Tumor Reoxygenation Research Articles

Tumour reoxygenation after intratumoural hydrogen peroxide (KORTUC) injection: a novel approach to enhance radiosensitivity

BackgroundKORTUC (0.5% hydrogen peroxide (H2O2) in 1% sodium-hyaluronate) releases cytotoxic levels of H2O2 in tissues after intratumoural injection. High levels of tumour control after radiotherapy plus KORTUC are reported in breast cancer patients. Here, we use human xenograft models to test the hypothesis that oxygen microbubbles released post-KORTUC are effective in modifying the hypoxic tumour microenvironment.Methods and materialsPimonidazole and Image-iT™ Red (live hypoxia marker) were utilised to assess dose-dependent changes in hypoxia post-H2O2 in HCT116 and LICR-LON-HN5 spheroids. Using a dual 2-nitroimidazole-marker technique and phospho-ATM we evaluated changes in hypoxia and reactive oxygen species (ROS) respectively, in HCT116 and LICR-LON-HN5 xenografts following intratumoural KORTUC.ResultsA significant reduction in Image-iT™ Red fluorescence was observed in spheroids 1 h post-H2O2 at ≥1.2 mM, maintained at 24 h. Ultrasound demonstrated sustained release of oxygen microbubbles within tumours, 1 h post-KORTUC. Hypoxia markers demonstrated significant tissue reoxygenation in both models post-KORTUC and significantly increased phospho-ATM foci reflecting increased ROS production.ConclusionIntratumoural KORTUC represents a novel oxygen delivery method, which can be exploited to enhance radiation response. If efficacy is confirmed in the ongoing phase 2 breast trial it could improve treatment of several tumour types where hypoxia is known to affect radiotherapy outcomes.

A Population-Based Tumor-Volume Model for Head and Neck Cancer During Radiation Therapy With a Dynamic Oxygenated Compartment

PurposeWith the coming era of digital wisdom medical technology, mathematical modelling of tumor becomes a key step to optimize and realize precision radiotherapy. The purpose of this study is to develop a mathematical model for simulating the change of head-and-neck tumor (HN) volume during radiotherapy. Methods and MaterialsA formula is developed to describe the dynamic change of oxygenated compartment within a tumor, which is combined with the LPL model to describe various cell processes during radiotherapy, including potentially lethal lesion repair and misrepair, cell proliferation/loss, and tumor reoxygenation. Parameter sensitivity analysis is performed to evaluate the impacts of the lesion-related and repair-related biological factors on radiotherapy outcome. ResultsWe tested our model on 14 available HN cancer patients and compared the performance with three other models. The mean error of our model for the twelve good fit cases is 12.2%, which is considerable smaller than that of the LQ model (19.7%), GLQ model (19.1%) and FLCP model (16.6%). Correlation analysis results reveal that for small tumors, there is a positive correlation (correlation coefficient r=0.9416) between hypoxic fraction and tumor volume, whereas the correlation becomes negative and not significant (r=−0.4365) for large tumors. It is demonstrated from sensitivity analysis that the production rate of lethal lesions (ηl) has a far greater impact on tumor volume than other parameters. The hypoxic fraction has insignificant impact on tumor volume, but it has notable influence on the volume of surviving cells. The final volume of surviving cells athf=0.5 is almost 8 ×102 times that of hf=0.01. The potentially lethal lesion-related parameters (ηpl,εpl, ε2pl) have rather small impacts (<1%) on both tumor volume and the volume of surviving cells, which indicates that the repaired and misrepaired sublethal cells only take up a small portion of the total cancer cell population. ConclusionsA population-based tumor-volume model for HN cancer during radiotherapy with a dynamic oxygenated compartment was developed in this study. Comprehensively considering the damage process of tumor cells caused by radiation therapy, the accurate prediction of the volume change of head-and-neck tumors during treatment has been revealed. Meanwhile, various cell activities and their principles in the process of anti-tumor treatment were reflected, and it has positive clinical reference significance for radiobiology.

