Anti-angiogenesis for cancer revisited: Is there a role for combinations with immunotherapy?

Inhibition of COX-2 and EGFR by Melafolone Improves Anti-PD-1 Therapy through Vascular Normalization and PD-L1 Downregulation in Lung Cancer

Checkpoint blockade therapy has been proven efficacious in lung cancer patients. However, primary/acquired resistance hampers its efficacy. Therefore, there is an urgent need to develop novel strategies to improve checkpoint blockade therapy. Here we tested whether dual inhibition of cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) by flavonoid melafolone improves program death 1 (PD-1) checkpoint blockade therapy through normalizing tumor vasculature and PD-1 ligand (PD-L1) downregulation. Virtual screening assay, cellular thermal shift assay, and enzyme inhibition assay identified melafolone as a potential inhibitor of COX-2 and EGFR. In Lewis lung carcinoma (LLC) and CMT167 models, dual inhibition of COX-2 and EGFR by melafolone promoted survival, tumor growth inhibition, and vascular normalization, and ameliorated CD8⁺ T-cell suppression, accompanied by the downregulation of transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), and PD-L1 in the tumor cells. Mechanistically, dual inhibition of COX-2 and EGFR in lung cancer cells by melafolone increased the migration of pericyte, decreased the proliferation and migration of endothelial cells, and enhanced the proliferation and effector function of CD8⁺ T cells through VEGF, TGF-β, or PD-L1 downregulation and PI3K/AKT inactivation. Notably, melafolone improved PD-1 immunotherapy against LLC and CMT167 tumors. Together, dual inhibition of COX-2 and EGFR by melafolone improves checkpoint blockade therapy through vascular normalization and PD-L1 downregulation and, by affecting vessels and immune cells, may be a promising combination strategy for the treatment of human lung cancer.

Apatinib for Advanced Osteosarcoma after Failure of Standard Multimodal Therapy: An Open Label Phase II Clinical Trial

BACKGROUND

Antiangiogenesis tyrosine kinase inhibitors (TKIs) have been shown to prolong progression-free survival (PFS) in advanced osteosarcoma. Methylsulfonic apatinib is a TKI that specifically inhibits vascular endothelial growth factor receptor-2. We aim to assess apatinib in patients with advanced high-grade osteosarcoma progressing upon chemotherapy.

MATERIALS AND METHODS

This phase II trial was conducted at Peking University People's Hospital. We enrolled participants (≥16 years of age) with progressive relapsed or unresectable osteosarcoma. Participants received 750 mg or 500 mg of apatinib according to body surface area once daily until disease progression or unacceptable toxicity. The primary endpoint was objective response rate and PFS at 4 months.

RESULTS

A total of 37 participants were finally included into the analysis. Until final follow-up, the objective response rate (complete response + partial response) was 43.24% (16/37). The 4-month PFS rate was 56.76% (95% confidence interval [CI], 39.43%-70.84%). Median PFS and overall survival were 4.50 (95% CI, 3.47-6.27) and 9.87 (95% CI 7.97-18.93) months, respectively. Toxic effects led to dose reductions or interruptions in a total of 25 of 37 (67.57%) patients. The most common grade 3-4 adverse events were pneumothorax in six (16.22%) patients, wound dehiscence in four (10.81%), proteinuria in three (8.11%), diarrhea in three (8.11%), and palmar-plantar erythrodysesthesia syndrome in three (8.11%). No other serious adverse events were reported during the trial. There were no treatment-related deaths.

CONCLUSION

Apatinib is a sensitive drug for advanced osteosarcoma with a high response rate after failure of chemotherapy, with similar duration of response compared to other TKIs.

IMPLICATIONS FOR PRACTICE

For advanced osteosarcoma progressing upon chemotherapy, antiangiogenesis tyrosine kinase inhibitors (TKIs) have been proved to be effective in prolonging the progression-free survival in previous multicenter trials and have been included into new National Comprehensive Cancer Network guidelines as second-line therapy. Apatinib is a TKI that specifically inhibits vascular endothelial growth factor receptor-2, which is domestically made in China. This phase II trial supports the use of apatinib in patients with advanced osteosarcoma progressing after chemotherapy.

Pre- and post-operative anti-PD-L1 plus anti-angiogenic therapies in mouse breast or renal cancer models of micro- or macro-metastatic disease

BACKGROUND

There are phase 3 clinical trials underway evaluating anti-PD-L1 antibodies as adjuvant (postoperative) monotherapies for resectable renal cell carcinoma (RCC) and triple-negative breast cancer (TNBC); in combination with antiangiogenic VEGF/VEGFR2 inhibitors (e.g., bevacizumab and sunitinib) for metastatic RCC; and in combination with chemotherapeutics as neoadjuvant (preoperative) therapies for resectable TNBC.

