Tumor Interstitial Pressure Research Articles

Natural MOF-Like Photocatalytic Nanozymes Alleviate Tumor Pressure for Enhanced Nanodrug Penetration.

In oncological nanomedicine, overcoming the dual-phase high interstitial pressure in the tumor microenvironment is pivotal for enhancing the penetration and efficacy of nanotherapeutics. The elevated tumor interstitial solid pressure (TISP) is largely attributed to the overaccumulation of collagen in the extracellular matrix, while the increased tumor interstitial fluid pressure (TIFP) stems from the accumulation of fluid due to the aberrant vascular architecture. In this context, metal-organic frameworks (MOFs) with catalytic efficiency have shown potential in degrading tumor interstitial components, thereby reducing interstitial pressure. However, the potential biotoxicity of the organic components of MOFs limits their clinical translation. To circumvent this, a MOF-like photocatalytic nanozyme, RPC@M, using naturally derived cobalt phytate (CoPA) and resveratrol (Res) is developed. This nanozyme not only facilitates the decomposition of water in the tumor interstitium under photoactivation to reduce TIFP, but also generates an abundance of reactive oxygen species through its peroxidase-like activity to exert cytotoxic effects on tumor cells. Moreover, Res contributes to the reduction of collagen deposition, thereby lowering TISP. The concurrent diminution of both TISP and TIFP by RPC@M leads to enhanced tumor penetration and potent antitumor activity, presenting an innovative approach in constructing tumor therapeutic nanozymes from natural products.

Positive Chemotaxis of CREKA-Modified Ceria@Polydopamine Biomimetic Nanoswimmers for Enhanced Penetration and Chemo-photothermal Tumor Therapy.

Tumor interstitial pressure represents the greatest barrier against drug diffusion into the depth of the tumor. Biometric nanomotors highlight the possibility of enhanced deep penetration and improve cellular uptake. However, control of their directionality remains difficult to achieve. Herein, we report cysteine-arginine-glutamic acid-lysine-alanine (CREKA)-modified ceria@polydopamine nanobowls as tumor microenvironment-fueled nanoscale motors for positive chemotaxis into the tumor depth or toward tumor cells. Upon laser irradiation, this nanoswimmer rapidly depletes the tumor microenvironment-specific hydrogen peroxide (H2O2) in the nanobowl, contributing to a self-generated gradient and subsequently propulsion (9.5 μm/s at 46 °C). Moreover, the asymmetrical modification of CREKA on nanobowls could automatically reconfigure the motion direction toward tumor depth or tumor cells in response to receptor-ligand interaction, leading to a deep penetration (70 μm in multicellular spheroids) and enhanced antitumor effects over conventional nanomedicine-induced chemo-photothermal therapy (tumor growth inhibition rate: 84.2% versus 56.9%). Thus, controlling the direction of nanomotors holds considerable potential for improved antitumor responses, especially in solid tumors with high tumor interstitial pressure.

Decrease in Tumor Interstitial Pressure for Enhanced Drug Intratumoral Delivery and Synergistic Tumor Therapy.

Currently, one of the main reasons for the ineffectiveness of tumor treatment is that the abnormally high tumor interstitial pressure (TIP) hinders the delivery of drugs to the tumor center and promotes intratumoral cell survival and metastasis. Herein, we designed a "nanomotor" by in situ growth of Ag2S nanoparticles on the surface of ultrathin WS2 to fabricate Z-scheme photocatalytic drug AWS@M, which could rapidly enter tumors by splitting water in interstitial liquid to reduce TIP, along with O2 generation. Moreover, the O2 would be further converted to reactive oxygen species (ROS), accompanied by increased local temperature of tumors, and the combination of ROS with thermotherapy could eliminate the deep tumor cells. Therefore, the "nanomotor'' could effectively reduce the TIP levels of cervical cancer and pancreatic cancer (degradation rates of 40.2% and 36.1%, respectively) under 660 nm laser irradiation, further enhance intratumor drug delivery, and inhibit tumor growth (inhibition ratio 95.83% and 87.61%, respectively), and the related mechanism in vivo was explored. This work achieves efficiently photocatalytic water-splitting in tumor interstitial fluid to reduce TIP by the nanomotor, which addresses the bottleneck problem of blocking of intratumor drug delivery, and provides a general strategy for effectively inhibiting tumor growth.

Targeted Depletion of Hyaluronic Acid Mitigates Murine Breast Cancer Growth.

