Normalizing Tumor Vasculature to Reduce Hypoxia, Enhance Perfusion, and Optimize Therapy Uptake

Construction of nitroreductase-responsive near-infrared composite nanoprobe and its application in tumor hypoxia imaging

Hypoxia is an important feature in the development of solid tumors. Nitroreductase (NTR) is closely related to the level of hypoxia, thus NTR-responsive fluorescent probes with high selectivity and sensitivity will help to evaluate the degree of hypoxia and guide personalized treatment. In this study, a near-infrared (NIR) NTR-activated composite nanoprobe 780-pNBC@MP-B was developed for tumor hypoxia imaging. The nanoprobe has a mesoporous organosilicon nanostructure functionalized with PEG for in vivo long circulation, and encapsulates a NIR molecular probe 780-pNBC for NTR imaging, which can exhibit responsive degradation to glutathione (GSH) attributed to the disulfide bond in the nanocarrier structure. Benefiting from the hydrophilic nanocarrier, 780-pNBC@MP-B with good water dispersibility and photostability was successfully applied to visualize NTR in hypoxic cells and tumor-bearing mice. Therefore, this work provides a new tool for tumor hypoxia detection and expands the new application of mesoporous silica in the field of enzyme probes.

Pituitary folliculo-stellate cells modulate tumor vasculature and extracellular matrix composition in experimental lactosomatotropinomas

Folliculo-stellate cells (FSCs) constitute 5-10 % of the adenohypophysis and have been proposed as paracrine regulators of pituitary cells. However, their participation in pituitary tumor development remains unclear. We generated a lacto-somatotropic tumor model by subcutaneous injection of GH3 (lacto-somatotrophs) and the FSCs TtT/GF, isolated or combined, in immunodeficient mice, to study the role of the FSCs on tumor formation, hormone secretion, vascularization and extra-cellular matrix involvement. The co-culture of both cell lines let us gain insight into the proliferative and secretory action of FSC in pituitary tumor modulation. Our results showed that initially GH3:TtT/GF tumors had an earlier onset, but lately, TtT/GF cells restrained GH3:TtT/GF tumor growth and their Prl synthesis, although no differences were observed in the proliferative potential of tumor cells in vivo. Instead, TtT/GF cells exerted a direct mitogenic action on GH3 cells in vitro. Moreover, GH3 tumors had fewer irrigating vessels, lower vascular area and a higher VEGF/bFGF ratio that correlated with Hif1a expression, consistent with the tissue hypoxia and hemorrhage. These features were downregulated in their co-injected counterparts, which interestingly showed an increased deposition of collagens, glycoproteins and mucopolysaccharides extra-cellular matrix (EMC) components. Isolated TtT/GF injected cells did not generate tumors, but they developed fibrous masses characterized by collagen and high bFGF production. In conclusion, our results demonstrate that FSCs are dual regulators of pituitary tumor growth, with a mitogenic action on tumor cells but also a restrictive tumor effect on the cancer processes angiogenesis, hypoxia, and ECM remodeling.

Role of the tumor microenvironment in cancer therapy: unveiling new targets to overcome drug resistance

Cancer is a leading cause of death globally, with resistance to therapy representing a major obstacle to effective treatment. The tumor microenvironment (TME), comprising a complex network to cellular and non-cellular components including cancer-associated fibroblasts, immune cells, the extracellular matrix and region of hypoxia, is integral to cancer progression and therapeutic resistance. This review delves into the multifaceted interactions within the TME that contribute to tumor growth, survival and immune evasion. Key elements such as the role of cancer- associated fibroblasts in remodeling the extracellular matrix and promoting angiogenesis, the influence of immune cells such as tumor-associated macrophages in creating an immunosuppressive milieu and the impact of hypoxia conditions on metabolic adaptation and therapy resistance are thoroughly examined. This review evaluates current and emerging TME-targeted therapeutic strategies, including inhibitors of extracellular matrix components, modulators of immune cell activity and approached to alleviate hypoxia. Combination therapies that integrate TME-targeted agents with conventional treatments such as chemotherapy and immunotherapy are also discussed for their potential to enhance treatment efficacy and circumvent resistance mechanisms. By synthesising recent advances in TME research and therapeutic innovation, this paper aims to underscore the importance of TME in cancer therapy and highlight promising avenues for improving patient outcomes through targeted intervention.

Proteoglycan-degrading enzymes engineered for enhanced tumor microenvironment interaction in renal cell carcinoma

This work optimized proteoglycan-degrading enzymes through targeted mutagenesis to enhance their interaction with the tumor microenvironment in Renal Cell Carcinoma (RCC). A comprehensive mutagenesis approach identified 60 key mutations significantly improving enzymatic activity, stability, and structural integrity. When compared to Wild Type (WT) enzyme, a remarkable increase in specific activity by 35 % (p < 0.001) and a considerable decrease in the Km values for hyaluronidases from 2.5 mM to 1.5 mM (p < 0.05), as a result of these modifications. Computational methods are then employed to analyze the active site of the enzymes to detect potential residues that may alter. These computational techniques include molecular docking and protein structure prediction. The structural models of the enzymes are created by utilizing homology modeling and crystallography. These models demonstrate the spatial arrangement of the amino acid enzymes. It also illustrated the specific mutations to improve the potential of enzymes to relate to the Extracellular Matrix (ECM) of tumors. The computational screening methods effectively predicted how the modifications impact enzyme catalytic efficiency and stability. The modified enzymes retained 85 % of the enzyme activity, while the WT retained 60 %. Thus, the modified enzymes demonstrated better thermal stability than WT. Vitro test analyses show that the proteoglycan breakdown was significantly reduced by 70 % (p < 0.001), and for effective proteoglycan breakdown, hyaluronidase concentration is needed. This work proposed a novel therapeutic approach called proteoglycan-degrading enzymes for the treatment of RCC. These proteoglycan-degrading enzymes are more stable and effective for treating RCC, as demonstrated in the outcomes. Customized proteoglycan-degrading enzymes make the therapy more effective. The effective breakdown of the tumor's ECM in RCC models establishes this customized proteoglycan-degrading enzyme. These enzymes are effective for this customized cancer treatment as they improve stability, activity, and interaction with the TME.

Magnetic resonance imaging to detect tumor hypoxia in brain malignant disease: A systematic review of validation studies

Tumor hypoxia indicates a worse prognosis in brain malignancies; however, current gold-standard methods for assessing tumor hypoxia are invasive and often inaccessible. Magnetic Resonance Imaging (MRI) is widely available, but its validity for identifying tumor hypoxia or hypoxia-related neoangiogenesis is not well characterized. A systematic literature search was performed across PubMed and Embase Databases. The search query identified MRI studies that validated hypoxia-surrogate imaging sequences against gold-standard hypoxia or neoangiogenesis detection methods in patients with brain malignancies. Literature screen identified 23 manuscripts published between 2007 and 2022. Among conventional MRI sequences, peritumoral edema and signal change after contrast administration were associated with gold-standard oxygen-assessment methods. T2*- and T2'-derived measures were associated with gold-standard methods, while reports on quantitative measures of oxygen extraction fraction were conflicting. Fiber density, tissue cellularity, blood volume, vascular transit time, and permeability measurements were associated with gold-standard methods, whereas blood flow measurements yielded conflicting results. MRI measures are promising surrogates for tumor hypoxia or hypoxia-related neoangiogenesis. Additional studies are needed to reconcile disparate findings. Future sensitivity analyses are needed to establish the MRI methods most accurate at identifying tumor hypoxia.

Long circulating XTEN864-HGV-Apoptin fusion protein for selective cancer therapy

The virus protein CAV-Apoptin and its homologue HGV-Apoptin selectively kill cancer cells but are not suitable for systemic treatment. The aim was to develop Apoptin-based fusion proteins for intravenous application in cancer therapy, which also contain the hydrophilic polypeptide XTEN, a cleavage site for MMP-2/9, and a TAT peptide for cell penetration. Expression of XTEN864-HGV-Apoptin in E. coli and purification using XTEN as a tag yielded 100 mg protein/L tissue culture. The expression of XTEN864-CAV-Apoptin did not generate a sufficient yield. Cytotoxic effects were assessed using MTT and Annexin A5 assays, whereas cellular uptake was visualized using Cy3.5-XTEN864-HGV-Apoptin. Blood half-life and biodistribution were evaluated with 99mTc-XTEN864-HGV-Apoptin using SPECT-CT and gamma counting. The fusion protein significantly reduced cancer cell growth and induced apoptosis with minimal effects on non-cancerous cells. It accumulates in the nucleus and associates with F-actin. In mice, the protein showed a blood half-life of 0.68 h (fast phase) and 17 h (slow phase), with a tumor/muscle ratio of 9.36 ± 6.22 (SD). In a 4T1 mouse tumor model, it effectively inhibited tumor growth. The cancer-specific cytotoxicity and prolonged circulation of XTEN864-HGV-Apoptin suggest its potential for systemically applicable, biodegradable, and E. coli-producible antitumor drugs.

