Overcoming adaptive resistance to anti-VEGF therapy by targeting CD5L.

Antiangiogenic treatment targeting the vascular endothelial growth factor (VEGF) pathway is a powerful tool to combat tumor growth and progression; however, drug resistance frequently emerges. We identify CD5L (CD5 antigen-like precursor) as an important gene upregulated in response to antiangiogenic therapy leading to the emergence of adaptive resistance. By using both an RNA-aptamer and a monoclonal antibody targeting CD5L, we are able to abate the pro-angiogenic effects of CD5L overexpression in both in vitro and in vivo settings. In addition, we find that increased expression of vascular CD5L in cancer patients is associated with bevacizumab resistance and worse overall survival. These findings implicate CD5L as an important factor in adaptive resistance to antiangiogenic therapy and suggest that modalities to target CD5L have potentially important clinical utility.

Enhancing oral delivery of plant-derived vesicles for colitis.

Plant-derived vesicles (PDVs) are attractive for therapeutic applications, including as potential nanocarriers. However, a concern with oral delivery of PDVs is whether they would remain intact in the gastrointestinal tract. We found that 82% of cabbage PDVs were destroyed under conditions mimicking the upper digestive tract. To overcome this limitation, we developed a delivery method whereby lyophilized Eudragit S100-coated cabbage PDVs were packaged into a capsule (Cap-cPDVs). Lyophilization and suspension of PDVs did not have an appreciable impact on PDV structure, number, or therapeutic effect. Additionally, packaging the lyophilized Eudragit S100-coated PDVs into capsules allowed them to pass through the upper gastrointestinal tract for delivery into the colon better than did suspension of PDVs in phosphate-buffered saline. Cap-cPDVs showed robust therapeutic effect in a dextran sulfate sodium-induced colitis mouse model. These findings could have broad implications for the use of PDVs as orally delivered nanocarriers of natural therapeutic plant compounds or other therapeutics.

Molecular Profiles of Serum-Derived Extracellular Vesicles in High-Grade Serous Ovarian Cancer.

Patients with high-grade serous ovarian cancer (HGSC) who have no visible residual disease (R0) after primary surgery have the best clinical outcomes, followed by patients who undergo neoadjuvant chemotherapy (NACT) and have a response enabling interval cytoreductive surgery. Clinically useful biomarkers for predicting these outcomes are still lacking. Extracellular vesicles (EVs) have been recognized as liquid biopsy-based biomarkers for early cancer detection and disease surveillance in other disease settings. In this study, we performed extensive molecular characterization of serum-derived EVs and correlated the findings with therapeutic outcomes in patients with HGSC. Using EV-DNA whole-genome sequencing and EV-RNA sequencing, we identified distinct somatic EV-DNA alterations in cancer-hallmark genes and in ovarian cancer genes, as well as significantly altered oncogenic pathways between the R0 group and NACT groups. We also found significantly altered EV-RNA transcriptomic variations and enriched pathways between the groups. Taken together, our data suggest that the molecular characteristics of EVs could enable prediction of patients with HGSC who could undergo R0 surgery or respond to chemotherapy.

Targeting CCR2+ macrophages with BET inhibitor overcomes adaptive resistance to anti-VEGF therapy in ovarian cancer.

PURPOSE: Tumor-associated macrophages (TAMs) are known to contribute to adaptive resistance to anti-vascular endothelial growth factor (VEGF) antibody (AVA) therapy in ovarian cancer. BET (bromodomain and extra-terminal domain) inhibitors (BETi) may have unique roles in targeting TAMs. Our objective was to examine the effects of BETi on TAMs, especially in the context of enhancing the efficacy of AVA therapy. METHODS: We conducted a series of in vitro (MTT assay, apoptosis, flow cytometry, and RNA sequencing) and in vivo (xenograft ovarian cancer model) experiments to determine the biological effects of BETi combined with AVA in ovarian cancer. For statistical analysis, a two-tailed Student's t test (equal variance) or ANOVA was used for multiple groups' comparison, and p < 0.05 was considered significant. RESULTS: BETi resulted in a dose-dependent decrease in cell viability and induced apoptosis (p < 0.01) in ovarian cancer cells (SKOV3ip1, OVCAR5, and OVCAR8). Treatment with BETi significantly increased apoptosis in THP-1 monocytes and macrophages (PMA-differentiated THP-1; p < 0.01). Furthermore, BETi selectively induced greater apoptosis in M2-like macrophages (PMA and IL-4, IL-13-differentiated THP-1) (31.3%-36.1%) than in M1-like macrophages (PMA and LPS-differentiated THP-1) (12.4%-18.5%) (p < 0.01). Flow cytometry revealed that the percentage of M1-like macrophages (CD68+/CD80+) was significantly increased after treatment with low-dose BETi (ABBV-075 0.1 µM; p < 0.05), whereas the percentage of CD68+/CCR2+ macrophages was significantly decreased (p < 0.001); these findings suggest that BETi may selectively inhibit the survival of CCR2+ macrophages and re-polarize the macrophages into an M1-like phenotype. RNA-seq analysis revealed that BETi selectively targeted macrophage infiltration-related cytokines/chemokines in ovarian cancer (adjusted p < 0.05 and Log2 fold change ≥ 1.5). Finally, using in vivo ovarian cancer models, compared with control or monotherapy, the combination of BETi (ABBV-075) and bevacizumab resulted in greater inhibition of tumor growth and macrophage infiltration (p < 0.05) and longer survival of tumor-bearing mice (p < 0.001). CONCLUSIONS: Our findings indicate a previously unrecognized role for BETi in selectively targeting CCR2+ TAMs and enhancing the efficacy of AVA therapy in ovarian cancer.

