Improve Tumor Oxygenation Research Articles

Hemoglobin nanoclusters-mediated regulation of KPNA4 in hypoxic tumor microenvironment enhances photodynamic therapy in hepatocellular carcinoma

BackgroundHepatocellular carcinoma (HCC) is a highly malignant tumor known for its hypoxic environment, which contributes to resistance against the anticancer drug Sorafenib (SF). Addressing SF resistance in HCC requires innovative strategies to improve tumor oxygenation and effectively deliver therapeutics.ResultsIn our study, we explored the role of KPNA4 in mediating hypoxia-induced SF resistance in HCC. We developed hemoglobin nanoclusters (Hb-NCs) capable of carrying oxygen, loaded with indocyanine green (ICG) and SF, named HPRG@SF. In vitro, HPRG@SF targeted HCC cells, alleviated hypoxia, suppressed KPNA4 expression, and enhanced the cytotoxicity of PDT against hypoxic, SF-resistant HCC cells. In vivo experiments supported these findings, showing that HPRG@SF effectively improved the oxygenation within the tumor microenvironment and countered SF resistance through combined photodynamic therapy (PDT).ConclusionThe combination of Hb-NCs with ICG and SF, forming HPRG@SF, presents a potent strategy to overcome drug resistance in hepatocellular carcinoma by improving hypoxia and employing PDT. This approach not only targets the hypoxic conditions that underlie resistance but also provides a synergistic anticancer effect, highlighting its potential for clinical applications in treating resistant HCC.

From Localized Mild Hyperthermia to Improved Tumor Oxygenation: Physiological Mechanisms Critically Involved in Oncologic Thermo-Radio-Immunotherapy.

(1) Background: Mild hyperthermia (mHT, 39-42 °C) is a potent cancer treatment modality when delivered in conjunction with radiotherapy. mHT triggers a series of therapeutically relevant biological mechanisms, e.g., it can act as a radiosensitizer by improving tumor oxygenation, the latter generally believed to be the commensurate result of increased blood flow, and it can positively modulate protective anticancer immune responses. However, the extent and kinetics of tumor blood flow (TBF) changes and tumor oxygenation are variable during and after the application of mHT. The interpretation of these spatiotemporal heterogeneities is currently not yet fully clarified. (2) Aim and methods: We have undertaken a systematic literature review and herein provide a comprehensive insight into the potential impact of mHT on the clinical benefits of therapeutic modalities such as radio- and immuno-therapy. (3) Results: mHT-induced increases in TBF are multifactorial and differ both spatially and with time. In the short term, changes are preferentially caused by vasodilation of co-opted vessels and of upstream normal tissue vessels as well as by improved hemorheology. Sustained TBF increases are thought to result from a drastic reduction of interstitial pressure, thus restoring adequate perfusion pressures and/or HIF-1α- and VEGF-mediated activation of angiogenesis. The enhanced oxygenation is not only the result of mHT-increased TBF and, thus, oxygen availability but also of heat-induced higher O2 diffusivities, acidosis- and heat-related enhanced O2 unloading from red blood cells. (4) Conclusions: Enhancement of tumor oxygenation achieved by mHT cannot be fully explained by TBF changes alone. Instead, a series of additional, complexly linked physiological mechanisms are crucial for enhancing tumor oxygenation, almost doubling the initial O2 tensions in tumors.

The development of live microorganism-based oxygen shuttles for enhanced hypoxic tumor therapy.

Hypoxia is a prominent feature of malignant tumors and contributes to tumor proliferation, metastasis, and drug resistance in various solid tumors. Therefore, improving tumor oxygenation is crucial for curing tumors. To date, multiple strategies, including oxygen delivering and producing materials, have been designed to increase the oxygen concentration in hypoxic tumors. However, the unsustainable supply of oxygen is still the main obstacle, resulting in a suboptimal outcome in treating oxygen-deprived tumors. Thus, a sufficient oxygen supply is highly desirable in the treatment of hypoxic tumors. Photosynthesis, as the main source of oxygen in nature through the conversion of light energy into chemical energy and oxygen, has been widely studied in scientific research. Moreover, photosynthetic microorganisms have been increasingly applied in cancer therapy by increasing oxygenation, which improves the therapeutic effect of oxygen-consuming tumor therapeutic tools such as radiotherapy and photodynamic therapy. In this review, we summarize recent advances in the design and manufacture of live bacteria as oxygen shuttles for a new generation of hypoxic tumor treatment strategies. Finally, current challenges and future directions are also discussed for successfully addressing hypoxic tumor issues.

