New Generation Nanomedicines Constructed from Self-Assembling Small-Molecule Prodrugs Alleviate Cancer Drug Toxicity

Self-assembling a natural small molecular inhibitor that shows aggregation-induced emission and potentiates antitumor efficacy

Targeted therapy using small molecular inhibitors has been developed to rewire key signaling pathways in tumor cells, but these inhibitors have had mixed success in the clinic due to their poor pharmaceutical properties and suboptimal intratumoral concentrations. Here, we developed a "self-assembling natural molecular inhibitor" strategy to test the efficacy and feasibility of the water-insoluble agent dasatinib (DAS), a tyrosine kinase inhibitor, for cancer therapy. By exploiting a facile reprecipitation protocol, the DAS inhibitor self-assembled into soluble supramolecular nanoparticles (termed sDNPs) in aqueous solution, without an exogenous excipient. This strategy is applicable for generating systemically injectable and colloid-stable therapeutic nanoparticles of hydrophobic small-molecule inhibitors. Concurrently, during this process, we observed aggregation-induced emission (AIE) of fluorescence for this self-assembled DAS, which makes sDNPs suitable for bioimaging and tracing of cellular trafficking. Notably, in an orthotopic model of breast cancer, administration of sDNPs induced a durable inhibition of primary tumors and reduced the metastatic tumor burden, significantly surpassing the effects of the free DAS inhibitor after oral delivery. In addition, low toxicity was observed for this platform, with effective avoidance of immunotoxicity. To the best of our knowledge, our studies provide the first successful demonstration of self-assembling natural molecular inhibitors with AIE and highlight the feasibility of this approach for the preparation of therapeutic nanoparticles for highly lethal human cancers and many other diseases.

Engineering Prodrug Nanomedicine for Cancer Immunotherapy

Immunotherapy has shifted the clinical paradigm of cancer management. However, despite promising initial progress, immunotherapeutic approaches to cancer still suffer from relatively low response rates and the possibility of severe side effects, likely due to the low inherent immunogenicity of tumor cells, the immunosuppressive tumor microenvironment, and significant inter- and intratumoral heterogeneity. Recently, nanoformulations of prodrugs have been explored as a means to enhance cancer immunotherapy by simultaneously eliciting antitumor immune responses and reversing local immunosuppression. Prodrug nanomedicines, which integrate engineering advances in chemistry, oncoimmunology, and material science, are rationally designed through chemically modifying small molecule drugs, peptides, or antibodies to yield increased bioavailability and spatiotemporal control of drug release and activation at the target sites. Such strategies can help reduce adverse effects and enable codelivery of multiple immune modulators to yield synergistic cancer immunotherapy. In this review article, recent advances and translational challenges facing prodrug nanomedicines for cancer immunotherapy are overviewed. Last, key considerations are outlined for future efforts to advance prodrug nanomedicines aimed to improve antitumor immune responses and combat immune tolerogenic microenvironments.

Salinomycin-Loaded Small-Molecule Nanoprodrugs Enhance Anticancer Activity in Hepatocellular Carcinoma

Background

There is currently no effective treatment for advanced hepatocellular carcinoma (HCC), and chemotherapy has little effect on long-term survival of HCC patients, largely due to the cancer stem cell (CSC) chemoresistance of HCC.

Methods

We constructed a small-molecule nanometer-sized prodrug (nanoprodrug) loaded with salinomycin (SAL) for the treatment of HCC. SAL was encapsulated by the prodrug LA-SN38 (linoleic acid modified 7-ethyl-10-hydroxycamptothecin) to construct a self-assembled nanoprodrug further PEGylated with DSPE-PEG₂₀₀₀. We characterized this codelivered nanoprodrug and its antitumor activity both in vitro in human HCC cell lines and in vivo in mice.

Results

Delivery of the SAL- and LA-SN38-based nanoprodrugs effectively promoted apoptosis of HCC cells, exerted inhibition of HCC tumor-sphere formation as well as HCC cell motility and invasion, and reduced the proportion of CD133+ HCC-CSC cells. In nude mice, the nanoprodrug suppressed growth of tumor xenografts derived from human cell lines and patient.

Conclusion

Our results show that SAL-based nanoprodrugs are a promising platform for treating patients with HCC and a novel strategy for combination therapy of cancers.

Dimerization-induced self-assembly of a redox-responsive prodrug into nanoparticles for improved therapeutic index

Although some formats of nanomedicines are now available for clinical use, the translation of new nanoparticles to the clinic remains a considerable challenge. Here, we describe a simple yet cost-effective strategy that converts a toxic drug, cabazitaxel, into a safe and effective nanomedicine. The strategy involves the ligation of drug molecules via a self-immolating spacer, followed by dimerization-induced self-assembly to assemble stable nanoparticles. Self-assembled cabazitaxel dimers could be further refined by PEGylation with amphiphilic polymers suitable for preclinical studies. This protocol enables the formation of systemically injectable nanoparticles (termed SNPs) with nearly quantitative entrapment efficiencies and exceptionally high drug loading (> 86%). In healthy mice, PEGylated SNPs show a favorable safety profile, with reduced systemic toxicity and negligible immunotoxicity. In two separate mouse xenograft models of cancer, administration of SNPs produces efficient antitumor activity with durable tumor suppression during therapeutic studies. Overall, this methodology opens up a practical and expedient route for the fabrication of clinically useful nanomedicines, transforming a hydrophobic and highly toxic drug into a systemic self-deliverable nanotherapy. STATEMENT OF SIGNIFICANCE: Despite the great progress in cancer nanomedicines, clinical translation of nanomedicines still remains a considerable challenge. In this study, we designed a self-assembling nanoplatform based on cabazitaxel dimer reversibly ligated via a bioactivatable linker. This approach enabled the generation of systemically injectable nanomedicines with quantitative entrapment efficiencies and exceptionally high drug loading (> 86%), which greatly obviates concerns about excipient-associated side effects. Self-assembled dimeric cabazitaxel exhibited a higher safety profile than free cabazitaxel and negligible immunotoxicity in animals. This is a practical and expedient example how the chemical ligation of a hydrophobic and highly toxic anticancer drug can be leveraged to create a self-assembling delivery nanotherapy which preserves inherent pharmacologic efficacy while reduces in vivo systemic and immune toxicity.