Endothelial p130cas confers resistance to anti-angiogenesis therapy.

Anti-angiogenic therapies, such as anti-VEGF antibodies (AVAs), have shown promise in clinical settings. However, adaptive resistance to such therapies occurs frequently. We use orthotopic ovarian cancer models with AVA-adaptive resistance to investigate the underlying mechanisms. Genomic profiling of AVA-resistant tumors guides us to endothelial p130cas. We find that bevacizumab induces cleavage of VEGFR2 in endothelial cells by caspase-10 and that VEGFR2 fragments internalize into the nucleus and autophagosomes. Nuclear VEGFR2 and p130cas fragments, together with TNKS1BP1 (tankyrase-1-binding protein), initiate endothelial cell death. Blockade of autophagy in AVA-resistant endothelial cells retains VEGFR2 at the membrane with bevacizumab treatment. Targeting host p130cas with RGD (Arg-Gly-Asp)-tagged nanoparticles or genomic ablation of vascular p130cas in p130casflox/floxTie2Cre mice significantly extends the survival of mice with AVA-resistant ovarian tumors. Higher vascular p130cas is associated with shorter survival of individuals with ovarian cancer. Our findings identify opportunities for new strategies to overcome adaptive resistance to AVA therapy.

Immune microenvironment composition in high-grade serous ovarian cancers based on BRCA mutational status.

PURPOSE: An in-depth analysis of the tumor microenvironment of ovarian cancer is needed. The purpose of this study was to elucidate the architecture of the immune microenvironment of high-grade serous ovarian cancers (HGSCs) with or without BRCA1 and BRCA2 mutations. METHODS: A cohort of highly annotated HGSC patients with known germline BRCA1 and BRCA2 status was selected, and pretreatment tumor tissue specimens were analyzed with a multiplexed staining technique aimed at detecting lymphocytes, macrophages, and fibroblasts in the whole tumor area and in specific regions including epithelium, stroma, and perivascular areas. RESULTS: BRCA1- or BRCA2-mutated tumors showed a more immunogenic microenvironment, characterized by a higher abundance of CD8+ and PD-L1+ cells, than did tumors with wild-type BRCA1 and BRCA2. High numbers of PD-L1+ and PD-L1+CD8+ cells were prognostic for event-free survival (hazard ratio [HR]: 0.41, 95% CI 0.21-0.79, p = 0.008 and HR 0.49, 95% CI 0.26-0.91, p = 0.025, respectively), as were high numbers of epithelial PD-L1+ and FAP+PD-L1+ cells (HR 0.52, 95% CI 0.28-0.96, p = 0.037 and HR 0.27, 95% CI 0.08-0.87, p = 0.029) and CD8+ cells (HR 0.51, 95% CI 0.28-0.93, p = 0.027). CONCLUSIONS: This study reveals substantial differences between the immune microenvironment composition of germline BRCA-mutated and BRCA wild-type HGSC.

CD63-mediated cloaking of VEGF in small extracellular vesicles contributes to anti-VEGF therapy resistance.

Despite wide use of anti-vascular endothelial growth factor (VEGF) therapy for many solid cancers, most individuals become resistant to this therapy, leading to disease progression. Therefore, new biomarkers and strategies for blocking adaptive resistance of cancer to anti-VEGF therapy are needed. As described here, we demonstrate that cancer-derived small extracellular vesicles package increasing quantities of VEGF and other factors in response to anti-VEGF therapy. The packaging process of VEGF into small extracellular vesicles (EVs) is mediated by the tetraspanin CD63. Furthermore, small EV-VEGF (eVEGF) is not accessible to anti-VEGF antibodies and can trigger intracrine VEGF signaling in endothelial cells. eVEGF promotes angiogenesis and enhances tumor growth despite bevacizumab treatment. These data demonstrate a mechanism where VEGF is partitioned into small EVs and promotes tumor angiogenesis and progression. These findings have clinical implications for biomarkers and therapeutic strategies for ovarian cancer.

MEK inhibition overcomes resistance to EphA2-targeted therapy in uterine cancer.