METHODS

This study investigated these and similar clinically relevant drug combinations in highly translational preclinical models of micro- and macro-metastatic disease that spontaneously develop after surgical resection of primary kidney or breast tumours derived from orthotopic implantation of murine cancer cell lines (RENCA^luc or EMT-6/CDDP, respectively).

RESULTS

In the RENCA^luc model, adjuvant sunitinib plus anti-PD-L1 improved overall survival compared to either drug alone, while the same combination was ineffective as early therapy for unresected primary tumours or late-stage therapy for advanced metastatic disease. In the EMT-6/CDDP model, anti-PD-L1 was highly effective as an adjuvant monotherapy, while its combination with paclitaxel chemotherapy (with or without anti-VEGF) was most effective as a neoadjuvant therapy.

CONCLUSIONS

Our preclinical data suggest that anti-PD-L1 plus sunitinib may warrant further investigation as an adjuvant therapy for RCC, while anti-PD-L1 may be improved by combining with chemotherapy in the neoadjuvant but not the adjuvant setting of treating breast cancer.

Crosstalk Between PD-1/PD-L1 Blockade and Its Combinatorial Therapies in Tumor Immune Microenvironment: A Focus on HNSCC

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide with a poor prognosis and high mortality. More than two-thirds of HNSCC patients still have no effective control of clinical progression, and the five-year survival rate is < 50%. Moreover, patients with platinum-refractory HNSCC have a median survival of < 6 months. The significant toxicity and low survival rates of current treatment strategies highlight the necessity for new treatment modalities. Recently, a large number of studies have demonstrated that programmed cell death protein-1 (PD-1) and its ligand, programmed cell death protein ligand-1 (PD-L1) play an essential role in tumor initiation and progression. PD-1/PD-L1 blockade has shown a desired and long-lasting therapeutic effect in the treatment of HNSCC and other malignancies. However, only a small number of patients with HNSCC can benefit from PD-1/PD-L1 blockade monotherapy, while the majority of patients do not respond. To overcome the unsatisfactory therapeutic effect of PD-1/PD-L1 blockade monotherapy, combining other treatment options for HNSCC (including chemotherapy, radiotherapy, targeted therapy, and immunotherapy) in the treatment scheme has become a commonly used strategy. Herein, the potential mechanisms underlying the crosstalk between PD-1/PD-L1 blockade and its combinatorial therapies for HNSCC were reviewed, and it is hoped that the improved understanding of the crosstalk process would provide further ideas for the design of a combinatorial regimen with a higher efficiency and response rate for the treatment of HNSCC and other malignancies.

Genetic variation determines VEGF-A plasma levels in cancer patients

Angiogenesis is essential in tumor biology and is regulated by vascular endothelial growth factor (VEGF) ligands and receptors. Here we aimed to discover genetic variants associated with levels of circulating angiogenic proteins in cancer patients. Plasma was collected at baseline in 216 pancreatic and 114 colorectal cancer patients. Thirty-one angiogenic proteins were measured by ELISA. 484,523 Single Nucleotide Polymorphisms (SNP) were tested for association with plasma levels for each protein in pancreatic cancer patients. Three top-ranked hits were then genotyped in colorectal cancer patients, where associations with the same proteins were measured. The results demonstrated rs2284284 and MCP1 (P-value = 6.7e–08), rs7504372 and VEGF-C (P-value = 9.8e–09), and rs7767396 and VEGF-A (P-value = 5.8e–09) were SNP-protein pairs identified in pancreatic cancer patients. In colorectal cancer patients, only rs7767396 (A > G) and VEGF-A was validated (P-value = 5.18e–05). The AA genotype of rs7767396 exhibited 2.04–2.3 and 2.7–3.4-fold higher VEGF-A levels than those with AG and GG genotypes. The G allele of rs7767396 reduces binding of the NF-AT1 transcription factor. In conclusion, a common genetic variant predicts the plasma levels of VEGF-A in cancer patients through altered binding of NF-AT1.

PDGFRα expression as a novel therapeutic marker in well-differentiated neuroendocrine tumors

AIMS

To evaluate the biological significance of dense vascular networks associated with low-grade NENs, we assessed the impact of PDGFRα tissue expression in 77 GEP/NEN patients, associating PDGFRα expression with the morphological characterization in low-grade tumors.

METHODS AND RESULTS

Paraffin-embedded specimens of 77 GEP- NEN tissues, collected from January 2006 to March 2018, were evaluated for PDGFRα tissue expression and correlations with clinicopathological characteristics. PDGFRα tissue expression was significantly correlated with grade and the NEN growth pattern (p < 0.001) but not with gender, primary site or lymph nodes metastatic status. PDGFRα staining was mainly localized in the vascular pole of the neuroendocrine cells and in Enterochromaffin (EC) cells. In particular PDGFRα tissue expression was significantly more expressed in G2 (p < 0.001) than G1 and G3 cases (p 0.004; p < 0.0002;) and correlated with an insular growth pattern. PDGFRα tissue expression was associated with the Ki67 index and we found a significant negative trend of association with the Ki67 proliferation index (P < 0.001): thus PDGFRα expression is referred to morphological and not to proliferative data.