Photoacoustic lifetime oxygen imaging of radiotherapy-induced tumor reoxygenation In Vivo

PurposeEarly detection and diagnosis of cancer is critical for achieving positive therapeutic outcomes. Biomarkers that can provide clinicians with clues to the outcome of a given therapeutic course are highly desired. Oxygen is a small molecule that is nearly universally present in biological tissues and plays a critical role in the effectiveness of radiotherapies by reacting with DNA radicals and subsequently impairing cellular repair of double strand breaks.Techniques for measuring oxygen in biological tissues often use blood oxygen saturation to approximate the oxygen partial pressure in surrounding tissues despite the complex, nonlinear, and dynamic relationship between these two separate oxygen populations. Methods and materialsWe combined a directly oxygen-sensitive, tumor-targeted, chemical contrast nanoelement with the photoacoustic lifetime-based (PALT) oxygen imaging technique to obtain image maps of oxygen in breast cancer tumors in vivo. The oxygen levels of patient-derived xenografts in a mouse model were characterized before and after a course of radiotherapy. ResultsWe show that, independent of tumor size, radiotherapy induced an increase in the overall oxygenation levels of the tumor. Further, this increase in the oxygenation of the tumor significantly correlated with a positive response to radiotherapy, as demonstrated by a reduction in tumor volume over the twenty-day monitoring period following therapy and histological staining. ConclusionOur PALT imaging presented here is simple, fast, and non-invasive. Facilized by the PALT approach, imaging of tumor reoxygenation may be utilized as a simple, early indicator for evaluating cancer response to radiotherapy. Further characterization of the reoxygenation degree, temporal onset, and possible theragnostic implications are warranted.

Sustained Tumour Reoxygenation After Intratumoural Hydrogen Peroxide (KORTUC) Injection Has Potential to Overcome an Important Cause of Radiation Resistance in Cancer Therapy.

Sustained Tumour Reoxygenation After Intratumoural Hydrogen Peroxide (KORTUC) Injection Has Potential to Overcome an Important Cause of Radiation Resistance in Cancer Therapy.

Neon ion (20 Ne10 + ) charged particle beams manipulate rapid tumor reoxygenation in syngeneic mouse models.

Charged particle beams induce various biological effects by creating high-density ionization through the deposition of energy along the beam's trajectory. Charged particle beams composed of neon ions (20 Ne10+ ) hold great potential for biomedical applications, but their physiological effects on living organs remain uncertain. In this study, we demonstrate that neon-ion beams expedite the process of reoxygenation in tumor models. We simulated mouse SCCVII syngeneic tumors and exposed them to either X-ray or neon-ion beams. Through an invivo radiobiological assay, we observed a reduction in the hypoxic fraction in tumors irradiated with 8.2 Gy of neon-ion beams 30 h after irradiation compared to 6 h post-irradiation. Conversely, no significant changes in hypoxia were observed in tumors irradiated with 8.2 Gy of X-rays. To directly quantify hypoxia in the irradiated living tumors, we utilized dynamic contrast-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging. These combined MRI techniques revealed that the non-hypoxic fraction in neon-irradiated tumors was significantly higher than that in X-irradiated tumors (69.53% vs. 47.67%). Simultaneously, the hypoxic fraction in neon-ion-irradiated tumors (2.77%) was lower than that in X-irradiated tumors (4.27%) and non-irradiated tumors (32.44%). These results support the notion that accelerated reoxygenation occurs more effectively with neon-ion beam irradiation compared to X-rays. These findings shed light on the physiological effects of neon-ion beams on tumors and their microenvironment, emphasizing the therapeutic advantage of using neon-ion charged particle beams to manipulate tumor reoxygenation.

“Primer shot” fractionation with an early treatment break is theoretically superior to consecutive weekday fractionation schemes for early-stage non-small cell lung cancer

PurposeRadiotherapy is traditionally given in equally spaced weekday fractions. We hypothesize that heterogeneous interfraction intervals can increase radiosensitivity via reoxygenation. Through modeling, we investigate whether this minimizes local failures and toxicity for early-stage non-small cell lung cancer (NSCLC). MethodsPreviously, a tumor dose-response model based on resource competition and cell-cycle-dependent radiosensitivity accurately predicted local failure rates for early-stage NSCLC cohorts. Here, the model mathematically determined non-uniform inter-fraction intervals minimizing local failures at similar normal tissue toxicity risk, i.e., iso-BED3 (iso-NTCP) for fractionation schemes 18Gyx3, 12Gyx4, 10Gyx5, 7.5Gyx8, 5Gyx12, 4Gyx15. Next, we used these optimized schedules to reduce toxicity risk (BED3) while maintaining stable local failures (TCP). ResultsOptimal schedules consistently favored a “primer shot” fraction followed by a 2-week break, allowing tumor reoxygenation. Increasing or decreasing the assumed baseline hypoxia extended or shortened this optimal break by up to one week. Fraction sizes of 7.5 Gy and up required a single primer shot, while smaller fractions needed one or two extra fractions for full reoxygenation. The optimized schedules, versus consecutive weekday fractionation, predicted absolute LF reductions of 4.6%-7.4%, except for the already optimal LF rate seen for 18Gyx3. Primer shot schedules could also reduce BED3 at iso-TCP with the biggest improvements for the shortest schedules (94.6Gy reduction for 18Gyx3). ConclusionA validated simulation model clearly supports non-standard “primer shot” fractionation, reducing the impact of hypoxia-induced radioresistance. A limitation of this study is that primer-shot fractionation is outside prior clinical experience and therefore will require clinical studies for definitive testing.