Photosensitizer-stabilized self-assembling nanoparticles potentiate chemo/photodynamic efficacy of patient-derived melanoma

Development of injectable nanoparticles for delivery of active anticancer compounds often requires complicated schemes that involve tedious synthetic protocols and nanoformulations. In particular, clinical translation of synergistic nanoparticles that can facilitate multimodal therapies remains a considerable challenge. Herein, we describe a self-assembling, small-molecule nanosystem with unique properties, including near-infrared (NIR) light-responsive drug activation, size transformability, combinatorial synergy, and substantially reduced toxicity. Ligation of anticancer cabazitaxel (CTX) drugs via a reactive oxygen species-activatable thioketal linkage generates a dimeric TKdC prodrug, and subsequent coassembly with a photosensitizer, chlorin e6 (Ce6), forms colloidal-stable nanoassemblies (termed psTKdC NAs). Upon NIR laser irradiation, psTKdC NAs are transformed into smaller size particles and facilitate production of pharmacologically active CTX. Importantly, reactive oxygen species yielded by coassembled Ce6 can synergize with chemotherapy to achieve potent combinatorial effects. In a preclinical orthotopic model of an aggressive, human melanoma patient-derived xenograft (PDX), we show that administration of psTKdC NAs followed by laser irradiation produced durable tumor regression, with the tumors being completely eradicated in three of six PDXs. Furthermore, low systemic toxicity of this smart, photo-activatable nanotherapy was observed in animals. The new self-deliverable combinatorial system addresses essential requirements for high efficacy, safety, and translational capacity and deserves further investigation.

Improved antitumor activity and tolerability of cabazitaxel derived remote-loading liposomes

The value of the clinical application of chemotherapeutic drugs is dependent on both systemic toxicity and treatment efficacy. Dose intensification and high tolerability suggest the potential for clinical cancer therapy. In this study, we developed a novel strategy for reconstructing a drug molecule into remote-loading liposomes. Two weak-base cabazitaxel derivatives were synthesized, and named CN and CN2. CN exhibited higher cytotoxic effects compared to CN2, and was selected for further study. CN was remotely loaded into nano-size liposomes (CN-LPs) via an ammonium sulfate gradient with high loading and encapsulation efficiency. When compared to the commercial formulation of cabazitaxel, JEVTANA®, CN-LPs showed less systemic toxicity and enhanced tolerability, with at least a 24-fold increase in the tolerated dose. Furthermore, CN-LPs significantly inhibited tumor growth in mice bearing 4T1 and RM-1 xenograft tumors. After intravenous injection, CN-LPs exhibited an extremely high drug concentration in blood, with a 757-fold increase in the area under the curve (AUC). Moreover, 48 h after a single intravenous injection, CN-LPs promoted higher drug accumulation in tumors compared to JEVTANA®. In summary, our liposome delivery system exhibits favorable pharmacologic efficacy and an improved safety profile.

Recent advances of sorafenib nanoformulations for cancer therapy: Smart nanosystem and combination therapy

Sorafenib, a molecular targeted multi-kinase inhibitor, has received considerable interests in recent years due to its significant profiles of efficacy in cancer therapy. However, poor pharmacokinetic properties such as limited water solubility, rapid elimination and metabolism lead to low bioavailability, restricting its further clinical application. Over the past decade, with substantial progress achieved in the development of nanotechnology, various types of smart sorafenib nanoformulations have been developed to improve the targetability as well as the bioavailability of sorafenib. In this review, we summarize various aspects from the preparation and characterization to the evaluation of antitumor efficacy of numerous stimuli-responsive sorafenib nanodelivery systems, particularly with emphasis on their mechanism of drug release and tumor microenvironment response. In addition, this review makes great effort to summarize the nanosystem-based combination therapy of sorafenib with other antitumor agents, which can provide detailed information for further synergistic cancer therapy. In the final section of this review, we also provide a detailed discussion of future challenges and prospects of designing and developing ideal sorafenib nanoformulations for clinical cancer therapy.

Kinetic stability-driven cytotoxicity of small-molecule prodrug nanoassemblies

Nanoassemblies (NAs) of small-molecule lipophilic prodrugs have been widely investigated for efficient drug delivery in cancer therapy, but their kinetic stability has not attracted sufficient attention in the past studies. Herein, we reported that kinetic stability has a great influence on the drug release from the NAs of lipophilic prodrugs in physiologically relevant media. Based on the co-assembled FRET nanosystems of two lipophilic fluorescent prodrugs, we demonstrated that NAs constructed by lipophilic prodrugs containing shorter alkyl chains or those with higher unsaturated degrees displayed poorer kinetic stability, which further resulted in remarkably faster drug release in mouse plasma and various tissue homogenates. More importantly, these kinetically unstable NAs also induced rapid intracellular drug release, resulting in much more potent cytotoxicity. These findings highlight the crucial role of kinetic stability in determining the drug release from the NAs of lipophilic prodrugs, which would effectively guide their rational designs for cancer therapy.