Simple SummaryBreast cancer often contains excessive stromal matrix components that serve as a barrier to therapy. One such component is hyaluronic acid (HA), which also plays important roles in tumor progression and spread. In this study, we engineered an attenuated Salmonella typhimurium secreting a bacterial hyaluronidase (YS-HAse) and show that it degrades HA within murine breast tumors, resulting in enhanced tumor permeability and growth control. YS-HAse represents a promising new therapeutic approach that could also be used alongside current treatments to improve their delivery and effectiveness.Hyaluronic acid (HA) is highly elevated in breast cancers compared to normal breast tissue and is associated with increased tumor aggressiveness and poor prognosis. HA interacts with cell-trafficking CD44 receptors to promote tumor cell migration and proliferation and regulates both pro- and anti-inflammatory cytokine production through tumor-associated macrophages. The highly negative charge of HA enables its uptake of vast amounts of water that greatly increases the tumor interstitial fluidic pressure, which, combined with the presence of other extracellular matrix components such as collagen, results in tumor stroma with abnormal vasculature, hypoxia, and increased drug resistance. Thus, the degradation of HA in breast cancer may attenuate growth and improve permeability to anticancer agents. Previous methods to deplete tumor HA have resulted in significant off-tumor effects due to the systemic use of mammalian hyaluronidases. To overcome this, we developed a hyaluronidase-secreting Salmonella typhimurium (YS-HAse) that specifically and preferentially colonizes tumors to deplete HA. We show that the systemic administration of YS-HAse in immunocompetent murine models of breast cancer enhances tumor perfusion, controls tumor growth, and restructures the tumor immune contexture. These studies highlight the utility of YS-HAse as a novel microbial-based therapeutic that may also be combined with existing therapeutic approaches.

Photocatalysis/enzymolysis-based biomimetic Schottky junction reduces tumor interstitial solid and fluid phases for deep-penetrating tumor therapy

Tumor interstitial solid phase-induced physical obstacles and fluid phase-induced hydrostatic pressure are regarded as the two main intractable barriers of drug delivery, leading to the survive of deep-seated tumor stem cells. Herein, a rational strategy is presented based on near-infrared light-stimuli enzymolysis and photocatalysis to decompose the tumor interstitial solid and fluid phases for boosting the tumor penetration of nanomedicine. In detail, a cuprous oxide/sliver nano-photocatalyst (Cu2O/Ag) is designed, which is covered with the thermosensitive papain-loaded tumor-homing homologous cytomembrane to form the nanomedicine (Cu2O/Ag-P@M). With the light irradiation, the heat generated by Cu2O/Ag promote the enzymolysis of extracellular matrix by papain, which eliminate the physical obstacles. Moreover, the photocatalytic water splitting of Cu2O/Ag reduce the volume of tumor interstitial fluid, which decrease the elevated hydrostatic pressure to boost the tumor penetration of nanomedicine. Additionally, during the intratumoral delivery, Cu2O/Ag-P@M is able to realize anti-tumor photothermal therapy and chemotherapy. The results indicate that the Cu2O/Ag-P@M decompose a majority of tumor extracellular matrix and interstitial fluid under light irradiation. The tumor interstitial hydrostatic pressure is reduced by 69.7%. The tumor penetration of Cu2O/Ag-P@M + L treated group is 5.03-fold than the Cu2O/Ag@M−L group, leading to the 95.19% of tumor inhibition rate.

TGF-β blockade-improved chemo-immunotherapy with pH/ROS cascade-responsive micelle via tumor microenvironment remodeling

Immunosuppressive tumor microenvironment and low delivery efficiency severely impede the tumor chemotherapy effect. To address this issue, we develop a pH/ROS cascade-responsive prodrug micelle to deliver siTGF-β with size-shrinkage and charge-reversal property, leading to synergistical tumor microenvironment remodeling. The nanosystem highly improved endocytosis efficiency and tumor penetration depth through charge reversal and size reduction upon exposure to weakly acidic tumor microenvironment. Moreover, the nanocarrier would rapidly escape from endo/lysosome, disassemble and release siTGF-β and hydroxycamptothecin in response to high intracellular ROS. Furthermore, the nanosystem significantly boosted antitumor immune response and reduced immune tolerance with remodeling tumor microenvironment, which significantly prolonged the survival time of tumor-bearing mice (75% survival rate upon 35 days). It is realized by the combined effects of chemotherapy-enhanced immunogenicity and recruitment of effector T cells, TGF-β-blockade immunotherapy-activated inhibition immunosuppressive tumor microenvironment and epithelial-to-mesenchymal transition (EMT), and regulation physical tumor microenvironment via reducing the dense tumor extracellular matrix and the high tumor interstitial pressure obstacles. To this end, the nanosystem not only overcame biobarriers and reinforced antitumor immune response, but also effectively inhibited tumor growth, metastasis and recurrence in vivo.

Pyroelectric Catalysis-Based "Nano-Lymphatic" Reduces Tumor Interstitial Pressure for Enhanced Penetration and Hydrodynamic Therapy.

