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Anti-programmed cell death protein 1 (PD-1) therapy has shown promising efficacy in hepatocellular carcinoma (HCC), but its response rates in advanced HCC are lower than 20%. A critical reason for this is the imbalance between CD8 + T cells and tumor burden. Here, a novel concept of vascular disruption and normalization dependent on a polymeric vascular disrupting agent (VDA) poly ( L -glutamic acid)- graft -methoxy poly (ethylene glycol)/combretastatin A4 (CA4-NPs) + a vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR2) inhibitor DC101 is applied to improve anti-PD-1 therapy, wherein CA4-NPs reduce tumor burden and DC101 simultaneously increases the number of intratumoral CD8 + T cells, successfully regulating the abovementioned imbalance in an H22 tumor model. Methods: Blood vessel density, tumor cell proliferation, and necrosis were evaluated to reveal the effects on reducing tumor burden by CA4-NP treatment. Pericyte coverage of blood vessels, tumor blood vessel perfusion, tumor hypoxia, and intratumoral immune cells were examined to verify their role in vascular normalization and immune cell homing of DC101. Furthermore, the effects of CA4-NPs + DC101 on reducing tumor burden and increasing the number of immune cells were studied. Finally, tumor suppression, intratumoral CD8 + T cell activation, and the synergistic effects of anti-PD-1 combined with CA4-NPs + DC101 were verified. Results: The tumor inhibition rate of anti-PD-1 antibody combined with CA4-NPs + DC101 reached 86.4%, which was significantly higher than that of anti-PD-1 (16.8%) alone. Importantly, the Q value reflecting the synergy between CA4-NPs + DC101 and anti-PD-1 was 1.24, demonstrating a strong synergistic effect. Furthermore, CA4-NPs + DC101 improved anti-PD-1 therapy by increasing the number of intratumoral CD8 + T cells (anti-PD-1, 0.31% vs triple drug combination, 1.18%). Conclusion: These results reveal a novel approach to enhance anti-PD-1 therapy with VDAs + VEGF/VEGFR2 inhibitors in HCC., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Background: In hypoxic tumors, positive feedback between oncogenic KRAS and HIF-1α involves impressive metabolic changes correlating with drug resistance and poor prognosis in colorectal cancer. Up to date, designed KRAS-targeting molecules do not show clear benefits in patient overall survival (POS) so pharmacological modulation of aberrant tricarboxylic acid (TCA) cycle in hypoxic cancer has been proposed as a metabolic vulnerability of KRAS-driven tumors. Methods: Annexin V-FITC and cell viability assays were carried out in order to verify vitamin C citotoxicity in KRAS mutant SW480 and DLD1 as well as in Immortalized Human Colonic Epithelial Cells (HCEC). HIF1a expression and activity were determined by western blot and functional analysis assays. HIF1a direct targets GLUT1 and PDK1 expression was checked using western blot and qRT-PCR. Inmunohistochemical assays were perfomed in tumors derived from murine xenografts in order to validate previous observations in vivo . Vitamin C dependent PDH expression and activity modulation were detected by western blot and colorimetric activity assays. Acetyl-Coa levels and citrate synthase activity were assessed using colorimetric/fluorometric activity assays. Mitochondrial membrane potential (Δ ψ ) and cell ATP levels were assayed using fluorometric and luminescent test. Results: PDK-1 in KRAS mutant CRC cells and murine xenografts was downregulated using pharmacological doses of vitamin C through the proline hydroxylation (Pro402) of the Hypoxia inducible factor-1(HIF-1)α, correlating with decreased expression of the glucose transporter 1 (GLUT-1) in both models. Vitamin C induced remarkable ATP depletion, rapid mitochondrial Δ ψ dissipation and diminished pyruvate dehydrogenase E1-α phosphorylation at Serine 293, then boosting PDH and citrate synthase activity. Conclusion: We report a striking and previously non reported role of vitamin C in the regulation of the pyruvate dehydrogenase (PDH) activity, then modulating the TCA cycle and mitochondrial metabolism in KRAS mutant colon cancer. Potential impact of vitamin C in the clinical management of anti-EGFR chemoresistant colorectal neoplasias should be further considered., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Rationale: Vascular abnormality stemming from