Nanotechnology for COVID-19: Therapeutics and Vaccine Research

The current global health threat by the novel coronavirus disease 2019 (COVID-19) requires an urgent deployment of advanced therapeutic options available. The role of nanotechnology is highly relevant to counter this "virus" nano enemy. Nano intervention is discussed in terms of designing effective nanocarriers to counter the conventional limitations of antiviral and biological therapeutics. This strategy directs the safe and effective delivery of available therapeutic options using engineered nanocarriers, blocking the initial interactions of viral spike glycoprotein with host cell surface receptors, and disruption of virion construction. Controlling and eliminating the spread and reoccurrence of this pandemic demands a safe and effective vaccine strategy. Nanocarriers have potential to design risk-free and effective immunization strategies for severe acute respiratory syndrome coronavirus 2 vaccine candidates such as protein constructs and nucleic acids. We discuss recent as well as ongoing nanotechnology-based therapeutic and prophylactic strategies to fight against this pandemic, outlining the key areas for nanoscientists to step in.

Emerging insights on drug delivery by fatty acid mediated synthesis of lipophilic prodrugs as novel nanomedicines

Many drug molecules that are currently in the market suffer from short half-life, poor absorption, low specificity, rapid degradation, and resistance development. The design and development of lipophilic prodrugs can provide numerous benefits to overcome these challenges. Fatty acids (FAs), which are lipophilic biomolecules constituted of essential components of the living cells, carry out many necessary functions required for the development of efficient prodrugs. Chemical conjugation of FAs to drug molecules may change their pharmacodynamics/pharmacokinetics in vivo and even their toxicity profile. Well-designed FA-based prodrugs can also present other benefits, such as improved oral bioavailability, promoted tumor targeting efficiency, controlled drug release, and enhanced cellular penetration, leading to improved therapeutic efficacy. In this review, we discuss diverse drug molecules conjugated to various unsaturated FAs. Furthermore, various drug-FA conjugates loaded into various nanostructure delivery systems, including liposomes, solid lipid nanoparticles, emulsions, nano-assemblies, micelles, and polymeric nanoparticles, are reviewed. The present review aims to inspire readers to explore new avenues in prodrug design based on the various FAs with or without nanostructured delivery systems.

Co-delivery of IKBKE siRNA and cabazitaxel by hybrid nanocomplex inhibits invasiveness and growth of triple-negative breast cancer

IKBKE is an oncogene in triple-negative breast cancer (TNBC), and we demonstrate that IKBKE small interfering RNA (siRNA) inhibits the proliferation, migration, and invasion of TNBC cells. Despite the recent success of siRNA therapeutics targeting to the liver, there still remains a great challenge to deliver siRNAs to solid tumors. Here, we report a hybrid nanocomplex to co-deliver the IKBKE siRNA and cabazitaxel to TNBC to achieve an optimal antitumor effect. The nanocomplex is modified with hyaluronic acid to target CD44 on TNBC cells. The nanocomplex shows higher cellular uptake and better tumor penetration of the encapsulated cargos. The nanocomplex also exhibits high tumor accumulation and antitumor activity in an orthotopic TNBC mouse model. Encapsulation of cabazitaxel in the nanocomplex enhances the activity of the IKBKE siRNA. The hybrid nanocomplex provides a novel and versatile platform for combination therapies using siRNAs and chemotherapy.

A novel oncolytic adenovirus inhibits hepatocellular carcinoma growth

OBJECTIVE

To evaluate the inhibitory role of a novel oncolytic adenovirus (OA), GP73-SphK1sR-Ad5, on the growth of hepatocellular carcinoma (HCC).

METHODS

GP73-SphK1sR-Ad5 was constructed by integrating Golgi protein 73 (GP73) promoter and sphingosine kinase 1 (SphK1)-short hairpin RNA (shRNA) into adenovirus serotype 5 (Ad5), and transfecting into HCC Huh7 cells and normal human liver HL-7702 cells. The expression of SphK1 and adenovirus early region 1 (E1A) was detected by quantitative real-time PCR (qRT-PCR) and western blot, respectively. Cell viability was detected by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay, and apoptotic rate was determined by flow cytometry. An Huh7 xenograft model was established in mice injected intratumorally with GP73-SphK1sR-Ad5. Twenty days after injection, the tumor volume and weight, and the survival time of the mice were recorded. The histopathological changes in tumor tissues were observed by hematoxylin-eosin (HE) staining and transmission electron microscopy (TEM).

RESULTS

Transfection of GP73-SphK1sR-Ad5 significantly upregulated E1A and downregulated SphK1 in Huh7 cells, but not in HL7702 cells. GP73-SphK1sR-Ad5 transfection significantly decreased the viability and increased the apoptotic rate of Huh7 cells, but had no effect on HL7702 cells. Intratumoral injection of GP73-SphK1sR-Ad5 into the Huh7 xenograft mouse model significantly decreased tumor volume and weight, and prolonged survival time. It also significantly decreased the tumor infiltration area and blood vessel density, and increased the percentages of cells with nucleus deformation and cells with condensed chromatin in tumor tissues.

CONCLUSIONS

GP73-SphK1sR-Ad5 serves as a novel OA and can inhibit HCC progression with high specificity and efficacy.

