Tumor Interstitial Fluid Pressure Research Articles

Curvature-mediated rapid extravasation and penetration of nanoparticles against interstitial fluid pressure for improved drug delivery

Elevated interstitial fluid pressure (IFP) within pathological tissues (e.g., tumors, obstructed kidneys, and cirrhotic livers) creates a significant hindrance to the transport of nanomedicine, ultimately impairing the therapeutic efficiency. Among these tissues, solid tumors present the most challenging scenario. While several strategies through reducing tumor IFP have been devised to enhance nanoparticle delivery, few approaches focus on modulating the intrinsic properties of nanoparticles to effectively counteract IFP during extravasation and penetration, which are precisely the stages obstructed by elevated IFP. Herein, we propose an innovative solution by engineering nanoparticles with a fusiform shape of high curvature, enabling efficient surmounting of IFP barriers during extravasation and penetration within tumor tissues. Through experimental and theoretical analyses, we demonstrate that the elongated nanoparticles with the highest mean curvature outperform spherical and rod-shaped counterparts against elevated IFP, leading to superior intratumoral accumulation and antitumor efficacy. Super-resolution microscopy and molecular dynamics simulations uncover the underlying mechanisms in which the high curvature contributes to diminished drag force in surmounting high-pressure differentials during extravasation. Simultaneously, the facilitated rotational movement augments the hopping frequency during penetration. This study effectively addresses the limitations posed by high-pressure impediments, uncovers the mutual interactions between the physical properties of NPs and their environment, and presents a promising avenue for advancing cancer treatment through nanomedicine.

Near-infrared Light-Triggered Size-Shrinkable theranostic nanomicelles for effective tumor targeting and regression

Most nanomedicines with suitable sizes (normally 100–200 nm) exhibit favorable accumulation in the periphery of tumors but hardly penetrate into deep tumors. Effective penetration of nanomedicines requires smaller sizes (less than 30 nm) to overcome the elevated tumor interstitial fluid pressure. Moreover, integrating an efficient diagnostic agent in the nanomedicines is in high demand for precision theranostics of tumors. To this end, a near-infrared light (NIR) −triggered size-shrinkable micelle system (Fe3O4@AuNFs/DOX-M) coloaded antitumor drug doxorubicin (DOX) and biomodal imaging agent magnetic gold nanoflower (Fe3O4@AuNFs) was developed to achieve efficient theranostic of tumors. Upon the accumulation of Fe3O4@AuNFs/DOX-M in the tumor periphery, a NIR laser was irradiated near the tumor site, and the loaded Fe3O4@Au NFs could convert the light energy to heat, which triggered the cleavage of DOX-M to the ultra-small micelles (∼5 nm), thus realizing the deep penetration of micelles and on-demand drug release. Moreover, Fe3O4@AuNFs in the micelles could also be used as CT/MRI dual-modal contrast agent to “visualize” the tumor. Up to 92.6 % of tumor inhibition was achieved for the developed Fe3O4@AuNFs/DOX-M under NIR irradiation. This versatile micelle system provided a promising drug carrier platform realizing efficient tumor dual-modal diagnosis and photothermal-chemotherapy integration.

Abstract 588: Preclinical evaluation of novel chimeric vesiculovirus mediated expression of proteolytic enzymes targeting two major stromal components of pancreatic ductal adenocarcinoma