the hypoxia-driven elevation of proangiogenic factors is a hallmark for many solid malignant tumors, including colorectal cancer (CRC) and its liver metastasis. We report a hypoxia-triggered liposome-supported metal-polyphenol-gene bio-nanoreactor to tune the proangiogenic factor-mediated immunotolerance and synergize the elicited tumoricidal immunity for CRC treatment. Methods: With the aid of polyphenol gallic acid, Cu 2+ ion-based intracellular bio-nanoreactor was synthesized for the delivery of small interfering RNA targeting vascular endothelial growth factor and then cloaked with a hybrid liposomal membrane that harbored a hypoxia-responsive azobenzene derivative. In hypoxic tumor, the liposomal shell disintegrated, and a shrunk-size bio-nanoreactor was burst released. Intracellularly, Cu 2+ from the bio-nanoreactor catalyzed a Fenton-like reaction with glutathione, which efficiently converted H 2 O 2 to •OH and enabled a chemodynamic therapy (CDT) in tumor sites. With the alleviation of proangiogenic factor-mediated immunotolerance and high production of CDT-induced tumor-associated antigens, robust tumoricidal immunity was co-stimulated. Results: With colorectal tumor and its liver metastasis models, we determined the underlying mechanism of proangiogenic factor-mediated immunotolerance and highlighted that the liposomal bio-nanoreactor could create positive feedback among the critical players in the vascular endothelium and synergize the elicited tumoricidal immunity. Conclusion: Our work provides an alternative strategy for exerting efficient tumoricidal immunity in the proangiogenic factor-upregulated subpopulation of CRC patients and may have a wide-ranging impact on cancer immune-anti-angiogenic complementary therapy in clinics., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

The hypoxic microenvironment in solid tumors severely limits the efficacy of photodynamic therapy (PDT). Therefore, the development of nanocarriers co-loaded with photosensitizers and oxygen, together with imaging guidance ability, is of great significance in cancer therapy. However, previously reported synthetic methods for these multi-functional probes are complicated, and the raw materials used are toxic. Methods: Herein, the human endogenous protein, hemoglobin (Hb), was used for the simultaneous biomimetic synthesis of Gd-based nanostructures and co-loading of Chlorine e6 (Ce6) and oxygen for alleviating the hypoxic environment of tumors and accomplishing magnetic resonance imaging (MRI)-guided enhanced PDT. The Gd@Hb Ce6-PEG nanoprobes were synthesized via a green and protein biomimetic approach. The physicochemical properties, including relaxivity, oxygen-carrying/release capability, and PDT efficacy of Gd@Hb Ce6-PEG , were measured in vitro and in vivo on tumor-bearing mice after intravenous injection. Morphologic and functional MRI were carried out to evaluate the efficacy of PDT. Results: The results demonstrated the successful synthesis of compact Gd@Hb Ce6-PEG nanostructures with desired multi-functionalities. Following treatment with the nanoparticles, the embedded MR moiety was effective in lighting tumor lesions and guiding therapy. The oxygen-carrying capability of Hb after biomimetic synthesis was confirmed by spectroscopic analysis and oxygen detector in vitro . Further, tumor oxygenation for alleviating tumor hypoxia in vivo after intravenous injection of Gd@Hb Ce6-PEG was verified by photoacoustic imaging and immunofluorescence staining. The potent treatment efficacy of PDT on early-stage was observed by the morphologic and functional MR imaging. Importantly, rapid renal clearance of the particles was observed after treatment. Conclusion: In this study, by using a human endogenous protein, we demonstrated the biomimetic synthesis of multi-functional nanoprobes for simultaneous tumor oxygenation and imaging-guided enhanced PDT. The therapeutic efficacy could be quantitatively confirmed at 6 h post PDT with diffusion-weighted imaging (DWI)., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Tumor-associated hypoxia influences the radiation response of head-and-neck cancer (HNSCC) patients, and a lack of early hypoxia resolution during treatment considerably deteriorates outcomes. As the detrimental effects of hypoxia are partly related to the induction of an immunosuppressive microenvironment, we investigated the interaction between