CONCLUSIONS

PDGFRα represents an effective target for new anti-angiogenic treatment in WD- GEP-NENs, in particular in G2 cases, and in G3 cases only when there is a mixed insular-acinar pattern. In this context, it is important to carefully delineate those tumors that might better respond to this type of treatment alone or in combination. Further investigation of the relationship between PD-L1 and PDGFRa is warranted, and may contribute to optimize the therapeutic approach in patients with GEP-NENs.

Targeting VEGF pathway to normalize the vasculature: an emerging insight in cancer therapy

Vascular normalization is a new concept of targeting angiogenesis to restore vessel structure and function and to increase blood perfusion and delivery of drugs. It has been confirmed that vascular normalization can decrease relapse and benefit other cancer therapy, including chemotherapy, radiotherapy, and immune cell therapy. The key point of this therapy is to inhibit pro-angiogenic factors and make it be balanced with anti-angiogenic factors, resulting in a mature and normal vessel characteristic. Vascular endothelial growth factor (VEGF) is a key player in the process of tumor angiogenesis, and inhibiting VEGF is a primary approach to tumor vessel normalization. Herein, we review newly uncovered mechanisms governing angiogenesis and vascular normalization of cancer and place emphasis on targeting VEGF pathway to normalize the vasculature. Also, important methods to depress VEGF pathway and make tumor vascular are discussed.

Tumor-infiltrating neutrophils predict therapeutic benefit of tyrosine kinase inhibitors in metastatic renal cell carcinoma

Tumor-infiltrating neutrophils (TINs) show diverse predictive effects in the context of different cancer types and therapeutic regimens. In this study we investigated their relevance with therapeutic effect of tyrosine kinase inhibitors (TKIs) in metastatic renal cell carcinoma (mRCC). Two independent datasets including 271 mRCC patients treated by TKIs or IL-2/IFN-α based immunotherapy were retrospective included, and TINs were detected by immunohistochemistry. The presence of TINs was observed in 50 (45.0%) samples of the TKI cohort and in 73 (45.6%) samples of the immunotherapy cohort. TINs were associated with shorter overall survival (HR, 1.776; 95%CI, 1.191-2.650; p = 0.004) in the TKI cohort, but not in the immunotherapy cohort (HR, 1.074; 95%CI, 0.767-1.505; p = 0.672). Multivariate Cox analysis confirmed the independent prognostic value of TINs for TKI-treated patients (HR, 2.078, 95%CI, 1.352-3.195; p = 0.001), apart from other parameters. Moreover, survival benefit of TKI therapy was superior to IL-2/IFN-α immunotherapy only among TINs-absent patients (HR, 1.561; 95%CI, 0.927-2.629; p = 0.094). Data mining in the TCGA cohort of renal cell carcinoma revealed the predominant immunosuppressive function of TINs in renal cell carcinoma. The negative correlation between TINs and intratumoral CD8⁺ T cells was further confirmed in the TKI cohort (p = 0.019), the immunotherapy cohort (p = 0.001) and the TCGA cohort (p < 0.001). In conclusion, the presence of TINs was an independent, unfavorable prognostic factor in TKI-treated mRCC patients. TINs could also predict therapeutic benefit of TKIs over IL-2/IFN-α immunotherapy. These findings should be further confirmed within datasets of clinical trials or prospective observational studies.

Efficacy and safety of apatinib treatment for gastric cancer, hepatocellular carcinoma and non-small cell lung cancer: a meta-analysis

Apatinib (Aitan^®, brand name in China) is a new anti-antiangiogenic agent that has recently been approved for the treatment of advanced gastric cancer (GC) in China. Nevertheless, its therapeutic efficacy against other types of advanced solid tumors remains unclear. This meta-analysis examines the short-term efficacy and safety of apatinib or combination therapy for GC, hepatocellular carcinoma (HCC) and non-small-cell lung cancer (NSCLC); and provides a discussion of its anti-angiogenesis therapy applications. Seven clinical studies met the inclusion criteria. The treatment of cancers using apatinib was more successful compared to therapy without apatinib. Both objective response rates (ORRs) and disease control rates (DCRs) were significantly improved in the apatinib group compared to those in the control group (RR=2.18, 95% CI 1.30–3.65; RR=2.09, 95% CI 1.21–3.60). The DCR of 850 mg qd and 750 mg qd were higher than those in the control group (P<0.05). Based on the short-term acute adverse reactions of apatinib, significant differences between groups were found for hypertension, urine protein, hand foot syndrome, and gastrointestinal reactions (diarrhea), while no significant differences were found for myelosuppression, nausea and vomiting. Moreover, the results showed that apatinib prolonged patient survival (HR=0.38, 95% CI: 0.28–0.52), and the effect was more pronounced in patients treated with 750 mg qd or 850 mg qd of apatinib than in those treated with a dose of ≤500 mg qd. Additionally, compared to its second-line application, the third-line application was shown to further reduce the risk ratio in patients. Furthermore, overall survival was longer in patients treated with apatinib. Apatinib was shown to have certain short-term effects and survival benefits on GC, HCC, and NSCLC with controllable adverse effects.

