High Interstitial Fluid Pressure Research Articles

Magnetic resonance imaging of tumor response to stroma-modifying pegvorhyaluronidase alpha (PEGPH20) therapy in early-phase clinical trials

Pre-clinical and clinical studies have shown that PEGPH20 depletes intratumoral hyaluronic acid (HA), which is linked to high interstitial fluid pressures and poor distribution of chemotherapies. 29 patients with metastatic advanced solid tumors received quantitative magnetic resonance imaging (qMRI) in 3 prospective clinical trials of PEGPH20: HALO-109-101 (NCT00834704), HALO-109-102 (NCT01170897), and HALO-109-201 (NCT01453153). Apparent Diffusion Coefficient of water (ADC), T1, ktrans, vp, ve, and iAUC maps were computed from qMRI acquired at baseline and ≥ 1 time point post-PEGPH20. Tumor ADC and T1 decreased, while iAUC, ktrans, vp, and ve increased, on day 1 post-PEGPH20 relative to baseline values. This is consistent with HA depletion leading to a decrease in tumor extracellular water content and an increase in perfusion, permeability, extracellular matrix space, and vascularity. Baseline parameter values predictive of pharmacodynamic responses were: ADC > 1.46 × 10−3 mm2/s (Balanced Accuracy (BA) = 72%, p < 0.01), T1 > 0.54 s (BA = 82%, p < 0.01), iAUC < 9.2 mM-s (BA = 76%, p < 0.05), ktrans < 0.07 min−1 (BA = 72%, p = 0.2), ve < 0.17 (BA = 68%, p < 0.01), and vp < 0.02 (BA = 60%, p < 0.01). A low ve at baseline was moderately predictive of response in any parameter (BA = 65.6%, p < 0.01 averaged across patients). These qMRI biomarkers are potentially useful for guiding patient pre-selection and post-treatment follow-up in future clinical studies of PEGPH20 and other tumor stroma-modifying anti-cancer therapies.

Abstract A040: Assessing the ability of Fc3TSR to remodel the tumor microenvironment and enhance efficacy of immunotherapies and chemotherapy in a murine model of pancreatic ductal adenocarcinoma

Abstract Introduction: Pancreatic Ductal Adenocarcinoma (PDAC) has a poor survival rate due to late diagnosis where metastasis has often occurred. Angiogenesis, the process by which new vessels form from pre-existing vasculature, is crucial for tumor growth and metastasis. Tumors aggressively upregulate expression of pro-angiogenic factors, stimulating rapid vessel formation. These vessels often lack pericyte coverage and have dysfunctional morphology, leading to high interstitial fluid pressure (IFP). Impaired perfusion and high IFP impede therapy uptake. Fc3TSR is a novel fusion protein derived from the potent angiogenic inhibitor thrombospondin 1, which we have shown to normalize vasculature in ovarian cancer, significantly decreasing tumor size and improving uptake of many therapies. In this study, we evaluated Fc3TSR’s ability to remodel the tumor microenvironment to induce tumor regression and to enhance efficacy of other therapies. Methods: We developed an orthotopic syngeneic murine model of PDAC, whereby we surgically injected 2.5 × 104 murine PDAC cells (KPC) into the tail of the pancreas of C57BL/6 mice. Tumors were allowed to progress for 14 days before intraperitoneal (IP) administration of Fc3TSR (0.158mg/kg) or PBS (control) on day 14 and 21. Gemcitabine (GEM) chemotherapy treated mice received either daily, metronomic dosages of GEM, or weekly, maximum tolerated dosages GEM starting on day 23. Checkpoint inhibitor mice received either PD-L1 (25ug) or CTLA4 (25ug) checkpoint inhibitors on day 23 and 26. Mice were euthanized on day 30 and tumors and the draining lymph nodes were collected and weighed. 1 hour before euthanasia, Fc3TSR and PBS mice were IP injected with Hypoxyprobe (Pimonidazole Hydrochloride) and tumors were immunostained for markers of blood vessels and tumor hypoxia. Results: Fc3TSR induced tumor regression when compared to PBS, but GEM at either dosage did not further enhance this effect. Following Fc3TSR, PD-L1, but not CTLA-4 checkpoint inhibitors significantly reduced tumor size when compared to mice pre-treated with PBS. Fc3TSR treatment also reduced the area of tumor hypoxia. Tumor vasculature is currently being imaged and analyzed for Fc3TSR’s effect on vessel morphology. Conclusion: Our data suggests that normalizing the tumor microenvironment can enhance the uptake and efficacy of combination therapies. Enhanced perfusion could facilitate the migration of activated immune cells and may enhance immune responses in PDAC patients. Here we demonstrate a novel approach to optimize therapeutic efficacy in advanced stage PDAC. Citation Format: Bianca Garlisi, Caroline Aitken, Sylvia Lauks, Julia Stewart, Duncan Petrik, Jack Lawler, Jim Petrik. Assessing the ability of Fc3TSR to remodel the tumor microenvironment and enhance efficacy of immunotherapies and chemotherapy in a murine model of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A040.