tumor hypoxia dynamics and the PD-1/PD-L1 axis in HNSCC patients undergoing chemoradiation and its relevance for patient outcomes in a prospective trial. Methods: 49 patients treated with definitive chemoradiation for locally advanced HNSCC were enrolled in this trial and received longitudinal hypoxia PET imaging using fluorine-18 misonidazole ([ 18 F]FMISO) at weeks 0, 2 and 5 during treatment. Pre-therapeutic tumor biopsies were immunohistochemically analyzed regarding the PD-1/PD-L1 expression both on immune cells and on tumor cells, and potential correlations between the PD-1/PD-L1 axis and tumor hypoxia dynamics during chemoradiation were assessed using Spearman's rank correlations. Hypoxia dynamics during treatment were quantified by subtracting the standardized uptake value (SUV) index at baseline from the SUV values at weeks 2 or 5, whereby SUV index was defined as ratio of maximum tumor [ 18 F]FMISO SUV to mean SUV in the contralateral sternocleidomastoid muscle ( i.e. tumor-to-muscle ratio). The impact of the PD-1/PD-L1 expression alone and in combination with persistent tumor hypoxia on locoregional control (LRC), progression-free survival (PFS) and overall survival (OS) was examined using log-rank tests and Cox proportional hazards models. Results: Neither PD-L1 nor PD-1 expression levels on tumor-infiltrating immune cells influenced LRC (HR = 0.734; p = 0.480 for PD-L1, HR = 0.991; p = 0.989 for PD-1), PFS (HR = 0.813; p = 0.597 for PD-L1, HR = 0.796; p = 0.713 for PD-1) or OS (HR = 0.698; p = 0.405 for PD-L1, HR = 0.315; p = 0.265 for PD-1). However, patients with no hypoxia resolution between weeks 0 and 2 and PD-L1 expression on tumor cells, quantified by a tumor proportional score (TPS) of at least 1%, showed significantly worse LRC (HR = 3.374, p = 0.022) and a trend towards reduced PFS (HR = 2.752, p = 0.052). In the multivariate Cox regression analysis, the combination of absent tumor hypoxia resolution and high tumoral PD-L1 expression remained a significant prognosticator for impaired LRC (HR = 3.374, p = 0.022). On the other side, tumoral PD-L1 expression did not compromise the outcomes of patients whose tumor-associated hypoxia declined between week 0 and 2 during chemoradiation (LRC: HR = 1.186, p = 0.772, PFS: HR = 0.846, p = 0.766). Conclusion: In this exploratory analysis, we showed for the first time that patients with both persistent tumor-associated hypoxia during treatment and PD-L1 expression on tumor cells exhibited a worse outcome, while the tumor cells' PD-L1 expression did not influence the outcomes of patients with early tumor hypoxia resolution. While the results have to be validated in an independent cohort, these findings form a foundation to investigate the combination of hypoxic modification and immune checkpoint inhibitors for the unfavorable subgroup, moving forward towards personalized radiation oncology treatment., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Photodynamic therapy (PDT) is a promising strategy in cancer treatment that utilizes photosensitizers (PSs) to produce reactive oxygen species (ROS) and eliminate cancer cells under specific wavelength light irradiation. However, special tumor environments, such as those with overexpression of glutathione (GSH), which will consume PDT-mediated ROS, as well as hypoxia in the tumor microenvironment (TME) could lead to ineffective treatment. Moreover, PDT is highly light-dependent and therefore can be hindered in deep tumor cells where light cannot easily penetrate. To solve these problems, we designed oxygen-dual-generating nanosystems MnO 2 @Chitosan-CyI (MCC) for enhanced phototherapy. Methods : The TME-sensitive nanosystems MCC were easily prepared through the self-assembly of iodinated indocyanine green (ICG) derivative CyI and chitosan, after which the MnO 2 nanoparticles were formed as a shell by electrostatic interaction and Mn-N coordinate bonding. Results : When subjected to NIR irradiation, MCC offered enhanced ROS production and heat generation. Furthermore, once endocytosed, MnO 2 could not only decrease the level of GSH but also serve as a highly efficient in situ oxygen generator. Meanwhile, heat generation-induced temperature increase accelerated in vivo blood flow, which effectively relieved the environmental tumor hypoxia. Furthermore, enhanced PDT triggered an acute immune response, leading to NIR-guided, synergistic