Clinically Translatable Transcrocetin Delivery Platform for Correction of Tumor Hypoxia and Enhancement of Radiation Therapy Effects.

Improving the tumor reoxygenation to sensitize the tumor to radiation therapy is a cornerstone in radiation oncology. Here, the pre-clinical development of a clinically transferable liposomal formulation encapsulating trans sodium crocetinate (NP TSC) is reported to improve oxygen diffusion through the tumor environment. Early pharmacokinetic analysis of the clinical trial of this molecule performed on 37 patients orient to define the optimal fixed dosage to use in a triple-negative breast cancer model to validate the therapeutic combination of radiation therapy and NP TSC. Notably, it is reported that this formulation is non-toxic in both humans and mice at the defined fixed concentration, provides a normalization of the tumor vasculature within 72h window after systemic injection, leads to a transient increase (50% improvement) in the tumor oxygenation, and significantly improves the efficacy of both mono-fractionated and fractionated radiation therapy treatment. Together, these findings support the introduction of a first-in-class therapeutic construct capable of tumor-specific reoxygenation without associated toxicities.

Killing three birds with one stone: Multi-stage metabolic regulation mediated by clinically usable berberine liposome to overcome photodynamic immunotherapy resistance

Nowadays, photodynamic therapy (PDT) has become a novel effect modality for cancer therapy. But, facing the extremely hypoxic tumor microenvironment, the efficacy of PDT is still impaired owing to the limited reactive oxygen species (ROS) production. Moreover, after PDT, the overexpression of programmed cell death-ligand 1 (PD-L1) and indoleamine-2,3-dioxygenase-1 (IDO1) could trigger the following impaired T cell infiltration and the further lowered anti-tumor immunity mediated by T cells. Regrettably, up to now, no simple nanosystem could solve these defects of PDT simultaneously and economically. To ameliorate such a situation, we rationally designed and prepared clinically usable hypoxia reversing berberine liposome (BBR@IR68-Lip) with PD-L1 and IDO1 dual-depression capacity simultaneously to overcome photodynamic immunotherapy resistance. In this nanosystem, BBR@IR68-Lip was constructed by using near-infrared photodynamic dye IR68 chemically modified DSPE-PEG2000 with tumor-targeting capacity as liposome component to encapsulate berberine (BBR) as a novel tumor oxygen and immune microenvironment regulation drug. Owing to the tumor-targeting capacity of IR68-Lip, the accumulation of BBR in tumors further reversed tumor hypoxia, depressed PD-L1 expression, and lowered IDO1 expression via metabolic regulation, which then lead to enhanced ROS generation and amplified T cell infiltration in CT26 tumors. To sum up, in this study, we presented a simple, safe, and clinically usable nanoplatform with ideal tumor re-oxygenation, PD-L1, and IDO1 immune pathways dual-regulation capacity to overcome photodynamic immunotherapy resistance, which may be potential for clinical cancer immunotherapy shortly.

Cascade two-stage tumor re-oxygenation and immune re-sensitization mediated by self-assembled albumin-sorafenib nanoparticles for enhanced photodynamic immunotherapy.