A novel gas embolotherapy using microbubbles electrocoalescence for cancer treatment

Background and ObjectiveEmbolotherapy has been increasingly used to disrupt tumor growth. Despite its success in the occlusion of microvessels, it has drawbacks such as limited access to the target location, limited control of the blocker size, and inattention to the tumor characteristics, especially high interstitial fluid pressure. The present work introduces a novel numerical method of gas embolotherapy for cancer treatment through tumor vessel occlusion. MethodsThe gas microbubbles are generated from Levovist bolus injection into the tumor microvessel. The microbubble movement in the blood flow is innovatively controlled by an electric field applied to the tumor-feeding vessel. The interaction between the Levovist microbubbles and the electric field is resolved by developing a fully coupled model using the phase-field model, Carreau model for non-Newtonian blood, Navier-Stokes equations and Maxwell stress tensor. Additionally, the critical effect of high interstitial fluid pressure as a characteristic of solid tumors is included. ResultsThe findings of this study indicate that the rates of microbubble deformation and displacement increase with the applied potential intensity to the microvessel wall. Accordingly, the required time for a microbubble to join the upper microvessel wall reduces from 1.97ms to 22 μs with an increase of the electric potential from 3.5V to 12.5V. Additionally, an electric potential of 12.5V causes the microbubbles coalescence and formation of a gas column against the bloodstream. ConclusionsClinically, our novel embolization procedure can be considered a non-invasive targeted therapy, and under a controlled electric field, the blocker size can be precisely controlled. Also, the proposed method has the potential to be used as a gradual treatment in advanced cancers as tumors develop resistance and relapse.

Predicting intratumoral fluid pressure and liposome accumulation using physics informed deep learning

Liposome-based anticancer agents take advantage of the increased vascular permeability and transvascular pressure gradients for selective accumulation in tumors, a phenomenon known as the enhanced permeability and retention(EPR) effect. The EPR effect has motivated the clinical use of nano-therapeutics, with mixed results on treatment outcome. High interstitial fluid pressure (IFP) has been shown to limit liposome drug delivery to central tumour regions. Furthermore, high IFP is an independent prognostic biomarker for treatment efficacy in radiation therapy and chemotherapy for some solid cancers. Therefore, accurately measuring spatial liposome accumulation and IFP distribution within a solid tumour is crucial for optimal treatment planning. In this paper, we develop a model capable of predicting voxel-by-voxel intratumoral liposome accumulation and IFP using pre and post administration imaging. Our approach is based on physics informed machine learning, a novel technique combining machine learning and partial differential equations. through application to a set of mouse data and a set of synthetically-generated tumours, we show that our approach accurately predicts the spatial liposome accumulation and IFP for an individual tumour while relying on minimal information. This is an important result with applications for forecasting tumour progression and designing treatment.

Reversibly size-switchable polyion complex micelles for antiangiogenic cancer therapy

Size is one of the most important characteristics of nanoparticles to influence their biodistribution and antitumoral efficacy. Particles with large sizes have difficulty in deep tumor penetration, while small particles are easily removed from tumor tissues due to the high tumor interstitial fluid pressure. To address these issues, an intelligent core-crosslinked polyion complex micelle (cPCM) with a reversibly size-switchable feature was engineered in this study. The micelles are consisting of methoxy poly(ethylene glycol)-poly(d,l-lactide) copolymer (mPEG-PLA), mPEG-PLA-(HE)6CC, and mPEG-PLA-(RG)6CC at an optimal mass ratio of 6:1:1 with an antiangiogenic compound, dabigatran etexilate (DE), encapsulated. The net charge inside the micelles is switchable when exposed to different pH conditions, thereby leading to revisable size-change of micelles. DE-loaded micelles (DE@cPCM) can swell and release drugs at the tumor sites with a mildly acidic pH, while they shrink and protect the cargo from leaking into the blood circulation with a neutral pH. Results indicated that DE@cPCM can inhibit tumor angiogenesis in vitro and in vivo, thereby efficiently restraining tumor growth in a 4T1-bearing mouse model. Collectively, the size-switchable cPCM is a promising nanoplatform for targeting delivery of anticarcinogens into the matrix of tumor tissues.