PDT/photothermal/immunotherapy capable of eliminating tumors and reducing tumor metastasis. Conclusion: The proposed novel nanosystems represent an important advance in altering TME for improved clinical PDT efficacy, as well as their potential as effective theranostic agents in cancer treatment., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Rationale: Nanoscale vehicles responsive to abnormal variation in tumor environment are promising for use in targeted delivery of therapeutic drugs specifically to tumor sites. Herein, we report the design and fabrication of self-accelerating H 2 O 2 -responsive plasmonic gold nanovesicles (GVs) encapsulated with tirapazamine (TPZ) and glucose oxidase (GOx) for synergistic chemo/starving therapy of cancers. Methods: Gold nanoparticles were modified with H 2 O 2 -responsive amphiphilic block copolymer PEG 45 - b -PABE 330 by ligand exchange. The TPZ and GOx loaded GVs (TG-GVs) were prepared through the self-assembly of PEG 45 - b -PABE 330 -grafted nanoparticles together with TPZ and GOx by solvent displacement method. Results: In response to H 2 O 2 in tumor, the TG-GVs dissociate to release the payloads that are, otherwise, retained inside the vesicles for days without noticeable leakage. The released GOx enzymes catalyze the oxidation of glucose by oxygen in the tumor tissue to enhance the degree of hypoxia that subsequently triggers the reduction of hypoxia-activated pro-drug TPZ into highly toxic free radicals. The H 2 O 2 generated in the GOx-catalyzed reaction also accelerate the dissociation of vesicles and hence the release rate of the cargoes in tumors. The drug-loaded GVs exhibit superior tumor inhibition efficacy in 4T1 tumor-bearing mice owing to the synergistic effect of chemo/starvation therapy, in addition to their use as contrast agents for computed tomography imaging of tumors. Conclusion: This nanoplatform may find application in managing tumors deeply trapped in viscera or other important tissues that are not compatible with external stimulus (e.g. light)., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Tumor hypoxia, acidosis, and excessive reactive oxygen species (ROS) were the main characteristics of the bladder tumor microenvironment (TME), and abnormal TME led to autophagy activation, which facilitated cancer cell proliferation. The therapeutic efficacy of autophagy inhibitors might also be impeded by abnormal TME. To address these issues, we proposed a new strategy that utilized manganese dioxide (MnO 2 ) nanoparticles to optimize the abnormal TME and revitalize autophagy inhibitors, and both oxygenation and autophagy inhibition may sensitize the tumor cells to radiation therapy. Methods: By taking advantage of the strong affinity between negatively charged MnO 2 and positively charged chloroquine (CQ), the nanoparticles were fabricated by integrating MnO 2 and CQ in human serum albumin (HSA)-based nanoplatform (HSA-MnO 2 -CQ NPs). Results: HSA-MnO 2 -CQ NPs NPs efficiently generated O 2 and increased pH in vitro after reaction with H + /H 2 O 2 and then released the encapsulated CQ in a H + /H 2 O 2 concentration-dependent manner. The NPs restored the autophagy-inhibiting activity of chloroquine in acidic conditions by increasing its intracellular uptake, and markedly blocked hypoxia-induced autophagic flux. In vivo studies showed the NPs improved pharmacokinetic behavior of chloroquine and effectively accumulated in tumor tissues. The NPs exhibited significantly decreased tumor hypoxia areas and increased tumor pH, and had remarkable autophagy inhibition efficacy on bladder tumors. Finally, a significant anti-tumor effect achieved by the enhanced autophagy inhibition and radiation sensitization. Conclusions: HSA-MnO 2 -CQ NPs synergistically regulated the abnormal TME and inhibited autophagic flux, and effectively sensitized radiation therapy to treat bladder cancers., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Abnormal tumor microenvironment, such as hypoxia, interstitial hypertension and low pH, leads to unexpected resistance for current tumor treatment. The development of versatile drug delivery systems which present responsive characteristics to tumor microenvironment (TME) has been extensively carried out, but remains challenging. In this study, zeolitic imidazolate framework-8 (ZIF-8) coated ZnS nanoparticles have been designed and prepared for