Mitochondrial respiration inhibitor enhances the anti-tumor effect of high-dose ascorbic acid in castration-resistant prostate cancer.

Previous evidences have demonstrated that anti-tumor effect of high-dose ascorbic acid is associated with the generation of reactive oxygen species (ROS) via autoxidation. Hypoxia induces therapy resistance in castration-resistant prostate cancer. As a mitochondrial respiration inhibitor, metformin has the potential to improve tumor oxygenation. In this study, we evaluate the anti-tumor effect of ascorbic acid combined with metformin in prostate cancer. We demonstrated that ascorbic acid inhibits prostate cancer cells proliferation by generating ROS, and metformin enhances the anti-tumor effects of ascorbic acid. Mechanistically, metformin reduces oxygen consumption rate and NADP+/NADPH value in prostate cancer cells, thereby increases the ROS content induced by ascorbic acid. In addition, our data demonstrated that ascorbic acid inhibits p-AKT signaling in a ROS-dependent pathway, leading to inhibition of p-mTOR expression. And metformin inhibits the p-mTOR expression by activating the AMPK signaling pathway, exerting a synergistic effect on tumor suppression with ascorbic acid. Furthermore, metformin improves tumor oxygenation, and the combined treatment effect of ascorbic acid and metformin were demonstrated in a xenograft model of prostate cancer. Taken together, our data demonstrate that metformin enhances the anti-tumor proliferation effect of ascorbic acid by increasing ROS content in castration-resistant prostate cancer. This provides a new strategy for the clinical application of high-dose ascorbic acid as an anti-tumor drug. KEY MESSAGES: Ascorbic acid inhibits tumor growth by inducing ROS generation. As a mitochondrial respiration inhibitor, metformin inhibits cellular oxygen consumption rate to improve oxygenation of prostate cancer. Metformin enhances anti-tumor effect of ascorbic acid by increasing ROS content. Ascorbic acid inhibits the mTOR expression via PI3K-AKT pathway, and metformin inhibits the mTOR expression by inhibiting AMPK signaling in prostate cancer cells.

Microvesicle-inspired oxygen-delivering nanosystem potentiates radiotherapy-mediated modulation of tumor stroma and antitumor immunity

The efficacy of radiotherapy is greatly challenged by intense hypoxia, intricate stroma and suppressive immune microenvironments in tumors. Herein, we rationally designed a microvesicle-inspired oxygen-delivering polyfluorocarbon nanosystem loading DiIC18(5) and halofuginone (M-FDH) with prominent capacity of improving tumor oxygenation and intratumor distribution, synergizing radiation to disrupt tumor stroma and boost antitumor immunity for combinational cancer therapy. M-FDH produced a 10.98-fold enhancement of tumor oxygenation and caused efficient production of reactive oxygen species (ROS) upon radiation. M-FDH + X ray treatment resulted in notable DNA damages, over 90% elimination of cancer-associated fibroblasts (CAFs) and major components of extracellular matrix, significant enhancement of tumoricidal CD3+CD8+ T cells, and profound elimination of suppressive immune cells in 4T1 tumors. The therapeutic benefits of M-FDH + X ray on suppressing tumor growth were confirmed in two murine tumor models. Therefore, this study provides an encouraging microvesicle-inspired strategy to target cancer cells and CAFs in tumors and synergize radiotherapy for effective cancer treatment.

Tumoral oxygenation and biodistribution of Lonidamine oxygen microbubbles following localized ultrasound-triggered delivery

Prior work has shown that microbubble-assisted delivery of oxygen improves tumor oxygenation and radiosensitivity, albeit over a limited duration. Lonidamine (LND) has been investigated because of its ability to stimulate glycolysis, lactate production, inhibit mitochondrial respiration, and inhibit oxygen consumption rates in tumors but suffers from poor bioavailability. The goal of this work was to characterize LND-loaded oxygen microbubbles and assess their ability to oxygenate a human head and neck squamous cell carcinoma (HNSCC) tumor model, while also assessing LND biodistribution. In tumors treated with surfactant-shelled microbubbles with oxygen core (SE61O2) and ultrasound, pO2 levels increased to a peak 19.5 ± 9.7 mmHg, 50 s after injection and returning to baseline after 120 s. In comparison, in tumors treated with SE61O2/LND and ultrasound, pO2 levels showed a peak increase of 29.0 ± 8.3 mmHg, which was achieved 70 s after injection returning to baseline after 300 s (p < 0.001). The co-delivery of O2andLNDvia SE61 also showed an improvement of LND biodistribution in both plasma and tumor tissues (p < 0.001). In summary, ultrasound-sensitive microbubbles loaded with O2 and LND provided prolonged oxygenation relative to oxygenated microbubbles alone, as well as provided an ability to locally deliver LND, making them more appropriate for clinical translation.