Perspectives for Improving the Tumor Targeting of Nanomedicine via the EPR Effect in Clinical Tumors.

Over the past few decades, the enhanced permeability and retention (EPR) effect of nanomedicine has been a crucial phenomenon in targeted cancer therapy. Specifically, understanding the EPR effect has been a significant aspect of delivering anticancer agents efficiently to targeted tumors. Although the therapeutic effect has been demonstrated in experimental models using mouse xenografts, the clinical translation of the EPR effect of nanomedicine faces several challenges due to dense extracellular matrix (ECM), high interstitial fluid pressure (IFP) levels, and other factors that arise from tumor heterogeneity and complexity. Therefore, understanding the mechanism of the EPR effect of nanomedicine in clinics is essential to overcome the hurdles of the clinical translation of nanomedicine. This paper introduces the basic mechanism of the EPR effect of nanomedicine, the recently discussed challenges of the EPR effect of nanomedicine, and various strategies of recent nanomedicine to overcome the limitations expected from the patients' tumor microenvironments.

Improved Therapeutic Delivery Targeting Clinically Relevant Orthotopic Human Pancreatic Tumors Engrafted in Immunocompromised Pigs Using Ultrasound-Induced Cavitation: A Pilot Study.

Pancreatic tumors can be resistant to drug penetration due to high interstitial fluid pressure, dense stroma, and disarrayed vasculature. Ultrasound-induced cavitation is an emerging technology that may overcome many of these limitations. Low-intensity ultrasound, coupled with co-administered cavitation nuclei consisting of gas-stabilizing sub-micron scale SonoTran Particles, is effective at increasing therapeutic antibody delivery to xenograft flank tumors in mouse models. Here, we sought to evaluate the effectiveness of this approach in situ using a large animal model that mimics human pancreatic cancer patients. Immunocompromised pigs were surgically engrafted with human Panc-1 pancreatic ductal adenocarcinoma (PDAC) tumors in targeted regions of the pancreas. These tumors were found to recapitulate many features of human PDAC tumors. Animals were intravenously injected with the common cancer therapeutics Cetuximab, gemcitabine, and paclitaxel, followed by infusion with SonoTran Particles. Select tumors in each animal were targeted with focused ultrasound to induce cavitation. Cavitation increased the intra-tumor concentrations of Cetuximab, gemcitabine, and paclitaxel by 477%, 148%, and 193%, respectively, compared to tumors that were not targeted with ultrasound in the same animals. Together, these data show that ultrasound-mediated cavitation, when delivered in combination with gas-entrapping particles, improves therapeutic delivery in pancreatic tumors under clinically relevant conditions.

Abstract 4599: Blood and lymphatic endothelial cell contractility-mediated vessel permeability regulates interstitial fluid pressure and T cell infiltration in the tumor microenvironment