Downregulating Heparanase-Induced Vascular Normalization: A New Approach To Increase the Bioavailability of Chemotherapeutics in Solid Tumors

Downregulating heparanase has been shown to reduce tumor angiogenesis and prevent chemoresistance, and it is becoming an appealing approach to treat solid tumors. However, little attention has been given to its underlying antitumor mechanisms, especially the relationship between heparanase and vascular development in solid tumors, which is not yet fully understood. In this study, we found that downregulating heparanase through orthotopic injection of heparanase small interfering RNA not only could reduce vascular density but, more importantly, lead to vascular normalization in solid tumors. Consequently, this may lead to a more efficient delivery of chemotherapeutic agents. These findings provide the basis for developing new approaches to treat solid tumors with a combination of heparanase inhibitors and chemotherapeutics.

Consensus guidelines for the use and interpretation of angiogenesis assays

The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference.

Histidine-rich glycoprotein-induced vascular normalization improves EPR-mediated drug targeting to and into tumors

Tumors are characterized by leaky blood vessels, and by an abnormal and heterogeneous vascular network. These pathophysiological characteristics contribute to the enhanced permeability and retention (EPR) effect, which is one of the key rationales for developing tumor-targeted drug delivery systems. Vessel abnormality and heterogeneity, however, which typically result from excessive pro-angiogenic signaling, can also hinder efficient drug delivery to and into tumors. Using histidine-rich glycoprotein (HRG) knockout and wild type mice, and HRG-overexpressing and normal t241 fibrosarcoma cells, we evaluated the effect of genetically induced and macrophage-mediated vascular normalization on the tumor accumulation and penetration of 10-20 nm-sized polymeric drug carriers based on poly(N-(2-hydroxypropyl)methacrylamide). Multimodal and multiscale optical imaging was employed to show that normalizing the tumor vasculature improves the accumulation of fluorophore-labeled polymers in tumors, and promotes their penetration out of tumor blood vessels deep into the interstitium.

Selective delivery of PLXDC1 small interfering RNA to endothelial cells for anti-angiogenesis tumor therapy using CD44-targeted chitosan nanoparticles for epithelial ovarian cancer

Angiogenesis plays an essential role in the growth and metastasis of tumor cells, and the modulation of angiogenesis can be an effective approach for cancer therapy. We focused on silencing the angiogenic gene PLXDC1 as an important factor for anti-angiogenesis tumor therapy. Herein, we developed PLXDC1 small interfering siRNA (siRNA)-incorporated chitosan nanoparticle (CH-NP/siRNA) coated with hyaluronic acid (HA) to target the CD44 receptor on tumor endothelial cells. This study aimed to improve targeted delivery and enhance therapeutic efficacy for tumor anti-angiogenesis. The HA-CH-NP/siRNA was 200 ± 10 nm in size with a zeta potential of 26.4 mV. The loading efficiency of siRNA to the HA-CH-NP/siRNA was up to 60%. The selective binding of HA-CH-NP/siRNA to CD44-positive tumor endothelial cells increased by 2.1-fold compared with that of the CD44 nontargeted CH-NP/siRNA. PLXDC1 silencing by the HA-CH-NP/siRNA significantly inhibited tumor growth in A2780 tumor-bearing mice compared with that in the control group (p < .01), and mRNA expression of PLXDC1 was significantly reduced in the HA-CH-NP/siRNA-treated group. Furthermore, treatment with HA-CH-NP/siRNA resulted in significant inhibition of cell proliferation (p < .001), reduced microvessel density (p < .001), and increased cell apoptosis (p < .001). This study demonstrates that HA-CH-NP/siRNA is a highly selective delivery platform for siRNA, and has broad potential to be used in anti-angiogenesis tumor therapy.

Modeling triple-negative breast cancer heterogeneity: Effects of stromal macrophages, fibroblasts and tumor vasculature

A hallmark of breast tumors is its spatial heterogeneity that includes its distribution of cancer stem cells and progenitor cells, but also heterogeneity in the tumor microenvironment. In this study we focus on the contributions of stromal cells, specifically macrophages, fibroblasts, and endothelial cells on tumor progression. We develop a computational model of triple-negative breast cancer based on our previous work and expand it to include macrophage infiltration, fibroblasts, and angiogenesis. In vitro studies have shown that the secretomes of tumor-educated macrophages and fibroblasts increase both the migration and proliferation rates of triple-negative breast cancer cells. In vivo studies also demonstrated that blocking signaling of selected secreted factors inhibits tumor growth and metastasis in mouse xenograft models. We investigate the influences of increased migration and proliferation rates on tumor growth, the effect of the presence on fibroblasts or macrophages on growth and morphology, and the contributions of macrophage infiltration on tumor growth. We find that while the presence of macrophages increases overall tumor growth, the increase in macrophage infiltration does not substantially increase tumor growth and can even stifle tumor growth at excessive rates.