PB2134: THE ROLE OF ADDITIONAL CARBOGEN GAS MIXTURE AND NICOTINAMIDE ON R-CHOP CHEMOTHERAPY IN DLBCL PATIENTS WITH TUMOR HYPOXIA

Background: Tumor hypoxia increases tumor aggressiveness, immunosuppression, & decreases sensitivity to chemoradiotherapy. The role of tumor hypoxia in DLBCL remains unclear. Hypoxia-inducible factor 1-alpha (HIF-1α) is an oxygen-dependent transcriptional factor that activates several tumor survival pathways. Hypoxia & inflammation have a positive correlation, one is defined by the HIF-1α & NFkB relationship. NFkB involves in cytokine regulations such as TNF-α & sIL-2R. Carbogen gas mixture (95% O2 and 5% CO2) & nicotinamide (an amide of vitamin B3) have been recently studied as a radiosensitizer in solid tumors & also improve tumor oxygenation level. We compared tumor size changes, TNF-α, & sIL-2R serum in DLBCL patients who received carbogen + nicotinamide during chemotherapy R-CHOP versus those who did not. Aims: The primary endpoint was tumor size reduction. Secondary endpoints were changes of TNF-α & sIL2R serum pre-& post-chemotherapy. Tumor MRI was used for examining the size reduction. Methods: This trial is an ongoing single-center, randomized controlled trial. Eligible DLBCL patients who had HIF-1α tissue expression ≥10% were included. Subjects were randomly assigned to the study group (nicotinamide 40 mg/kgBW + carbogen 10 liter/minute during R-CHOP) or control group (R-CHOP) for 1 cycle. Tumor MRI and blood parameters examinations were performed before and 7-days after interventions. Results: Between April-December 2021, 20 patients were enrolled (median age 56.5 years; min & max 21-65 years). For the baseline data, median tumor volume were 152.8 cm3 (4.3-1,542.5 cm3) & 172.2 cm3 (6.4-2,349.7 cm3), median sIL-2R serum were 304 U/mL (24-1,625 U/mL) & 417 U/mL (13-1,897 U/mL), median TNF-α serum were1.95 pg/mL (1.2-4.2 pg/mL) & 1.65 pg/mL (0.8-6.7 pg/mL) in control and subject group respectively, there were no statistically significant differences in these results. Post-chemotherapy, median tumor volume were 34.54 cm3 (1.86-297.5 cm3) & 112 cm3 (1.2-862.98 cm3), there were no significant differences of median Δ tumor size reduction in both groups (-118 cm3 & -85 cm3; p = 0.762) control & subject group respectively. Median sIL-2R serum in control group was increased; 519 U/mL (24-1,557 U/mL) & decreased in subject group; 157 U/mL (13-464 U/mL) although there were no statistically significance (p = 0.314 & p = 0.109 respectively). Median TNF-α serum were 2.1 pg/mL (0.8-6.9 pg/mL) & 1.8 pg/mL (0.4-3.3 pg/mL) in control & subject group respectively (p = 0.671 & p = 0.766). There was a positive correlation between Δ tumor size & Δ sIL-2R serum (p = 0.04 & r = 0.463). 2 patients complaint minor rash & itchy skin. Summary/Conclusion: We found no difference in tumor size reduction between two groups. However, we found a clinical reduction trend of serum sIL-2R in the subject group although it was not statistically significant, this is because of the incomplete sample collection. Serum sIL-2R level also had a positive correlation with tumor size reduction which showed an interesting field of study for the upcoming research.