BACKGROUND: Our pilot clinical study of EphA2 inhibitor (dasatinib) plus paclitaxel and carboplatin showed interesting clinical activity in endometrial cancer with manageable toxicity. However, the underlying mechanisms of dasatinib resistance in uterine cancer are unknown. Here, we investigated potential mechanisms underlying resistance to EphA2 inhibitors in uterine cancer and examined the anti-tumor activity of EphA2 inhibitors alone and in combination with a MEK inhibitor. METHODS: We evaluated the antitumor activity of EphA2 inhibitors plus a MEK inhibitor using in vitro and in vivo orthotopic models of uterine cancer. RESULTS: EphA2 inhibitor induced MAPK in dasatinib-resistant uterine cancer cells (HEC-1A and Ishikawa) and BRAF/CRAF heterodimerization in HEC-1A cells. EphA2 inhibitor and trametinib significantly increased apoptosis in cancer cells resistant to EphA2 inhibitors compared with controls (p < 0.01). An in vivo study with the orthotopic HEC-1A model showed significantly greater antitumor response to combination treatment compared with dasatinib alone (p < 0.01). Combination treatment increased EphrinA1 and BIM along with decreased pMAPK, Jagged 1, and c-MYC expression in dasatinib-resistant cells. In addition, Spearman analysis using the TCGA data revealed that upregulation of EphA2 was significantly correlated with JAG1, MYC, NOTCH1, NOTCH3 and HES1 expression (p < 0.001, r = 0.25-0.43). Specifically, MAP3K15 and the NOTCH family genes were significantly related to poor clinical outcome in patients with uterine cancer. CONCLUSIONS: These findings indicate that the MAPK pathway is activated in dasatinib-resistant uterine cancer cells and that EphrinA1-mediated MEK inhibition overcomes dasatinib resistance. Dual targeting of both EphA2 and MEK, combined with chemotherapy, should be considered for future clinical development.

Assessment of In Vivo siRNA Delivery in Cancer Mouse Models.

RNA interference (RNAi) has rapidly become a powerful tool for target discovery and therapeutics. Small interfering RNAs (siRNAs) are highly effective in mediating sequence-specific gene silencing. However, the major obstacle for using siRNAs for cancer therapeutics is their systemic delivery from the administration site to target cells in vivo. This chapter describes approaches to deliver siRNA effectively for cancer treatment and discusses in detail the current methods to assess pharmacokinetics and biodistribution of siRNAs in vivo.

Gain-of-function p53 protein transferred via small extracellular vesicles promotes conversion of fibroblasts to a cancer-associated phenotype.

Tumor and stromal interactions consist of reciprocal signaling through cytokines, growth factors, direct cell-cell interactions, and extracellular vesicles (EVs). Small EVs (≤200 nm) have been considered critical messengers of cellular communication during tumor development. Here, we demonstrate that gain-of-function (GOF) p53 protein can be packaged into small EVs and transferred to fibroblasts. GOF p53 protein is selectively bound by heat shock protein 90 (HSP90), a chaperone protein, and packaged into small EVs. Inhibition of HSP90 activity blocks packaging of GOF, but not wild-type, p53 in small EVs. GOF p53-containing small EVs result in their conversion to cancer-associated fibroblasts. In vivo studies reveal that GOF p53-containing small EVs can enhance tumor growth and promote fibroblast transformation into a cancer-associated phenotype. These findings provide a better understanding of the complex interactions between cancer and stromal cells and may have therapeutic implications.

6-Phosphofructo-2-Kinase/Fructose-2,6-Biphosphatase-2 Regulates TP53-Dependent Paclitaxel Sensitivity in Ovarian and Breast Cancers.

PURPOSE: Paclitaxel is an integral component of primary therapy for breast and epithelial ovarian cancers, but less than half of these cancers respond to the drug. Enhancing the response to primary therapy with paclitaxel could improve outcomes for women with both diseases.Experimental Design: Twelve kinases that regulate metabolism were depleted in multiple ovarian and breast cancer cell lines to determine whether they regulate sensitivity to paclitaxel in Sulforhodamine B assays. The effects of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 2 (PFKFB2) depletion on cell metabolomics, extracellular acidification rate, nicotinamide adenine dinucleotide phosphate, reactive oxygen species (ROS), and apoptosis were studied in multiple ovarian and breast cancer cell lines. Four breast and ovarian human xenografts and a breast cancer patient-derived xenograft (PDX) were used to examine the knockdown effect of PFKFB2 on tumor cell growth in vivo. RESULTS: Knockdown of PFKFB2 inhibited clonogenic growth and enhanced paclitaxel sensitivity in ovarian and breast cancer cell lines with wild-type TP53 (wtTP53). Silencing PFKFB2 significantly inhibited tumor growth and enhanced paclitaxel sensitivity in four xenografts derived from two ovarian and two breast cancer cell lines, and prolonged survival in a triple-negative breast cancer PDX. Transfection of siPFKFB2 increased the glycolysis rate, but decreased the flow of intermediates through the pentose-phosphate pathway in cancer cells with wtTP53, decreasing NADPH. ROS accumulated after PFKFB2 knockdown, which stimulated Jun N-terminal kinase and p53 phosphorylation, and induced apoptosis that depended upon upregulation of p21 and Puma. CONCLUSIONS: PFKFB2 is a novel target whose inhibition can enhance the effect of paclitaxel-based primary chemotherapy upon ovarian and breast cancers retaining wtTP53.