As a promising modality for cancer therapy, photodynamic therapy (PDT) still acquired limited success in clinical nowadays due to the extremely serious hypoxia and immunosuppression tumor microenvironment. To ameliorate such a situation, we rationally designed and prepared cascade two-stage re-oxygenation and immune re-sensitization BSA-MHI148@SRF nanoparticles via hydrophilic and hydrophobic self-assembly strategy by using near-infrared photodynamic dye MHI148 chemically modified bovine serum albumin (BSA-MHI148) and multi-kinase inhibitor Sorafenib (SRF) as a novel tumor oxygen and immune microenvironment regulation drug. Benefiting from the accumulation of SRF in tumors, BSA-MHI148@SRF nanoparticles dramatically enhanced the PDT efficacy by promoting cascade two-stage tumor re-oxygenation mechanisms: (i) SRF decreased tumor oxygen consumption via inhibiting mitochondria respiratory. (ii) SRF increased the oxygen supply via inducing tumor vessel normalization. Meanwhile, the immunosuppression micro-environment was also obviously reversed by two-stage immune re-sensitization as follows: (i) Enhanced immunogenic cell death (ICD) production amplified by BSA-MHI148@SRF induced reactive oxygen species (ROS) generation enhanced T cell infiltration and improve its tumor cell killing ability. (ii) BSA-MHI148@SRF amplified tumor vessel normalization by VEGF inhibition also obviously reversed the tumor immune-suppression microenvironment. Finally, the growth of solid tumors was significantly depressed by such well-designed BSA-MHI148@SRF nanoparticles, which could be potential for clinical cancer therapy.

Hyperbaric oxygen facilitates teniposide-induced cGAS-STING activation to enhance the antitumor efficacy of PD-1 antibody in HCC

BackgroundEmerging evidence indicates that the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) axis plays a pivotal role in intrinsic antitumor immunity. Previous studies demonstrate that the conventional chemotherapy agent, teniposide,...

Accurate Three-Dimensional Thermal Dosimetry and Assessment of Physiologic Response Are Essential for Optimizing Thermoradiotherapy.

Simple SummaryMany clinical trials have shown benefit for adding hyperthermia (heat) treatment to radiotherapy. Despite overall success, some patients do not derive maximum benefit from this combination treatment. Tumor hypoxia (low oxygen concentration) is a major cause for radiotherapy treatment resistance. In this paper, we examine the question of whether hyperthermia reduces hypoxia and, if so, whether reduction in hypoxia is associated with treatment outcome. The review is focused mainly on several clinical trials conducted in humans and companion dogs with cancer treated with hyperthermia and radiotherapy. Detailed measurements of temperature, hypoxia and perfusion were made and compared with treatment outcome. These analyses show that reoxygenation after hyperthermia occurs in patients and is related to treatment outcome. Further, reoxygenation is most likely caused by variable intra-tumoral temperatures that improve perfusion and reduce oxygen consumption rate. Directions for future research on this important issue are indicated.Numerous randomized trials have revealed that hyperthermia (HT) + radiotherapy or chemotherapy improves local tumor control, progression free and overall survival vs. radiotherapy or chemotherapy alone. Despite these successes, however, some individuals fail combination therapy; not every patient will obtain maximal benefit from HT. There are many potential reasons for failure. In this paper, we focus on how HT influences tumor hypoxia, since hypoxia negatively influences radiotherapy and chemotherapy response as well as immune surveillance. Pre-clinically, it is well established that reoxygenation of tumors in response to HT is related to the time and temperature of exposure. In most pre-clinical studies, reoxygenation occurs only during or shortly after a HT treatment. If this were the case clinically, then it would be challenging to take advantage of HT induced reoxygenation. An important question, therefore, is whether HT induced reoxygenation occurs in the clinic that is of radiobiological significance. In this review, we will discuss the influence of thermal history on reoxygenation in both human and canine cancers treated with thermoradiotherapy. Results of several clinical series show that reoxygenation is observed and persists for 24–48 h after HT. Further, reoxygenation is associated with treatment outcome in thermoradiotherapy trials as assessed by: (1) a doubling of pathologic complete response (pCR) in human soft tissue sarcomas, (2) a 14 mmHg increase in pO2 of locally advanced breast cancers achieving a clinical response vs. a 9 mmHg decrease in pO2 of locally advanced breast cancers that did not respond and (3) a significant correlation between extent of reoxygenation (as assessed by pO2 probes and hypoxia marker drug immunohistochemistry) and duration of local tumor control in canine soft tissue sarcomas. The persistence of reoxygenation out to 24–48 h post HT is distinctly different from most reported rodent studies. In these clinical series, comparison of thermal data with physiologic response shows that within the same tumor, temperatures at the higher end of the temperature distribution likely kill cells, resulting in reduced oxygen consumption rate, while lower temperatures in the same tumor improve perfusion. However, reoxygenation does not occur in all subjects, leading to significant uncertainty about the thermal–physiologic relationship. This uncertainty stems from limited knowledge about the spatiotemporal characteristics of temperature and physiologic response. We conclude with recommendations for future research with emphasis on retrieving co-registered thermal and physiologic data before and after HT in order to begin to unravel complex thermophysiologic interactions that appear to occur with thermoradiotherapy.