Role and mechanisms of exercise therapy in enhancing drug treatment for glioma: a review

Gliomas, particularly glioblastoma (GBM), are among the most aggressive and challenging brain tumors to treat. Although current therapies such as chemotherapy, radiotherapy, and targeted treatments have extended patient survival to some extent, their efficacy remains limited and is often accompanied by severe side effects. In recent years, exercise therapy has gained increasing attention as an adjunctive treatment in clinical and research settings. Exercise not only improves patients' physical function and cognitive abilities but may also enhance the efficacy of conventional drug treatments by modulating the immune system, suppressing inflammatory responses, and improving blood-brain barrier permeability. This review summarizes the potential mechanisms of exercise in glioma treatment, including enhancing immune surveillance through activation of natural killer (NK) cells and T cells, and increasing drug penetration by improving blood-brain barrier function. Additionally, studies suggest that exercise can synergize with chemotherapy and immunotherapy, improving treatment outcomes while reducing drug-related side effects. Although the application of exercise therapy in glioma patients is still in the exploratory phase, existing evidence indicates its significant clinical value as an adjunctive approach, with the potential to become a new standard in glioma treatment in the future.

Targeting endothelial MYC using siRNA or miR-218 nanoparticles sensitizes chemo- and immuno-therapies by recapitulating the Notch activation-induced tumor vessel normalization

Background: The chaotic, over-activated tumor vasculature promotes tumor growth and erodes most current therapies. Although Notch activation critically regulates angiogenesis, the broad roles of Notch has dampened its druggability. Methods: Gene-modified mice with a Cdh5-CreERT transgene were employed to activate/block Notch signaling in endothelial cells (ECs). Multiple transcriptome analyses were conducted to compare gene expression profiles. qRT-PCR and western blotting were used to determine gene expression level. Immunofluorescence and flow cytometry were used to observe morphological alterations and immune microenvironment in tumors. Nanoparticles (PEI-PEG-cRGD) were used to deliver siRNA into tumor ECs (TECs) in vivo. Results: Genetic Notch activation or blockade in TECs normalizes or deteriorates tumor vessels, respectively. Single-cell RNA sequencing showed that Notch activation selectively reduced the proliferating TEC subset, which accounted for about 30% of TECs and gave rise to other TEC subsets. Notch activation or blockade downregulated or upregulated MYC, respectively. MYC overexpression canceled Notch activation-induced proliferation arrest of TECs in vitro, and a MYC inhibitor normalized tumor vessels in RBPj deficient mice, suggesting that MYC is the authentic Notch target in normalizing tumor vessels. Nanoparticles encapsulated with MYC siRNA (EC-siMYC) or miR-218 (EC-miR-218), a Notch-downstream miRNA suppressing MYC, were able to mitigate Notch inhibition-induced tumor vessel defects. Combination of cisplatin with MYC blockade exhibited improved therapeutic effects. Moreover, MYC blockade promoted T cell infiltration and enhanced anti-PD1 immunotherapy. Conclusions: Together, our data have demonstrated that Notch activation normalizes tumor vessels by repressing the proliferating TEC subset via MYC, and targeting endothelial MYC using nanoparticles bearing siRNA or miRNA is an efficient strategy for tumor anti-angiogenic therapy.

Hypoxia signaling in cancer: HIF-1α stimulated by COVID-19 can lead to cancer progression and chemo-resistance in oral squamous cell carcinoma (OSCC)

The potential implications of Coronavirus disease-2019 (COVID-19) on oral squamous cell carcinoma (OSCC) development, chemo-resistance, tumor recurrence, and patient outcomes are explored, emphasizing the urgent need for tailored therapeutic strategies to mitigate these risks. The role of hypoxia-inducible factor 1-alpha (HIF-1α) in OSCC studies has highlighted HIF-1α as a crucial prognostic marker in OSCC, with implications for disease prognosis and patient survival. Its overexpression has been linked to aggressive subtypes in early OSCC stages, indicating its significance as an early biomarker for disease progression. Moreover, dysplastic lesions with heightened HIF-1α expression exhibit a greater propensity for malignant transformation, underscoring its role in early oral carcinogenesis. Cancer patients, including those with OSCC, face an elevated risk of severe COVID-19 complications, which may further impact cancer progression and treatment outcomes. Understanding the interplay between COVID-19 infection, HIF-1α activation, and OSCC pathogenesis is crucial for enhancing clinical management strategies. So, insights from this review shed light on the significance of HIF-1α in OSCC tumorigenesis, metastasis formation, and patient prognosis. The review underscores the need for further research to elucidate the precise mechanisms through which HIF-1α modulates cancer progression and chemo-resistance in the context of COVID-19 infection. Such knowledge is essential for developing targeted therapeutic interventions to improve outcomes for OSCC patients.

177Lu-Labeled Heterodimeric Agent with High Stability Targeting Neovascularization for Tumor Radioligand Therapy

Radiopharmaceutical theranostics holds significant promise in tumor diagnosis and treatment, but suboptimal tumor uptake and retention remain a persistent limitation. We have conjugated a unique albumin binder to our previously developed heterodimeric precursor HX01 and achieved a novel precursor L6, aiming to prolong circulation time and enhance tumor accumulation and retention. However, we observed that the NGR sequence of L6 was gradually rearranged to iso-DGR under alkaline conditions, resulting in decreased stability. In this study, we further modified the L6 to synthesize XH02, subsequently assessing their in vitro and in vivo properties following radiolabeling. Utilizing positron emission tomography (PET)/computed tomography (CT) imaging, single-photon emission computed tomography (SPECT)/CT imaging, and biodistribution study in BxPC-3 xenograft mice, we observed striking accumulation and retention of radiopharmaceutical within tumors. Two cycles of administration of 177Lu-XH02 displayed exceptional tumor growth inhibition in BxPC-3 tumors while causing minimal side effects. This promising result underscores the immense potential of this agent for further clinical translation and investigation.

Molecular and Cellular Machinery of Lymphatic Metastasis in Breast Cancer

Breast cancer is one of the most common malignant tumours in women worldwide. A primary route for breast cancer cells to disseminate is through regional lymphatic vessels and nodes. Cancer cell-induced lymphangiogenesis plays a crucial role in lymphatic metastasis and is associated with poor survival of breast cancer. Advances in molecular biology have led to the identification of biomarkers associated with lymphangiogenesis and lymphatic metastasis, including lymphatic vessel endothelial cell (LVEC) markers and tumour microenvironment markers, such as vascular endothelial growth factor receptor 3 (VEGFR3), podoplanin (PDPN), and lymphatic endothelial hyaluronan receptor-1 (LYVE1). LVEC molecular markers play a profound role in both the formation of new lymphatic vessels and the invasive expansion of primary tumour. Abnormal expression of LVEC markers may contribute to lymphatic vessel disease and/or metastasis of cancer cells through the lymphatic system. These molecular markers may present a potential for targeted therapies and precision diagnostics for managing lymphatic metastasis in breast cancer. This review aims to provide a comprehensive summary of the current understanding of the molecular and cellular machinery underlying lymphatic metastasis in breast cancer, with a particular focus on the lymphangiogenic markers and their role in the lymphatic dissemination.