co-delivery of ICG/TPZ molecules, denoted as ZSZIT, for H 2 S-amplified synergistic therapy. Methods: The ZSZ nanoparticles were characterized using SEM, TEM and XRD. The in vitro viabilities of cancer cells cultured with ZSZIT under normoxia/hypoxia conditions were evaluated by cell counting kit-8 (CCK-8) assay. In addition, in vivo anti-tumor effect was also performed using male Balb/c nude mice as animal model. Results: ZSZIT shows cascade PDT and hypoxia-activated chemotherapeutic effect under an 808nm NIR irradiation. Meanwhile, ZSZIT degrades under tumor acidic environment, and H 2 S produced by ZnS cores could inhibit the expression of catalase, which subsequently favors the hypoxia and antitumor effect of TPZ drug. Both in vitro and in vivo studies demonstrate the H 2 S-sensitized synergistic antitumor effect based on cascade PDT/chemotherapy. Conclusion: This cascade H 2 S-sensitized synergistic nanoplatform has enabled more effective and lasting anticancer treatment., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Rationale : A cascade, or domino, reaction consists of two, or more, consecutive reactions such that subsequent reactions occur only if some chemical functionality has first been established in the prior step. However, while construction of predesigned and desired molecular domino reactors in a tailored manner is a valuable endeavor, it is still challenging. Methods : To address this challenge, we herein report an aptamer-based photodynamic domino reactor built through automated modular synthesis. The engineering of this reactor takes advantage of the well-established solid-phase synthesis platform to incorporate a photosensitizer into G-quadruplex/ hemin DNAzyme at the molecular level. Results : As a proof of concept, our photodynamic domino reactor, termed AS1411/hemin- pyrochlorophyll A, achieves in vivo photodynamic domino reaction for efficient cancer treatment by using a high concentration of hydrogen peroxide (H 2 O 2 ) in the tumor microenvironment (TME) to produce O 2 , followed by consecutive generation of singlet oxygen ( 1 O 2 ) using the pre-produced O 2 . More specifically, phosphoramidite PA (pyrochlorophyll A) is coupled to aptamer AS1411 to form AS1411-PA ApDC able to simultaneously perform in vivo targeted imaging and photodynamic therapy (PDT). The insertion of hemin into the AS1411 G-quadruplex was demonstrated to alleviate tumor hypoxia by decomposition of H 2 O 2 to produce O 2 . This was followed by the generation of 1 O 2 by PA to trigger cascading amplified PDT. Conclusion : Therefore, this study provides a general strategy for building an aptamer-based molecular domino reactor through automated modular synthesis. By proof of concept, we further demonstrate a novel method of achieving enhanced PDT, as well as alleviating TME hypoxia at the molecular level., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Hypoxia, a hallmark of malignant tumors, often correlates with increasing tumor aggressiveness and poor treatment outcomes. Due to a lack of vasculature, effective drug delivery to hypoxic tumor regions remains challenging. Signaling through the chemokine SDF-1α and its receptor CXCR4 plays a critical role in the homing of stem cells to ischemia for potential use as drug-delivery vehicles. To harness this mechanism for targeting tumor hypoxia, we developed polymeric nanoparticle-induced CXCR4-overexpressing human adipose-derived stem cells (hADSCs). Using glioblastoma multiforme (GBM) as a model tumor, we evaluated the ability of CXCR4-overexpressing hADSCs to target tumor hypoxia in vitro using a 2D migration assay and a 3D collagen hydrogel model. Compared to untransfected hADSCs, CXCR4-overexpressing hADSCs showed enhanced migration in response to hypoxia and penetrated the hypoxic core within tumor spheres. When injected in the contralateral brain in a mouse intracranial GBM xenograft, CXCR4-overexpressing hADSCs exhibited long-range migration toward GBM and preferentially penetrated the hypoxic tumor core. Intravenous injection also led to effective targeting of tumor hypoxia in a subcutaneous tumor model. Together, these results validate polymeric nanoparticle-induced CXCR4-overexpressing hADSCs as a potent cellular vehicle for targeting tumor hypoxia, which may be broadly useful for enhancing drug delivery to various cancer types., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.