Additional carbogen gas mixture and nicotinamide on chemotherapy in tumor hypoxic DLBCL patients.

e19579 Background: Tumor hypoxia increases tumor aggressiveness, immunosuppression, &amp; decreases sensitivity to chemoradiotherapy. The role of tumor hypoxia in DLBCL remains unclear. Hypoxia-inducible factor 1-alpha (HIF-1α) is an oxygen-dependent transcriptional factor that activates several tumor survival pathways. Hypoxia &amp; inflammation have a positive correlation, one is defined by the HIF-1α &amp; NFkB relationship. NFkB involves in cytokine regulations such as TNF-α &amp; sIL-2R. Carbogen gas mixture (95% O2 and 5% CO2) &amp; nicotinamide (an amide of vitamin B3) have been recently studied as a radiosensitizer in solid tumors &amp; also improve tumor oxygenation level. We compared tumor size changes, TNF-α, &amp; sIL-2R serum in DLBCL patients who received carbogen + nicotinamide during chemotherapy R-CHOP versus those who did not. Methods: This trial is an ongoing single-center, randomized controlled trial. Eligible DLBCL patients who had HIF-1α tissue expression ≥10% were included. Subjects were randomly assigned to the study group (nicotinamide 40 mg/kgBW + carbogen 10 liter/minute during R-CHOP) or control group (R-CHOP) for 1 cycle. The primary endpoint was tumor size reduction. Secondary endpoints were changes of TNF-α &amp; sIL2R serum pre-&amp; post-chemotherapy. Tumor MRI was used for examining the size reduction. Results: Between April-December 2021, 20 patients were enrolled (median age 56.5 years; min &amp; max 21-65 years). For the baseline data, median tumor volume were 152.8 cm3 (4.3-1,542.5 cm3) &amp; 172.2 cm3 (6.4-2,349.7 cm3), median sIL-2R serum were 304 U/mL (24-1,625 U/mL) &amp; 417 U/mL (13-1,897 U/mL), median TNF-α serum were1.95 pg/mL (1.2-4.2 pg/mL) &amp; 1.65 pg/mL (0.8-6.7 pg/mL) in control and subject group respectively, there were no statistically significant differences in these results. Post-chemotherapy, median tumor volume were 34.54 cm3 (1.86-297.5 cm3) &amp; 112 cm3 (1.2-862.98 cm3), there were no significant differences of median Δ tumor size reduction in both groups (-118 cm3 &amp; -85 cm3; p = 0.762) control &amp; subject group respectively. Median sIL-2R serum in control group was increased; 519 U/mL (24-1,557 U/mL) &amp; decreased in subject group; 157 U/mL (13-464 U/mL) although there were no statistically significance (p = 0.314 &amp; p = 0.109 respectively). Median TNF-α serum were 2.1 pg/mL (0.8-6.9 pg/mL) &amp; 1.8 pg/mL (0.4-3.3 pg/mL) in control &amp; subject group respectively (p = 0.671 &amp; p = 0.766). There was a positive correlation between Δ tumor size &amp; Δ sIL-2R serum (p = 0.04 &amp; r = 0.463). 2 patients complaint minor rash &amp; itchy skin. Conclusions: We found no difference in tumor size reduction between two groups. However, we found a clinical reduction trend of serum sIL-2R in the subject group although it was not statistically significant, this is because of the incomplete sample collection. Serum sIL-2R level also had a positive correlation with tumor size reduction which showed an interesting field of study for the upcoming research. Clinical trial information: 77237304.

Enhancing Photodynamic Therapy Efficacy Against Cancer Metastasis by Ultrasound-Mediated Oxygen Microbubble Destruction to Boost Tumor-Targeted Delivery of Oxygen and Renal-Clearable Photosensitizer Micelles.

Hypoxic tumor microenvironment and nonspecific accumulation of photosensitizers are two key factors that limit the efficacy of photodynamic therapy (PDT). Herein, a strategy of oxygen microbubbles (MBs) boosting photosensitizer micelles is developed to enhance PDT efficacy and inhibit tumor metastasis by self-assembling renal-clearable ultrasmall poly(ethylene glycol)-modified protoporphyrin IX micelles (PPM) and perfluoropentane (PFP)-doped oxygen microbubbles (OPMBs), followed by ultrasound imaging-guided OPMB destruction to realize the tumor-targeted delivery of PPM and oxygen in tumor. Doping PFP into oxygen MBs increases the production of MBs and stability of oxygen MBs, allowing for persistent circulation in blood. Following co-injection, destruction of OPMBs with ultrasound leads to ∼2.2-fold increase of tumor-specific PPM accumulation. Furthermore, the burst release of oxygen by MB destruction improves tumor oxygenation from 22 to 50%, which not only raises the production of singlet oxygen but also significantly reduces the expression of hypoxia-inducible factor-1 alpha and related genes, thus preventing angiogenesis and epithelial-mesenchymal transition. It is verified that this strategy effectively eradicates orthotopic breast cancer and inhibits lung metastasis. Furthermore, the survival rate of mice bearing orthotopic pancreatic tumor is significantly extended by such interventional PDT strategy. Therefore, the combination of ultrasmall PPM and OPMBs represents a simple but effective strategy in overcoming the limitations of PDT.