Normalization of tumor vasculature by imiquimod: proposal for a new anticancer therapeutic indication for a TLR7 agonist

Imiquimod (IMQ), a drug from aminoquinoline group, is the toll-like receptor 7 (TLR7) agonist. It acts as an immunostimulant and radio-sensitizing agent. IMQ stimulates both innate and adaptive immune response. Despite studies conducted, there are no unambiguous data showing how IMQ affects the condition of tumor blood vessels. Tumor vasculature plays the main role in tumor progression. Formation of abnormal blood vessels increases area of hypoxia which recruits suppressor cells, blocks tumor infiltration by CD8+ T lymphocytes, inhibits efficacy of chemoterapeutic drug and leads to cancer relapse. Normalization is a type of therapy targeted at abnormal tumor blood vessels. Here, we demonstrated that 50 µg of IMQ inhibits the growth of melanoma tumors more efficiently, compared to other tested doses and the control group. Dose escalation did not improve the therapeutic antitumor potential of TLR7 agonist. A dose of 50 µg of IMQ most effectively reduced tumor blood vessel density. Imiquimod normalized tumor vasculature both structurally (by reducing vessel tortuosity and increasing pericyte coverage) and functionally (by improving tumor perfusion) in a dose-dependent manner. Hypoxia regions in tumors of treated mice were significantly reduced after IMQ administration. A dose of 50 µg of IMQ had also the greatest impact on the changes in tumor-infiltrating T lymphocytes levels. TLR7 agonist inhibited angiogenesis in treated mice. Functional vascular normalization by IMQ increases the effectiveness of low dose of doxorubicin. Higher dose of IMQ showed worse effects than lower doses including decreased tumor perfusion, increased tumor hypoxia and immunosuppression. This knowledge may help to optimize the combination of the selected IMQ dose with e.g. chemotherapy or radiotherapy to elicit synergistic effect in cancer treatment. To conclude, we outline IMQ repurposing as a vascular normalizing agent. Our research results may contribute to expanding the therapeutic indications for the use of IMQ in anticancer therapy in the future.

Vascular regional analysis unveils differential responses to anti-angiogenic therapy in pancreatic xenografts through macroscopic photoacoustic imaging

Background: Amongst the various imaging techniques that provide surrogate tumor radiographic indications to aid in planning, monitoring, and predicting outcomes of therapy, ultrasound-guided photoacoustic imaging (US-PAI) is a promising non-ionizing modality based on endogenous blood (hemoglobin) and blood oxygen saturation (StO₂) contrast. Adaptation of US-PAI to the clinical realm requires macroscopic system configurations for adequate depth visualization. Methods: Here we present a vascular regional analysis (VRA) methodology of obtaining areas of low and high vessel density regions within the tumor (LVD and HVD respectively) by frequency domain filtering of macroscopic PA images. In this work, we evaluated the various vascular and oxygenation profiles of different murine xenografts of pancreatic cancer (AsPC-1, MIA PaCa-2, and BxPC-3) that have varying levels of angiogenic potentials and investigated the effects of receptor tyrosine kinase inhibitor (sunitinib) on the tumor microvessel density and StO₂. Results: The administration of sunitinib resulted in transient deoxygenation and reduction in vessel density within 72 h in two (AsPC-1 and MIA PaCa-2) of the three tumor types. Utilizing VRA, the regional change in StO2 (∆StO2) revealed the preferential targeting of sunitinib in LVD regions in only the AsPC-1 tumors. We also identified the presence of vascular normalization (validated through immunohistochemistry) in the sunitinib treated AsPC-1 tumors at day 8 post-treatment where a significant increases in HVD ∆StO2 (~20%) were seen following the 72-hour time point, indicative of improved vessel flow and functionality. Treated AsPC-1 vasculature displayed increased maturity and functionality compared to non-treated tumors on day 8, while these same metrics showed no conclusive evidence of vascular normalization in MIA PaCa-2 or BxPC-3 tumors. Conclusion: Overall, VRA as a tool to monitor treatment response allowed us to identify time points of vascular remodeling, highlighting its ability to provide insights into the tumor microenvironment for sunitinib treatment and other anti-angiogenic therapies.

Alleviating Tumor Hypoxia and Immunosuppression via Sononeoperfusion: A New Ally for potentiating anti-PD-L1 blockade of solid Tumor

The hypoxic and immunosuppressive tumor microenvironment (TME) remains a major obstacle to impede cancer immunotherapy. Here, we found that sononeoperfusion-a new effect of tumor perfusion enhancement induced by low mechanical index ultrasound stimulated microbubble cavitation (USMC)-ameliorated tumor tissue oxygenation and induced tumor vascular normalization (TVN). This TVN might be associated with the down-regulation of hypoxia-inducible factor 1-alpha (HIF-1α) and vascular endothelial growth factor (VEGF) within tumors. Moreover, the sononeoperfusion effect reduced the accumulation of immunosuppressive cells, such as regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs) and M2-like tumor-associated macrophages (M2-TAMs), and decreased the production of immune inhibitory factors like transforming growth factor-β1 (TGF-β1), interleukin 10 (IL-10), chemoattractant chemokines CC-chemokine ligand 22 (CCL22), CCL28, adenosine and lactate within tumors. Notably, flow cytometry analysis revealed that sononeoperfusion not only increased the percentage of tumor infiltrating-CD8+ T cells, but also promoted the generation of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) by these cells. Furthermore, the improved immune TME by sononeoperfusion effect sensitized anti-PD-L1 treatment both in MC38 colon cancer and Lewis lung carcinoma mice, resulting in tumor regression and prolonged survival. Mechanically, the enhanced efficacy of combination therapy was mainly based on promoting the infiltration and function of CD8+ T cells within tumors. Together, sononeoperfusion could ameliorate hypoxia and immunosuppression in the TME, thereby potentiating anti-PD-L1 therapy for solid tumors. This novel method of USMC generating sononeoperfusion effect may provide a new therapeutic modality for facilitating cancer immunotherapy.

Prolonged inhibition of intratumoral mast cells enhances efficacy of low-dose antiangiogenic therapy

Low-dose antiangiogenic therapies have demonstrated the ability to enhance normalization of tumor vessels, consequently improving hypoxia levels, drug delivery, and promoting anticancer immune responses. Mast cells have been identified as contributors to resistance against antiangiogenic therapy and facilitators of abnormal neoangiogenesis. In this study, we demonstrate that by simultaneously targeting intratumoral mast cells with Imatinib and administering low-dose anti-VEGFR2 therapy, antitumor efficacy can be enhanced in preclinical models. Thus, combinatory treatment overcomes therapy resistance, while concurrently promoting tumor vessel normalization. Notably, histomorphometric analysis of tumor sections revealed that vessel perfusion could be improved through mast cell inhibition and, despite a significantly reduced microvessel density, the combination treatment did not result in elevated tumor hypoxia levels compared to anti-VEGFR2 therapy alone. Short-term Imatinib application effectively increased antitumor efficacy, and by prolonging the application of Imatinib tumor vessel normalization was additionally improved. The combination of mast cell depletion and antiangiogenic treatments has not been investigated in detail and promises to help overcoming therapy resistance. Further studies will be required to explore their impact on other treatment approaches, and subsequently to validate these findings in a clinical setting.

Image-Guided Targeting of Mitochondrial Metabolism Sensitizes Pediatric Malignant Rhabdoid Tumors to Low Dose Radiotherapy

Tumor hypoxia leads to radioresistance and markedly worse clinical outcomes for pediatric malignant rhabdoid tumors (MRT). Our transcriptomics and bioenergetic profiling data reveal that mitochondrial oxidative phosphorylation (OXPHOS) is a metabolic vulnerability of MRT and can be exploited to overcome consumptive hypoxia by repurposing an FDA-approved anti-malarial drug, Atovaquone (AVO). We then establish the utility of Oxygen-Enhanced-Multispectral Optoacoustic Tomography (OE-MSOT), a label-free, ionizing radiation-free imaging modality, to visualize and quantify spatiotemporal changes in tumor hypoxia in response to AVO. We show a potent but transient increase in tumor oxygenation upon AVO treatment which results in complete elimination of tumors in all tested mice when combined with 10 Gy radiotherapy, a dose several times lower than the current clinic standard. Finally, we use translational mathematical modeling for systematic evaluation of dosing regimens, administration timing, and therapeutic synergy in a virtual clinical patient population. Together, our work establishes a framework for safe and pediatric patient-friendly image-guided metabolic radiosensitization of rhabdoid tumors.

Acute remote ischemic conditioning enhances (CD3+)- but not (FoxP3+)-T-cell invasion in the tumor center and increases IL 17 and TNF-alpha expression in a murine melanoma model

Introduction

Hypoxia can drive tumor progression, suppress anti-tumor immunity, and reduce the effectiveness of radiotherapy and chemotherapy. This study aimed to assess the impact of remote ischemic conditioning (RIC) on tumor oxygenation (sO2) and the anti-tumor immune response.

Material and methods

Fourteen B16-Ova tumor-bearing C57BL/6N mice received six 5-minute RIC cycles, while another fourteen underwent anesthesia only. Pimonidazole was administered 1.5 hours before sacrifice. Blood flow, sO2, and hemoglobin levels were measured in the non-ischemic hind limb and tumor. Tumor hypoxia was assessed using pimonidazole and CA IX immunohistochemistry, and T cell infiltration by CD3 and FoxP3 staining. Serum levels of 23 cytokines were analyzed using a multiplex immunoassay.

