von Roemeling, Christina A

Abstract Current advances in the treatment of melanoma brain metastases through immune checkpoint blockade and targeted therapy has significantly improved outcomes and patient survival. Yet, half of all patients continue to die from brain metastases despite use of these therapies and the addition of localized therapies like surgery and stereotactic radiosurgery. Novel treatments are needed to improve the morbidity and mortality associated with melanoma brain metastases. We have identified the inflammatory myddosomal pathway as a novel potential target of therapy in melanoma brain metastases, with gross upregulation in both tumor tissue and tumor-infiltrating immune cells. These cells display upregulation in MYD88, IRAK-1, IRAK-4, and downstream mediators of inflammatory activation at both the gene and protein level. We have previously shown the ability of the oral IRAK-4 inhibitor emavusertib (CA-4948) to penetrate the blood brain barrier and inhibit the myddosomal pathway in metastatic melanoma and primary CNS lymphoma. In this study we further show the capacity for IRAK-4 inhibition with emavusertib to improve the therapeutic efficacy of anti-PD-1 immune checkpoint blockade in melanoma brain metastases. Emavusertib in combination with anti-PD-1 therapy results in improved tumor-infiltrating lymphocyte recruitment, decreased myeloid derived suppressor cell function, and upregulation of interferon γ signaling resulting in improved survival in aggressive mouse models of melanoma brain metastases. This work supports the development of combination strategies of emavusertib with immune checkpoint blockade in melanoma brain metastases.

Abstract Purpose: An ongoing challenge in cancer is the management of primary and metastatic brain malignancies. This is partly due to restrictions of the blood-brain barrier and their unique microenvironment. These challenges are most evident in cancers such as lymphoma and melanoma, which are typically responsive to treatment in systemic locations but resistant when established in the brain. We propose interleukin-1 receptor-associated kinase-4 (IRAK-4) as a potential target across these diseases and describe the activity and mechanism of oral IRAK-4 inhibitor CA-4948. Experimental Design: Human primary central nervous system lymphoma (PCNSL) and melanoma brain metastases (MBM) samples were analyzed for expression of IRAK-4 and downstream transcription pathways. We next determined the central nervous system (CNS) applicability of CA-4948 in naïve and tumor-bearing mice using models of PCNSL and MBM. The mechanistic effect on tumors and the tumor microenvironment was then analyzed. Results: Human PCNSL and MBM have high expression of IRAK-4, IRAK-1, and nuclear factor kappa B (NF-κB). This increase in inflammation results in reflexive inhibitory signaling. Similar profiles are observed in immunocompetent murine models. Treatment of tumor-bearing animals with CA-4948 results in the downregulation of mitogen-activated protein kinase (MAPK) signaling in addition to decreased NF-κB. These intracellular changes are associated with a survival advantage. Conclusions: IRAK-4 is an attractive target in PCNSL and MBM. The inhibition of IRAK-4 with CA-4948 downregulates the expression of important transcription factors involved in tumor growth and proliferation. CA-4948 is currently being investigated in clinical trials for relapsed and refractory lymphoma and warrants further translation into PCNSL and MBM.

Abstract During development of pancreatic cancer, alternatively activated macrophages contribute to fibrogenesis, pancreatic intraepithelial neoplasia (PanIN) lesion growth, and generation of an immunosuppressive environment. Here, we show that the immunomodulatory agent pomalidomide depletes pancreatic lesion areas of alternatively activated macrophage populations. Pomalidomide treatment resulted in downregulation of interferon regulatory factor 4, a transcription factor for M2 macrophage polarization. Pomalidomide-induced absence of alternatively activated macrophages led to a decrease in fibrosis at PanIN lesions and in syngeneic tumors; this was due to generation of an inflammatory, immune-responsive environment with increased expression of IL1α and presence of activated (IFNγ-positive) CD4+ and CD8+ T-cell populations. Our results indicate that pomalidomide could be used to decrease fibrogenesis in pancreatic cancer and may be ideal as a combination treatment with chemotherapeutic drugs or other immunotherapies. Significance: These findings reveal new insights into how macrophage populations within the pancreatic cancer microenvironment can be modulated, providing the means to turn the microenvironment from immunosuppressive to immune-responsive.

AbstractA major challenge in the development of cancer nanomedicine is the inability for nanomaterials to efficiently penetrate and deliver therapeutic agents into solid tumors. Previous studies have shown that tumor vasculature and extracellular matrix regulate the transvascular and interstitial transport of nanoparticles, both critical for successfully delivering nanomedicine into solid tumors. Within the malignant tumor microenvironment, blood vessels are morphologically abnormal and functionally exhibit substantial permeability. Furthermore, the tumor extracellular matrix (ECM), unlike that of the normal tissue parenchyma, is densely packed with collagen. These pathophysiological properties greatly impede intratumoral delivery of nanomaterials. By using an antivascular endothelial growth factor receptor antibody, DC101, and an antitransforming growth factor β1 (TGF‐β1) antibody, normalization of the tumor vasculature and ECM is achieved, respectively, in a syngeneic murine glioma model. This normalization effect results in a more organized vascular network, improves tissue perfusion, and reduces collagen density, all of which contribute to enhanced nanoparticle delivery and distribution within tumors. These findings suggest that combined vascular and ECM normalization strategies can be used to remodel the tumor microenvironment and improve nanomedicine delivery into solid tumors, which has significant implications for developing more effective combinational therapeutic strategies using cancer nanomedicine.