Targeting VEGF/VEGFR to Modulate Antitumor Immunity

In addition to the crucial role in promoting the growth of tumor vessels, vascular endothelial growth factor (VEGF) is also immunosuppressive. VEGF can inhibit the function of T cells, increase the recruitment of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs), and hinder the differentiation and activation of dendritic cells (DCs). Recent studies have investigated the role of antiangiogenic agents in antitumor immunity, especially in recent 3 years. Therefore, it is necessary to update the role of targeting VEGF/VEGFR in antitumor immunity. In this review, we focus on the latest clinical and preclinical findings on the modulatory role of antiangiogenic agents targeting VEGF/VEGFR in immune cells, including effector T cells, Tregs, MDSCs, DCs, tumor-associated macrophages, and mast cells. Our review will be potentially helpful for the development of combinations of angiogenesis inhibitors with immunological modulators.

Construction of a human monoclonal antibody against bFGF for suppression of NSCLC

Compelling evidence implicates that overexpression of basic fibroblast growth factor (bFGF) and fibroblast growth factor receptor 1 (FGFR1) in non-small cell lung cancer (NSCLC) drives tumor progression, can serve as prognostic biomarkers or therapeutic targets for NSCLC patients. But at present, we still lack of effective drugs for bFGF. The preparation of monoclonal antibodies against bFGF or to understand its mechanism of action is urgently need. Previously, we used hybridoma technology to produce a murine anti-bFGF monoclonal antibody (E12). However, E12 carries risks of heterogeneity and immunogenicity. In the present work, we produced three humanized variants (H1L1, H2L2 and H3L3) based on E12 by substituting residues in or near the complementarity-determining region (CDR). In addition, we thoroughly explored VH/VL domain combinations to simulate full-length IgG1 antibodies using computational protein design. H3L3 was selected for further study, as it demonstrated the best humanization and strongest affinity for bFGF. Specially, humanization of H3L3's light chain and heavy chain were 100% and 98.89%, respectively. The FGF2 neutralizing effect of H3L3 were confirmed by ELISA. We also found that H3L3 can effectively suppress the growth and angiogenesis of cancer through reduce the phosphorylation of AKT and MAPK. Moreover, H3L3 dramatically reduced tumor size and micro-vessel density in nude mice. Altogether, our study demonstrates that H3L3 exerts anti-tumor effects by impeding NSCLC development.

Vinorelbine, cyclophosphamide and 5-FU effects on the circulating and intratumoural landscape of immune cells improve anti-PD-L1 efficacy in preclinical models of breast cancer and lymphoma

Background

Anti-PD-1 and anti-PD-L1 checkpoint inhibitors (CIs) are clinically active in many types of cancer. However, only a minority of patients achieve a complete and/or long-lasting clinical response. We studied the effects of different doses of three widely used, orally active chemotherapeutics (vinorelbine, cyclophosphamide and 5-FU) over local and metastatic tumour growth, and the landscape of circulating and tumour-infiltrating immune cells involved in CI activity.

Methods

Immunocompetent Balb/c mice were used to generate models of breast cancer (BC) and B-cell lymphoma. Vinorelbine, cyclophosphamide and 5-FU (alone or in combination with CIs), were given at low-dose metronomic, medium, or maximum tolerable dosages.

Results

Cyclophosphamide increased circulating myeloid derived suppressor cells (MDSC). Vinorelbine, cyclophosphamide and 5-FU reduced circulating APCs. Vinorelbine and cyclophosphamide (at medium/high doses) reduced circulating Tregs. Cyclophosphamide (at low doses) and 5-FU (at medium doses) slightly increased circulating Tregs. Cyclophosphamide was the most potent drug in reducing circulating CD3+CD8+ and CD3+CD4+ T cells. Vinorelbine, cyclophosphamide and 5-FU reduced the number of circulating B cells, with cyclophosphamide showing the most potent effect. Vinorelbine reduced circulating NKs, whereas cyclophosphamide and 5-FU, at low doses, increased circulating NKs. In spite of reduced circulating T, B and NK effector cells, preclinical synergy was observed between chemotherapeutics and anti-PD-L1. Most-effective combinatorial regimens where associated with neoplastic lesions enriched in B cells, and, in BC-bearing mice (but not in mice with lymphoma) also in NK cells.

Conclusions

Vinorelbine, cyclophosphamide and 5-FU have significant preclinical effects on circulating and tumour-infiltrating immune cells and can be used to obtain synergy with anti-PD-L1.