Because of the deficiency of lymphatic reflux in the tumor, the retention of tumor interstitial fluid causes aggravation of the tumor interstitial pressure (TIP), which leads to unsatisfactory tumor penetration of nanomedicine. It is the main inducement of tumor recurrence and metastasis. Herein, we design a pyroelectric catalysis-based "Nano-lymphatic" to decrease the TIP for enhanced tumor penetration and treatments. It realizes photothermal therapy and decomposition of tumor interstitial fluid under NIR-II laser irradiation after reaching the tumor, which reduces the TIP for enhanced tumor penetration. Simultaneously, reactive oxygen species generated during the pyroelectric catalysis can further damage deep tumor stem cells. The results indicate that the "Nano-lymphatic" relieves 52% of TIP, leading to enhanced tumor penetration, which effectively inhibits the tumor proliferation (93.75%) and recurrence. Our finding presents a rational strategy to reduce TIP by pyroelectric catalysis for enhanced tumor penetration and improved treatments, which is of great significance for drug delivery.

Rapid pH-responsive self-disintegrating nanoassemblies balance tumor accumulation and penetration for enhanced anti-breast cancer therapy

The dilemma of tumor accumulation and deep penetration has always been a barrier in antitumor therapy. Stimuli-responsive size changeable drug delivery systems provide possible solutions. Nevertheless, the low size-shrinkage efficiency limited the antitumor effects. In this study, an instant pH-responsive size shrinkable nanoassemblies named self-aggregated DOX@HA-CD (SA-DOX@HA-CD) was formulated using small-sized hyaluronic acid modified carbon dots (HA-CD) as monomers, which could self-aggregate into raspberry-like structure via hydrophobicity force in neutral pH and rapidly disassemble into shotgun-like DOX-loaded CD monomer in simulated tumor microenvironment (pH 6.5), owing to the transformation in electrical charge and hydrophobicity/hydrophilicity of this system. The transmission electron microscopy showed that the clustered SA-DOX@HA-CD had a diameter of ~150 nm, and thoroughly disassembled into ~30 nm nanoparticles in response to acidic environment. The disassemble efficiency was approximately 100%. Attributed to this property, SA-DOX@HA-CD led to enhanced cellular internalization and accumulation in 4T1 cells in simulated tumor microenvironment, as well as deep tumor penetration in 3D tumor spheroid model. Besides, the imine bond between DOX and HA-CD endowed DOX with pH-responsive release profile in the acidic lysosome environment. Furthermore, in the orthotopic 4T1 tumor-bearing mouse model, SA-DOX@HA-CD demonstrated higher tumor accumulation than non-aggregated DOX-HA-CD. Meanwhile, in response to the acid tumor microenvironment, the dissociated DOX-HA achieved deep tumor penetration, which consequently resulted in 2.5-fold higher antitumor efficiency. The formulation of self-aggregated SA-DOX@HA-CD provides a simple and effective alternative to prepare pH-responsive size-shrinkable nanodrug delivery systems. Statement of significanceThe heterogeneity of tumor vasculature and the high tumor interstitial pressure lead to the barriers in tumor accumulation and deep penetration, which calls for opposite properties (e.g. size) of drug delivery systems. To address this dilemma, various size changeable nanoparticles have been developed utilizing special features of tumor microenvironment, such as pH, enzyme and reactive oxygen species. Nevertheless, the current strategies face the problems of incomplete hydrolysis of chemical bonds or insufficient enzyme degradation, which result in only partial size shrinkage, hindering the tumor deep penetration effects. Here we developed a self-assembled nanocluster, which could respond to acidic pH rapidly and thoroughly disassemble into small nanodots due to the alteration of hydrophobicity/hydrophilicity/charge, leading to approximately 100% dissociation. This strategy provides a new concept for design of size changeable drug delivery systems.

Pan-lysyl oxidase inhibition with Pxs-5505 decreases tumor burden and interstitial pressure of murine cholangiocarcinoma - a novel therapeutic strategy for clinical translation

Pan-lysyl oxidase inhibition with Pxs-5505 decreases tumor burden and interstitial pressure of murine cholangiocarcinoma - a novel therapeutic strategy for clinical translation

Relaxin-expressing oncolytic adenovirus induces remodeling of physical and immunological aspects of cold tumor to potentiate PD-1 blockade

BackgroundCurrently, several antibody (Ab)-based therapies have shown excellent therapeutic effects in the clinic. Nonetheless, Ab penetration into tumor tissues is limited due to abnormal vasculature, tumor interstitial pressure, and excessive...

Contrast-enhanced ultrasound imaging of acute changes in pancreatic cancer following targeted hyaluronan treatment.