Modelling the effect of vascular status on tumour evolution and outcome after thermal therapy

Microscale oxygenation plays a prominent role in tumour progression. Spatiotemporal variability of oxygen distribution in the tumour microenvironment contributes to cellular heterogeneity and to the emergence of normoxic and hypoxic populations. Local levels of oxygen strongly affect the response of tumours to the administration of different therapeutic modalities and, more generally, to the phenomenon of resistance to treatments. Several interventions have been proposed to improve tumour oxygenation, being the elevation of the local temperature (hyperthermia) an important one. While other factors such as the metabolic activity have to be considered, the proficiency of the tumour vascular system is a key factor both for the tissue oxygenation and for its temperature maps. Consequently, the interplay of these factors has attracted considerable attention from the mathematical modelling perspective. Here we put forward a transport-based system of partial differential equations aimed at describing the dynamics of healthy and tumour cell subpopulations at the microscale in a region placed between two blood vessels. By using this model with diverse flow conditions, we analyse the oxygen and temperature profiles that arise in different scenarios of vascular status, both during free progression and under thermal therapy. We find that low oxygen levels are associated to elevations of temperature in locations preferentially populated by hypoxic cells, and hyperthermia-induced cell death, being strongly dependent on blood flow, would only appear under highly disrupted conditions of the local vasculature. This results in a noticeable effect of heat on hypoxic cells. Additionally, when pronounced cell death occurs, it is followed by a significant increase in the oxygen levels. Our results provide quantitative insight to the physiological and biological processes taking place at sub-voxel sizes, currently not accessible to standard functional imaging due to spatial resolution limitations.

PH-responsive nanomedicine co-encapsulated with Erlotinib and chlorin e6 can enable effective treatment of triple negative breast cancer via reprogramming tumor vasculature

High expression of epidermal growth factor receptor (EGFR) involved in promoting tumor proliferation, hypoxia, and many others has found to be associated with poor prognosis of diverse cancers including triple negative breast cancer (TNBC). The newest progresses have indicated that anti-EGFR chemotherapy could reinforce various cancer treatments by normalizing the abnormal tumor vasculature to improve tumor oxygenation, but suffers from severe side effects owing to the constitutive expression of EGFR in normal tissues. Herein, we develop a pH-responsive nanomedicine simultaneously loaded of Erlotinib, an inhibitor of EGFR tyrosine kinase, and chlorin e6 (Ce6), a photosensitizer, via the CaCO3-assistant emulsion method. The obtained Erlotinib-Ce6-loaded CaCO3 nanoparticles (ECCaNPs) show pH-responsive release of payloads and efficient tumor accumulation, thus enable the normalization of tumor vasculature to improve intratumoral oxygenation and decrease tumor growth by inhibiting EGFR/extracellular regulated protein kinases (ERK)/ AKT serine/threonine kinase 1 (AKT) axis. ECCaNPs together with light exposure can collectively suppress the growth of TNBC cell-line-derived and patient-derived xenograft mouse models through combined chemo- & photodynamic therapy. This study highlights that anti-EGFR chemotherapy programmed tumor vasculature could thereby enhance the therapeutic efficacy of oxygen-consuming cancer treatments, offering a promising strategy to figure out efficient combination cancer treatments to benefit TNBC patients.

Improved Oxygenation of Human Skin, Subcutis and Superficial Cancers Upon Mild Hyperthermia Delivered by WIRA-Irradiation.