Abstract Solid tumors such as breast and pancreatic cancer are characterized by poor prognostic outcomes with high interstitial fluid pressure (IFP), which promotes tumor progression by modulating angiogenesis, matrix metalloproteinase activity, and cancer cell motility and compromises immunotherapies by keeping immune cells (e.g., T cells) from infiltrating into the tumor. To reduce tumor IFP, researchers tried to decrease solid stress and normalize hyperpermeable blood vessels (BV) in tumors, but how lymphatic vessels (LV) are impaired in the tumor microenvironment is poorly understood. Several studies reported that vascular endothelial growth factor C (VEGFC) treatment defeated tumors by promoting lymphangiogenesis and boosting T cell recruitment, while it has also been recognized to promote lymph node metastasis. Given the controversial roles of VEGFC, the main goals of this study are to control LV permeability and promote drainage by identifying currently unappreciated roles of rho-associated protein kinase 1 and 2 (ROCK1/2) in regulating lymphatic endothelial cell (LEC) contractility, junctions, and drainage in tumors. We will have blood endothelial cells (BEC) as controls to understand how ROCK1/2 and cell contractility affect LEC/BEC junctions and permeability differently. Here, we created a three-dimensional (3D) bioengineered model of vascularized pancreatic and breast tumors to study vessel junctions, permeability, and IFP formation. The device consisted of a LEC or BEC lined, perfusable channel and a tumor-filled ECM chamber. We observed impaired barrier function of tumor BV/LV with increased permeability and loss of tight junctions compared to healthy vessels. To quantify the contractility of LEC/BEC, we employed traction force microscopy (TFM) by creating a 2D biomimicry of the endothelial monolayers using micropatterned polyacrylamide gel substrates with tunable stiffness. Using TFM, we showed that the combination of tumor-secreted factors and elevated matrix stiffness increased the traction of LEC/BEC, resulting in their loss of tight junctions. Using Rho kinase blockade to inhibit ROCK1/2 reduced the contractility of endothelial cells, reconstructed vessel structural integrity and functionality, and reduced intratumoral IFP in animal models. We expect that a decrease in the tumor IFP due to the restoration of lymphatic drainage would increase T cell infiltration, suppress tumor growth, and improve the survival of tumor-bearing mice combined with the anti-PD-1 or anti-PD-L1 therapy in our future studies. Together, our study provides new insights into understanding the physical interaction of endothelial, tumor, and immune cells, evidence of rho-kinases as a target for cancer immunotherapy, as well as a promising way to increase the efficacy of immunotherapies in cancer patients. Citation Format: Yansong Peng, Esak Lee. Blood and lymphatic endothelial cell contractility-mediated vessel permeability regulates interstitial fluid pressure and T cell infiltration in the tumor microenvironment. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4599.

Abstract 4009: Discovery of PLM-102, a highly potent 3rd generation FLT3 inhibitor, in drug-resistant FLT3-ITD-TKD mutated acute myeloid leukemia

Abstract Mutations of the FMS-like tyrosine kinase 3 (FLT3) gene occur in approximately 25 ~ 30% of all acute myeloid leukemia (AML) cases and FLT3-ITD mutations are associated with a particularly unfavorable prognosis, with an increased risk of relapse and shorter overall survival (OS) compared with AML patients without the mutation. Even though multiple FLT3 inhibitors are in various stages of clinical evaluation, resistance to FLT3 inhibitors resulting from acquired point mutations in tyrosine kinase domain (TKD) have limited the sustained efficacy of treatments. Among them, a “gatekeeper” mutation (F691L) is resistant to most available FLT3 inhibitors. Here, we show the efficacy and mechanism of PLM-102, developed an orally available and highly selective small molecule, in overcoming drug-resistant FLT3-ITD-TKD mutations as a strong candidate of the 3rd generation of FLT3 inhibitor. PLM-102 displays extraordinary potency of enzyme inhibitory activities of all FLT3 WT/mutants including F691L with IC50 values of &amp;lt;1 nM. In FLT3-ITD-positive cell lines (MV4-11, MOLM-13, MOLM-14, Ba/F3-ITD-D835Y, Ba/F3-ITD-F691L), PLM-102 shows about 18~25-fold higher anti-proliferative activities than Gilteritinib. Also, PLM-102 potently inhibited the phosphorylation of FLT3 and its downstream signaling pathways, and induced apoptosis as evidenced by PARP-cleavage and caspase-3 activation. Moreover, in AML-related xenograft mouse models (MV4-11, MOLM-14, Ba/F3-ITD-D835Y, Ba/F3-ITD-F691L), once-daily oral dose of PLM-102 significantly suppressed the tumor growth and achieved complete tumor regression. In addition, the outstanding efficacy of our compound has been confirmed in large tumor xenograft models. These results are very encouraging because large tumors have a limited blood supply and high interstitial fluid pressure, leading to a poor absorption of anticancer drugs. Pharmacokinetics of PLM-102 displayed higher bone-marrow exposure indicating better target engagement and benefits in the clinical translation in AML. In conclusion, PLM-102 is a promising therapeutic candidate for the FLT3-ITD-mutated AML as well as the acquired resistance to current FLT3 inhibitors. Citation Format: Jin-Hee Park, Jae-Seon Lee, Su-jin Oh, So-Deok Lee, Yong June Choi, Keon Wook Kang, Miran Moon, Soo Yeon Jang, Myung Jin Kim, Yong-Chul Kim. Discovery of PLM-102, a highly potent 3rd generation FLT3 inhibitor, in drug-resistant FLT3-ITD-TKD mutated acute myeloid leukemia. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4009.