Platelet Metabolism and Other Targeted Drugs; Potential Impact on Immunotherapy

The role of platelets in cancer progression has been well recognized in the field of cancer biology. Emerging studies are elaborating further the additional roles and added extent that platelets play in promoting tumorigenesis. Platelets release factors that support tumor growth and also form heterotypic aggregates with tumor cells, which can provide an immune-evasive advantage. Their most critical role may be the inhibition of immune cell function that can negatively impact the body’s ability in preventing tumor establishment and growth. This review summarizes the importance of platelets in tumor progression, therapeutic response, survival, and finally the notion of immunotherapy modulation being likely to benefit from the inclusion of platelet inhibitors.

CYP4X1 Inhibition by Flavonoid CH625 Normalizes Glioma Vasculature through Reprogramming TAMs via CB2 and EGFR-STAT3 Axis

Tumor-associated macrophages (TAMs) are pivotal effector cells in angiogenesis. Here, we tested whether CYP4X1 inhibition in TAMs by flavonoid CH625 prolongs survival and normalizes glioma vasculature. CH625 was selected against the CYP4X1 3D model by virtual screening and showed inhibitory activity on the CYP4X1 catalytic production of 14,15-EET-EA in the M2-polarized human peripheral blood mononuclear cells (IC₅₀ = 16.5 μM). CH625 improved survival and reduced tumor burden in the C6 and GL261 glioma intracranial and subcutaneous model. In addition, CH625 normalized vasculature (evidenced by a decrease in microvessel density and HIF-1α expression and an increase in tumor perfusion, pericyte coverage, and efficacy of temozolomide therapy) accompanied with the decreased secretion of 14,15-EET-EA, VEGF, and TGF-β in the TAMs. Furthermore, CH625 attenuated vascular abnormalization and immunosuppression induced by coimplantation of GL261 cells with CYP4X1^high macrophages. In vitro TAM polarization away from the M2 phenotype by CH625 inhibited proliferation and migration of endothelial cells, enhanced pericyte migration and T cell proliferation, and decreased VEGF and TGF-β production accompanied with the downregulation of CB2 and EGFR-dependent downstream STAT3 expression. These effects were reversed by overexpression of CYP4X1 and STAT3 or exogenous addition of 14,15-EET-EA, VEGF, TGF-β, EGF, and CB2 inhibitor AM630. These results suggest that CYP4X1 inhibition in TAMs by CH625 prolongs survival and normalizes tumor vasculature in glioma via CB2 and EGFR-STAT3 axis and may serve as a novel therapeutic strategy for human glioma.

Histopathological growth patterns as a candidate biomarker for immunomodulatory therapy

The encroachment of a growing tumor upon the cells and structures of surrounding normal tissue results in a series of histopathological growth patterns (HGPs). These morphological changes can be assessed in hematoxylin-and-eosin (H&E) stained tissue sections from primary and metastatic tumors and have been characterized in a range of tissue types including liver, lung, lymph node and skin. HGPs in different tissues share certain general characteristics like the extent of angiogenesis, but also appropriate tissue-specific mechanisms which ultimately determine differences in the biology of HGP subtypes. For instance, in the well-characterized HGPs of liver metastases, the two main subtypes, replacement and desmoplastic, recapitulate two responses of the normal liver to injury: regeneration and fibrosis. HGP subtypes have distinct cytokine profiles and differing levels of lymphocytic infiltration which suggests that they are indicative of immune status in the tumor microenvironment. HGPs predict response to bevacizumab and are associated with overall survival (OS) after surgery for liver metastases in colorectal cancer (CRC). In addition, HGPs can change over time in response to therapy. With standard scoring methods being developed, HGPs represent an easily accessible, dynamic biomarker to consider when determining strategies for treatment using anti-VEGF and immunomodulatory drugs.

M1-like macrophages change tumor blood vessels and microenvironment in murine melanoma

Tumor-associated macrophages (TAMs) play a significant role in at least two key processes underlying neoplastic progression: angiogenesis and immune surveillance. TAMs phenotypic changes play important role in tumor vessel abnormalization/ normalization. M2-like TAMs stimulate immunosuppression and formation of defective tumor blood vessels leading to tumor progression. In contrast M1-like TAMs trigger immune response and normalize irregular tumor vascular network which should sensitize cancer cells to chemo- and radiotherapy and lead to tumor growth regression. Here, we demonstrated that combination of endoglin-based DNA vaccine with interleukin 12 repolarizes TAMs from tumor growth-promoting M2-like phenotype to tumor growth-inhibiting M1-like phenotype. Combined therapy enhances tumor infiltration by CD4⁺, CD8⁺ lymphocytes and NK cells. Depletion of TAMs as well as CD8⁺ lymphocytes and NK cells, but not CD4⁺ lymphocytes, reduces the effect of combined therapy. Furthermore, combined therapy improves tumor vessel maturation, perfusion and reduces hypoxia. It caused that suboptimal doses of doxorubicin reduced the growth of tumors in mice treated with combined therapy. To summarize, combination of antiangiogenic drug and immunostimulatory agent repolarizes TAMs phenotype from M2-like (pro-tumor) into M1-like (anti-tumor) which affects the structure of tumor blood vessels, improves the effect of chemotherapy and leads to tumor growth regression.