Results

Isoflurane anesthesia caused a slight intraindividual increase in blood flow (p = 0.07) and sO2 (p = 0.06) of the hind limb and a sole increase in tumor sO2 (p = 0.035), whereas RIC improved sO2 of the tumor in relation to the hind limb (p=0.03). The median of the tumor oxygen saturation reached 51.4% in the control group and 62.7% in the RIC group (p = 0.09), exhibiting a slight tendency towards better oxygenation in the RIC group. Pimonidazole (p=0.24) and CA IX hypoxia score (p=0.48) did not reveal statistically significant differences between the two groups. In RIC-treated tumors, the number of CD3 (p=0.006), but not FoxP3- positive cells (p = 0.84), in the tumor core was significantly higher compared to the control group. In the RIC group, the mean fluorescence intensity (MFI) of IL-17 was significantly higher (p=0.035), and TNF-α was trend-wise higher (p=0.063) compared to the control group.

Conclusion

Both isoflurane anesthesia and RIC have an impact on microcirculation. The application of RIC counteracted some of the effects of isoflurane, primarily in healthy tissue, and led to a significant improvement in relative tumor tissue oxygenation compared to the non-ischemic hind limb. RIC selectively enhanced immune infiltration within the tumor center, probably by previously activated tumor infiltrating T cells, while having no significant impact on T-regulatory cells. RIC appears to impact the cytokine profile, as indicated by elevated MFIs of TNF-α and IL-17.

Targeting Tumor Hypoxia with Nanoparticle-Based Therapies: Challenges, Opportunities, and Clinical Implications

Hypoxia is a crucial factor in tumor biology, affecting various solid tumors to different extents. Its influence spans both early and advanced stages of cancer, altering cellular functions and promoting resistance to therapy. Hypoxia reduces the effectiveness of radiotherapy, chemotherapy, and immunotherapy, making it a target for improving therapeutic outcomes. Despite extensive research, gaps persist, necessitating the exploration of new chemical and pharmacological interventions to modulate hypoxia-related pathways. This review discusses the complex pathways involved in hypoxia and the associated pharmacotherapies, highlighting the limitations of current treatments. It emphasizes the potential of nanoparticle-based platforms for delivering anti-hypoxic agents, particularly oxygen (O2), to the tumor microenvironment. Combining anti-hypoxic drugs with conventional cancer therapies shows promise in enhancing remission rates. The intricate relationship between hypoxia and tumor progression necessitates novel therapeutic strategies. Nanoparticle-based delivery systems can significantly improve cancer treatment efficacy by targeting hypoxia-associated pathways. The synergistic effects of combined therapies underscore the importance of multimodal approaches in overcoming hypoxia-mediated resistance. Continued research and innovation in this area hold great potential for advancing cancer therapy and improving patient outcomes.

Gas Delivery Relevant to Human Health using Porous Materials

Gases are essential for various applications relevant to human health, including in medicine, biomedical imaging, and pharmaceutical synthesis. However, gases are significantly more challenging to safely handle than liquids and solids. Herein, we review the use of porous materials, such as metal-organic frameworks (MOFs), zeolites, and silicas, to adsorb medicinally relevant gases and facilitate their handling as solids. Specific topics include the use of MOFs and zeolites to deliver H2S for therapeutic applications, 129Xe for magnetic resonance imaging, O2 for the treatment of cancer and hypoxia, and various gases for use in organic synthesis. This Perspective aims to bring together the organic, inorganic, medicinal, and materials chemistry communities to inspire the design of next-generation porous materials for the storage and delivery of medicinally relevant gases.

The Past and Future of Angiogenesis as a Target for Cancer Therapy and Prevention

Cancer growth is dependent on angiogenesis, the formation of new blood vessels, which represents a hallmark of cancer. After this concept was established in the 1970s, inhibition of tumor development and metastases by blocking the neoangiogenic process has been an important approach to the treatment of tumors. However, antiangiogenic therapies are often administered when cancer has already progressed. The key to reducing the cancer burden is prevention. We noticed 20 years ago that a series of possible cancer chemopreventive agents showed antiangiogenic properties when tested in experimental models. This article reviews the relevant advances in the understanding of the rationale for targeting angiogenesis for cancer therapy, prevention, and interception and recently investigated substances with antiangiogenic activity that may be suitable for such strategies. Many compounds, either dietary derivatives or repurposed drugs, with antiangiogenic activity are possible tools for cancer angioprevention. Such molecules have a favorable safety profile and are likely to allow the prolonged duration necessary for an efficient preventive strategy. Recent evidence on mechanisms and possible use is described here for food derivatives, including flavonoids, retinoids, triterpenoids, omega fatty acids, and carotenoids from marine microorganisms. As examples, a number of compounds, including epigallocatechin, resveratrol, xanthohumol, hydroxytyrosol, curcumin, fenretinide, lycopene, fucoxanthin, and repurposed drugs, such as aspirin, β blockers, renin-angiotensin-aldosterone inhibitors, carnitines, and biguanides, are reviewed.

Thetumor microenvironment'sinpancreatic cancer:Effects onimmunotherapy successandnovel strategiestoovercomethehostile environment

Cancer is a significant global health issue that poses a considerable burden on both patients and healthcare systems. Many different types of cancers exist that often require unique treatment approaches and therapies. A hallmark of tumor progression is the creation of an immunosuppressive environment, which poses complex challenges for current treatments. Amongst the most explored characteristics is a hypoxic environment, high interstitial pressure, and immunosuppressive cells and cytokines. Traditional cancer treatments involve radiotherapy, chemotherapy, and surgical procedures. The advent of immunotherapies was regarded as a promising approach with hopes of greatly increasing patients' survival and outcome. Although some success is seen with various immunotherapies, the vast majority of monotherapies are unsuccessful. This review examines how various aspects of the tumor microenvironment (TME) present challenges that impede the success of immunotherapies. Subsequently, we review strategies to manipulate the TME to facilitate the success of immunotherapies.

Vascular regional analysis unveils differential responses to anti-angiogenic therapy in pancreatic xenografts through macroscopic photoacoustic imaging

Pancreatic cancer (PC) is a highly lethal malignancy and the third leading cause of cancer deaths in the U.S. Despite major innovations in imaging technologies, there are limited surrogate radiographic indicators to aid in therapy planning and monitoring. Amongst the various imaging techniques Ultrasound-guided photoacoustic imaging (US-PAI) is a promising modality based on endogenous blood (hemoglobin) and blood oxygen saturation (StO 2 ) contrast to monitor response to anti-angiogenic therapies. Adaptation of US-PAI to the clinical realm requires macroscopic configurations for adequate depth visualization, illuminating the need for surrogate radiographic markers, including the tumoral microvessel density (MVD). In this work, subcutaneous xenografts with PC cell lines AsPC-1 and MIA-PaCa-2 were used to investigate the effects of receptor tyrosine kinase inhibitor (sunitinib) treatment on MVD and StO 2 . Through histological correlation, we have shown that regions of high and low vascular density (HVD and LVD) can be identified through frequency domain filtering of macroscopic PA images which could not be garnered from purely global analysis. We utilized vascular regional analysis (VRA) of treatment-induced StO 2 and total hemoglobin (HbT) changes. VRA as a tool to monitor treatment response allowed us to identify potential timepoints of vascular remodeling, highlighting its ability to provide insights into the TME not only for sunitinib treatment but also other anti-angiogenic therapies.

Fas Ligand enhances vessel maturation and inhibits vascular leakage associated with age-related macular degeneration

Neovascular age-related macular degeneration (AMD), results from choroidal neovascularization (CNV), retinal edema and loss of photoreceptors. Previous studies suggested that Fas Ligand (FasL) on retinal pigment epithelial cells inhibited CNV by inducing apoptosis of infiltrating Fas+ vascular endothelial cells. However, induction of apoptosis depends on membrane-bound (mFasL) while the FasL cleavage product (sFasL) is neuroprotective. To better understand how FasL regulates the development of CNV, we used a mouse model of laser CNV to evaluate the development of CNV in mice with a FasL cleavage site mutation (ΔCS) and can only express the membrane-bound form of FasL. There was no significant difference in CNV size and area of vascular leakage in homozygous FasLΔCS/ΔCS mice when compared to wild type mice. Unexpectedly, heterozygous FasLΔCS/WT mice developed significantly less vascular leakage and showed accelerated neovessel maturation. However, CNV was not prevented in heterozygous FasLΔCS/WT mice if the Fas receptor was deleted in myeloid cells (FasLΔCS/+ Fasflox/flox CreLysM). Thus, FasL-mediated CNV inhibition depends on the extent of FasL cleavage, and on FasL engagement of Fas+ myeloid cells. Moreover, accelerated neovessel maturation prevents vascular leakage in AMD.

