Improvement of intratumor microdistribution of PEGylated liposome via tumor priming by metronomic S-1 dosing

Using imaging modalities to predict nanoparticle distribution and treatment efficacy in solid tumors: The growing role of ultrasound

Nanomedicine in oncology has not had the success in clinical impact that was anticipated in the early stages of the field's development. Ideally, nanomedicines selectively accumulate in tumor tissue and reduce systemic side effects compared to traditional chemotherapeutics. However, this has been more successful in preclinical animal models than in humans. The causes of this failure to translate may be related to the intra- and inter-patient heterogeneity of the tumor microenvironment. Predicting whether a patient will respond positively to treatment prior to its initiation, through evaluation of characteristics like nanoparticle extravasation and retention potential in the tumor, may be a way to improve nanomedicine success rate. While there are many potential strategies to accomplish this, prediction and patient stratification via noninvasive medical imaging may be the most efficient and specific strategy. There have been some preclinical and clinical advances in this area using MRI, CT, PET, and other modalities. An alternative approach that has not been studied as extensively is biomedical ultrasound, including techniques such as multiparametric contrast-enhanced ultrasound (mpCEUS), doppler, elastography, and super-resolution processing. Ultrasound is safe, inexpensive, noninvasive, and capable of imaging the entire tumor with high temporal and spatial resolution. In this work, we summarize the in vivo imaging tools that have been used to predict nanoparticle distribution and treatment efficacy in oncology. We emphasize ultrasound imaging and the recent developments in the field concerning CEUS. The successful implementation of an imaging strategy for prediction of nanoparticle accumulation in tumors could lead to increased clinical translation of nanomedicines, and subsequently, improved patient outcomes. This article is categorized under: Diagnostic Tools In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery Emerging Technologies.

Pre-treatment of oncolytic reovirus improves tumor accumulation and intratumoral distribution of PEG-liposomes

PEGylated liposomes (PEG-liposomes) are a promising drug delivery vehicle for tumor targeting because of their efficient tumor disposition profiles via the enhanced permeability and retention (EPR) effect. However, tumor targeting of PEG-liposomes, particularly their delivery inside the tumors, is often disturbed by physical barriers in the tumor, including tumor cells themselves, extracellular matrices, and interstitial pressures. In this study, B16 melanoma tumor-bearing mice were injected intravenously with oncolytic reovirus before administration of PEG-liposomes to enhance PEG-liposomes' tumor disposition. Three days after reovirus administration, significant expression of reovirus sigma 3 protein, elevation of apoptosis-related gene expression, and activation of caspase 3 in the tumors were found. Apoptotic cells were found inside the tumors. These data indicated that reovirus efficiently replicated in the tumors and induced apoptosis of tumor cells. The tumor disposition levels of PEG-liposomes were approximately doubled by reovirus pre-administration, compared with a PBS-pretreated group. PEG-liposomes were widely distributed in the tumors of reovirus-pretreated mice, whereas in the PBS-pretreated group, PEG-liposomes were found mainly around or inside the blood vessels in the tumors. Pre-treatment with reovirus also improved the tumor accumulation of PEG-liposomes in human pancreatic BxPC-3 tumors. 3D imaging analysis of whole BxPC-3 tumors demonstrated that pretreatment with reovirus led to the enhancement of PEG-liposome accumulation inside the tumors. Combination treatment with reovirus and paclitaxel-loaded PEG-liposomes (PTX-PEG-liposomes) significantly suppressed B16 tumor growth. These results provide important information for clinical use of combination therapy of reovirus and nanoparticle-based drug delivery system (DDS).

Research on the synthesis of nanoparticles of betulinic acid and their targeting antitumor activity

Betulinic acid (BA), a natural pentacyclic lupine-type triterpene, has shown its prominent efficiency on the selective antitumor activity. However, its poor water solubility and bioavailability have limited its application. Herein, targeting nanoparticles were prepared to improve BA-based liposome (BL)'s restricted chemotherapeutic efficacy. Multi-layers membranes from the cancer cells were added as highly penetrative targeting ligands to functionalize the BA-based liposomes. In vitro experiments including the MTT assay and the fluorescence imaging of live/dead staining were adopted to prove its great inhibition in the growth of tumor cells. And it manifests that the antitumor efficacy of BL coated with cell membranes (BLCM) achieves nearly 4.3 times as that of BL under the same conditions in the MTT experiments. In addition, the fluorescence imaging stained with DAPI-FITC was applied to prove the targeting positioning effects on the BLCM. In a nutshell, the nanomedicine has good targeting antitumor efficacy and has great potential in being applied for the personalized cancer clinical treatment.

Factors affecting the dynamics and heterogeneity of the EPR effect: pathophysiological and pathoanatomic features, drug formulations and physicochemical factors

INTRODUCTION

The enhanced permeability and retention (EPR) effect serves as the foundation of anticancer nanomedicine design. EPR effect-based drug delivery is an effective strategy for most solid tumors. However, the degree of efficacy depends on the pathophysiological conditions of tumors, drug formulations, and other factors.

AREAS COVERED

Vascular mediators including nitric oxide, bradykinin , and prostaglandins are vital for facilitating and maintaining EPR effect dynamics. Progression to large, advanced cancers may induce activated blood coagulation cascades, which lead to thrombus formation in tumor vasculature. Rapidly growing tumors cause obstructed or suppressed blood flow in tumor vasculature related to embolism or occluded blood vessels. The resulting limited tumor blood flow leads to less drug delivered to tumors, i.e. no or poor EPR effect. High stromal content also suppresses vascular permeability and drug diffusion. Restoring obstructed tumor blood flow and improving tumor vascular permeability via vascular mediators will improve drug delivery and the EPR effect. Physicochemical features of nanomedicines also influence therapeutic outcomes and are vital for the EPR effect.