Modulating tumor mechanics with nanomedicine for cancer therapy.

Over the past several decades, the importance of the tumor mechanical microenvironment (TMME) in cancer progression or cancer therapy has been recognized by researchers worldwide. The abnormal mechanical properties of tumor tissues include high mechanical stiffness, high solid stress, and high interstitial fluid pressure (IFP), which form physical barriers resulting in suboptimal treatment efficacy and resistance to different types of therapy by preventing drugs infiltrating the tumor parenchyma. Therefore, preventing or reversing the establishment of the abnormal TMME is critical for cancer therapy. Nanomedicines can enhance drug delivery by exploiting the enhanced permeability and retention (EPR) effect, so nanomedicines that target and modulate the TMME can further boost antitumor efficacy. Herein, we mainly discuss the nanomedicines that can regulate mechanical stiffness, solid stress, and IFP, with a focus on how nanomedicines change abnormal mechanical properties and facilitate drug delivery. We first introduce the formation, characterizing methods and biological effects of tumor mechanical properties. Conventional TMME modulation strategies will be briefly summarized. Then, we highlight representative nanomedicines capable of modulating the TMME for augmented cancer therapy. Finally, current challenges and future opportunities for regulating the TMME with nanomedicines will be provided.

Fluid-sensitive migration mechanisms predict association between metastasis and high interstitial fluid pressure in pancreatic cancer

A remarkable feature in pancreatic cancer is the propensity to metastasize early, even for small, early stage cancers. We use a computer-based pancreatic model to simulate tumor progression behavior where fluid-sensitive migration mechanisms are accounted for as a plausible driver for metastasis. The model has been trained to comply with in vitro results to determine input parameters that characterize the migration mechanisms. To mimic previously studied preclinical xenografts we run the computer model informed with an ensemble of stochastic-generated realizations of unknown parameters related to tumor microenvironment only constrained such that pathological realistic values for interstitial fluid pressure (IFP) are obtained. The in silico model suggests the occurrence of a steady production of small clusters of cancer cells that detach from the primary tumor and form isolated islands and thereby creates a natural prerequisite for a strong invasion into the lymph nodes and venous system. The model predicts that this behavior is associated with high interstitial fluid pressure (IFP), consistent with published experimental findings. The continuum-based model is the first to explain published results for preclinical models which have reported associations between high IFP and high metastatic propensity and thereby serves to shed light on possible mechanisms behind the clinical aggressiveness of pancreatic cancer.

Recent advances in bacteria-mediated cancer therapy.

Cancer is among the leading cause of deaths worldwide. Although conventional therapies have been applied in the fight against the cancer, the poor oxygen, low extracellular pH, and high interstitial fluid pressure of the tumor microenvironment mean that these treatments fail to completely eradicate cancer cells. Recently, bacteria have increasingly been considered to be a promising platform for cancer therapy thanks to their many unique properties, such as specific tumor-targeting ability, high motility, immunogenicity, and their use as gene or drug carriers. Several types of bacteria have already been used for solid and metastatic tumor therapies, with promising results. With the development of synthetic biology, engineered bacteria have been endowed with the controllable expression of therapeutic proteins. Meanwhile, nanomaterials have been widely used to modify bacteria for targeted drug delivery, photothermal therapy, magnetothermal therapy, and photodynamic therapy, while promoting the antitumor efficiency of synergistic cancer therapies. This review will provide a brief introduction to the foundation of bacterial biotherapy. We begin by summarizing the recent advances in the use of many different types of bacteria in multiple targeted tumor therapies. We will then discuss the future prospects of bacteria-mediated cancer therapies.

Development of Injectable and Biodegradable Needle-Type Starch Implant for Effective Intratumoral Drug Delivery and Distribution.

IntroductionCompared to intravenous administration, intratumoral drug administration enables the direct delivery of drugs to tumors and mitigates the systemic absorption of drugs and associated drug-induced side effects. However, intratumoral drug administration presents several challenges. The high interstitial fluid pressure (IFP) of the tumor prevents the retention of drugs within the tumor; thus, significant amounts of the drugs are absorbed systemically through the bloodstream or delivered to non-target sites. To solve this problem, in this study, a drug-enclosed needle-type starch implant was developed that can overcome IFP and remain in the tumor.MethodsInjectable needle-type starch implants (NS implants) were prepared by starch gelatinization and drying. The structure, cytotoxicity, and anticancer effects of the NS implants were evaluated. Biodistribution of NS implants was evaluated in pork (in vitro), dissected liver (ex vivo), and 4T1 tumors in mice (in vivo) using a fluorescence imaging device.ResultsThe prepared NS implants exhibited a hydrogel structure after water absorption. NS implants showed effective cytotoxicity and anticancer effects by photothermal therapy (PTT). The NS implant itself has sufficient strength and can be easily injected into a desired area. In vivo, the NS implant continuously delivered drugs to the tumor more effectively and uniformly than conventional hydrogels and solutions.ConclusionThis study demonstrated the advantages of needle-type implants. An injectable NS implant can be a new formulation that can effectively deliver drugs and exhibit anticancer effects.

