabolism, intermediary metabolism, and biomarkers of myocardial injury. Multiple biomarkers predicted incident DHFA, including 2 biomarkers related to mineral metabolism/calcification (fibroblast growth factor-23 and OPG [osteoprotegerin]), 3 inflammatory biomarkers (tumor necrosis factor-alpha, sTNFRI [soluble tumor necrosis factor-receptor I], and interleukin-6), YKL-40 (related to liver injury and inflammation), 2 biomarkers related to intermediary metabolism and adipocyte biology (fatty acid binding protein-4 and growth differentiation factor-15), angiopoietin-2 (related to angiogenesis), matrix metalloproteinase-7 (related to extracellular matrix turnover), ST-2, and N-terminal pro-B-type natriuretic peptide. A machine-learning-derived model using a combination of biomarkers was strongly predictive of the risk of DHFA (standardized hazard ratio: 2.85; 95% confidence interval: 2.03 to 4.02; p < 0.0001) and markedly improved the risk prediction when added to the MAGGIC (Meta-Analysis Global Group in Chronic Heart Failure Risk Score) risk score. In an independent cohort (PHFS), the model strongly predicted the risk of DHFA (standardized hazard ratio: 2.74; 95% confidence interval: 1.93 to 3.90; p < 0.0001), which was also independent of the MAGGIC risk score. CONCLUSIONS: Various novel circulating biomarkers in key pathophysiological domains are predictive of outcomes in HFpEF, and a multimarker approach coupled with machine-learning represents a promising strategy for enhancing risk stratification in HFpEF.

Pan-TAM Tyrosine Kinase Inhibitor BMS-777607 Enhances Anti-PD-1 mAb Efficacy in a Murine Model of Triple-Negative Breast Cancer.

Tyro3, Axl, and Mertk (TAM) represent a family of homologous tyrosine kinase receptors known for their functional role in phosphatidylserine (PS)-dependent clearance of apoptotic cells and also for their immune modulatory functions in the resolution of inflammation. Previous studies in our laboratory have shown that Gas6/PS-mediated activation of TAM receptors on tumor cells leads to subsequent upregulation of PD-L1, defining a putative PS→TAM receptor→PD-L1 inhibitory signaling axis in the cancer microenvironment that may promote tolerance. In this study, we tested combinations of TAM inhibitors and PD-1 mAbs in a syngeneic orthotopic E0771 murine triple-negative breast cancer model, whereby tumor-bearing mice were treated with pan-TAM kinase inhibitor (BMS-777607) or anti-PD-1 alone or in combination. Tyro3, Axl, and Mertk were differentially expressed on multiple cell subtypes in the tumor microenvironment. Although monotherapeutic administration of either pan-TAM kinase inhibitor (BMS-777607) or anti-PD-1 mAb therapy showed partial antitumor activity, combined treatment of BMS-777607 with anti-PD-1 significantly decreased tumor growth and incidence of lung metastasis. Moreover, combined treatment with BMS-777607 and anti-PD-1 showed increased infiltration of immune stimulatory T cells versus either monotherapy treatment alone. RNA NanoString profiling showed enhanced infiltration of antitumor effector T cells and a skewed immunogenic immune profile. Proinflammatory cytokines increased with combinational treatment. Together, these studies indicate that pan-TAM inhibitor BMS-777607 cooperates with anti-PD-1 in a syngeneic mouse model for triple-negative breast cancer and highlights the clinical potential for this combined therapy. SIGNIFICANCE: These findings show that pan-inhibition of TAM receptors in combination with anti-PD-1 may have clinical value as cancer therapeutics to promote an inflammatory tumor microenvironment and improve host antitumor immunity.

Discovery of the Selective CYP17A1 Lyase Inhibitor BMS-351 for the Treatment of Prostate Cancer.

Efforts to identify a potent, reversible, nonsteroidal CYP17A1 lyase inhibitor with good selectivity over CYP17A1 hydroxylase and CYPs 11B1 and 21A2 for the treatment of castration-resistant prostate cancer (CRPC) culminated in the discovery of BMS-351 (compound 18), a pyridyl biaryl benzimidazole with an excellent in vivo profile. Biological evaluation of BMS-351 at a dose of 1.5 mg in castrated cynomolgus monkeys revealed a remarkable reduction in testosterone levels with minimal glucocorticoid and mineralcorticoid perturbation. Based on a favorable profile, BMS-351 was selected as a candidate for further preclinical evaluation.

Discovery of BMS-641988, a novel and potent inhibitor of androgen receptor signaling for the treatment of prostate cancer.