Abstract Clear cell renal cell carcinoma (ccRCC) is the most common subtype of kidney cancer and has the highest propensity to manifest as metastatic disease. Recent characterizations of the genetic signature of ccRCC have revealed several factors correlated with tumor cell migration and invasion; however, the specific events driving malignancy are not well defined. Furthermore, there remains a lack of targeted therapies that result in long-term, sustainable response in patients with metastatic disease. We show here that neuronal pentraxin 2 (NPTX2) is overexpressed specifically in ccRCC primary tumors and metastases, and that it contributes to tumor cell viability and promotes cell migration through its interaction with the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunit GluR4. We propose NPTX2 as a novel molecular target for therapy for patients with ccRCC diagnosed with or at risk of developing metastatic disease. Cancer Res; 74(17); 4796–810. ©2014 AACR.

Abstract Purpose: We set out to identify Stearoyl-CoA desaturase 1 (SCD1) as a novel molecular target in clear cell renal cell carcinoma (ccRCC) and examine its role in tumor cell growth and viability in vitro and in vivo independently as well as in combination with current U.S. Food and Drug Administration (FDA)-approved regimens. Experimental Design: Patient normal and ccRCC tissue samples and cell lines were examined for SCD1 expression. Genetic knockdown models and targeted inhibition of SCD1 through use of a small molecule inhibitor, A939572, were analyzed for growth, apoptosis, and alterations in gene expression using gene array analysis. Therapeutic models of synergy were evaluated utilizing pharmacologic inhibition of SCD1 with the tyrosine kinase inhibitors (TKI) sunitinib and pazopanib, and the mTOR inhibitor temsirolimus. Results: Our studies identify increased SCD1 expression in all stages of ccRCC. Both genetic knockdown and pharmacologic inhibition of SCD1 decreased tumor cell proliferation and induced apoptosis in vitro and in vivo. Upon gene array, quantitative real-time PCR, and protein analysis of A939572-treated or SCD1 lentiviral knockdown samples, induction of endoplasmic reticulum stress response signaling was observed, providing mechanistic insight for SCD1 activity in ccRCC. Furthermore, combinatorial application of A939572 with temsirolimus synergistically inhibited tumor growth in vitro and in vivo. Conclusions: Increased SCD1 expression supports ccRCC viability and therefore we propose it as a novel molecular target for therapy either independently or in combination with an mTOR inhibitor for patients whose disease cannot be remedied with surgical intervention, such as in cases of advanced or metastatic disease. Clin Cancer Res; 19(9); 2368–80. ©2013 AACR.

Abstract Metastatic solid tumors are aggressive and mostly drug resistant, leading to few treatment options and poor prognosis as seen with clear cell renal cell carcinoma (ccRCC) and triple-negative breast cancer (TNBC). Therefore, the identification of new therapeutic regimes for the treatment of metastatic disease is desirable. ccRCC and TNBC cell lines were treated with the HDAC inhibitor romidepsin and the methyltransferase inhibitor decitabine, two epigenetic modifying drugs approved by the U.S. Food and Drug Administration for the treatment of various hematologic malignancies. Cell proliferation analysis, flow cytometry, quantitative PCR, and immunoblotting techniques were used to evaluate the antitumor synergy of this drug combination and identify the reexpression of epigenetically silenced tumor suppressor genes. Combinatorial treatment of metastatic TNBC and stage IV ccRCC cell lines with romidepsin/decitabine leads to synergistic inhibition of cell growth and induction of apoptosis above levels of individual drug treatments alone. Synergistic reexpression of the tumor suppressor gene secreted frizzled-related protein one (sFRP1) was observed in combinatorial drug-treated groups. Silencing sFRP1 (short hairpin RNA) before combinatorial drug treatment showed that sFRP1 mediates the growth inhibitory and apoptotic activity of combined romidepsin/decitabine. Furthermore, addition of recombinant sFRP1 to ccRCC or TNBC cells inhibits cell growth in a dose-dependent manner through the induction of apoptosis, identifying that epigenetic silencing of sFRP1 contributes to renal and breast cancer cell survival. Combinatorial treatment with romidepsin and decitabine in drug resistant tumors is a promising treatment strategy. Moreover, recombinant sFRP1 may be a novel therapeutic strategy for cancers with suppressed sFRP1 expression. Mol Cancer Ther; 11(10); 2105–15. ©2012 AACR.