Collagenase-Loaded H-TiO2 Nanoparticles Enhance Ultrasound Imaging-Guided Sonodynamic Therapy in a Pancreatic Carcinoma Xenograft Model via Digesting Stromal Barriers.

Sonodynamic therapy (SDT), a noninvasive therapy that relies on sonosensitizers and generates reactive oxygen species (ROS), has attracted considerable attention in the treatment of pancreatic cancer. However, being surrounded by dense stromal barriers, pancreatic cancer exhibits high interstitial fluid pressure (IFP) and hypoxia in the tumor microenvironment (TME), resulting in poor SDT efficacy. Collagenase-loaded hollow TiO2 (Col-H-TiO2) nanoparticles (NPs) capable of degrading stromal barriers and producing sufficient ROS production were synthesized in this study. After administration of NPs in the patient-derived xenograft (PDX) model, ultrasonic irradiation-released collagenase degraded tumor matrix fibers, decreased intratumoral IFP, and enhanced the penetration and retention of NPs within tumor tissues. Moreover, the NPs accumulated within the tumor not only generate abundant ROS under the influence of ultrasound irradiation but also improve intratumoral ultrasound signal, providing ultrasonic imaging-guided highly effective SDT for pancreatic cancer. In conclusion, this research improves the SDT technique and enhances the visualization of pancreatic cancer by remodeling the TME and is a promising strategy for further clinical applications.

Tumor Biology; Usefulness of Thermosensitive and pH Sensitive Polymeric Nanoparticles for Tumor Targeting: A Review

Polymeric nanoparticles (PNPs) have attracted the interest of many scientists and have been utilized in an increasing number of fields during the last two decades. The conventional chemotherapeutic agents have poor pharmacokinetic parameters such as non-specific distribution of drugs, the lack of drug specific affinity towards a pathological site, and thus necessitating large dose of a drug to achieve high local concentration in the body leading to systemic toxicity associated with serious side effects. A thorough and precise understanding of tumor microenvironment such as angiogenesis, tumor pH, enhanced permeation and retention (EPR) effect, abnormal lymphatics, multidrug resistance (MDR) and high interstitial fluid pressure, allows designing drug delivery systems that specifically target anti-cancer drugs to tumors. An attempt has been made in this article to highlight the temperature and pH sensitive PNPs, and PNPs with dual and double response to both temperature and pH that have a distinct capacity to target tumors with limited effect on healthy tissues. The stimuli responsive nanoparticles are classified based on their mechanism of response to temperature and pH. Structure of the polymer, methods of drug loading, and characterization of PNPs are elucidated.&#x0D; Keywords: Polymeric nanoparticles; pH sensitive polymers; Thermosensitive polymers; Tumor microenvironment; Multidrug resistance; Drug loading.

Abstract 1042: Fc3TSR improves intratumoral treatment delivery by normalizing tumor vasculature and reducing interstitial fluid pressure in an orthotopic, syngeneic mouse model of epithelial ovarian cancer