The purpose of this study was to monitor acute changes in pancreatic tumor perfusion with contrast-enhanced ultrasound (CEUS) imaging following targeted hyaluronan (HA) treatment. Intratumoral accumulation of HA is one of contributing factors that can lead to an increased tumor interstitial pressure (TIP). These elevated TIP levels can hinder delivery of chemotherapeutic drugs and cause treatment failure. For this study, pancreatic cancer-bearing mice were imaged at baseline and again at 2 h after intravenous administration of physiological saline (control group) or PEGPH20, which targets HA (therapy group). CEUS data were collected for 5 min and the temporal sequence was first analyzed using a singular value filter (SVF) to remove any background clutter signal. Given the time history of contrast agent flow, a tumor perfusion parametric analysis was performed. A series of morphological image operations was applied to quantify structural features of the tumor angiogenic network including vessel count, density, length, diameter, tortuosity, and branching points. After imaging, animals were euthanized, and tumors excised for histological processing. Acute microvascular changes were found at 2 h after drug administration as confirmed by CEUS imaging. Further, histologic analysis of tumor sections revealed lower HA accumulation in the therapy group animals. Overall, these findings suggest that CEUS imaging of acute changes in tumor perfusion may help identify an optimal window whereby follow-up chemotherapeutic drug dosing would be more effective.

Remodeling the Tumor Microenvironment Sensitizes Breast Tumors to Anti-Programmed Death-Ligand 1 Immunotherapy.

Immunotherapies targeting immune checkpoint inhibitors have changed the landscape of cancer treatment, however, many patients are resistant or refractory to immunotherapy. The sensitivity of tumor cells to immunotherapy may be influenced by hyaluronan (HA) accumulation in the tumor microenvironment (TME). Enzymatic degradation of HA by pegvorhyaluronidase alfa (PEGPH20; PVHA) remodels the TME. This leads to reduced tumor interstitial pressure and decompressed tumor blood vessels, which are both associated with increased exposure of tumor cells to chemotherapy drugs. Here, we demonstrate PVHA increased the uptake of anti-programmed death-ligand 1 (PD-L1) antibody in HA-accumulating animal models of breast cancer. The increased levels of anti-PD-L1 antibody were associated with increased accumulation of T cells and natural killer cells and decreased myeloid-derived suppressor cells. PD-L1 blockade significantly inhibited tumor growth when combined with PVHA, but not alone. Our results suggest that PVHA can sensitize HA-accumulating tumors to anti-PD-L1 immunotherapy. SIGNIFICANCE: These findings show removal of hyaluronan in the tumor microenvironment improves immune cells and checkpoint inhibitors access to tumors. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/79/16/4149/F1.large.jpg.

Abstract 97: The effect of hyaluronan degradation on the uptake and cytotoxic activity of liposome-encapsulated doxorubicin in 3D tumor spheroid models

Abstract The accumulation of hyaluronan (HA) in the solid tumor microenvironment (TME) can be associated with poor prognosis in several human cancers. Accumulation of HA in the TME can increase interstitial pressure that compresses local blood vessels and impairs the access of anti-cancer therapy. In preclinical models, enzymatic degradation of HA by pegvorhyaluronidase alfa (PEGPH20; PVHA), a PEGylated form of recombinant human hyaluronidase PH20 (rHuPH20), is associated with decreased tumor interstitial pressure, improved tumor vascular perfusion, and increased access and anti-tumor efficacy of cytotoxic and immunotherapies. The functional effect of HA degradation on the TME has been mostly characterized in animal tumor models. Here, we describe the utilization of 3D tumor spheroid models to evaluate the effects of HA degradation on the cytotoxic effect of anti-cancer therapies. A number of commonly used human colorectal cancer (CRC) cell lines were assessed for HA accumulation and tumor spheroid morphology: HCT 116, HT-29 parental, and HT-29/HAS3 (HT-29 cells engineered to over-express hyaluronan synthase 3). CRC 3D tumor spheroid models were developed to evaluate the uptake and cytotoxic activity of liposome-encapsulated doxorubicin (DOX) using the IncuCyte® S3 Live-Cell Analysis System. The effect of HA degradation on DOX uptake and cytotoxic activity was initially tested with rHuPH20 treatment in all three models, and further evaluated with PVHA treatment in HT-29 parental and HT-29/HAS3 models. A dose-dependent uptake and cytotoxic activity of DOX was observed in HCT 116 tumor spheroids. HA degradation after rHuPH20 treatment enhanced DOX uptake by an average of 6.1% (up to 7.7%) and cytotoxicity by an average of 37.9% (up to 58.2%) over the 5-day duration of the experiment compared with DOX alone. Dose-dependent uptake and cytotoxic activity of DOX in HT-29/HAS3 tumor spheroids were enhanced with rHuPH20 treatment to a greater extent than in HT-29 parental tumor spheroids. Specifically, rHuPH20 treatment led to an average increase in DOX uptake of 9.2% (up to 14.6%) with HT-29/HAS3 spheroids and 2.6% (up to 5.1%) with HT-29 parental spheroids. The addition of rHuPH20 resulted in an average increase in DOX cytotoxicity of 101% (up to 227.6%) with HT-29/HAS3 spheroids and 24.9% (up to 63.9%) with HT-29 parental spheroids. Enhanced uptake and cytotoxic activity of DOX was also observed with PVHA treatment in HT-29 and HT-29/HAS3 models. These data corroborate our previous findings with in vivo tumor models, in which the combination of PVHA-mediated HA degradation and other anti-cancer therapies display enhanced anti-tumor activity compared with either agent alone. Further, 3D tumor spheroid models may be used to evaluate the effect of extracellular matrix remodeling such as HA degradation and serve as a bridge between 2D cell-based assays and in vivo tumor models. Citation Format: Feng Gao, Susan Zimmerman, Kelly Chen, Daniel C. Maneval, Chunmei Zhao. The effect of hyaluronan degradation on the uptake and cytotoxic activity of liposome-encapsulated doxorubicin in 3D tumor spheroid models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 97.