OC-0281 Tumour reoxygenation by intratumoural hydrogen peroxide: a mechanism for enhanced radiosensitivity

OC-0281 Tumour reoxygenation by intratumoural hydrogen peroxide: a mechanism for enhanced radiosensitivity

Abstract 3067: Exploring strategies to modulate mitochondrial metabolism to alleviate tumor hypoxia

Abstract Radiation therapy is a standard type of treatment modality used as a part of curative or palliative treatment in more than 50% of all cancer patients. However, tumor hypoxia reduces the effectiveness of radiation therapy by limiting the biologically effective dose. Here, we explore and compare strategies to alleviate hypoxia by modifying the oxygen supply or demand within mouse tumor models. We used pODD-Luc, a dynamic in vivo luciferase reporter system that monitors relative levels of tumor hypoxia in real time. We show that in mouse tumor models, contrary to the reported results of human clinical trials, acute manipulation of systemic oxygen delivery significantly reduces the level of hypoxia. We then examined pharmacological manipulation of oxygen demand, which is an emerging trend in therapeutic efforts to sensitize tumors to anti-cancer therapy. Mitochondrial oxygen consumption (OCR) constitutes more than 90% of cellular oxygen demand by coupling carbon source oxidation with ATP generation in a series of redox reactions transferring electrons from reduced cofactors to molecular oxygen. Mechanistically, a decrease in mitochondrial OCR would lead to increased oxygen availability within the tumor, allowing initially hypoxic areas to become re-oxygenated. We found that strategies that directly stimulate mitochondrial OCR exacerbate levels of hypoxia while OCR suppression in turn promotes tumor re-oxygenation. We have previously shown that papaverine, an FDA-approved phosphodiesterase 10A (PDE10A) inhibitor effectively reduces hypoxic tumor fractions in vivo by an off-target effect that inhibits mitochondrial complex I. Here we show that its novel derivative SMV-32 that acts as complex I inhibitor with reduced PDE10A effect mediates superior OCR inhibition in both orthotopic and heterotopic mouse tumor models. These findings further establish the direct impact of OCR manipulation on tumor hypoxia and support the role of mitochondrial metabolism as an attractive target to alleviate tumor hypoxia and overcome treatment resistance. Citation Format: Martin Benej, Jinghai Wu, McKenzie Kreamer, Sandip Vibhute, Ioanna Papandreou, Nicholas C. Denko. Exploring strategies to modulate mitochondrial metabolism to alleviate tumor hypoxia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3067.

Spectroscopic investigation of radiation-induced reoxygenation in radiation-resistant tumors

Fractionated radiation therapy is believed to reoxygenate and subsequently radiosensitize surviving hypoxic cancer cells. Measuring tumor reoxygenation between radiation fractions could conceivably provide an early biomarker of treatment response. However, the relationship between tumor reoxygenation and local control is not well understood. We used noninvasive optical fiber-based diffuse reflectance spectroscopy to monitor radiation-induced changes in hemoglobin oxygen saturation (sO2) in tumor xenografts grown from two head and neck squamous cell carcinoma cell lines – UM-SCC-22B and UM-SCC-47. Tumors were treated with 4 doses of 2 Gy over 2 consecutive weeks and diffuse reflectance spectra were acquired every day during the 2-week period. There was a statistically significant increase in sO2 in the treatment-responsive UM-SCC-22B tumors immediately following radiation. This reoxygenation trend was due to an increase in oxygenated hemoglobin (HbO2) and disappeared over the next 48 h as sO2 returned to preradiation baseline values. Conversely, sO2 in the relatively radiation-resistant UM-SCC-47 tumors increased after every dose of radiation and was driven by a significant decrease in deoxygenated hemoglobin (dHb). Immunohistochemical analysis revealed significantly elevated expression of hypoxia-inducible factor (HIF-1) in the UM-SCC-47 tumors prior to radiation and up to 48 h postradiation compared with the UM-SCC-22B tumors. Our observation of a decrease in dHb, a corresponding increase in sO2, as well as greater HIF-1α expression only in UM-SCC-47 tumors strongly suggests that the reoxygenation within these tumors is due to a decrease in oxygen consumption in the cancer cells, which could potentially play a role in promoting radiation resistance.