Abstract A hallmark of solid tumors is the need for vascularization to supply oxygen and nutrients. Aggressive pro-angiogenic signals induced by tumors lead to malformation of vessels characterized by reduced pericyte coverage and low perfusion. As a result of this vascular dysfunction, tumors have elevated hypoxia and high interstitial fluid pressure (IFP), yielding an aggressive phenotype, and reducing efficacy and trafficking of intravenous therapies to the tumor core. Anti-angiogenic therapies aim to reduce angiogenic stimuli and normalize tumor vessels. The three type-1-repeat (3TSR) region of thrombospondin-1 contains the majority of its anti-angiogenic properties in a small bioactive peptide. These functions are mediated through the membrane protein, CD36. We have previously shown that administration of native 3TSR leads to improved tumor perfusion, and enhancing delivery of chemotherapy drugs and oncolytic viruses. We have developed a novel compound, Fc3TSR, that has two 3TSR peptides linked with a Fc to increase in vitro and in vivo efficacy. In an orthotopic, mouse model of ovarian cancer, we examined the effect of Fc3TSR treatment on tumor IFP using a 1.2Fr pressure catheter guided into the tumor core of anesthetized mice. Compared to untreated controls, mice treated with Fc3TSR had significantly lower IFP, even after considering differences in heart rate among animals. Immunofluorescence on fixed sentinel lymph nodes revealed enhanced presence of immune cells, a positive predictor of lymphatic patency. To determine impact on chemotherapy delivery, mice were injected with 40mCi paclitaxel and tumor uptake of the isotope was measured. At 12, 24 and 48h post injection, Fc3TSR treated tumors had significantly increased uptake of paclitaxel compared to untreated or 3TSR treated mice. In vitro cell viability assays and western blot analysis of cleaved-caspase-3 revealed that Fc3TSR enhances direct apoptosis in human ovarian cell lines (OVCAR-2 and 36M2) compared to untreated cells or those treated with native 3TSR at equimolar concentrations. In a human subcutaneous xenograft model using 36M2 cells in SCID mice, Fc3TSR significantly reduced tumor volume as a single agent compared to PBS controls.Fc3TSR causes direct ovarian tumor cell apoptosis in vitro and significant anti-tumor effects in vivo. In vivo, Fc3TSR causes potent vascular normalization, decreases tumor hypoxia and IFP in the tumor core. As such, Fc3TSR has the potential to remodel multiple aspects of the tumor microenvironment which would otherwise obstruct treatment delivery and efficacy in solid tumors. The multi-modal aspects of Fc3TSR makes this therapeutic approach attractive for the treatment of advanced ovarian cancer and other malignancies that typically overcome single-agent therapy. Citation Format: Kathy Matuszewska, Madison Pereira, Leslie Ogilvie, Duncan Petrik, Allison Gartung, Dipak Panigrahy, Kin-Ming Lo, Jack Lawler, Jeremy Simpson, Jim Petrik. Fc3TSR improves intratumoral treatment delivery by normalizing tumor vasculature and reducing interstitial fluid pressure in an orthotopic, syngeneic mouse model of epithelial ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1042.

Abstract 5796: Targeting poorly differentiated and anaplastic thyroid cancer microenvironment via TNF-α/TGF-β/LOX signaling to improve drug delivery and treatment efficacy

Abstract A major limitation of current systemic solid cancer therapies is the failure to effectively deliver drugs to cancer cells. Solid tumors have high cell density and poor lymphatic drainage, leading to higher interstitial fluid pressure (IFP). We previously showed that the tumor microenvironment of poorly-differentiated (PDTC) and anaplastic thyroid cancer (ATC) can be selectively and effectively treated with nanomedicine carrying recombinant human Tumor Necrosis Factor α (TNFα)(CYT6091), resulting in vascular leakage, decreased IFP, and increased intratumoral concentration of paclitaxel in vivo. The purpose of this study is to investigate the mechanisms involved in a TNFα-induced reduction of IFP. We investigated the effects of TNF-α on cytokines and extracellular matrix (ECM) proteins in tumor microenvironment. Our data showed that TNFα treatment downregulated transforming growth factor-beta (TGF-β) and Lysyl oxidase (LOX) and upregulated several ECM proteins. However, we observed LOX upregulation when we treated thyroid cancer with siTNF-α-receptor 1 or 2 followed by TNF-α, suggesting the involvement of TNF-α-receptors in treatment resistance. In addition to the role of LOX in stiffening the ECM, causing a barrier to drug delivery, we showed overexpression of LOX in aggressive thyroid cancer. We observed increased vascular leakage in siLOX-treated thyroid cancer xenografts, mimicking the effect of CYT-6091. Furthermore, we confirmed that the LOX expression in thyroid cancer is positively associated with transforming growth factor receptor 1 (TGFBR1). In TCGA thyroid cancer database the mRNA expression of TGFBR1 was positively correlated with those of ECM regulatory genes (ITGB2, ITGA2 and COL1A1) which were downregulated with TNF-α treated thyroid cancer cells. To assess the role of TGF-β on vascular permeability, we found that the TGF-β inhibitor (SB-431542) induced in vitro vascular leakage, while the recombinant TGF-β reversed TNF-α-induced in vitro vascular leakage in HUVEC cells. SB-431542 and TGF-β neutralizing antibodies independently and markedly improved treatment efficacy of paclitaxel in in vitro thyroid cancer 3D tumor spheroids. Moreover, TGF-β1 inhibition downregulates the protein levels of Smad3 molecules in thyroid cancer cells. TCGA database studies of thyroid cancer patient samples showed that SMAD3 positively correlated with TGFBR1 and LOX, suggesting the involvement of SMAD3 in TGF-β/LOX signaling in the TME. Citation Format: DIPRANJAN LAHA. Targeting poorly differentiated and anaplastic thyroid cancer microenvironment via TNF-α/TGF-β/LOX signaling to improve drug delivery and treatment efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5796.