Impact of hydrostatic pressure on phase-change contrast agent activation by pulsed ultrasound.

A phase-change contrast agent (PCCA) can be activated from a liquid (nanodroplet) state using pulsed ultrasound (US) energy to form a larger highly echogenic microbubble (MB). PCCA activation is dependent on the ambient pressure of the surrounding media, so any increase in hydrostatic pressure demands higher US energies to phase transition. In this paper, the authors explore this basic relationship as a potential direction for noninvasive pressure measurement and foundation of a unique technology the authors are developing termed tumor interstitial pressure estimation using ultrasound (TIPE-US). TIPE-US was developed using a programmable US research scanner. A custom scan sequence interleaved pulsed US transmissions for both PCCA activation and detection. An automated US pressure sweep was applied, and US images were acquired at each increment. Various hydrostatic pressures were applied to PCCA samples. Pressurized samples were imaged using the TIPE-US system. The activation threshold required to convert PCCA from the liquid to gaseous state was recorded for various US and PCCA conditions. Given the relationship between the hydrostatic pressure applied to the PCCA and US energy needed for activation, phase transition can be used as a surrogate of hydrostatic pressure. Consistent with theoretical predictions, the PCCA activation threshold was lowered with increasing sample temperature and by decreasing the frequency of US exposure, but it was not impacted by PCCA concentration.

730P - A pilot study of gemcitabine, nab-paclitaxel, PEGPH20 (PAG) and rivaroxaban for advanced pancreatic adenocarcinoma: Interim safety and efficacy analysis

Background: PEGPH20 (P) degrades hyaluronan (HA), a key component of pancreatic adenocarcinoma (PDAC) tumor microenvironment, leading to reduction of tumor interstitial pressure, decompression of tumor blood vessels and improvement in delivery of chemotherapeutics. A prior study of P with chemotherapy in PDAC (HALO-202) found an increased risk of thromboembolic (TE) events, 43%, effectively reduced with enoxaparin prophylaxis. Rivaroxaban (R) is a safe and effective oral anticoagulant for treating cancer-related TE. Methods: Patients considering frontline therapy for advanced PDAC and with KPS ≥ 70 were studied. 28 patients without prior TE (cohort 1) and 14/28 planned patients with prior TE (cohort 2) were enrolled. Patients received treatment with PAG (P; 3 µg/kg IV 2x/wk x 3 wks in C1, then 1x/wk x 3 wks in C2+, plus standard dose and schedule nab-paclitaxel and gemcitabine (AG)) every 28 days, with R (15 mg twice daily for 21 days, followed by 20 mg once daily). Primary endpoint is TE event rate. Secondary endpoints include PFS, OS, major bleeding rate and RR. Results: All 42 patients are evaluable for efficacy and safety. Key patient characteristics: median age = 61, M/F 22/20, stage III/IV 5/37. Median follow-up is 10.9 mo. One (2.4%) grade 4 TE event occurred. Two grade 3 GI hemorrhages occurred, both resolved with supportive measures. Best responses: complete response 2 (4.8%), partial response 19 (45.2%), stable disease 15 (35.7%), progressive disease 2 (4.8%), and overall disease control rate of 85.7%. Median PFS is 7.0 mo, mOS has not been reached. Safety and efficacy are similar across both cohorts (see Table).Table: 730PVariableCohort 1Cohort 2OverallSafetyn = 28n = 14n = 42TE Events1 (3.6%)0 (0%)1 (2.4%)Major Bleeding2 (7.1%)0 (0%)2 (4.8%)EfficacyComplete Response1 (3.6%)1 (7.1%)2 (4.8%)Partial Response14 (50.0%)5 (35.7%)19 (45.2%)Stable Disease8 (28.6%)7 (50.0%)15 (35.7%)Progressive Disease2 (7.1%)0 (0%)2 (4.8%)Not Evaluable3 (10.7%)1 (7.1%)4 (9.5%)PFS6.0 mo8.0 mo7.0 moOSNot ReachedNot ReachedNot Reached Open table in a new tab Conclusions: Interim analysis shows R is safe and effectively prevents TE events in patients receiving PAG. Responses and disease control rate are encouraging in this tumor HA-level unselected patient population. Updated safety and efficacy data will be reported. Clinical trial identification: NCT02921022. Legal entity responsible for the study: Memorial Sloan Kettering Cancer Center. Funding: Halozyme Therapeutics, Inc. Disclosure: All authors have declared no conflicts of interest.