Activatable nanomedicine for overcoming hypoxia-induced resistance to chemotherapy and inhibiting tumor growth by inducing collaborative apoptosis and ferroptosis in solid tumors

Hypoxia has been firmly correlated to the drug resistance of solid tumors. Alleviation of hypoxia by tumor reoxygenation is expected to sensitize the chemotherapy toward solid tumors. Alternatively, ferroptosis provides a therapeutic strategy to overcome apoptotic resistance and multidrug resistance of solid tumors, collaboratively strengthening the chemotherapy toward hypoxic tumors. Herein, an ultrasound (US)-activatable nanomedicine was developed for overcoming hypoxia-induced resistance to chemotherapy and efficiently inhibiting tumor growth by inducing sensitized apoptosis and collaborative ferroptosis of tumor cells. This nanomedicine was constructed by integrating ferrate and doxorubicin into biocompatible hollow mesoporous silica nanoplatforms, followed by assembling a solid-liquid phase-change material of n-heneicosane. The US-induced mild hyperthermia initiates the phase change of n-heneicosane, enabling US-activated co-release of ferrate and doxorubicin. Results reveal that the released ferrate effectively reacts with water as well as the over-expressed hydrogen peroxide and glutathione in tumor cells, achieving tumor-microenvironment-independent reoxygenation and glutathione-depletion in tumors. The reoxygenation down-regulates expressions of hypoxia-inducible factor 1α and multidrug resistance gene/transporter P-glycoprotein in tumor cells, sensitizing the apoptosis-based doxorubicin chemotherapy. More importantly, exogenous iron metabolism from the nanomedicine initiates intracellular Fenton reactions, leading to reactive oxygen species overproduction and iron-dependent ferroptotic death of tumor cells. Furthermore, the glutathione-depletion inactivates the glutathione peroxidase 4 (GPX4, a critical regulatory target in ferroptosis), inhibiting the reduction of lipid peroxides and reinforcing the ferroptotic cell death. The sensitized chemotherapy together with the iron-dependent ferroptosis of tumor cells play a synergistic role in boosting the growth suppression of hypoxic osteosarcoma in vivo. Additionally, the nanomedicine acts as a nanoprobe for in vivo photoacoustic imaging and glutathione tracking, showing great potential as theranostic agents for hypoxic solid tumors treatment.

Effect of reoxygenation on hypofractionated radiotherapy of prostate cancer.

To assess the role of reoxygenation of hypoxic tumor cells in hypofractionated radiotherapy of prostate cancer. The considered radiobiological model is based on the assumption of two populations (compartments) of cells: oxygenated (aerobic) cells and hypoxic cells. After each fraction of radiation, some of the hypoxic cells reoxygenate while a fraction of initially aerobic cells becomes hypoxic. The kinetics of this process between successive treatments is described by coupled, first-order differential equations. To determine the effect of reoxygenation on cell kill in the treatment target, we utilize the linear-quadratic (LQ) model assuming different radiosensitivities for the aerobic and hypoxic cells. Analytical solutions for the number of surviving malignant cells are obtained for special cases of slow and fast reoxygenation. The radiobiological effect of reoxygenation for different fractionation regimens is also evaluated numerically. In this study, a radiobiological model for kinetics of reoxygenation in tumors is used to evaluate different fractionation schedules in radiotherapy of prostate cancer. The obtained results indicate that in the case of low alpha/beta ratio for malignant cells (e.g., =1.5Gy), treatment schedule with 4-10 fractions and dose per fraction >4-5Gy can result in increased cell kill in the treatment target at the same level of rectal toxicity as compared to conventional fractionation. The findings of this study also suggest that radiotherapy of the prostate with 1-3 fractions can be radiobiologically inferior to treatments with greater number of fractions.

Dual-Tracer Assessment of Dynamic Changes in Reoxygenation and Proliferation Decrease During Fractionated Radiotherapy in Murine Tumors.