Microbubbles Ultrasonic Cavitation Regulates Tumor Interstitial Fluid Pressure and Enhances Sonodynamic Therapy

Sonodynamic therapy (SDT) is a promising treatment method for solid tumors. However, the high interstitial fluid pressure (IFP) in tumor tissues limits the accumulation of sonosensitizers. In the present study, microbubbles ultrasonic cavitation was used to regulate the tumor’s IFP and evaluate SDT effects. Rabbit VX2 tumor tissues were treated with microbubbles ultrasonic cavitation. The IFP of different tumor parts before and after cavitation was measured by the WIN method. The accumulation of the sonosensitizers hematoporphyrin monomethyl ether (HMME) in tumor tissues was observed using an ultramicro spectrophotometer and laser confocal microscope. Then, tumor-bearing rabbits were treated with SDT once a week for eight weeks and the therapeutic effect was evaluated. After microbubbles ultrasonic cavitation treatment, the tumor’s IFP decreased and the HMME concentration increased. We concluded that microbubbles ultrasonic cavitation can increase HMME accumulation in rabbit VX2 tumors and increase SDT therapeutic effects.

A Magnetocatalytic Propelled Cobalt–Platinum@Graphene Navigator for Enhanced Tumor Penetration and Theranostics

A Magnetocatalytic Propelled Cobalt–Platinum@Graphene Navigator for Enhanced Tumor Penetration and Theranostics

Tumor Solid Stress: Assessment with MR Elastography under Compression of Patient-Derived Hepatocellular Carcinomas and Cholangiocarcinomas Xenografted in Mice.

Simple SummaryTumor biomechanical properties, including high viscoelasticity and tumor pressure (solid stress and interstitial fluid pressure), are linked to tumor severity. While tumor viscoelasticity can be quantified with MR elastography, a non-invasive method to quantify tumor pressure remains elusive. In patient-derived hepatocellular carcinomas and cholangiocarcinomas xenografted in mice, we observed that basal elasticity determined during MR elastography under compression had high diagnostic performance in assessing tumor fibrosis content and was independently influenced by interstitial fluid pressure. In contrast, compression stiffening rate had high diagnostic performance in assessing solid stress. Assessment of compression stiffening with MR elastography may provide a non-invasive biomarker of tumor solid stress.Malignant tumors have abnormal biomechanical characteristics, including high viscoelasticity, solid stress, and interstitial fluid pressure. Magnetic resonance (MR) elastography is increasingly used to non-invasively assess tissue viscoelasticity. However, solid stress and interstitial fluid pressure measurements are performed with invasive methods. We studied the feasibility and potential role of MR elastography at basal state and under controlled compression in assessing altered biomechanical features of malignant liver tumors. MR elastography was performed in mice with patient-derived, subcutaneously xenografted hepatocellular carcinomas or cholangiocarcinomas to measure the basal viscoelasticity and the compression stiffening rate, which corresponds to the slope of elasticity versus applied compression. MR elastography measurements were correlated with invasive pressure measurements and digital histological readings. Significant differences in MR elastography parameters, pressure, and histological measurements were observed between tumor models. In multivariate analysis, collagen content and interstitial fluid pressure were determinants of basal viscoelasticity, whereas solid stress, in addition to collagen content, cellularity, and tumor type, was an independent determinant of compression stiffening rate. Compression stiffening rate had high AUC (0.87 ± 0.08) for determining elevated solid stress, whereas basal elasticity had high AUC for tumor collagen content (AUC: 0.86 ± 0.08). Our results suggest that MR elastography compression stiffening rate, in contrast to basal viscoelasticity, is a potential marker of solid stress in malignant liver tumors.