Abstract 3704: Efficacy of DR5-targeted immunoliposomes in pancreatic cancer models primed with SMO inhibitors

Abstract Background: Pancreatic cancer (PaCA) is a deadly disease with 5-year survival of 6%. Poor prognosis is attributed to low tumor microvessel density, poor perfusion, and amplified stroma, constituting a drug delivery barrier. Tumor priming using NVP-LDE225, an inhibitor of sonic hedgehog (sHH) signaling, can compromise the stromal drug delivery barrier by mediating stromal thinning, and discharge of tumor interstitial pressure (IFP) and decompression of tumor vasculature, resulting in increased perfusion and deposition of drug-containing nanoparticles into tumors. However, convective fluid efflux may increase as interstitial tumor pressure declines during priming, increasing drug washout. We hypothesize that a targeting nanoparticle delivery system will increase drug retention during priming, thereby increasing efficacy. Approach: Patient-derived xenograft (PDX) PaCA tumors possessing varied stromal architecture and degrees of desmoplasia were implanted s.c. in SCID mice. They ranged from low- to high desmoplasia and varied in microvessel density. The sHH inhibitor (sHHI) NVP-LDE225 was administered p.o. for 10 days, and fluorescent 80nm sterically-stabilized liposomes (SSL) were administered at intervals to probe tumor vascular perfusion/permeability. Efficacy was investigated with SSL liposomes containing doxorubicin (SSL-DXR), optionally coupled covalently with Death Receptor 5 monoclonal antibody AMG655 (SSL-DXR-DR5), which binds the pro-apoptotic DR5 receptor and initiates the extrinsic apoptotic pathway. Results: Quantitative fluorescence microscopy showed that sHH inhibitor treatment mediated a temporal window of enhanced permeability/perfusion and deposition of SSL that varied with the amount of desmoplasia in PDX models, which are otherwise highly impermeant to SSL. Quantitative IFP measurements using the “wick and needle” technique showed reduction of IFP paralleled establishment of the priming window. In the absence of sHH inhibitor priming, SSL-DXR (2 mg/kg), SSL-DXR-DR5 (2 mg/kg of DXR), and free DR5 (dose-matched to SSL-DXR-DR5 protein) were administered to evaluate the effect of tumor priming on therapeutic efficacy. Any DR5-containing treatment was curative for MiaPaCA-2 tumors (high DR5 expression). The response of Panc-1 tumors (low DR5 expression) was greatest with SSL-DXR-DR5. Tumor responses with the PDX model #12424, (high DR5 expression) were greater in sHHI-treated animals compared to controls. SSL-DXR + free DR5 mediated a transient inhibition of tumor progression, whereas a durable inhibition of tumor progression was observed with SSL-DXR-DR5 immunoliposomes. Conclusions: Efficacy of SSL-DXR-DR5 immunoliposomes was superior to other treatments in two cell line-based tumors, and tumor response varied with DR5 receptor density. Efficacy in low permeability/perfusion PDX tumors was greatest following tumor priming by sHH inhibitors. Citation Format: Darren Chan, Charlene Minx, Jun Wang, Arindam Sen, Michael Johnston, Wen Wee Ma, Christopher J. Scott, Robert M. Straubinger. Efficacy of DR5-targeted immunoliposomes in pancreatic cancer models primed with SMO inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3704.