Abstract The vesiculovirus genus has recently garnered interest as an oncolytic virotherapy for pancreatic ductal adenocarcinoma (PDAC). A new synthetic chimeric vesiculovirus, VMG, demonstrated efficacy and safety against PDAC both in vitro and in vivo. The therapeutic effectiveness of virotherapies against PDAC is often hindered by immunosuppressive factors in the tumor environment, as well as the presence of hyaluronic acid (HA) and collagen (CN), which increase tumor stiffness and interstitial fluid pressure, leading to reduced drug/oncolytic virus and immune cell penetration into tumor. To address this, we engineered VMG viruses incorporating enzymes PH20, collagenase (CNase), and novel proteolytic enzyme SMC, the latter exhibits both PH20 and CNase-like activity. We characterized these modified viruses for their cytotoxicity and performance in vitro. Various PDAC cell lines displayed varied sensitivity to VMG vectors, yet they showed consistent oncolytic effects relative to the parent VMG-GFP virus. Our results revealed no compromise in viral replication or apoptosis-inducing ability after transgene insertion, which is evident as infectious viral progenies were produced to approximately similar level of magnitude of around 108 TCID50/ml in all the cell line tested. Additionally, the VMG-SMC and VMG-hPH20-CNase variants demonstrated notable enzyme activity. To enhance clinical relevance, we utilized an ex vivo live tumor platform, which indicated around 20% tumor cell death using VMG vectors compared to that of the control, signifying tumor viability and virus replicability 72 hours post-infection. Fluorescent imagery highlighted the viruses' ability to spread and express functional enzymes within tumors. In summary, VMG vectors expressing stroma-degrading proteolytic enzymes can effectively express PH20, CNase and SMC enzymes that degrade stromal barrier of HA and CN without interrupting the replicability, performance, and oncolytic characteristics of the VMG vectors. Future research should prioritize the safety of these vectors and their potential to augment neoantigen expression and immune cell infiltration in vivo, which are the hallmarks of antitumor efficacy. Citation Format: Khandoker Usran Ferdous, Mulu Z. Tesfay, Camila C. Simoes, Aleksandra Cios, Bolni Marius Nagalo. Preclinical evaluation of novel chimeric vesiculovirus mediated expression of proteolytic enzymes targeting two major stromal components of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 588.

Smart Lipid Nanoparticle that Remodels Tumor Microenvironment for Activatable H2S Gas and Photodynamic Immunotherapy.

Hydrogen sulfide (H2S) has shown promise for gas therapy. However, it is still controversial whether H2S can remodel the tumor microenvironment (TME) and induce robust antitumor immunity. Here, a tumor-targeting and TME-responsive "smart" lipid nanoparticle (1-JK-PS-FA) is presented, which is capable of delivering and releasing H2S specifically in tumor tissues for on-demand H2S gas and photodynamic immunotherapy. 1-JK-PS-FA enables a burst release of H2S in the acidic TME, which promptly reduces the embedded organic electrochromic materials and consequently switches on near-infrared fluorescence and photodynamic activity. Furthermore, we found that high levels of H2S can reprogram the TME by reducing tumor interstitial fluid pressure, promoting angiogenesis, increasing vascular permeability, ameliorating hypoxia, and reducing immunosuppressive conditions. This leads to increased tumor uptake of 1-JK-PS-FA, thereby enhancing PDT efficacy and eliciting strong immunogenic cell death during 808 nm laser irradiation. Therefore, 1-JK-PS-FA permits synergistic H2S gas and photodynamic immunotherapy, effectively eradicating orthotopic breast tumors and preventing tumor metastasis and recurrence. This work showcases the capacity of H2S to reprogram the TME to enhance H2S gas and immunotherapy.

Predicting stress and interstitial fluid pressure in tumors based on biphasic theory

The uncontrolled proliferation of cancer cells causes the growth of the tumor mass. Consequently, the normal surrounding tissue exerts a compressive force on the tumor mass to oppose its expansion. These stresses directly promote tumor metastasis and invasion and affect drug delivery.In the past, the mechanical behavior of solid tumors has been extensively studied using linear elastic and nonlinear hyperelastic constitutive models. In this study, we develop a two-dimensional biomechanical model based on the biphasic assumption of the solid matrix and fluid phase of the tissues. Heterogeneous vasculature and nonuniform blood perfusion are also investigated by incorporating in the model a necrotic core and a well-vascularized zone. The findings of our study demonstrate a significant difference between the linear and nonlinear tissue responses to stress, while the interstitial fluid pressure (IFP) distribution is found to be independent of the constitutive model. The proposed biphasic model may be useful for elasticity imaging techniques aiming at predicting stress and IFP in tumors.

Amelioration of Tumor-promoting Microenvironment via Vascular Remodeling and CAF Suppression Using E7130: Biomarker Analysis by Multimodal Imaging Modalities.