Transforming a toxic drug into an efficacious nanomedicine using a lipoprodrug strategy for the treatment of patient-derived melanoma xenografts

Despite the progress made with the recent clinical use of the anticancer compound cabazitaxel, the efficacy in patients remains unsatisfactory, largely due to the high in vivo toxicity of the agent. Therefore, strategies that achieve favorable outcomes and good safety profiles will greatly expand the repertoire of this potent agent. Here, we propose a combinatorial strategy to reform the cabazitaxel agent and the use of sequential supramolecular nanoassembly with liposomal compositions to assemble a prodrug-formulated liposome, termed lipoprodrug, for safe and effective drug delivery. Reconstructing cabazitaxel with a polyunsaturated fatty acid (i.e., docosahexaenoic acid) via a hydrolyzable ester bond confers the generated prodrug with the ability to be readily integrated into the lipid bilayer of liposomes for systemic administration. The resulting lipoprodrug scaffold showed significantly sustained drug release profiles and improved pharmacokinetics in rats as well as a reduction in systemic toxicity in vivo. Notably, the lipoprodrug outperformed free cabazitaxel in terms of in vivo therapeutic efficacy in multiple separate tumor xenograft-bearing mouse models, one of which was a patient-derived xenograft model. Surprisingly, the lipoprodrug was able to reduce tumor invasiveness and reprogram the tumor immunosuppressive microenvironment by proinflammatory macrophage polarization. Our findings validate this lipoprodrug approach as a simple yet effective strategy for transforming the highly toxic cabazitaxel agent into an efficacious nanomedicine with excellent in vivo tolerability. This approach could also be applied to rescue other drugs or drug candidates that have failed in clinical trials due to poor pharmacokinetic properties or unacceptable toxicity in patients.

Enhanced in vitro antitumor efficacy of a polyunsaturated fatty acid-conjugated pH-responsive self-assembled ion-pairing liposome-encapsulated prodrug

The development of clinical chemotherapeutics is always challenging due to the toxicity and side effects of drugs not only for tumor cells but also for normal cells. Therefore, nano-drug delivery systems and prodrug strategies have been applied to address this challenge. Herein, we report a liposome-encapsulated small-molecule prodrug nanosystem, self-assembled by doxorubicin (DOX) and mixed polyunsaturated fatty acid (MPUFA) ion-pairing (MPUFAs-DOX@Liposomes), which has a high omega-3 PUFA content. The increased lipophilicity of ion-paired MPUFAs-DOX can significantly improve the drug loading efficiency (∼97%). Electrostatic interaction, the hydrophobic effect and hydrogen bonding between the ion-pairing agents led to superior pH-responsive release of DOX from liposomes over DOX-loaded liposomes (DOX@Liposomes), with a more rapid release rate at pH 5.0 than at pH 7.4, which is beneficial for decreasing the toxicity of DOX under physiological conditions. Finally, the in vitro antitumor effects were investigated for two tumor cell types, A549 and MCF-7, and the results demonstrated that MPUFAs-DOX@Liposomes showed the highest cytotoxicity compared with free DOX and DOX@Liposomes because of the ready uptake under the effect of PUFAs. Hence, liposomes loaded with ion-paired MPUFAs-DOX is a promising formulation for combination cancer therapy.

pH-sensitive small molecule nanodrug self-assembled from amphiphilic vitamin B6-E analogue conjugate for targeted synergistic cancer therapy

To promote the targeted cancer therapy, the pH-sensitive small molecule nanodrug self-assembled from amphiphilic vitamin B6-E analogue conjugate was successfully constructed. Herein, water-soluble vitamin B6 with pKa (5.6) was chemically conjugated to lipid-soluble vitamin E succinate (α-TOS), which showed selective cancer cell killing ability and this amphiphilic small molecule vitamin conjugate could self-assemble to be free nanoparticles (NPs) and doxorubicin-loaded NPs (α-TOS-B6-NPs-DOX). The small molecule nanodrugs could perform the following characteristic: (i) stability in the sodium dodecyl sulfonate (SDS) solution and long-term storage stability in PBS via surface negative charge; (ii) tumor accumulation by enhanced penetration and retention (EPR) effect; (iii) improved cellular internalization by means of vitamin B6 transporting membrane carrier (VTC); and (iv) facilitating endosomal escape and rapid drug release for synergistic toxicity to tumor cells via charge reversal and ester hydrolysis at intracellular pH and/or esterase. Moreover, α-TOS-B6-NPs-DOX exhibited long blood circulation stability and significant tumor accumulation and inhibition with the decreased side effects in vivo. Thus, the pH-sensitive small molecule nanodrug self-assembled from amphiphilic vitamin B6-E analogue conjugate could be the potential drug carriers in targeted synergistic cancer therapy.

Nanoscale Self-Assembly for Therapeutic Delivery

Self-assembly is the process of association of individual units of a material into highly arranged/ordered structures/patterns. It imparts unique properties to both inorganic and organic structures, so generated, via non-covalent interactions. Currently, self-assembled nanomaterials are finding a wide variety of applications in the area of nanotechnology, imaging techniques, biosensors, biomedical sciences, etc., due to its simplicity, spontaneity, scalability, versatility, and inexpensiveness. Self-assembly of amphiphiles into nanostructures (micelles, vesicles, and hydrogels) happens due to various physical interactions. Recent advancements in the area of drug delivery have opened up newer avenues to develop novel drug delivery systems (DDSs) and self-assembled nanostructures have shown their tremendous potential to be used as facile and efficient materials for this purpose. The main objective of the projected review is to provide readers a concise and straightforward knowledge of basic concepts of supramolecular self-assembly process and how these highly functionalized and efficient nanomaterials can be useful in biomedical applications. Approaches for the self-assembly have been discussed for the fabrication of nanostructures. Advantages and limitations of these systems along with the parameters that are to be taken into consideration while designing a therapeutic delivery vehicle have also been outlined. In this review, various macro- and small-molecule-based systems have been elaborated. Besides, a section on DNA nanostructures as intelligent materials for future applications is also included.