Tumor-Targeted Perfluorinated Micelles as Efficient Theranostic Agents Combining Positron Emission Tomography and Radiosensitization

We report the synthesis of biocompatible perfluorinated micelles designed to improve radiotherapeutic efficacy in a radioresistant tumor environment. In vitro and in vivo behaviors of perfluorinated micelles were assessed at both cellular and tissular levels. The micellar platform offers key advantages as theranostic tool: (i) small size, allowing deep tissue penetration; (ii) oxygen transport to hypoxic tissues; (iii) negligible toxicity in the absence of ionizing radiation; (iv) internalization into cancer cells; (v) potent radiosensitizing effect; and (vi) excellent tumor-targeting properties, as monitored by positron emission tomography. We have demonstrated strong in vitro radiosensitizing effects of the micelle and in vivo tumor targeting, making this nanometric carrier a promising tool for the potentiation of focused radiotherapy.

Mitochondria-related chemoradiotherapy resistance genes-based machine learning model associated with immune cell infiltration on the prognosis of esophageal cancer and its value in pan-cancer

Esophageal cancer, known for its high incidence and low five-year survival rate, poses significant treatment challenges. A key aspect of this challenge is the close link between mitochondria and resistance to chemoradiotherapy (CRT). Currently, there is a scarcity of biomarkers for predicting CRT response and prognosis in esophageal cancer. Our study addresses this gap by developing a prognostic model that incorporates mitochondria-related CRT resistance (MRCRTR) genes, including CTSL, TBL1X, CLN8, MMP1, PDPN, and MRPL37. Survival analysis using Kaplan-Meier curves reveals that patients with high MRCRTR scores have lower survival rates than those with low scores. Utilizing a nomogram, we successfully predict the one-, two-, and three-year overall survival rates for esophageal cancer patients. Cox regression analysis confirms the MRCRTR score as an independent prognostic factor. Furthermore, our single-cell and correlation analyses suggested that MRCRTR genes might influence CRT resistance by modulating the immune microenvironment and impacting angiogenesis. Our pan-cancer analysis also indicates the potential applicability of MRCRTR scores to head and neck squamous cell carcinoma. The validation of these findings, conducted with samples from Xiang-ya Hospital, aligns closely with our bioinformatics results. Our study not only explores the role of MRCRTR genes in predicting the prognosis of esophageal cancer but also enhances the understanding of the interplay between CRT, mitochondria, and patient outcomes.

Marine-Derived Leads as Anticancer Candidates by Disrupting Hypoxic Signaling through Hypoxia-Inducible Factors Inhibition

The inadequate vascularization seen in fast-growing solid tumors gives rise to hypoxic areas, fostering specific changes in gene expression that bolster tumor cell survival and metastasis, ultimately leading to unfavorable clinical prognoses across different cancer types. Hypoxia-inducible factors (HIF-1 and HIF-2) emerge as druggable pivotal players orchestrating tumor metastasis and angiogenesis, thus positioning them as prime targets for cancer treatment. A range of HIF inhibitors, notably natural compounds originating from marine organisms, exhibit encouraging anticancer properties, underscoring their significance as promising therapeutic options. Bioprospection of the marine environment is now a well-settled approach to the discovery and development of anticancer agents that might have their medicinal chemistry developed into clinical candidates. However, despite the massive increase in the number of marine natural products classified as 'anticancer leads,' most of which correspond to general cytotoxic agents, and only a few have been characterized regarding their molecular targets and mechanisms of action. The current review presents a critical analysis of inhibitors of HIF-1 and HIF-2 and hypoxia-selective compounds that have been sourced from marine organisms and that might act as new chemotherapeutic candidates or serve as templates for the development of structurally similar derivatives with improved anticancer efficacy.

Thrombospondins in the tumor microenvironment

Many cancers begin with the formation of a small nest of transformed cells that can remain dormant for years. Thrombospondin-1 (TSP-1) initially promotes dormancy by suppressing angiogenesis, a key early step in tumor progression. Over time, increases in drivers of angiogenesis predominate, and vascular cells, immune cells, and fibroblasts are recruited to the tumor mass forming a complex tissue, designated the tumor microenvironment. Numerous factors, including growth factors, chemokine/cytokine, and extracellular matrix, participate in the desmoplastic response that in many ways mimics wound healing. Vascular and lymphatic endothelial cells, and cancer-associated pericytes, fibroblasts, macrophages and immune cells are recruited to the tumor microenvironment, where multiple members of the TSP gene family promote their proliferation, migration and invasion. The TSPs also affect the immune signature of tumor tissue and the phenotype of tumor-associated macrophages. Consistent with these observations, expression of some TSPs has been established to correlate with poor outcomes in specific types of cancer.

Key processes in tumor metastasis and therapeutic strategies with nanocarriers: a review

Cancer metastasis is the leading cause of cancer-related death. Metastasis occurs at all stages of tumor development, with unexplored changes occurring at the primary site and distant colonization sites. The growing understanding of the metastatic process of tumor cells has contributed to the emergence of better treatment options and strategies. This review summarizes a range of features related to tumor cell metastasis and nanobased drug delivery systems for inhibiting tumor metastasis. The mechanisms of tumor metastasis in the ideal order of metastatic progression were summarized. We focus on the prominent role of nanocarriers in the treatment of tumor metastasis, summarizing the latest applications of nanocarriers in combination with drugs to target important components and processes of tumor metastasis and providing ideas for more effective nanodrug delivery systems.

Nanodrugs Reprogram Cancer-Associated Fibroblasts and Normalize Tumor Vasculatures for Sequentially Enhancing Photodynamic Therapy of Hepatocellular Carcinoma

Background

The failure of cancer photodynamic therapy (PDT) is largely ascribed to excessive stroma and defective vasculatures that restrain the photosensitizer permeation and the oxygen perfusion in tumors.

Method and Results

In this study, a nanodrug that integrated the cancer-associated fibroblast (CAF) regulation with tumor vessel normalization was tailored to sequentially sensitize PDT. The nanodrug exhibited high targeting towards CAFs and efficiently reversed the activated CAFs into quiescence, thus decreasing collagen deposition in the tumor microenvironment (TME), which overcame the protective physical barrier. Furthermore, the nanodrug regulated vascular endothelial cells and restored the tumor vasculatures, thereby improving vascular permeability. Based on the combined effects of reprogramming the TME, the nanodrug improved tumor accumulation of photosensitizers and alleviated hypoxia in the TME, which facilitated the subsequent PDT. Importantly, the nanodrug regulated the immunosuppressive TME by favoring the infiltration of immunostimulatory cells over immunosuppressive cells, which potentiated the PDT-induced immune response.

Conclusion

Our work demonstrates a sequential treatment strategy in which the combination of the CAF regulation and tumor vasculature normalization, followed by PDT, could be a promising modality for sensitizing tumor to PDT.

Normalizing Tumor Blood Vessels to Improve Chemotherapy and Inhibit Breast Cancer Metastasis by Multifunctional Nanoparticles

The abnormal tumor blood vessels with high leakage can promote tumor cells to infiltrate into the systemic circulation and increase the risk of tumor metastasis. In addition, chemotherapy may destroy tumor blood vessels and further aggravate metastasis. Normalizing tumor blood vessels can reduce vascular leakage and increase vascular integrity. The simultaneous administration of vascular normalization drugs and chemotherapy drugs may resist the blood vessels' destruction of chemotherapy. Here, multifunctional nanoparticles (CCM@LMSN/DOX&St), which combined chemotherapy with tumor blood vessel normalization, were prepared for the treatment of breast cancer. The results showed that CCM@LMSN/DOX&St-loaded sunitinib (St) promoted the expression of junction proteins Claudin-4 and VE-cadherin of endothelial cells, reversed the destruction of DOX to the endothelial cell layer, protected the integrity of the endothelial cell layer, and inhibited the migration of 4T1 tumor cells across the endothelial cell layer. In vivo experiments showed that CCM@LMSN/DOX&St effectively inhibited tumor growth in situ; what is exciting was that it also inhibited distal metastasis of breast cancer. CCM@LMSN/DOX&St encapsulated with St can normalize tumor blood vessels, reverse the damage of DOX to tumor blood vessels, increase the integrity of blood vessels, and prevent tumor cell invasion into blood vessels, which can inhibit breast cancer spontaneous metastasis and reduce chemotherapy-induced metastasis. This drug delivery platform effectively inhibited the progression of tumors and provided a promising solution for effective tumor treatment.