Clinical trials have shown that mild hyperthermia (HT) serves as an adjunct to cancer treatments such as chemo- and radiotherapy. Recently, a high efficacy of mild HT immediately followed by hypofractionated radiotherapy (RT) in treatment of recurrent breast cancer has been documented if temperatures of 39-43°C are achieved for 40-60 min. In the present study, temperature and oxygenation profiles were measured in superficial tissues of healthy volunteers exposed to water-filtered infrared-A- (wIRA)- irradiation, to verify that adequate thermal doses together with the improved tumor oxygenation necessary for radiosensitisation are obtained. Experiments were performed using a wIRA-system equipped with two wIRA-radiators, each with a thermography camera for real-time monitoring of the skin surface temperature. Temperatures within the abdominal wall were measured with fibre optic sensors at defined tissue depths (subepidermal, and 1-20 mm inside the tissue). The corresponding tissue pO2 values were assessed with fluorometric microsensors. In selected situations, hyperspectral tissue imaging was used to visualise the oxygenation status of normal skin and superficial tumours in patients. Pre-treatment skin surface temperature was 34.6°C. Upon wIRA exposure, average skin surface temperatures reached 41.6°C within 5-12 min. Maximum tissue temperatures of 41.8°C were found at a tissue depth of 1mm, with a steady decline in deeper tissue layers (41.6°C @ 5mm, 40.8°C @ 10mm, 40.6°C @ 15mm, and 40.1°C @ 20mm). Effective HT levels ≥39°C were established in tissue depths up to 25 mm. Tissue heating was accompanied by a significant increase in tissue pO2 values [e.g., at a tissue depth of 13 mm mean pO2 rose from 46mmHg to 81mmHg (@ T=40.5°C). In the post-heating phase (+ 5min), pO2 was 79mmHg (@ T=38°C) and 15 min post-heat pO2 was 72mmHg (@ T=36.8°C)]. pO2 values remained elevated for 30-60 min post-heat. Non-invasive monitoring of normal skin and of recurrent breast cancers confirmed the improved O2 status by wIRA-HT. In conclusion, wIRA-irradiation enables effective tissue heating (T=39-43°C) associated with distinct increases in blood flow and pO2. These adjustments unequivocally meet the requirement for effective radiosensitisation.

Eribulin improves tumor oxygenation demonstrated by 18F-DiFA hypoxia imaging, leading to radio-sensitization in human cancer xenograft models.

Eribulin, an inhibitor of microtubule dynamics, is known to show antitumor effects through its remodeling activity in the tumor vasculature. However, the extent to which the improvement of tumor hypoxia by eribulin affects radio-sensitivity remains unclear. We utilized 1-(2,2-dihydroxymethyl-3-18F-fluoropropyl)-2-nitroimidazole (18F-DiFA), a new PET probe for hypoxia, to investigate the effects of eribulin on tumor hypoxia and evaluate the radio-sensitivity during eribulin treatment. Mice bearing human breast cancer MDA-MB-231 cells or human lung cancer NCI-H1975 cells were administered a single dose of eribulin. After administration, mice were injected with18F-DiFA and pimonidazole, and tumor hypoxia regions were analyzed. For the group that received combined treatment with radiation, 18F-DiFA PET/CT imaging was performed before tumors were locally X-irradiated. Tumor size was measured every other day after irradiation. Eribulin significantly reduced18F-DiFA accumulation levels in a dose-dependent manner. Furthermore, the reduction in 18F-DiFA accumulation levels by eribulin was most significant 7days after treatment. These results were also supported by reduction of the pimonidazole-positive hypoxic region. The combined treatment showed significant retardation of tumor growth in comparison with the control, radiation-alone, and drug-alone groups. Importantly, tumor growth after irradiation was inversely correlated with 18F-DiFA accumulation. These results demonstrated that 18F-DiFA PET/CT clearly detected eribulin-induced tumor oxygenation and that eribulin efficiently enhanced the antitumor activity of radiation by improving tumor oxygenation.

A Robust Oxygen-Carrying Hemoglobin-Based Natural Sonosensitizer for Sonodynamic Cancer Therapy.

The development of novel sonosensitizers with outstanding reactive oxygen (ROS) generation capacity and great biocompatibility poses a significant challenge for the clinical practice of sonodynamic therapy (SDT). In this work, hemoglobin (Hb) with natural metalloporphyrin was first shown to possess great potential as a sonosensitizer. Compared with traditional organic sonosensitizers, Hb had satisfactory sono-sensitizing efficiency because four the porphyrin molecules were separated by four polypeptide chains. This effectively avoided the problem of low ROS quantum yield caused by the stacking of hydrophobic porphyrins. Meanwhile, Hb is an efficient and safe oxygen carrier that may release O2 at hypoxic tumors site, which improved tumor oxygenation and subsequently enhanced SDT efficacy. Therefore, Hb was integrated with zeolitic imidazolate framework 8 (ZIF-8) to form a nanoplatform that demonstrated a potent suppression effect on deep-seated tumors under ultrasound irradiation.

Targeting tumor vascularization: promising strategies for vascular normalization.