Effects of Terminal Motif on the Self-Assembly of Dexamethasone Derivatives

Tailoring the terminal motif of molecules including drugs might significantly affect their self-assembly tendency in aqueous solution, thus providing a rational strategy to modulate its macroscopic characteristics of supramolecular assembly. A model drug of dexamethasone (Dex) was esterified by different fatty acids [succinic acid (SA), glutaric acid (GA), and adipic acid (AA)] and aromatic acid [phthalic acid (PA)] to generate a series of Dex derivatives. Aqueous solution of Dex-SA, Dex-GA, and Dex-AA turned into hydrogel spontaneously after a period time of incubation (24, 48, and 72 h, respectively) via the auto-hydrolytic strategy, while aqueous solution of Dex-PA did not result in hydrogelation during 3 days of incubation. Aqueous solutions of Dex-SA, Dex-GA, and Dex-AA underwent apparent hydrolysis (10.73 ± 0.64%, 15.17 ± 2.24%, and 17.29 ± 1.39%, respectively), while Dex-PA exhibited a minimal hydrolysis (<1%) in a period of 28 days study, as indicated by in vitro hydrolytic test. Morphological observation showed that the hydrogel formed by Dex-SA was composed of uniform nanofibers, while hydrogels formed by Dex-GA, and Dex-AA were derived from irregular particles. The mechanical strength of hydrogel formed by Dex-SA was much bigger than that of hydrogels formed by Dex-GA and Dex-AA, as indicated by rheological test. Moreover, the acylation of Dex did not compromise its potent anti-inflammatory activity in a lipopolysaccharide (LPS)-activated RAW 264.7 macrophage.

Layered double hydroxide nanosheets: towards ultrasensitive tumor microenvironment responsive synergistic therapy

The tumor microenvironment (TME), which is characterised by high H₂O₂ and glutathione (GSH) levels, low pH value and hypoxia, imposes crucial influences on tumor therapeutic outcomes. Rational design and preparation of nanomaterial systems that are responsive to the intrinsic properties of the TME open a promising avenue towards tumor-specific treatment. Herein, CoMn-layered double hydroxide (CoMn-LDH) nanosheets were synthesized via a bottom-up method followed by surface modification with a photosensitizer, chlorin e6 (Ce6), which exhibited TME-responsive imaging as well as photodynamic and chemodynamic synergistic therapy (PDT/CDT). Due to their ultralow bond energy and large adsorption energy, CoMn-LDH nanosheets show fast self-degradability in a GSH (10 mM) microenvironment, giving an excellent CDT activity in mildly acidic conditions (pH = 6.5), superior GSH removal ability (99.82%) and O₂ production (35.37 μg L^-1 s^-1). Moreover, Ce6/CoMn-LDH nanosheets display satisfactory photoacoustic (PA) imaging and GSH-enhanced magnetic resonance imaging (MRI) with a 45.1-fold T₁-enhancement. In addition, both in vitro and in vivo therapeutic tests based on Ce6/CoMn-LDH demonstrate a satisfactory anticancer activity with complete cancer cell apoptosis and dramatic tumor elimination. This work provides a new perspective for the design of multifunctional 2D nanosheets towards a fully promoted TME-responsive synergistic therapy, which holds great promise for future clinical diagnosis and treatment.

Self-Assembled Gemcitabine Prodrug Nanoparticles Show Enhanced Efficacy against Patient-Derived Pancreatic Ductal Adenocarcinoma

Effective new therapies for pancreatic ductal adenocarcinoma (PDAC) are desperately needed as the prognosis of PDAC patients is dismal and treatment remains a major challenge. Gemcitabine (GEM) is commonly used to treat PDAC; however, the clinical use of GEM has been greatly compromised by its low delivery efficacy and drug resistance. Here, we describe a very simple yet cost-effective approach that synergistically combines drug reconstitution, supramolecular nanoassembly, and tumor-specific targeting to address the multiple challenges posed by the delivery of the chemotherapeutic drug GEM. Using our developed PUFAylation technology, the GEM prodrug was able to spontaneously self-assemble into colloidal stable nanoparticles with sub-100 nm size on covalent attachment of hydrophobic linoleic acid via amide linkage. The prodrug nanoassemblies could be further refined by PEGylation and PDAC-specific peptide ligand for preclinical studies. In vitro cell-based assays showed that not only were GEM nanoparticles superior to free GEM but also the decoration with PDAC-homing peptide facilitated the intracellular uptake of nanoparticles and thereby augmented the cytotoxic activity. In two separate xenograft models of human PDAC, one of which was a patient-derived xenograft model, the administration of targeted nanoparticles resulted in marked inhibition of tumor progression as well as alleviated systemic toxicity. Together, these data unequivocally confirm that the hydrophilic and rapidly metabolized drug GEM can be feasibly transformed into a pharmacologically efficient nanomedicine through exploiting the PUFAylation technology. This strategy could also potentially be applied to rescue many other therapeutics that show unfavorable outcomes in the preclinical studies because of pharmacologic obstacles.