Objective: The present work aimed to assess reoxygenation and tumor inhibition during fractionated radiotherapy (FRT) in murine tumors using 18F-fluoromisonidazole (18F-FMISO) and 18F-fluorothymidine (18F-FLT) based micro positron emission tomography/computed tomography (PET/CT).Materials and Methods: A nude mouse xenograft model was established with the head and neck squamous carcinoma cell (FaDu), followed by administration of FRT. Imaging was carried out with both 18F-FMISO and 18F-FLT PET/CT, prior to FRT (Pre-FRT, 0 Gy), during FRT (Inter-FRT, 21 Gy), and after FRT (Post-FRT, 40 Gy). The maximum standardized uptake (SUVmax) and tumor-to-normal muscle ratio (TNR) were determined in regions of interest (ROIs) in 18F-FMISO and 18F-FLT PET/CT images. Then, hypoxic (HV) and proliferative tumor (PTV) volumes obtained by PET/CT were analyzed. Immunohistochemistry was performed to analyze the changes of hypoxia-inducible factor- (HIF)-1α, carbonic anhydrase 9 (CAIX), Ki67 and proliferating cell nuclear antigen (PCNA). Associations of the levels of these biomarkers with PET/CT parameters were analyzed.Results: 18F-FMISO PET/CT demonstrated markedly elevated reduction rates of SUVmax (30.3 vs. 14.5%, p = 0.012), TNR (27.9 vs. 18.3%, p = 0.032) and HV (85.0 vs. 71.4%, p = 0.047) from Pre-FRT to Inter-FRT compared with values from Inter-FRT to Post-FRT. Meanwhile, PTV reduction rate in 18F-FLT PET/CT from Pre-FRT to Inter-FRT was significantly decreased compared with that from Inter-FRT to Post-FRT (21.2 vs. 82.7%, p = 0.012). Tumor HIF-1α, CAIX, Ki67, and PCNA amounts were continuously down-regulated during radiotherapy. TNR (FMISO) showed significant correlations with HIF-1α (r = 0.692, p = 0.015) and CAIX (r = 0.801, p = 0.006) amounts in xenografts, while associations of SUVmax (FMISO) with hypoxia markers were weak (r = 0.418, p = 0.041 and r = 0.389, p = 0.037, respectively). SUVmax (FLT) was significantly correlated with Ki67 (r = 0.792, p = 0.003) and PCNA (r = 0.837, p = 0.004).Conclusions: Tumor reoxygenation occurs early during radiotherapy, while inhibition of cell proliferation by tumoricidal effects mainly takes place gradually with the course of radiotherapy. 18F-FMISO and 18F-FLT PET/CT are sensitive and non-invasive tools for the monitoring of tumor reoxygenation and proliferation during radiotherapy.

Phospholipid membrane-decorated deep-penetrated nanocatalase relieve tumor hypoxia to enhance chemo-photodynamic therapy

Hypoxia is a serious impediment to current treatments of many malignant tumors. Catalase, an antioxidant enzyme, is capable of decomposing endogenous hydrogen peroxide (H2O2) into oxygen for tumor reoxygenation, but suffered from in vivo instability and limited delivery to deep interior hypoxic regions in tumor. Herein, a deep-penetrated nanocatalase-loading DiIC18 (5, DiD) and soravtansine (Cat@PDS) were provided by coating catalase nanoparticles with PEGylated phospholipids membrane, stimulating the structure and function of erythrocytes to relieve tumor hypoxia for enhanced chemo-photodynamic therapy. After intravenous administration, Cat@PDS preferentially accumulated at tumor sites, flexibly penetrated into the interior regions of tumor mass and remarkably relieved the hypoxic status in tumor. Notably, the Cat@PDS + laser treatment produced striking inhibition of tumor growth and resulted in a 97.2% suppression of lung metastasis. Thus, the phospholipids membrane-coated nanocatalase system represents an encouraging nanoplatform to relieve tumor hypoxia and synergize the chemo-photodynamic cancer therapy.

Eribulin Suppresses Clear Cell Sarcoma Growth by Inhibiting Cell Proliferation and Inducing Melanocytic Differentiation Both Directly and Via Vascular Remodeling.