E7130 is a novel anticancer agent created from total synthetic study of the natural compound norhalichondrin B. In addition to inhibiting microtubule dynamics, E7130 also ameliorates tumor-promoting aspects of the tumor microenvironment (TME) by suppressing cancer-associated fibroblasts (CAF) and promoting remodeling of tumor vasculature. Here, we demonstrate TME amelioration by E7130 using multi-imaging modalities, including multiplexed mass cytometry [cytometry by time-of-flight (CyTOF)] analysis, multiplex IHC analysis, and MRI. Experimental solid tumors characterized by large numbers of CAFs in TME were treated with E7130. E7130 suppressed LAP-TGFβ1 production, a precursor of TGFβ1, in CAFs but not in cancer cells; an effect that was accompanied by a reduction of circulating TGFβ1 in plasma. To our best knowledge, this is the first report to show a reduction of TGFβ1 production in TME. Furthermore, multiplex IHC analysis revealed reduced cellularity and increased TUNEL-positive apoptotic cells in E7130-treated xenografts. Increased microvessel density (MVD) and collagen IV (Col IV), an extracellular matrix (ECM) component associated with endothelial cells, were also observed in the TME, and plasma Col IV levels were also increased by E7130 treatment. MRI revealed increased accumulation of a contrast agent in xenografts. Moreover, diffusion-weighted MRI after E7130 treatment indicated reduction of tumor cellularity and interstitial fluid pressure. Overall, our findings strongly support the mechanism of action that E7130 alters the TME in therapeutically beneficial ways. Importantly, from a translational perspective, our data demonstrated MRI as a noninvasive biomarker to detect TME amelioration by E7130, supported by consistent changes in plasma biomarkers.

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.

Modulation of cancer-associated fibroblasts by nanodelivery system to enhanceefficacy of tumor therapy.

Cancer-associated fibroblasts (CAFs) are the most common cells in the tumor stroma and are essential for tumor development and metastasis. While decreasing the release and infiltration of nanomedicine through nonspecific internalization, CAFs specifically increase solid tumor pressure and interstitial fluid pressure by secreting tumor growth- and migration-promoting cytokines, which increases vascular and organ pressure caused by solid tumor pressure. Nanoparticles have good permeability and can penetrate tumor tissue to reach the lesion area, inhibiting tumor growth. Thus, CAFs are used as modifiable targets. Here, the authors review the biological functions, originsand biomarkers of CAFs andsummarize strategies for modulating CAFs in nanodelivery systems. This study provides a prospective guide to modulating CAFs to enhance oncology treatment.

Noninvasive Estimation of Tumor Interstitial Fluid Pressure from Subharmonic Scattering of Ultrasound Contrast Microbubbles

The noninvasive estimation of interstitial fluid pressure (IFP) using ultrasound contrast agent (UCA) microbubbles as pressure sensors will provide tumor treatments and efficacy assessments with a promising tool. This study aimed to verify the efficacy of the optimal acoustic pressure in vitro in the prediction of tumor IFPs based on UCA microbubbles' subharmonic scattering. A customized ultrasound scanner was used to generate subharmonic signals from microbubbles' nonlinear oscillations, and the optimal acoustic pressure was determined in vitro when the subharmonic amplitude reached the most sensitive to hydrostatic pressure changes. This optimal acoustic pressure was then applied to predict IFPs in tumor-bearing mouse models, which were further compared with the reference IFPs measured using a standard tissue fluid pressure monitor. An inverse linear relationship and good correlation (r = -0.853, p < 0.001) existed between the subharmonic amplitude and tumor IFPs at the optimal acoustic pressure of 555 kPa, and pressure sensitivity was 1.019 dB/mmHg. No statistical differences were found between the pressures measured by the standard device and those estimated via the subharmonic amplitude, as confirmed by cross-validation (mean absolute errors from 2.00 to 3.09 mmHg, p > 0.05). Our findings demonstrated that in vitro optimized acoustic parameters for UCA microbubbles' subharmonic scattering can be applied for the noninvasive estimation of tumor IFPs.

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 4000: A novel pegylated bispecific antibody-drug conjugate (P-BsADC) targeting Her2+ cancers with improved efficacy and therapeutic window