Preclinical Evaluation of a Cabazitaxel Prodrug Using Nanoparticle Delivery for the Treatment of Taxane-Resistant Malignancies

Taxane-based chemotherapeutics are clinically available as frontline treatment regimens for cervical cancer. However, drug resistance and life-threatening toxicity impair the clinical efficacy of taxanes, so more effective and less toxic therapeutic modalities are urgently needed. Cabazitaxel has attracted increasing interest due to its potential to circumvent the drug resistance by taxanes. We previously showed that tethering docosahexaenoic acid (DHA) to cabazitaxel enabled the prodrug to self-assemble into nanoparticles in water. Despite this encouraging finding, the DHA-cabazitaxel conjugate formulation requires further optimization to enhance nanoparticle retention and tumor delivery. We here integrated this conjugate into amphiphilic poly(ethylene glycol)-block-poly(_D,L-lactic acid) copolymers to assemble dCTX NPs The nanoparticle abrogated P-glycoprotein-mediated resistance in cancer cells. In a docetaxel-resistant cervical tumor xenograft-bearing mouse model, the efficacy was augmented by the nanotherapy when compared with solution-based free drugs (i.e., docetaxel and cabazitaxel). Dose intensification of dCTX NPs markedly suppressed the tumor growth in this model. Detailed studies revealed that systemic toxicity was alleviated, and MTD of dCTX NPs was at least 3 times higher than that of free cabazitaxel in animals, which may enable dose increases for clinical studies. In conclusion, the new formulation addresses essential requirements in terms of the stability, safety, and translational capacity for initiating early-phase clinical trials.

PEGylation of lipophilic SN38 prodrug with DSPE-mPEG2000 versus cremophor EL: comparative study for intravenous chemotherapy

The lipophilic prodrug of hydrophobic drugs with well-designed molecular structures can form stable pure prodrug nanoparticles (NPs), but rapid NPs aggregation in plasma greatly restricted their direct use for intravenous chemotherapy. To address this, DSPE-mPEG2000 and Cremophor EL are two of the most widely used lipophilic PEG derivatives to enhance their colloidal stability in plasma. However, their drug delivery performances have never been comparatively studied. Here, a redox-responsive lipophilic prodrug of SN38 was chosen as the model drug for such comparative investigations. We found that Cremophor EL/NPs having a small diameter (∼15 nm) and poor kinetic stability displayed an enhanced cell internalization, higher cytotoxicity and prolonged circulation time as compared with DSPE-mPEG2000/NPs. Most importantly, these superiorities further resulted in a much more potent antitumor activity in CT26 colorectal cancer xenograft, but the increased loss of body weight was also noted. These results suggested that Cremophor EL could be more advantageous than DSPE-mPEG2000 in terms of the improvement of antitumor activity, but the enhanced toxicity warranted further attention in the future study.

Self-assembling poly(ethylene glycol)-block-polylactide-cabazitaxel conjugate nanoparticles for anticancer therapy with high efficacy and low in vivo toxicity

Traditional approaches used for transforming hydrophobic anticancer drugs into therapeutically available nanoparticles heavily rely on the noncovalent formulation of drugs within amphiphilic copolymers. However, these nanotherapies have not yet shown the expected favorable clinical outcomes in cancer patients, presumably due to their insufficient stability. To solve this dilemma, we conceive a new class of nanotherapies assembled with polymeric prodrugs that maintain pharmacological activity while substantially alleviate the drug toxicity in animals. By exploiting methoxypoly(ethylene glycol)-block-poly(D, L-lactic acid) (mPEG-PLA) as a promoiety, cabazitaxel is tethered to the terminus of the PLA fragment via a hydrolysable ester linkage. These conjugates recapitulate the self-assembly to produce colloidal stable nanotherapies. In a xenograft model of prostate cancer, this nanotherapy shows a durable inhibition of tumor progression upon the administration of a tolerable dose. Our results suggest that a hydrophobic and highly toxic drug can be rationally converted into a pharmacologically efficient and self-deliverable nanotherapy.

Cancer nanotechnology: Enhancing tumor cell response to chemotherapy for hepatocellular carcinoma therapy

Hepatocellular carcinoma (HCC) is one of the deadliest cancers due to its complexities, reoccurrence after surgical resection, metastasis and heterogeneity. In addition to sorafenib and lenvatinib for the treatment of HCC approved by FDA, various strategies including transarterial chemoembolization, radiotherapy, locoregional therapy and chemotherapy have been investigated in clinics. Recently, cancer nanotechnology has got great attention for the treatment of various cancers including HCC. Both passive and active targetings are progressing at a steady rate. Herein, we describe the lessons learned from pathogenesis of HCC and the understanding of targeted and non-targeted nanoparticles used for the delivery of small molecules, monoclonal antibodies, miRNAs and peptides. Exploring current efficacy is to enhance tumor cell response of chemotherapy. It highlights the opportunities and challenges faced by nanotechnologies in contemporary hepatocellular carcinoma therapy, where personalized medicine is increasingly becoming the mainstay. Overall objective of this review is to enhance our understanding in the design and development of nanotechnology for treatment of HCC.