NIR diagnostic imaging of triple-negative breast cancer and its lymph node metastasis for high-efficiency hypoxia-activated multimodal therapy

BACKGROUND

Triple-negative breast cancer (TNBC) possesses special biological behavior and clinicopathological characteristics, which is highly invasive and propensity to metastasize to lymph nodes, leading to a worse prognosis than other types of breast cancer. Thus, the development of an effective therapeutic method is significant to improve the survival rate of TNBC patients.

RESULTS

In this work, a liposome-based theranostic nanosystem (ILA@Lip) was successfully prepared by simultaneously encapsulating IR 780 as the photosensitizer and lenvatinib as an anti-angiogenic agent, together with banoxantrone (AQ4N) molecule as the hypoxia-activated prodrug. The ILA@Lip can be applied for the near-infrared (NIR) fluorescence diagnostic imaging of TNBC and its lymph node metastasis for multimodal therapy. Lenvatinib in ILA@Lip can inhibit angiogenesis by cutting oxygen supply, thereby leading to enhanced hypoxia levels. Meanwhile, large amounts of reactive oxygen species (ROS) were produced while IR 780 was irradiated by an 808 nm laser, which also rapidly exhausted oxygen in tumor cells to worsen tumor hypoxia. Through creating an extremely hypoxic in TNBC, the conversion of non-toxic AQ4N to toxic AQ4 was much more efficiency for hypoxia-activated chemotherapy. Cytotoxicity assay of ILA@Lip indicated excellent biocompatibility with normal cells and tissues, but showed high toxicity in hypoxic breast cancer cells. Also, the in vivo tumors treated by the ILA@Lip with laser irradiation were admirably suppressed in both subcutaneous tumor model and orthotopic tumor models.

CONCLUSION

Utilizing ILA@Lip is a profound strategy to create an extremely hypoxic tumor microenvironment for higher therapeutic efficacy of hypoxia-activated chemotherapy, which realized collective suppression of tumor growth and has promising potential for clinical translation.

Angiogenesis modulated by CD93 and its natural ligands IGFBP7 and MMRN2: a new target to facilitate solid tumor therapy by vasculature normalization

The tumor vasculature was different from the normal vasculature in both function and morphology, which caused hypoxia in the tumor microenvironment (TME). Previous anti-angiogenesis therapy had led to a modest improvement in cancer immunotherapy. However, antiangiogenic therapy only benefitted a few patients and caused many side effects. Therefore, there was still a need to develop a new approach to affect tumor vasculature formation. The CD93 receptor expressed on the surface of vascular endothelial cells (ECs) and its natural ligands, MMRN2 and IGFBP7, were now considered potential targets in the antiangiogenic treatment because recent studies had reported that anti-CD93 could normalize the tumor vasculature without impacting normal blood vessels. Here, we reviewed recent studies on the role of CD93, IGFBP7, and MMRN2 in angiogenesis. We focused on revealing the interaction between IGFBP7-CD93 and MMRN2-CD93 and the signaling cascaded impacted by CD93, IGFBP7, and MMRN2 during the angiogenesis process. We also reviewed retrospective studies on CD93, IGFBP7, and MMRN2 expression and their relationship with clinical factors. In conclusion, CD93 was a promising target for normalizing the tumor vasculature.

The Efficacy of Nanoparticle Delivery to Hypoxic Solid Tumors by ciRGD Co-Administration Depends on Neuropilin-1 and Neutrophil Levels

The ability to improve nanoparticle delivery to solid tumors is an actively studied domain, where various mechanisms are looked into. In previous work, the authors have looked into nanoparticle size, tumor vessel normalization, and disintegration, and here it is aimed to continue this work by performing an in-depth mechanistic study on the use of ciRGD peptide co-administration. Using a multiparametric approach, it is observed that ciRGD can improve nanoparticle delivery to the tumor itself, but also to tumor cells specifically better than vessel normalization strategies. The effect depends on the level of tumor perfusion, hypoxia, neutrophil levels, and vessel permeability. This work shows that upon characterizing tumors for these parameters, conditions can be selected that can optimally benefit from ciRGD co-administration as a means to improve NP delivery to solid tumors.

Hypoxia effects on oncolytic virotherapy in Cancer: Friend or Foe?

Researchers have tried to find novel strategies for cancer treatment in the past decades. Among the utilized methods, administering oncolytic viruses (OVs) alone or combined with other anticancer therapeutic approaches has had promising outcomes, especially in solid tumors. Infecting the tumor cells by these viruses can lead to direct lysis or induction of immune responses. However, the immunosuppressive tumor microenvironment (TME) is considered a significant challenge for oncolytic virotherapy in treating cancer. Based on OV type, hypoxic conditions in the TME can accelerate or repress virus replication. Therefore, genetic manipulation of OVs or other molecular modifications to reduce hypoxia can induce antitumor responses. Moreover, using OVs with tumor lysis capability in the hypoxic TME may be an attractive strategy to overcome the limitations of the therapy. This review summarizes the latest information available in the field of cancer virotherapy and discusses the dual effect of hypoxia on different types of OVs to optimize available related therapeutic methods.

Photodynamic Stromal Depletion in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest solid malignancies, with a five-year survival of less than 10%. The resistance of the disease and the associated lack of therapeutic response is attributed primarily to its dense, fibrotic stroma, which acts as a barrier to drug perfusion and permits tumour survival and invasion. As clinical trials of chemotherapy (CT), radiotherapy (RT), and targeted agents have not been successful, improving the survival rate in unresectable PDAC remains an urgent clinical need. Photodynamic stromal depletion (PSD) is a recent approach that uses visible or near-infrared light to destroy the desmoplastic tissue. Preclinical evidence suggests this can resensitise tumour cells to subsequent therapies whilst averting the tumorigenic effects of tumour-stromal cell interactions. So far, the pre-clinical studies have suggested that PDT can successfully mediate the destruction of various stromal elements without increasing the aggressiveness of the tumour. However, the complexity of this interplay, including the combined tumour promoting and suppressing effects, poses unknowns for the clinical application of photodynamic stromal depletion in PDAC.

Murine Breast Cancer Radiosensitization Using Oxygen Microbubbles and Metformin: Vessels Are the Key

Radiotherapy is a cornerstone of cancer treatment, but tumor hypoxia and resistance to radiation remain significant challenges. Vascular normalization has emerged as a strategy to improve oxygenation and enhance therapeutic outcomes. In this study, we examine the radiosensitization potential of vascular normalization using metformin, a widely used anti-diabetic drug, and oxygen microbubbles (OMBs). We investigated the synergistic action of metformin and OMBs and the impact of this therapeutic combination on the vasculature, oxygenation, invasiveness, and radiosensitivity of murine 4T1 breast cancer. We employed in vivo Doppler ultrasonographic imaging for vasculature analysis, electron paramagnetic resonance oximetry, and immunohistochemical assessment of microvessels, perfusion, and invasiveness markers. Our findings demonstrate that both two-week metformin therapy and oxygen microbubble treatment normalize abnormal cancer vasculature. The combination of metformin and OMB yielded more pronounced and sustained effects than either treatment alone. The investigated therapy protocols led to nearly twice the radiosensitivity of 4T1 tumors; however, no significant differences in radiosensitivity were observed between the various treatment groups. Despite these improvements, resistance to treatment inevitably emerged, leading to the recurrence of hypoxia and an increased incidence of metastasis.

Induced Vascular Normalization-Can One Force Tumors to Surrender to a Better Microenvironment?

Immunotherapy has changed the way many cancers are being treated. Researchers in the field of immunotherapy and tumor immunology are investigating similar questions: How can the positive benefits achieved with immunotherapies be enhanced? Can this be achieved through combinations with other agents and if so, which ones? In our view, there is an urgent need to improve immunotherapy to make further gains in the overall survival for those patients that should benefit from immunotherapy. While numerous different approaches are being considered, our team believes that drug delivery methods along with appropriately selected small-molecule drugs and drug candidates could help reach the goal of doubling the overall survival rate that is seen in some patients that are given immunotherapeutics. This review article is prepared to address how immunotherapies should be combined with a second treatment using an approach that could realize therapeutic gains 10 years from now. For context, an overview of immunotherapy and cancer angiogenesis is provided. The major targets in angiogenesis that have modulatory effects on the tumor microenvironment and immune cells are highlighted. A combination approach that, for us, has the greatest potential for success involves treatments that will normalize the tumor's blood vessel structure and alter the immune microenvironment to support the action of immunotherapeutics. So, this is reviewed as well. Our focus is to provide an insight into some strategies that will engender vascular normalization that may be better than previously described approaches. The potential for drug delivery systems to promote tumor blood vessel normalization is considered.