Abstract Despite the fact that ADCs improve the efficacy and target selectivity comparing to the non-specific small molecule cytotoxicity drugs in cancer treatment, traditional ADCs still suffer from many issues which include low tumor penetration and accumulation, inefficient internalization, undesired efflux of ADC from tumor cells, significant on-target off-tumor toxicity, Fc mediated uptake that results in off-target toxicity, limited extravasation across capillary walls due to big molecular size, poor diffusion into the tumor masses due to increased tumor interstitial fluid pressure, and the binding-site-barrier. To address these issues, we previously reported that the compound JY201, a Polyethylene Glycol (PEG)-based bispecific ADC (P-BsADC) targeting two epitopes of Her2, demonstrated advantages in tumor penetration, internalization efficiency, lysosome trafficking effectiveness, no Fc related toxicity, and better efficacy in tumor inhibition than transtuzumab deruxtecan (Ds-8201). Continuing from our previous study, here we further reveal that JY201 can penetrate the tumor deeply and distribute more homogeneously in entire tumor masses while Ds-8201 limits its diffusion to the regions very close to the blood vessels in the tumor. Furthermore, JY201 shows better efficacy than Ds-8201 in inhibiting tumors with low expression of Her2 in pdx (patient derived xenograft) and cdx models. In addition, JY201 can effectively inhibit tumors resistant to Ds-8201. In an in-vitro plasma stability test, JY201 demonstrated high stability in cynomolgus monkey and human serums. JY201 also has a biodistribution profile advocating better safety than Ds-8201 in tumor bearing mice. In the repeated-dosing toxicological study in Her2 transgenic mice, JY201 with the dose of 50mg/kg was well tolerated and did not induce any tissue/organ damage to the animals. Due to much shorter half-life (5 times shorter) in mice for PEGylated proteins than in primates, we expect JY201 will have much higher tolerated dose than the 50mg/kg in primates. In summary, the findings from this study provide solid preclinical evidence for JY201 to be developed further as an efficacious and safe clinical treatment for patients with Her2 positive cancers. Citation Format: Yu (Yvonne) Wen, Shuqiang Yin, Weidong Lyu, Yang Lei, Qiudong Zhuo, Zibin Wu, Bin Sun, Shuangyu Tan, Lidong Jiang, Teng Zhang, Bo Gao, Rui Xu, Yong Li, Liling Zheng, Shumin Liu, David (Dechun) Wu. A novel pegylated bispecific antibody-drug conjugate (P-BsADC) targeting Her2+ cancers with improved efficacy and therapeutic window. [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 4000.

Modulating tumour vascular normalisation using triptolide-loaded NGR-functionalized liposomes for enhanced cancer radiotherapy

Radiotherapy is an effective therapy in tumour treatment. However, the characteristics of the tumour microenvironment, including hypoxia, low pH, and interstitial fluid pressure bring about radioresistance. To improve the anti-tumour effect of radiotherapy, it has been demonstrated that antiangiogenic therapy can be employed to repair the structural and functional defects of tumour angiogenic vessels, thereby preventing radioresistance or poor therapeutic drug delivery. In this study, we prepared triptolide (TP)-loaded Asn-Gly-Arg (NGR) peptide conjugated mPEG2000-DSPE-targeted liposomes (NGR-PEG-TP-LPs) to induce tumour blood vessel normalisation, to the end of increasing the sensitivity of tumour cells to radiotherapy. Further, to quantify the tumour vessel normalisation window, the structure and functionality of tumour blood vessels post NGR-PEG-TP-LPs treatment were evaluated. Thereafter, the anti-tumour effect of radiotherapy following these treatments was evaluated using HCT116 xenograft-bearing mouse models based on the tumour vessel normalisation period window. The results obtained showed that NGR-PEG-TP-LPs could modulate tumour vascular normalisation to increase the oxygen content of the tumour microenvironment and enhance the efficacy of radiotherapy. Further, liver and kidney toxicity tests indicated that NGR-PEG-TP-LPs are safe for application in cancer treatment

Multi-dimensional modeling of nanoparticles transportation from capillary bed into the tumor microenvironment