PO-263 Assessment of the accumulation of hyaluronan in the tumour microenvironment (TME) of solid tumours

IntroductionHyaluronan (HA), a primary component of the extracellular matrix, can accumulate in a variety of solid malignancies, where histological analyses of patient tumour tissues demonstrated that HA levels may correlate with patient outcomes. HA accumulation in the TME may be associated with poor prognosis. Preclinical studies demonstrated elevated TME HA levels increased tumour interstitial pressure, reduced tumour blood flow, and resulted in poor penetration of anticancer agents and immune cells. A PEGylated recombinant human hyaluronidase, pegvorhyaluronidase alfa (PEGPH20), depolymerizes HA, increases tumour vascular perfusion, and may increase access and anti-tumour efficacy of cytotoxic and immunotherapies.Material and methodsPegvorhyaluronidase alfa is being evaluated in clinical studies for pancreatic, breast, lung, cholangiocarcinoma, and gastric cancers. To broaden the spectrum of possible tumour types that may benefit from pegvyorhyaluronidase alfa, we assessed the prevalence and accumulation of HA in 3633 human histological samples in 22 solid tumour types. HA levels were measured using tissue microarrays (TMAs) stained with a proprietary HA probe, HTI–601, a recombinant immunoadhesin containing a modified HA–specific link domain from TNF-Stimulated Gene 6 protein (TSG–6) and the Fc portion of human IgG1. The resulting HA probe was biotinylated for use in an affinity-based histochemistry method. HA staining was evaluated with research-grade histological image analysis software. HA levels associated with distinct tumour compartments (stroma or tumour cells) were assessed. HA accumulation associated with immune infiltrates present in the TMA cores was also evaluated.Results and discussionsDistribution of HA accumulation across compartments fell into 4 main arrangements:- For desmoplastic tumour indications (pancreatic ductal adenocarcinoma, cholangiocarcinoma), the stroma was associated with high percentage of surface area stained with HTI-601 relative to the tumour cells;- Comparable distribution of HA staining in both tumour cells and stroma (gall bladder and glioblastoma);- Sub-clusters of HA staining within a specific tumour type (NSCLC non-squamous);- Distribution bias towards increased or decreased HA intensity staining (head and neck excluding nasopharyngeal cavities and renal cell carcinoma, respectively).ConclusionUnderstanding HA prevalence and accumulation in solid tumours may potentially identify malignancies that may benefit from pegvorhyaluronidase alfa therapy targeting HA.

Pilot study of gemcitabine, nab-paclitaxel, PEGPH20, and rivaroxaban for advanced pancreatic adenocarcinoma: An interim analysis.

405 Background: PEGPH20 (P) degrades hyaluronan (HA), a key component of pancreatic adenocarcinoma (PDAC) tumor microenvironment, leading to reduction of tumor interstitial pressure, decompression of tumor blood vessels and improvement in delivery of chemotherapeutics. A prior study of P with chemotherapy in PDAC (HALO-202) found an increased risk of thromboembolic (TE) events, 43%, effectively reduced with subcutaneous enoxaparin treatment. Rivaroxaban (R) is a safe and effective oral anticoagulant for treating cancer-related TE. Methods: 28 patients with advanced PDAC, KPS ≥ 70 and without prior TE were enrolled from January to June 2017. Patients received treatment with PAG (P; 3 µg/kg IV 2x/wk x 3 wks in C1, then 1x/wk x 3 wks in C2+, plus AG) every 28 days, with R (15 mg twice daily for 21 days, followed by 20 mg once daily). Primary endpoint is symptomatic TE event rate; secondary endpoints include PFS, OS, major bleeding rate and RR. Results: All 28 patients are evaluable for efficacy and safety. Key patient characteristics: age = 62 (range 45-76), M/F = 15/13, stage III/IV = 4/24, KPS 70/80/90 = 1/13/14. Median follow-up is 5.4 mo. No symptomatic and one grade 2, asymptomatic TE event (DVT) occurred (1/28 = 3.6%). Two grade 3 GI hemorrhages occurred. Best responses: partial response 11 (39%), stable disease 13 (46%), progressive disease 4 (14%), and overall disease control rate of 86%. Median PFS and OS have not been reached. Conclusions: Interim analysis shows R is safe and effectively prevents TE events in patients receiving PAG. Responses and disease control rate are encouraging in this tumor HA-level unselected patient population. Updated safety and efficacy data will be reported. Clinical trial information: NCT02921022.