Smart cancer nanomedicine

Nanomedicines are extensively employed in cancer therapy. We here propose four strategic directions to improve nanomedicine translation and exploitation. (1) Patient stratification has become common practice in oncology drug development. Accordingly, probes and protocols for patient stratification are urgently needed in cancer nanomedicine, to identify individuals suitable for inclusion in clinical trials. (2) Rational drug selection is crucial for clinical and commercial success. Opportunistic choices based on drug availability should be replaced by investments in modular (pro)drug and nanocarrier design. (3) Combination therapies are the mainstay of clinical cancer care. Nanomedicines synergize with pharmacological and physical co-treatments, and should be increasingly integrated in multimodal combination therapy regimens. (4) Immunotherapy is revolutionizing the treatment of cancer. Nanomedicines can modulate the behaviour of myeloid and lymphoid cells, thereby empowering anticancer immunity and immunotherapy efficacy. Alone and especially together, these four directions will fuel and foster the development of successful cancer nanomedicine therapies.

Design, Synthesis and In Vitro Mechanistic Investigation of Novel Hexacyclic Cage-Like Hybrid Heterocycles

Novel hexacyclic cage-like hybrid heterocycles have been synthesized in excellent yields employing a relatively less explored non-stabilized azomethine ylides derived from acenaphthenequinone and tyrosine with functionalized dipolarophiles using [3 + 2] cycloaddition strategy. The synthesized hexacyclic cage-like hybrid heterocycles were characterized by spectroscopic analysis. Following the physical characterization, these cage-like hybrid heterocycles were tested for their biological activity by means of different cancer (A549 and Jurkat cells) and non-cancer (BRL-3A and PCS-130) in vitro cell culture systems. The results of the study under tested concentrations (up to 100 μM) indicated that these compounds are not affecting any viability to the cell growth of non-cancer cells, while providing significant anticancer activity against both of the cancer cells. Further analysis of in-depth mechanistic study for the cell death indicated that these compounds are exhibiting late apoptosis or early necrosis pathway to the cells where it is operated by the induction of caspases.

Orally Deliverable Nanotherapeutics for the Synergistic Treatment of Colitis-Associated Colorectal Cancer

Purpose: Colitis-associated colorectal cancer (CAC) poses substantial challenges for effective treatment. Currently, there is a considerable need for the development of orally bioavailable dosage forms that enable the safe and effective delivery of therapeutic drugs to local diseased lesions in the gastrointestinal tract. Experimental Design: In this study, we developed orally deliverable nanotherapeutics for the synergistic treatment of inflammatory bowel diseases (IBDs) and CAC. Water-insoluble curcumin (CUR) and 7-ethyl-10-hydroxycamptothecin (SN38), which served as anti-inflammatory and cytotoxic agents, respectively, were chemically engineered into hydrophilic mucoadhesive chitosan for the generation of chitosan-drug amphiphiles. Results: The resulting amphiphilic constructs formed core-shell nanostructures in aqueous solutions and were orally administered for in vivo therapeutic studies. Using a preclinical CAC mouse model, we showed that the orally delivered nanotherapeutics locally accumulated in inflamed intestinal regions and tumor tissues. Furthermore, the therapeutic synergy of the combined nanotherapeutics in CAC mice was evaluated. Compared with their individual drug forms, combined CUR and SN38 nanoparticles yielded synergistic effects to alleviate intestinal inflammation and protect mice from ulcerative colitis. Notably, the combinatorial therapy demonstrated a remarkable tumor shrinkage with only ~6% of the total tumors exceeding 4 mm in diameter, whereas ~35% of tumors were observed to exceed a diameter of 4 mm in the saline-treated CAC mice. These data suggest a new and reliable approach for improving the treatment of IBD and CAC. Conclusions: Our results showed that bioadhesive chitosan materials can be used to produce colloidal-stable nanotherapeutics that are suitable for oral delivery. Both nanotherapeutics exhibited substantial accumulation in inflamed intestinal regions and tumor tissues and showed good synergy for treating CAC, warranting further clinical translation.

Carrier-Enhanced Anticancer Efficacy of Sunitinib-Loaded Green Tea-Based Micellar Nanocomplex beyond Tumor-Targeted Delivery

Although a few nanomedicines have been approved for clinical use in cancer treatment, that recognizes improved patient safety through targeted delivery, their improved efficacy over conventional drugs has remained marginal. One of the typical drawbacks of nanocarriers for cancer therapy is a low drug-loading capacity that leads to insufficient efficacy and requires an increase in dosage and/or frequency of administration, which in turn increases carrier toxicity. In contrast, elevating drug-loading would cause the risk of nanocarrier instability, resulting in low efficacy and off-target toxicity. This intractable drug-to-carrier ratio has imposed constraints on the design and development of nanocarriers. However, if the nanocarrier has intrinsic therapeutic effects, the efficacy would be synergistically augmented with less concern for the drug-to-carrier ratio. Sunitinib-loaded micellar nanocomplex (SU-MNC) was formed using poly(ethylene glycol)-conjugated epigallocatechin-3-O-gallate (PEG-EGCG) as such a carrier. SU-MNC specifically inhibited the vascular endothelial growth factor-induced proliferation of endothelial cells, exhibiting minimal cytotoxicity to normal renal cells. SU-MNC showed enhanced anticancer effects and less toxicity than SU administered orally/intravenously on human renal cell carcinoma-xenografted mice, demonstrating more efficient effects on anti-angiogenesis, apoptosis induction, and proliferation inhibition against tumors. In comparison, a conventional nanocarrier, SU-loaded polymeric micelle (SU-PM) comprised of PEG-b-poly(lactic acid) (PEG-PLA) copolymer, only reduced toxicity with no elevated efficacy, despite comparable drug-loading and tumor-targeting efficiency to SU-MNC. Improved efficacy of SU-MNC was ascribed to the carrier-drug synergies with the high-performance carrier of PEG-EGCG besides tumor-targeted delivery.