In this study, we examined the extravasation of pharmaceutical inorganic nanoparticles (NPs) with a new approach from the leaky endothelium of tumor microvasculature (TMV) into the tumor microenvironment (TME) multi-dimensionally. We proposed a combination of prevailing macroscopic and microscopic methods and addressed the effect of interstitial fluid (IF) retention in solid tumor as an imperative parameter in drug delivery modeling. The Navier-Stokes equations and Darcy's law were utilized for blood flow and porous media, and the Starling's law was brought in for coupling effect. The blood flow was simulated as a non-Newtonian fluid alongside the Newtonian IF. We applied the Galerkin finite element method for the simulations. Our parametric study includes examining the effect of IF retention and TMV pressure on the distribution of tumor interstitial fluid pressure (TIFP), NPs concentration, and diameter on the penetration process, together with the time effect, on two-dimensional (2D) delivery of NPs. Our findings indicate that the IF retention in tumor cells increases TIFP depending on the amount of TMV pressure and IF retained. In addition to doubling pressure in the tumor necrotic region rather than the rest of TME, it enhances the TIFP which is an important parameter in drug delivery to solid tumors. By decreasing pressure drop within the TMV, pressure distribution within the TME becomes more uniform, creating a better condition for homogeneous penetration of NPs. Increasing both inlet pressure and NPs concentration leads to a nonlinear increase in the average concentration of tumor. Decreasing the diameter of NPs increases the penetration of NPs with a higher ratio in the TME.

A fully-decoupled discontinuous Galerkin approximation of the Cahn–Hilliard–Brinkman–Ohta–Kawasaki tumor growth model

In this article, we consider the Cahn–Hilliard–Brinkman–Ohta–Kawasaki tumor growth system, which couples the Brinkman flow equations in the porous medium and the Cahn–Hilliard type equation with the nonlocal Ohta–Kawasaki term. We first construct a fully-decoupled discontinuous Galerkin method based on a decoupled, stabilized energy factorization approach and implicit-explicit Euler method in the time discretization, and strictly prove its unconditional energy stability. The optimal error estimate for the tumor interstitial fluid pressure is further obtained. Numerical results are also carried out to demonstrate the effectiveness of the proposed numerical scheme and verify the theoretical results. Finally, we apply the scheme to simulate the evolution of brain tumors based on patient-specific magnetic resonance imaging, and the obtained computational results show that the proposed numerical model and scheme can provide realistic calculations and predictions, thus providing an in-depth understanding of the mechanism of brain tumor growth.

MoS2 nanoflower-mediated enhanced intratumoral penetration and piezoelectric catalytic therapy

The absence of lymphatic vessels in tumors leads to the retention of interstitial fluid, and the formation of an inverse pressure difference between the tumor and blood vessels hinders drug delivery deep into the tumor, which leads to tumor recurrence and metastasis. Therefore, we designed a novel strategy to downregulate tumor interstitial fluid pressure (TIFP) by water splitting in the tumor interstitium based on piezoelectric catalysis nanomedicine. First, the chemotherapeutic drug doxorubicin (DOX) was loaded on the piezoelectric catalytic material MoS2 and then encapsulated with tumor cell membrane (CM) to obtain MD@C. MD@C could not only target the tumor through homologous targeting but, more importantly, also triggered piezoelectric catalytic water splitting under ultrasound (US) stimulation; as a result, the TIFPs of U14 and PAN02 tumor-bearing mice were reduced to 57.14% and 45.5%, respectively, and the tumor inhibition rates of MD@C were 96.75% and 99.21%, which increased the perfusion of blood-derived drugs in the tumors. Moreover, the hydroxyl radicals generated by piezoelectric catalysis could effectively inhibit the growth of tumors in combination with DOX. Consequently, the piezoelectric catalytic water splitting strategy of MD@C can enhance drug delivery, providing a new universal platform for the treatment of solid malignant tumors.

The ambivalent nature of the relationship between lymphatics and cancer

Do lymphatic vessels support cancer cells? Or are they vessels that help suppress cancer development? It is known that the lymphatic system is a vehicle for tumor metastasis and that the lymphangiogenic regulator VEGF-C supports the tumor. One such role of VEGF-C is the suppression of the immune response to cancer. The lymphatic system has also been correlated with an increase in interstitial fluid pressure of the tumor microenvironment. On the other hand, lymphatic vessels facilitate immune surveillance to mount an immune response against tumors with the support of VEGF-C. Furthermore, the activation of lymphatic fluid drainage may prove to filter and decrease tumor interstitial fluid pressure. In this review, we provide an overview of the dynamic between lymphatics, cancer, and tumor fluid pressure to suggest that lymphatic vessels may be used as an antitumor therapy due to their capabilities of immune surveillance and fluid pressure drainage. The application of this potential may help to prevent tumor proliferation or increase the efficacy of drugs that target cancer.

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.