Despite an excellent initial response to first-line hormonal treatment, most patients with metastatic prostate cancer will succumb to a hormone-refractory form of the disease. Because these tumors are still dependent on a functional androgen receptor (AR), there is a need to find novel and more potent antiandrogens. While searching for small molecules that bind to the AR and inhibit its transcriptional activity, BMS-641988 was discovered. This novel antiandrogen showed an increased (>1 log) potency compared with the standard antiandrogen, bicalutamide, in both binding affinity to the AR and inhibition of AR-mediated transactivation in cell-based reporter assays. In mature rats, BMS-641988 strongly inhibited androgen-dependent growth of the ventral prostate and seminal vesicles. In the CWR-22-BMSLD1 human prostate cancer xenograft model, BMS-641988 showed increased efficacy over bicalutamide (average percent tumor growth inhibition >90% versus <50%), even at exposure levels of bicalutamide 3-fold greater than what can be attained in humans. Furthermore, BMS-641988 was efficacious in CWR-22-BMSLD1 tumors initially refractory to treatment with bicalutamide. BMS-641988 was highly efficacious in the LuCaP 23.1 human prostate xenograft model, inducing stasis throughout the approximately 30-day dosing. To explore the functional mechanisms of BMS-641988, gene expression profiling analysis was done on CWR-22-BMSLD1 xenograft models in mice. Treatment with BMS-641988 resulted in a global gene expression profile more similar to castration compared with that of bicalutamide. Overall, these data highlight that the unique preclinical profile of BMS-641988 may provide additional understanding for the hormonal treatment of prostate cancer.

The androgen receptor can signal through Wnt/beta-Catenin in prostate cancer cells as an adaptation mechanism to castration levels of androgens.

BACKGROUND: A crucial event in Prostate Cancer progression is the conversion from a hormone-sensitive to a hormone-refractory disease state. Correlating with this transition, androgen receptor (AR) amplification and mutations are often observed in patients failing hormonal ablation therapies. beta-Catenin, an essential component of the canonical Wnt signaling pathway, was shown to be a coactivator of the AR signaling in the presence of androgens. However, it is not yet clear what effect the increased levels of the AR could have on the Wnt signaling pathway in these hormone-refractory prostate cells. RESULTS: Transient transfections of several human prostate cancer cell lines with the AR and multiple components of the Wnt signaling pathway demonstrate that the AR overexpression can potentiate the transcriptional activities of Wnt/beta-Catenin signaling. In addition, the simultaneous activation of the Wnt signaling pathway and overexpression of the AR promote prostate cancer cell growth and transformation at castration levels of androgens. Interestingly, the presence of physiological levels of androgen or other AR agonists inhibits these effects. These observations are consistent with the nuclear co-localization of the AR and beta-Catenin shown by immunohistochemistry in human prostate cancer samples. Furthermore, chromatin immunoprecipitation assays showed that Wnt3A can recruit the AR to the promoter regions of Myc and Cyclin D1, which are well-characterized downstream targets of the Wnt signalling pathway. The same assays demonstrated that the AR and beta-Catenin can be recruited to the promoter and enhancer regions of a known AR target gene PSA upon Wnt signaling. These results suggest that the AR is promoting Wnt signaling at the chromatin level. CONCLUSION: Our findings suggest that the AR signaling through the Wnt/beta-Catenin pathway should be added to the well established functional interactions between both pathways. Moreover, our data show that via this interaction the AR could promote prostate cell malignancy in a ligand-independent manner.

Identification of a novel series of tetrahydrodibenzazocines as inhibitors of 17beta-hydroxysteroid dehydrogenase type 3.

A novel series of 17beta-hydroxysteroid dehydrogenase type 3 (17beta-HSD3) inhibitors has been identified. These inhibitors, based on a dibenzazocine core, exhibited picomolar to low nanomolar inhibition of 17beta-HSD3 in cell-free enzymatic as well as in cell-based transcriptional reporter assays.

Identification of novel functional inhibitors of 17beta-hydroxysteroid dehydrogenase type III (17beta-HSD3).

BACKGROUND: Endocrine therapy of prostate cancer (PCa) relies on agents which disrupt the biosynthesis of testosterone in the testis and/or by direct antagonism of active hormone on the androgen receptor (AR) in non-gonadal target tissues of hormone action such as the prostate. METHODS: In an effort to evaluate new therapies which could inhibit gonadal or non-gonadal testosterone biosynthesis, we developed high throughput biochemical and cellular screening assays to identify inhibitors of 17beta-hydroxysteroid dehydrogenase type III (17beta-HSD3), the enzyme catalyzing the conversion of androstenedione (AdT) to testosterone. RESULTS: Initial screening efforts identified a natural product, 18beta-glycyrrhetinic acid, and a novel derivative of AdT, 3-O-benzylandrosterone, as potent inhibitors of the enzyme. Further efforts led to the identification of several classes of non-steroidal, low molecular weight compounds that potently inhibited 17beta-HSD3 enzymatic activity. One of the most potent classes of 17beta-HSD3 inhibitors was a series of anthranilamide small molecules identified from a collection of compounds related to non-steroidal modulators of nuclear hormone receptors. The anthranilamide based 17beta-HSD3 inhibitors were exemplified by BMS-856, a compound displaying low nanomolar inhibition of 17beta-HSD3 enzymatic activity. In addition, this series of compounds displayed potent inhibition of 17beta-HSD3-mediated cellular conversion of AdT to testosterone and inhibited the 17beta-HSD3-mediated conversion of testosterone necessary to promote AR-dependent transcription. CONCLUSIONS: The identification of non-steroidal functional inhibitors of 17beta-HSD3 may be a useful complementary approach for the disruption of testosterone biosynthesis in the treatment of PCa.