PA/US dual-modality imaging to guide VEGFR-2 targeted photothermal therapy using ZnPc-/PFH-loaded polymeric nanoparticles

Angiogenesis is a common pathological characteristic of many solid tumors and vulnerable atherosclerotic plaques.

The Effects of Administrated Sildenafil Citrate on Uterine Luminal Epithelium Height Associated with Ovarian Angiogenesis: An Experimental Animal Study

Background

Ovarian angiogenesis (OA) remains in lifetime and normal ovarian function depends to this continual remodeling of a complex vascular system. Endometrial thickness (ET) is one of the strongest predictors of successful implantation and pregnancy. Appropriate OA effects on ET by facilitating of ovarian hormone delivery.

Materials and Methods

Thirty adult female mice and twenty adult male mice were purchased. The female mice were divided into three groups: (1) control group without any intervention (n = 10), (2) gonadotropin group: receiving human menopausal gonadotropin (HMG) and human chorionic gonadotropin (n = 10), and (3) gonadotropin and sildenafil citrate (SC) group: receiving HMG and SC administration (n = 10). After mating, animals were deeply anesthetized, and the ovary and uterus was rapidly removed for histology and immunohistochemistry process.

Results

Four days after ovarian induction, all three layers of the uterus with specified thickness can be clearly seen. The heights of endometrial epithelial cells in gonadotropin group were not significantly different than those in control group. In gonadotropin and SC group, heights of the cells were significantly (P < 0.05) shorter than control and gonadotropin groups. ETs in all groups were not significantly deferent from each other (P > 0.05 each). Our results of immunohistochemistry survey for ovarian CD31 demonstrated that administrated SC increased OA but not significantly (P > 0.05 each).

Conclusion

It may finally conclude that administration of SC does not cause notable alterations in OA and ET; although for realistic decision about the SC effects on aforementioned parameters, more molecular investigations and longer drug consumption period are necessary.

Ginsenoside-Rb1-Mediated Anti-angiogenesis via Regulating PEDF and miR-33a through the Activation of PPAR-γ Pathway

Angiogenesis is the formation of new blood vessels from the existing vasculature, which is involved in multiple biological processes, including atherosclerosis, ischemic heart disease, and cancer. Ginsenoside-Rb1 (Rb1), the most abundant ginsenoside isolated form Panax ginseng, has been identified as a promising anti-angiogenic agent via the up-regulation of PEDF. However, the underlying molecular mechanisms still unknown. In the present study, human umbilical vein endothelial cells (HUVECs) were selected to perform in vitro assays. Rb1 (0-20 nM) treatment induced pigment epithelial-derived factor (PEDF) protein expression in concentration and time-dependent manners. Interestingly, it was also demonstrated that the exposure of Rb1 (10 nM) could increase PEDF protein expression without any alteration on mRNA level, suggesting the involvement of posttranscriptional regulation. Furthermore, bioinformatics predictions indicated the regulation of miR-33a on PEDF mRNA 3'-UTR, which was further confirmed by luciferase reporter gene assay and real-time PCR. Over-expression of pre-miR-33a was found to regress partly Rb1-mediated PEDF increment and anti-angiogenic effect in HUVECs. Additionally, Rb1-reduced miR-33a and increased PEDF expression was prevented by pre-incubation with peroxisome proliferator-activated receptor-γ (PPAR-γ) antagonist (GW9662) or transfection with PPAR-γ siRNA in HUVECs. Taken together, our findings demonstrated that Rb1 exerted anti-angiogenic effects through PPAR-γ signaling pathway via modulating miR-33a and PEDF expressions. Thus, Rb1 may have the potential of being developed as an anti-angiogenic agent, however, further appropriate studies are warranted to evaluate the effect in vivo.

Fishing anti(lymph)angiogenic drugs with zebrafish

Zebrafish, an amenable small teleost fish with a complex mammal-like circulatory system, is being increasingly used for drug screening and toxicity studies. It combines the biological complexity of in vivo models with a higher-throughput screening capability compared with other available animal models. Externally growing, transparent embryos, displaying well-defined blood and lymphatic vessels, allow the inexpensive, rapid, and automatable evaluation of drug candidates that are able to inhibit neovascularisation. Here, we briefly review zebrafish as a model for the screening of anti(lymph)angiogenic drugs, with emphasis on the advantages and limitations of the different zebrafish-based in vivo assays.