EXPERT OPINION

The tumor microenvironment, especially tumor blood flow, is critical for a potent EPR effect. A rational strategy for circumventing EPR effect barriers must include restoring tumor blood flow.

Chondroitin sulfate modified and adriamycin preloaded hybrid nanoparticles for tumor-targeted chemotherapy of lung cancer

Promising cancer treatment requires the assistant of drug delivery systems (DDS) with the aim to increase the accumulation of drugs in tumor tissue. Herein, a hybrid DDS was successfully developed to integrate chondroitin sulfate (CS) and calcium carbonate (CC) in to one system. Anticancer drug adriamycin (Adr) was preloaded into CC nanoparticles to obtain Adr-loaded CC nanoparticles (CC/Adr). The resulted CS-CC/Adr nanoparticles as a biocompatible DDS was able to specifically target cancer cells to enhance the chemotherapy of lung cancer due to the surface modification of CS. Intracellular uptake as well as in vivo imaging results revealed the obtained CS-CC/Adr nanoparticles (size of ~100 nm) showed CS mediated tumor specific accumulation into A549 and LLC cells than unmodified CC/Adr, in which the CD44 receptor might be involved, which finally resulted in stronger anticancer capability than Adr or CC/Adr. As a result, CS-CC/Adr nanoparticles could be further extended to clinical administration in our future works.

Multi-targeted approach by 2-benzimidazolylquinoxalines-loaded cationic arginine liposomes against сervical cancer cells in vitro

Multi-targeted approaches for inhibition of сervical cancer cells in vitro were developed by implementing two different strategies and drug combination for creation of new therapeutic target agents and for nanotechnological-enhancement of intracellular delivery. New 2-benzimidazolylquinoxalines derivatives were synthesized and characterized by combining two different pharmacophores - benzimidazole and quinoxaline rings directly bonded in their structures. Spectrophotometric technique for determination of content of compounds in various media was developed to evaluate their solubility in water and micellar solutions of surfactants. The bioavailability of poorly water-soluble 2-benzimidazolylquinoxalines was improved by PEGylated liposomes as antitumor drug delivery carriers. 2-benzimidazolylquinoxalines-loaded PEGylated liposomes, with size close to 100 nm and negative zeta potential ranging from -13 mV to -27 mV, were time-stable at room temperature. The design of liposomal formulations for improving cellular uptake and in vitro antitumor efficacy was performed by modification of liposome surface with the new arginine surfactant. The cell viability of 2-benzimidazolylquinoxalines-loaded arginine liposomes on human cancer M-Hela cells was 16% at the concentration 0.15 mg/ml. Moreover, these liposomes showed a lower toxicity (40%) against normal human Gang liver cells both at the lowest and highest tested concentrations.

Imaging of Nanoparticle Distribution to Assess Treatments That Alter Delivery

Molecular imaging is a vital tool to non-invasively measure nanoparticle delivery to solid tumors. Despite the myriad of nanoparticles studied for cancer, successful applications of nanoparticles in humans is limited by inconsistent and ineffective delivery. Successful nanoparticle delivery in preclinical models is often attributed to enhanced permeability and retention (EPR)-a set of conditions that is heterogeneous and transient in patients. Thus, researchers are evaluating therapeutic strategies to modify nanoparticle delivery, particularly treatments which have demonstrated effects on EPR conditions. Imaging nanoparticle distribution provides a means to measure the effects of therapeutic intervention on nanoparticle delivery to solid tumors. This review focuses on the utility of imaging to measure treatment-induced changes in nanoparticle delivery to tumors and provides preclinical examples studying a broad range of therapeutic interventions.

Transport of drugs from blood vessels to tumour tissue

The effectiveness of anticancer drugs in treating a solid tumour is dependent on delivery of the drug to virtually all cancer cells in the tumour. The distribution of drug in tumour tissue depends on the plasma pharmacokinetics, the structure and function of the tumour vasculature and the transport properties of the drug as it moves through microvessel walls and in the extravascular tissue. The aim of this Review is to provide a broad, balanced perspective on the current understanding of drug transport to tumour cells and on the progress in developing methods to enhance drug delivery. First, the fundamental processes of solute transport in blood and tissue by convection and diffusion are reviewed, including the dependence of penetration distance from vessels into tissue on solute binding or uptake in tissue. The effects of the abnormal characteristics of tumour vasculature and extravascular tissue on these transport properties are then discussed. Finally, methods for overcoming limitations in drug transport and thereby achieving improved therapeutic results are surveyed.

Overcoming obstacles in the tumor microenvironment: Recent advancements in nanoparticle delivery for cancer theranostics

Despite rapid advancements in the field of nanotechnology, there is mounting frustration in the scientific community regarding the translational impact of nanomedicine. Modest therapeutic performance of FDA-approved nanomedicines combined with multiple disappointing clinical trials (such as phase III HEAT trial) have raised questions about the future of nanomedicine. Encouraging breakthroughs, however, have been made in the last few years towards the development of new classes of nanoparticles that can respond to tumor microenvironmental conditions and successfully deliver therapeutic agents to cancer cells. Concurrently, a great deal of effort has also been devoted to alter various parameters of tumor pathophysiology to pre-treat tumors before nanoparticles are administered. Such 'priming' treatments improve access of the systemically administered agents to the tumor and promote drug penetration into the deeper layers of tumor tissue. This review will highlight recent advances in cancer nanomedicine exploiting both nanoparticle design and tumor microenvironment modification; and provide a critical perspective on the future development of nanomedicine delivery in oncology.