Tumor recurrence after the clinical cure of tumor often results from the presence of an abnormal microenvironment, including an aberrant vasculature. The tumor microenvironment is rich in pro-angiogenic factors but lacks pro-maturation factors. Pro-angiogenic conditions in the tumor microenvironment, such as hypoxia, are double-edged swords, promoting both the repair of normal tissues and the development of an abnormal blood vessel network. The coexistence of perfusion and hypoxic zones and uneven blood vessel distribution in tumor tissues profoundly influence tumor deterioration, recurrence, and metastasis. Traditional anti-angiogenic therapies have shown limited efficacy, and promote drug resistance, and even metastasis. In contrast, vascular normalization therapy induces a more physiological-like state, leading to better outcomes and fewer side effects. Vascular normalization entails modifying the tumor vascular system to improve tumor oxygenation and substance transport, thereby contributing to improving the efficacy of radiotherapy, chemotherapy, and immunotherapy. This review mainly focuses on the process of tumor vascularization; potential therapeutic targets, including cells, metabolism, signaling pathways, and angiogenesis-related genes; and possible strategies to normalize blood vessels through regulating tumor vessel generation, the development of tumor vessels, and blood vessel fusion and pruning.

Compressed vessels bias red blood cell partitioning at bifurcations in a hematocrit-dependent manner: Implications in tumor blood flow

The tumor microenvironment is abnormal and associated with tumor tissue hypoxia, immunosuppression, and poor response to treatment. One important abnormality present in tumors is vessel compression. Vessel decompression has been shown to increase survival rates in animal models via enhanced and more homogeneous oxygenation. However, our knowledge of the biophysical mechanisms linking tumor decompression to improved tumor oxygenation is limited. In this study, we propose a computational model to investigate the impact of vessel compression on red blood cell (RBC) dynamics in tumor vascular networks. Our results demonstrate that vessel compression can alter RBC partitioning at bifurcations in a hematocrit-dependent and flow rate-independent manner. We identify RBC focusing due to cross-streamline migration as the mechanism responsible and characterize the spatiotemporal recovery dynamics controlling downstream partitioning. Based on this knowledge, we formulate a reduced-order model that will help future research to elucidate how these effects propagate at a whole vascular network level. These findings contribute to the mechanistic understanding of hemodilution in tumor vascular networks and oxygen homogenization following pharmacological solid tumor decompression.

Liquid exfoliation of TiN nanodots as novel sonosensitizers for photothermal-enhanced sonodynamic therapy against cancer

Ultrasound (US)-activated sonodynamic therapy (SDT), as a non-invasive therapy method, has the advantages of large tissue penetration depth promising for treatment of large internal tumors. However, due to the hypoxic characteristic of tumor microenvironment and lack of effective sonosensitizers, the efficacy of SDT is still not satisfactory. In addition, there is still a lot of space for the exploration of SDT-based collaborative cancer treatment. Herein, ultra-small titanium nitride (TiN) nanodots are successfully synthesized for photothermal-enhanced SDT against cancer. Ultra-small TiN nanodots with an average size of 1.5 nm are prepared by the liquid exfoliation method. The obtained TiN nanodots have satisfactory second near-infrared (NIR II) absorption, which can be used for photoacoustic (PA) imaging and photothermal therapy (PTT) of tumors. Interestingly, TiN nanodots can also be used as efficient sonosensitizers to generate reactive oxygen species (ROS) under US irradiation owing to the special defect structure and surface partial oxidation to TiO2 for sonodynamic cancer therapy. The mild photothermal heating of tumors generated by TiN nanodots under NIR II laser irradiation can facilitate intra-tumoral blood flow and improve tumor oxygenation, thereby achieving a significant synergistic treatment effect by combining PTT and SDT. Importantly, most of these TiN nanodots due to their ultra-small size can be promptly metabolized from the mouse body, thus avoiding the concerns about long-term toxicity of nanomaterials. Our work thus for the first time demonstrates the potential use of metal nitride nanomaterials as a new type of multifunctional nano-agents with intriguing properties for cancer theranostic applications.

Oxygen-Delivering Polyfluorocarbon Nanovehicles Improve Tumor Oxygenation and Potentiate Photodynamic-Mediated Antitumor Immunity.