Immunogenomic Classification of Colorectal Cancer and Therapeutic Implications

The immune system has a substantial effect on colorectal cancer (CRC) progression. Additionally, the response to immunotherapeutics and conventional treatment options (e.g., chemotherapy, radiotherapy and targeted therapies) is influenced by the immune system. The molecular characterization of colorectal cancer (CRC) has led to the identification of favorable and unfavorable immunological attributes linked to clinical outcome. With the definition of consensus molecular subtypes (CMSs) based on transcriptomic profiles, multiple characteristics have been proposed to be responsible for the development of the tumor immune microenvironment and corresponding mechanisms of immune escape. In this review, a detailed description of proposed immune phenotypes as well as their interaction with different therapeutic modalities will be provided. Finally, possible strategies to shift the CRC immune phenotype towards a reactive, anti-tumor orientation are proposed per CMS.

A perforated microhole-based microfluidic device for improving sprouting angiogenesis in vitro

Microfluidic technology is an important research tool for investigating angiogenesis in vitro. Here, we fabricated a polydimethylsiloxane (PDMS) microfluidic device with five cross-shaped chambers using a coverslip molding method. Then, the perforated PDMS microhole arrays prepared by soft lithography were assembled in the device as barriers; a single microhole had a diameter of 100 μm. After injecting type I collagen into the middle gel chamber, we added a culture medium containing a vascular endothelial growth factor (VEGF) into the middle chamber. It would generate a linear concentration gradient of VEGF across the gel region from the middle chamber to the four peripheral chambers. Human umbilical vein endothelial cells (HUVECs) were then seeded on the microhole barrier. With VEGF stimulation, cells migrated along the inner walls of the microholes, formed annularly distributed cell clusters at the gel-barrier interface, and then three-dimensionally (3D) sprouted into the collagen scaffold. After 4 days of culture, we quantitatively analyzed the sprouting morphogenesis. HUVECs cultured on the microhole barrier had longer sprouts than HUVECs cultured without the barrier (controls). Furthermore, the initial distribution of sprouts was more regular and more connections of tube-like structures were generated when the microhole barrier was used. This study introduces a novel microfluidic device containing both microtopographic structures and 3D collagen. HUVECs cultured with the microhole barrier could form well-interconnected tube-like structures and are thus an ideal in vitro angiogenesis model.

Fine-Tuning Tumor Endothelial Cells to Selectively Kill Cancer

Tumor endothelial cells regulate several aspects of tumor biology, from delivering oxygen and nutrients to shaping the immune response against a tumor and providing a barrier against tumor cell dissemination. Accordingly, targeting tumor endothelial cells represents an important modality in cancer therapy. Whereas initial anti-angiogenic treatments focused mainly on blocking the formation of new blood vessels in cancer, emerging strategies are specifically influencing certain aspects of tumor endothelial cells. For instance, efforts are generated to normalize tumor blood vessels in order to improve tumor perfusion and ameliorate the outcome of chemo-, radio-, and immunotherapy. In addition, treatment options that enhance the properties of tumor blood vessels that support a host’s anti-tumor immune response are being explored. Hence, upcoming anti-angiogenic strategies will shape some specific aspects of the tumor blood vessels that are no longer limited to abrogating angiogenesis. In this review, we enumerate approaches that target tumor endothelial cells to provide anti-cancer benefits and discuss their therapeutic potential.

miRNAs: micro-managers of anticancer combination therapies

Angiogenesis is one of the hallmarks of cancer progression and as such has been considered a target of therapeutic interest. However, single targeted agents have not fully lived up to the initial promise of anti-angiogenic therapy. Therefore, it has been suggested that combining therapies and agents will be the way forward in the oncology field. In recent years, microRNAs (miRNAs) have received considerable attention as drivers of tumor development and progression, either acting as tumor suppressors or as oncogenes (so-called oncomiRs), as well as in the process of tumor angiogenesis (angiomiRs). Not only from a functional, but also from a therapeutic view, miRNAs are attractive tools. Thus far, several mimics and antagonists of miRNAs have entered clinical development. Here, we review the provenance and promise of miRNAs as targets as well as therapeutics to contribute to anti-angiogenesis-based (combination) treatment of cancer.

The clinical application of angiostatic therapy in combination with radiotherapy: past, present, future

Although monotherapy with angiostatic drugs is still far from effective, there is abundant evidence that angiostatic therapy can improve the efficacy of conventional treatments like radiotherapy. This has instigated numerous efforts to optimize and clinically implement the combination of angiostatic drugs with radiation treatment. The results from past and present clinical trials that explored this combination therapy indeed show encouraging results. However, current findings also show that the combination has variable efficacy and is associated with increased toxicity. This indicates that combining radiotherapy with angiostatic drugs not only holds opportunities but also provides several challenges. In the current review, we provide an update of the most recent insights from clinical trials that evaluated the combination of angiostatic drugs with radiation treatment. In addition, we discuss the outstanding questions for future studies in order to improve the clinical benefit of combining angiostatic therapy with radiation therapy.