Tanshinone IIA promotes vascular normalization and boosts Sorafenib's anti-hepatoma activity via modulating the PI3K-AKT pathway

Introduction: Angiogenesis is an essential feature of liver cancer. Tumor hypoxia results from abnormal vessel architecture. Numerous studies have sufficiently demonstrated that Tanshinone IIA (Tan IIA) can increase blood flow and enhance microcirculation. The objectives of this study are to: 1 assess the impact of Tan IIA on tumor angiogenesis and architecture, 2 determine the impact of Tan IIA on tumor hypoxia and susceptibility to Sorafenib, and 3 clarify the relevant mechanisms. Methods: CCK8 and flow cytometry measured cell proliferation and apoptosis, respectively. Tube creation assay was used to investigate medication effects on angiogenesis and structure. Drug effects on tumor development, metastasis, and hypoxic tumor microenvironment are assessed in an orthotopic xenograft model of liver tumors. Protein expression was measured by Western blotting and immunohistochemistry. Results: Our results demonstrated that Tan IIA could not reduce tumor proliferation or enhance Sorafenib's anti-tumor effect in vitro. Nevertheless, it can prevent Sorafenib from demolishing the typical vascular structure and aid sorafenib in blocking the recruitment of vascular endothelial cells by liver cancer cells. Although Tan IIA cannot inhibit tumor growth in vivo, it can significantly boost Sorafenib's inhibitory effect on liver cancer, alleviate tumor microenvironment hypoxia, and minimize lung metastasis. This effect may be achieved by reducing HIF-1α and HIF-2α expression via the PI3K-AKT signal pathway. Discussion: Our results reveal the mechanism of Tan IIA in normalizing tumor blood vessels, provide innovative concepts and approaches to overcome chemotherapy resistance, and provide a theoretical basis for the clinical transformation and usage of Tan IIA.

Targeting oral tumor microenvironment for effective therapy

Oral cancers are among the common head and neck malignancies. Different anticancer therapy modalities such as chemotherapy, immunotherapy, radiation therapy, and also targeted molecular therapy may be prescribed for targeting oral malignancies. Traditionally, it has been assumed that targeting malignant cells alone by anticancer modalities such as chemotherapy and radiotherapy suppresses tumor growth. In the last decade, a large number of experiments have confirmed the pivotal role of other cells and secreted molecules in the tumor microenvironment (TME) on tumor progression. Extracellular matrix and immunosuppressive cells such as tumor-associated macrophages, myeloid-derived suppressor cells (MDSCs), cancer-associated fibroblasts (CAFs), and regulatory T cells (Tregs) play key roles in the progression of tumors like oral cancers and resistance to therapy. On the other hand, infiltrated CD4 + and CD8 + T lymphocytes, and natural killer (NK) cells are key anti-tumor cells that suppress the proliferation of malignant cells. Modulation of extracellular matrix and immunosuppressive cells, and also stimulation of anticancer immunity have been suggested to treat oral malignancies more effectively. Furthermore, the administration of some adjuvants or combination therapy modalities may suppress oral malignancies more effectively. In this review, we discuss various interactions between oral cancer cells and TME. Furthermore, we also review the basic mechanisms within oral TME that may cause resistance to therapy. Potential targets and approaches for overcoming the resistance of oral cancers to various anticancer modalities will also be reviewed. The findings for targeting cells and potential therapeutic targets in clinical studies will also be reviewed.

In vivo imaging of acute physiological responses after treatment of cancer with near-infrared photoimmunotherapy

PURPOSE

Near-infrared photoimmunotherapy (NIR-PIT) is a new cancer phototherapy using an antibody-photosensitizer conjugate (Ab-IR700). By NIR light irradiation, Ab-IR700 forms a water-insoluble aggregation on the plasma membrane of cancer cells, leading to lethal membrane damage of cancer cells with high selectivity. However, IR700 produces singlet oxygen, which induces non-selective inflammatory responses such as edema in normal tissues around the tumor. Understanding such treatment-emergent responses is important to minimize side effects and improve clinical outcomes. Thus, in this study, we evaluated physiological responses during NIR-PIT by magnetic resonance imaging (MRI) and positron emission tomography (PET).

PROCEDURES

Ab-IR700 was intravenously injected into tumor-bearing mice with two tumors on the right and left sides of the dorsum. At 24 h after injection, a tumor was irradiated with NIR light. Edema formation was examined by T1/T2/diffusion-weighted MRI and inflammation was investigated by PET with 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG). Because inflammation can increase vascular permeability via inflammatory mediators, we evaluated changes in oxygen levels in tumors using a hypoxia imaging probe, [¹⁸F]fluoromisonidazole ([¹⁸F]FMISO).

RESULTS

The uptake of [¹⁸F]FDG in the irradiated tumor was significantly decreased compared to the control tumor, indicating the impairment of glucose metabolism induced by NIR-PIT. MRI and [¹⁸F]FDG-PET images showed that inflammatory edema with [¹⁸F]FDG accumulation was present in the surrounding normal tissues of the irradiated tumor. Furthermore, [¹⁸F]FMISO accumulation in the center of the irradiated tumor was relatively low, indicating the enhancement of oxygen supply due to increased vascular permeability. In contrast, high [¹⁸F]FMISO accumulation was observed in the peripheral region, indicating enhancement of hypoxia in the region. This could be because inflammatory edema was formed in the surrounding normal tissues, which blocked blood flow to the tumor.

CONCLUSIONS

We successfully monitored inflammatory edema and changes in oxygen levels during NIR-PIT. Our findings on the acute physiological responses after light irradiation will help to develop effective measures to minimize the side effects in NIR-PIT.

Nanotechnological strategies to increase the oxygen content of the tumor

Hypoxia is a negative prognostic indicator of solid tumors, which not only changes the survival state of tumors and increases their invasiveness but also remarkably reduces the sensitivity of tumors to treatments such as radiotherapy, chemotherapy and photodynamic therapy. Thus, developing therapeutic strategies to alleviate tumor hypoxia has recently been considered an extremely valuable target in oncology. In this review, nanotechnological strategies to elevate oxygen levels in tumor therapy in recent years are summarized, including (I) improving the hypoxic tumor microenvironment, (II) oxygen delivery to hypoxic tumors, and (III) oxygen generation in hypoxic tumors. Finally, the challenges and prospects of these nanotechnological strategies for alleviating tumor hypoxia are presented.

Gold nanoparticles as antiangiogenic and antimetastatic agents

Angiogenesis and metastasis are two interdependent cancer hallmarks, the latter of which is the key cause of treatment failure. Thus, establishing effective antiangiogenesis/antimetastasis agents is the final frontier in cancer research. Gold nanoparticles (GNPs) may provide disruptive advancements in this regard due to their intrinsic physical and physiological features. Here, we comprehensively discuss recent potential therapeutical strategies to treat angiogenesis and metastasis and present a critical review on the state-of-the-art in vitro and in vivo evaluations of the antiangiogenic/antimetastatic activity of GNPs. Finally, we provide perspectives on the contribution of GNPs to the advancement of cancer management.

A New Treatment Landscape for RCC: Association of the Human Microbiome with Improved Outcomes in RCC

Microbes play different roles in metabolism, local or systemic inflammation, and immunity, and the human microbiome in tumor microenvironment (TME) is important for modulating the response to immunotherapy in cancer patients. Renal cell carcinoma (RCC) is an immunogenic tumor, and immunotherapy is the backbone of its treatment. Correlations between the microbiome and responsiveness to immune checkpoint inhibitors have been reported. This review summarizes the recent therapeutic strategies for RCC and the effects of TME on the systemic therapy of RCC. The current understanding and advances in microbiome research and the relationship between the microbiome and the response to immunotherapy for RCC are also discussed. Improving our understanding of the role of the microbiome in RCC treatment will facilitate the development of microbiome targeting therapies to modify the tumor microbiome and improve treatment outcomes.

Functional biomarkers derived from computed tomography and magnetic resonance imaging differentiate PDAC subgroups and reveal gemcitabine-induced hypo-vascularization

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is a molecularly heterogeneous tumor entity with no clinically established imaging biomarkers. We hypothesize that tumor morphology and physiology, including vascularity and perfusion, show variations that can be detected by differences in contrast agent (CA) accumulation measured non-invasively. This work seeks to establish imaging biomarkers for tumor stratification and therapy response monitoring in PDAC, based on this hypothesis.