Clear cell sarcoma (CCS) is a rare but chemotherapy-resistant and often fatal high-grade soft-tissue sarcoma (STS) characterized by melanocytic differentiation under control of microphthalmia-associated transcription factor (MITF). Eribulin mesilate (eribulin) is a mechanistically unique microtubule inhibitor commonly used for STS treatment, particularly liposarcoma and leiomyosarcoma. In this study, we examined the antitumor efficacy of eribulin on four human CCS cell lines and two mouse xenograft models. Eribulin inhibited CCS cell proliferation by inducing cell-cycle arrest and apoptosis, shrunk CCS xenograft tumors, and increased tumor vessel density. Eribulin induced MITF protein upregulation and stimulated tumor cell melanocytic differentiation through ERK1/2 inactivation (a MITF negative regulator) in vitro and in vivo Moreover, tumor reoxygenation, probably caused by eribulin-induced vascular remodeling, attenuated cell growth and inhibited ERK1/2 activity, thereby upregulating MITF expression and promoting melanocytic differentiation. Finally, downregulation of MITF protein levels modestly debilitated the antiproliferative effect of eribulin on CCS cells. Taken together, eribulin suppresses CCS through inhibition of cell proliferation and promotion of tumor differentiation by acting both directly on tumor cells and indirectly through tumor reoxygenation.

Tumor reoxygenation for enhanced combination of radiation therapy and microwave thermal therapy using oxygen generation in situ by CuO nanosuperparticles under microwave irradiation.

As known, radiation therapy (RT) can exacerbate the degree of hypoxia of tumor cells, which induces serious resistance to RT and in turn, is the greatest obstacle to RT. Reoxygenation can restore the hypoxic state of tumor cells, which plays an important role in reshaping tumor microenviroment for achieving optimal therapeutic efficacy. Herein, we report for the first time that microwave (MW)-triggered IL-Quercetin-CuO-SiO2@ZrO2-PEG nanosuperparticles (IQuCS@Zr-PEG NSPs) have been used to achieve an optimal RT therapeutic outcomes by the strategy of upregulating tumor reoxygenation, i.e. hypoxic cells acquire oxygen and return to normal state.Methods: We prepared a promising multifunctional nanosuperparticle to upregulate tumor reoxygenation by utilizing CuO nanoparticle to generate oxygen under MW irradiation in the tumor microenvironment. The IQuCS@Zr-PEG NSPs were obtained by introducing CuO nanoparticles, MW sensitizer of 1-butyl-3-methylimidazolium hexafluorophosphate (IL), radiosensitizer of Quercetin (Qu) and surface modifier of monomethoxy polyethylene glycol sulfhyl (mPEG-SH, 5k Da) into mesoporous sandwich SiO2@ZrO2 nanosuperparticles (SiO2@ZrO2 NSPs). The release oxygen by IQuCS@Zr-PEG NSPs under MW irradiation was investigated by a microcomputer dissolved oxygen-biochemical oxygen demand detector (DO-BOD) test. Finally, we used the 99mTc-HL91 labeled reoxygenation imaging, Cellular immunofluorescence, immunohistochemistry, and TUNEL experiments to verify that this unique MW-responsive reoxygenation enhancer can be used to stimulate reshaping of the tumor microenvironment.Results: Through experiments we found that the IQuCS@Zr-PEG NSPs can persistently release oxygen under the MW irradiation, which upregulates tumor reoxygenation and improve the combined tumor treatment effect of RT and microwave thermal therapy (MWTT). Cellular immunofluorescence and immunohistochemistry experiments demonstrated that the IQuCS@Zr-PEG NSPs can downregulate the expression of hypoxia-inducible factor 1α (HIF-1α) under MW irradiation. The 99mTc-HL91 labeled reoxygenation imaging experiment also showed that the oxygen generated by IQuCS@Zr-PEG NSPs under MW irradiation can significantly increase the reoxygenation capacity of tumor cells, thus reshaping the tumor microenvironment. The high inhibition rate of 98.62% was achieved in the antitumor experiments in vivo. In addition, the IQuCS@Zr-PEG NSPs also had good computed tomography (CT) imaging effects, which can be used to monitor the treatment of tumors in real-time.Conclusions: The proof-of-concept strategy of upregulating tumor reoxygenation is achieved by MW triggered IQuCS@Zr-PEG NSPs, which has exhibited optimal therapeutic outcomes of combination of RT and MWTT tumor. Such unique MW-responsive reoxygenation enhancer may stimulate the research of reshaping tumor microenvironment for enhancing versatile tumor treatment.