Multistage pH-responsive codelivery liposomal platform for synergistic cancer therapy

BackgroundSmall interfering RNA (siRNA) is utilized as a potent agent for cancer therapy through regulating the expression of genes associated with tumors. While the widely application of siRNAs in cancer treatment is severely limited by their insufficient biological stability and its poor ability to penetrate cell membranes. Targeted delivery systems hold great promise to selectively deliver loaded drug to tumor site and reduce toxic side effect. However, the elevated tumor interstitial fluid pressure and efficient cytoplasmic release are still two significant obstacles to siRNA delivery. Co-delivery of chemotherapeutic drugs and siRNA represents a potential strategy which may achieve synergistic anticancer effect. Herein, we designed and synthesized a dual pH-responsive peptide (DPRP), which includes three units, a cell-penetrating domain (polyarginine), a polyanionic shielding domain (ehG)n, and an imine linkage between them. Based on the DPRP surface modification, we developed a pH-responsive liposomal system for co-delivering polo-like kinase-1 (PLK-1) specific siRNA and anticancer agent docetaxel (DTX), D-Lsi/DTX, to synergistically exhibit anti-tumor effect.ResultsIn contrast to the results at the physiological pH (7.4), D-Lsi/DTX lead to the enhanced penetration into tumor spheroid, the facilitated cellular uptake, the promoted escape from endosomes/lysosomes, the improved distribution into cytoplasm, and the increased cellular apoptosis under mildly acidic condition (pH 6.5). Moreover, both in vitro and in vivo study indicated that D-Lsi/DTX had a therapeutic advantage over other control liposomes. We provided clear evidence that liposomal system co-delivering siPLK-1 and DTX could significantly downregulate expression of PLK-1 and inhibit tumor growth without detectable toxic side effect, compared with siPLK-1-loaded liposomes, DTX-loaded liposomes, and the combinatorial administration.ConclusionThese results demonstrate great potential of the combined chemo/gene therapy based on the multistage pH-responsive codelivery liposomal platform for synergistic tumor treatment.Graphical

Intravesical Mucoadhesive Hydrogel Induces Chemoresistant Bladder Cancer Ferroptosis through Delivering Iron Oxide Nanoparticles in a Three-Tier Strategy.

Bladder cancer (BCa) is the most costly solid tumor owing to its high recurrence. Relapsed cancer is known to acquire chemoresistant features after standard intravesical chemotherapy. This cancer state is vulnerable to ferroptosis, which occurs when lipid peroxides generated by iron metabolism accumulate to lethal levels. Increasing the labile iron pool (LIP) by iron oxide nanoparticles (IONPs) promises to inhibit chemoresistant BCa (CRBCa), but systemically administered IONPs do not sufficiently accumulate at the tumor site. Therefore, their efficacy is weakened. Here, we present a three-tier delivery strategy through a mucoadhesive hydrogel platform conveying hyaluronic acid-coated IONPs (IONP-HA). When instilled, the hydrogel platform first adhered to the interface of the tumor surface, sustainably releasing IONP-HA. Subsequently, the tumor stiffness and interstitial fluid pressure were reduced by photothermal therapy, promoting IONP-HA diffusion into the deep cancer tissue. As CRBCa expressed high levels of CD44, the last delivery tier was achieved through antibody-mediated endocytosis to increase the LIP, ultimately inducing ferroptosis. This three-tiered strategy delivered the IONPs stepwise from anatomical to cellular levels and increased the iron content by up to 50-fold from that of systematic administration, which presents a potential regimen for CRBCa.

The Role of Ultrasound in Modulating Interstitial Fluid Pressure in Solid Tumors for Improved Drug Delivery.

The unique microenvironment of solid tumors, including desmoplasia within the extracellular matrix, enhanced vascular permeability, and poor lymphatic drainage, leads to an elevated interstitial fluid pressure which is a major barrier to drug delivery. Reducing tumor interstitial fluid pressure is one proposed method of increasing drug delivery to the tumor. The goal of this topical review is to describe recent work using focused ultrasound with or without microbubbles to modulate tumor interstitial fluid pressure, through either thermal or mechanical effects on the extracellular matrix and the vasculature. Furthermore, we provide a review on techniques in which ultrasound imaging may be used to diagnose elevated interstitial fluid pressure within solid tumors. Ultrasound-based techniques show high promise in diagnosing and treating elevated interstitial pressure to enhance drug delivery.