METHODS AND MATERIALS

Regional CA accumulation in PDAC was correlated with tumor vascularization, stroma content, and tumor cellularity in murine and human subjects. Changes in CA distribution in response to gemcitabine (GEM) were monitored longitudinally with computed tomography (CT) Hounsfield Units ratio (HUr) of tumor to the aorta or with magnetic resonance imaging (MRI) ΔR1 area under the curve at 60 s tumor-to-muscle ratio (AUC60r). Tissue analyses were performed on co-registered samples, including endothelial cell proliferation and cisplatin tissue deposition as a surrogate of chemotherapy delivery.

RESULTS

Tumor cell poor, stroma-rich regions exhibited high CA accumulation both in human (meanHUr 0.64 vs. 0.34, p < 0.001) and mouse PDAC (meanAUC60r 2.0 vs. 1.1, p < 0.001). Compared to the baseline, in vivo CA accumulation decreased specifically in response to GEM treatment in a subset of human (HUr -18%) and mouse (AUC60r -36%) tumors. Ex vivo analyses of mPDAC showed reduced cisplatin delivery (GEM: 0.92 ± 0.5 mg/g, vs. vehicle: 3.1 ± 1.5 mg/g, p = 0.004) and diminished endothelial cell proliferation (GEM: 22.3% vs. vehicle: 30.9%, p = 0.002) upon GEM administration.

CONCLUSION

In PDAC, CA accumulation, which is related to tumor vascularization and perfusion, inversely correlates with tumor cellularity. The standard of care GEM treatment results in decreased CA accumulation, which impedes drug delivery. Further investigation is warranted into potentially detrimental effects of GEM in combinatorial therapy regimens.

Advances in neovascularization after diabetic ischemia

With the high incidence of diabetes around the world, ischemic complications cause a serious influence on people's production and living. Neovascularization plays a significant role in its development. Therefore, neovascularization after diabetic ischemia has aroused attention and has become a hot spot in recent years. Neovascularization is divided into angiogenesis represented by atherosclerosis and arteriogenesis characterized by coronary collateral circulation. When mononuclear macrophages successively migrate to the ischemia anoxic zone after ischemia or hypoxia, they induce the secretion of cytokines, such as vascular endothelial growth factor and hypoxia-inducible factor, activate signaling pathways such as classic Wnt and phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) pathways, trigger oxidative stress response, activate endothelial progenitor cells or enter the glycolysis or lactic acid process and promote the formation of new blood vessels, remodeling them into mature blood vessels and restoring blood supply. However, the hypoglycemic condition has different impacts on neovascularization. Consequently, this review aimed to introduce the mechanisms of neovascularization after diabetic ischemia, increase our un-derstanding of diabetic ischemic complications and their therapies and provide more treatment options for clinical practice and effectively relieve patients' pain. It is believed that in the near future, neovascularization will bring more benefits and hope to patients with diabetes.

Targeting the tumor stroma for cancer therapy

Tumors are comprised of both cancer cells and surrounding stromal components. As an essential part of the tumor microenvironment, the tumor stroma is highly dynamic, heterogeneous and commonly tumor-type specific, and it mainly includes noncellular compositions such as the extracellular matrix and the unique cancer-associated vascular system as well as a wide variety of cellular components including activated cancer-associated fibroblasts, mesenchymal stromal cells, pericytes. All these elements operate with each other in a coordinated fashion and collectively promote cancer initiation, progression, metastasis and therapeutic resistance. Over the past few decades, numerous studies have been conducted to study the interaction and crosstalk between stromal components and neoplastic cells. Meanwhile, we have also witnessed an exponential increase in the investigation and recognition of the critical roles of tumor stroma in solid tumors. A series of clinical trials targeting the tumor stroma have been launched continually. In this review, we introduce and discuss current advances in the understanding of various stromal elements and their roles in cancers. We also elaborate on potential novel approaches for tumor-stroma-based therapeutic targeting, with the aim to promote the leap from bench to bedside.

Ultrasonic Microbubble Cavitation Enhanced Tissue Permeability and Drug Diffusion in Solid Tumor Therapy

Chemotherapy has an essential role not only in advanced solid tumor therapy intervention but also in society's health at large. Chemoresistance, however, seriously restricts the efficiency and sensitivity of chemotherapeutic agents, representing a significant threat to patients' quality of life and life expectancy. How to reverse chemoresistance, improve efficacy sensitization response, and reduce adverse side effects need to be tackled urgently. Recently, studies on the effect of ultrasonic microbubble cavitation on enhanced tissue permeability and retention (EPR) have attracted the attention of researchers. Compared with the traditional targeted drug delivery regimen, the microbubble cavitation effect, which can be used to enhance the EPR effect, has the advantages of less trauma, low cost, and good sensitization effect, and has significant application prospects. This article reviews the research progress of ultrasound-mediated microbubble cavitation in the treatment of solid tumors and discusses its mechanism of action to provide new ideas for better treatment strategies.

Effective low-dose Anlotinib induces long-term tumor vascular normalization and improves anti-PD-1 therapy

Anlotinib is a new multitarget tyrosine kinase inhibitor for tumor angiogenesis, and its monotherapy exhibits a decent clinical efficacy. However, the process of combining Anlotinib and immune checkpoint therapy to achieve optimal antitumor effects while limiting side effects remains unclear. In this study, we found that effective low-dose Anlotinib was sufficient to inhibit tumor growth while reducing side effects compared with high doses. Effective low-dose Anlotinib treatments induced durable tumor vascular normalization and improved anti-PD-1 therapy in both short- and long-term treatment regimens. Mechanistically, the combination therapy increased the proportions of intratumoral CD4⁺ T, CD8⁺ T, and NK cells. Anlotinib-associated antitumor effects were independent of interferon γ; however, the combination therapy required CD8⁺ T cells to suppress tumor growth. Together, these results suggest that the combination of effective low-dose Anlotinib and PD-1 blockade induces durable antitumor effects with fewer side effects. Our findings indicate that antiangiogenic treatments combined with immune checkpoint therapy at an effective low-dose, rather than a tolerable high dose, would be more efficacious and safer.

Recent advances in smart nanoplatforms for tumor non-interventional embolization therapy

Tumor embolization therapy has attracted great attention due to its high efficiency in inhibiting tumor growth by cutting off tumor nutrition and oxygen supply by the embolic agent. Although transcatheter arterial embolization (TAE) is the mainstream technique in the clinic, there are still some limitations to be considered, especially the existence of high risks and complications. Recently, nanomaterials have drawn wide attention in disease diagnosis, drug delivery, and new types of therapies, such as photothermal therapy and photodynamic therapy, owing to their unique optical, thermal, convertible and in vivo transport properties. Furthermore, the utilization of nanoplatforms in tumor non-interventional embolization therapy has attracted the attention of researchers. Herein, the recent advances in this area are summarized in this review, which revealed three different types of nanoparticle strategies: (1) nanoparticles with active targeting effects or stimuli responsiveness (ultrasound and photothermal) for the safe delivery and responsive release of thrombin; (2) tumor microenvironment (copper and phosphate, acidity and GSH/H2O2)-responsive nanoparticles for embolization therapy with high specificity; and (3) peptide-based nanoparticles with mimic functions and excellent biocompatibility for tumor embolization therapy. The benefits and limitations of each kind of nanoparticle in tumor non-interventional embolization therapy will be highlighted. Investigations of nanoplatforms are undoubtedly of great significance, and some advanced nanoplatform systems have arrived at a new height and show potential applications in practical applications.

Mutant p53, the Mevalonate Pathway and the Tumor Microenvironment Regulate Tumor Response to Statin Therapy

Tumor cells have the ability to co-opt multiple metabolic pathways, enhance glucose uptake and utilize aerobic glycolysis to promote tumorigenesis, which are characteristics constituting an emerging hallmark of cancer. Mutated tumor suppressor and proto-oncogenes are frequently responsible for enhanced metabolic pathway signaling. The link between mutant p53 and the mevalonate (MVA) pathway has been implicated in the advancement of various malignancies, with tumor cells relying heavily on increased MVA signaling to fuel their rapid growth, metastatic spread and development of therapy resistance. Statin drugs inhibit HMG-CoA reductase, the pathway’s rate-limiting enzyme, and as such, have long been studied as a potential anti-cancer therapy. However, whether statins provide additional anti-cancer properties is worthy of debate. Here, we examine retrospective, prospective and pre-clinical studies involving the use of statins in various cancer types, as well as potential issues with statins’ lack of efficacy observed in clinical trials and future considerations for upcoming clinical trials.