Hypoxia is a critical cause of tumor immunosuppression, and it significantly limits the efficacy of many anticancer modalities. Herein, we report an amphiphilic F11-derivative-based oxygen-delivering polyfluorocarbon nanovehicle loading photodynamic DiIC18(5) and reactive oxygen species (ROS)-sensitive prodrug of chemo-immunomodulatory gemcitabine (PF11DG), aimed at relieving tumor hypoxia and boosting antitumor immunity for cancer therapy. We optimized F11-based polyfluorocarbon nanovehicles with a 10-fold enhancement of tumor oxygenation. PF11DG exhibited intriguing capabilities, such as oxygen-dissolving, ROS production, and responsive drug release. In tumors, PF11DG exhibited flexible intratumoral permeation and boosted robust antitumor immune responses upon laser irradiation. Notably, the treatment of PF11DG plus laser irradiation (PF11DG+L) significantly retarded the tumor growth with an 82.96% inhibition in the 4T1 breast cancer model and a 93.6% inhibition in the PANC02 pancreatic cancer model with better therapeutic benefits than non-oxygen-delivering nanovehicles. Therefore, this study presents an encouraging polyfluorocarbon nanovehicle with deep tumor-penetrating and hypoxia-relieving capacity to boost antitumor immunity for cancer treatment.

Fever range whole body hyperthermia for re-irradiation of head and neck squamous cell carcinomas: Final results of a prospective study

ObjectivesFever-range whole body hyperthermia (FRWBH) has been shown to improve tumor oxygenation in vivo. A prospective pilot study addressed the question if addition of FRWBH to re-irradiation is feasible in recurrent head and neck squamous cell carcinomas (HNSCC) with unfavorable prognostic features. Materials and methodsThe study completed accrual with the recruitment of ten patients between April 2018 and March 2020. Re-irradiation was administered using volumetric arc hyperfractionated radiotherapy with bi-daily 1.2 Gray (Gy) single fractions and a total dose of 66 Gy to all macroscopic tumor lesions. Concomitant chemotherapy consisted mostly of cisplatin (7 patients). FRWBH was scheduled weekly during re-irradiation. The study was registered in the clinicaltrials.gov database (NCT03547388). ResultsOnly five patients received all cycles of FRWBH. Poor patient compliance, active infections during treatment and study restrictions due to the Covid-19 pandemic were the main reasons for omitting FRWBH. No increase of acute toxicity was observed by FRWBH. Exploratory evaluation of outcome data suggests that FRWBH treatment according to protocol does not seem to have a detrimental effect on tumor control or survival and might even increase treatment efficacy. ConclusionFRWBH is difficult to apply concomitant to re-irradiation in HNSCC. No excess toxicity was observed in patients receiving FRWBH and exploratory analyses suggest potential anti-tumor activity and decreased patient-reported depression scores after FRWBH.

Oxygen-Enhanced Optoacoustic Tomography Reveals the Effectiveness of Targeting Heme and Oxidative Phosphorylation at Normalizing Tumor Vascular Oxygenation.

Multispectral optoacoustic tomography (MSOT) is an emerging noninvasive imaging modality that can detect real-time dynamic information about the tumor microenvironment in humans and animals. Oxygen enhanced (OE)-MSOT can monitor tumor vasculature and oxygenation during disease development or therapy. Here, we used MSOT and OE-MSOT to examine in mice the response of human non-small cell lung cancer (NSCLC) xenografts to a new class of antitumor drugs, heme-targeting agents heme-sequestering peptide 2 (HSP2) and cyclopamine tartrate (CycT). HSP2 inhibits heme uptake, while CycT inhibits heme synthesis in NSCLC cells, where heme is essential for ATP generation via oxidative phosphorylation. HSP2 and CycT can inhibit ATP generation and thereby suppress NSCLC cell tumorigenic functions. MSOT showed that treatment of NSCLC tumors with HSP2 or CycT reduced total hemoglobin, increased oxygen saturation, and enhanced the amplitude of response to oxygen gas breathing challenge. HSP2 and CycT normalized tumor vasculature and improved tumor oxygenation, where levels of several hypoxia markers in NSCLC tumors were reduced by treatment with HSP2 or CycT. Furthermore, treatment with HSP2 or CycT reduced levels of angiogenic factor VEGFA, its receptor VEGFR1, and vascular marker CD34. Together, our data show that heme-targeting drugs HSP2 and CycT elicit multiple tumor-suppressing functions, such as inhibiting angiogenic function, normalizing tumor vasculature, alleviating tumor hypoxia, and inhibiting oxygen consumption and ATP generation. SIGNIFICANCE: Heme-targeting agents HSP2 and CycT effectively normalize tumor vasculature and alleviate tumor hypoxia, raising the possibility of their combination with chemo-, radio-, and immunotherapies to improve antitumor efficacy.See related commentary by Tomaszewski, p. 3461.