Phase II study of olaratumab with paclitaxel/carboplatin (P/C) or P/C alone in previously untreated advanced NSCLC

BackgroundIn non-small cell lung cancer (NSCLC), platelet-derived growth factor receptor (PDGFR) mediates angiogenesis, tissue invasion, and tumor interstitial pressure. Olaratumab (IMC-3G3) is a fully human anti-PDGFRα monoclonal antibody. This Phase II study assessed safety and efficacy of olaratumab+paclitaxel/carboplatin (P/C) versus P/C alone for previously untreated advanced NSCLC. Materials and methodsPatients received up to six 21-day cycles of P 200mg/m2 and C AUC 6 (day 1)±olaratumab 15mg/kg (days 1 and 8). Primary endpoint was PFS. Olaratumab was continued in the olaratumab+P/C arm until disease progression. Results131 patients were: 67 with olaratumab+P/C and 64 with P/C; 74% had nonsquamous NSCLC. Median PFS was similar between olaratumab+P/C and P/C (4.4 months each) (HR 1.29; 95% CI [0.86–1.93]; p=0.21). Median OS was similar between olaratumab+P/C (11.8 months) and P/C (11.5 months) (HR 1.04; 95% CI [0.68–1.57]; p=0.87). Both arms had similar toxicity profiles. All evaluable cases were PDGFR-negative by immunohistochemistry. Tumor stroma PDGFR expression was evaluable in 23/131 patients, of which 78% were positive. ConclusionsThe addition of olaratumab to P/C did not result in significant prolongation of PFS or OS in advanced NSCLC. Olaratumab studies in other patient populations, including soft tissue sarcoma (NCT02783599), pancreatic cancer (NCT03086369), and pediatric malignancies (NCT02677116) are underway.

Abstract OT2-02-02: A randomized, open-label, multicenter, phase 1b/2 study of eribulin mesylate in combination with PEGylated recombinant human hyaluronidase in patients with human epidermal growth factor receptor 2-negative, high-hyaluronan metastatic breast cancer

Abstract Eribulin (ERI), a non-taxane microtubule inhibitor, is approved for treatment in patients (pts) with advanced or metastatic breast cancer (MBC) who have received ≥1 (European Union) or ≥2 (United States) prior chemotherapy regimens for metastatic disease, including an anthracycline and taxane in either the adjuvant or metastatic setting. In a phase 2 study, ERI has demonstrated single-agent activity in first line treatment of pts with human epidermal growth factor receptor 2-negative (HER2−) MBC. Hyaluronan (HA) is a major component of the tumor microenvironment, specifically within the stroma, and high levels of HA are associated with disease progression. In HA-High, triple-negative breast cancer (TNBC) xenografts, the anti-tumor effect of ERI was enhanced by addition of PEGylated recombinant human hyaluronidase (PEGPH20). PEGPH20 is an engineered enzyme under investigation for use in combination with anticancer therapies in pts with tumors that accumulate HA. PEGPH20 acts by temporarily degrading HA to reduce tumor interstitial pressure and decompress blood vessels, thus increasing access of anticancer agents and immune cells to tumor sites. This randomized, open-label, multicenter, study of ERI in combination with PEGPH20 vs ERI alone was designed to evaluate safety and tolerability and efficacy in pts with HER2−, HA-High, MBC previously treated with 0–1 systemic (cytotoxic or targeted) anticancer therapy. The trial was activated in June 2016 and will enroll approximately 96 pts (aged ≥18 yrs; n=6–18 in phase 1b; n=84 randomized to obtain 80 evaluable pts in phase 2).Pts with measurable disease of ≥1 lesion ≥10 mm in long-axis diameter (nonlymph nodes) or ≥15 mm in short-axis diameter (lymph nodes) with ECOG PS of 0 or 1 will be included. Pts will be excluded for having had adjuvant chemotherapy within the past 6 months, hormonal/biological therapy within the past 3 wks, or radiation or small molecule targeted therapy within the past 2 wks. Pts will also be excluded if they were previously treated with ERI or any hyaluronidase agent. Phase 1b includes at least 1 initial safety run-in cohort in which 6 pts (any HA level) will receive PEGPH20 3 μg/kg intravenous (IV) on days −1 and 7 of a 21-day cycle, each dose followed approximately 24 (±4) hours later with ERI 1.4 mg/m2 IV on days 1 and 8. Dose-limiting toxicity (DLT) will be assessed in the first cycle.The primary endpoint in phase 1b is the recommended phase 2 dose (RP2D) of the ERI and PEGPH20 combination, defined as the maximum dose at which ≤1 pt experiences a DLT.Alternatively, modified dose levels will be evaluated in additional cohorts. In phase 2, HA-High pts will be stratified by TNBC vs other HER2− status and randomized to receive RP2D combination treatment or ERI alone. Pts with clinical benefit will remain on ERI or both study drugs until unacceptable toxicity or disease progression. The primary endpoint in phase 2 is objective response rate. Secondary endpoints include progression-free survival and overall survival. Exploratory endpoints include clinical benefit rate, disease control rate, and duration of response. Citation Format: Alvarez RH, Savulsky C, Almonte A, Xing D, Lokker N, Chondros D. A randomized, open-label, multicenter, phase 1b/2 study of eribulin mesylate in combination with PEGylated recombinant human hyaluronidase in patients with human epidermal growth factor receptor 2-negative, high-hyaluronan metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-02-02.