Trastuzumab-Coated Nanoparticles Loaded With Docetaxel for Breast Cancer Therapy

Docetaxel (DTX) is commonly used for breast cancer treatment. Tween 80 used for DTX dissolution in its clinical formulation causes severe hypersensitivity and other adverse reactions. In this study, trastuzumab (Tmab)-coated lipid-polymer hybrid nanoparticles (PLNs) were prepared, composed of poly (d, l-lactide-co-glycolide), PLGA; polyethylenimine (PEI); and lipids. The PLGA/PEI/lipid formed a hydrophobic core, while Tmab was electrostatically adsorbed on the surface of the PLNs as a ligand that targets human epidermal growth factor receptor 2 (HER2)-positive breast cancer cells. The resulting PLNs, electrostatically adsorbed Tmab-bearing PLGA/PEI/lipid nanoparticles (eTmab-PPLNs), had a mean particle size of 217.4 ± 13.36 nm, a ζ potential of 0.056 ± 0.315 mV, and good stability. In vitro, the eTmab-PPLNs showed increased cytotoxicity in HER2-postive BT474 cells but not in HER2-negative MCF7 cells. Studies of the ability of eTmab-PPLNs to target HER2 were performed. The uptake of eTmab-PPLNs was shown to be dependent on HER2 expression level. Therefore, eTmab-PPLNs provide a promising therapeutic for the treatment of breast cancer.

Light-Activatable Prodrug and AIEgen Copolymer Nanoparticle for Dual-Drug Monitoring and Combination Therapy

Polyprodrug nanoparticles have been employed recently for safer and more effective cancer treatment. However, it remains a challenge to elucidate how and when the polyprodrug nanoparticles are dissociated and activated to release active drugs in cancer cells. Herein, a visible light-activatable Pt(IV) prodrug and an aggregation-induced emission luminogen (AIEgen) were copolymerized and embedded in the main chain of PtAIECP, and the chemotherapeutic doxorubicin (DOX) was subsequently encapsulated in the nanoparticles self-assembled by PtAIECP (PtAIECP@DOX NP). PtAIECP@DOX NP enabled the monitoring of both the light-activation of Pt(IV) prodrug to active Pt(II) and release of encapsulated DOX intracellularly through the fluorescence "turn-on" in the course of visible-light-induced polymer-main-chain cleavage and self-assembled structure dissociation in vitro and ex vivo. The synergistic anticancer efficacy of the activated Pt(II) drug and DOX in PtAIECP@DOX NP was also investigated in vitro and in vivo. The implementation of polyprodrug and AIE combination strategy empowered dual drug release and monitoring, which could be further used to guide the temporal and spatial control of light irradiation to maximize therapeutic efficiency, and will inspire other combinational bioimaging and therapy strategies.

A CD44-Targeting Programmable Drug Delivery System for Enhancing and Sensitizing Chemotherapy to Drug-Resistant Cancer

Programmable drug delivery systems hold great promise to enhance cancer treatment. Herein, a programmable drug delivery system using a chondroitin sulfate (CS)-based composite nanoparticle was developed for enhancing and sensitizing chemotherapy to drug-resistant cancer. The nanoparticle was composed of a cross-linked CS hydrogel shell and hydrophobic cores containing both free drugs and CS-linked prodrugs. Interestingly, the nanoparticle could mediate tumor-specific CD44 targeting. After specific cellular uptake, the payloads were suddenly released because of the decomposition of the CS shell, and the free drug molecules with synergistic effects induced tumor-specific cytotoxicity rapidly. Subsequently, the inner cores of the nanoparticles sustainedly release their cargos in drug-resistant tumor cells to keep the effective drug concentration against the drug efflux mediated by P-glycoprotein. CS dissociated from the outer shell and sensitized cancer cells to the antitumor drugs through downregulation of Bcl-XL, an antiapoptosis protein. Such a programmable drug delivery system with specific tumor-targeting and sensitized therapy is promising for rational drug delivery and provides more versatility for controlled release in biomedical applications.

Influence of pristine and hydrophobic ZnO nanoparticles on cytotoxicity and endoplasmic reticulum (ER) stress-autophagy-apoptosis gene expression in A549-macrophage co-culture

Exposure to ZnO nanoparticles (NPs) might modulate endoplasmic reticulum (ER) stress-autophagy gene expression, but the possible influence of hydrophobic surface coating on these responses was less studied. This study used A549-macrophage co-culture as the in vitro model for lung barrier and investigated the toxicity of pristine and hydrophobic ZnO NPs. Pristine and hydrophobic NPs exhibited different Zeta potential and solubility in water, which suggested that hydrophobic surface coating might alter the colloidal aspects of ZnO NPs. However, pristine and hydrophobic ZnO NPs induced cytotoxicity and reduced the release of soluble monocyte chemotactic protein-1 (sMCP-1) in A549-macrophage co-culture to a similar extent. Exposure to pristine ZnO NPs significantly promoted the expression of ER stress-apoptosis genes, namely DDIT3, XBP-1s, CASP9, CASP12 and BAX (p < 0.05), but hydrophobic ZnO NPs only significantly promoted the expression of BAX (p < 0.05). Exposure to pristine ZnO NPs also significantly reduced the expression of autophagic gene BECN1 (p < 0.05) but not ATG7 (p > 0.05), whereas hydrophobic ZnO NPs significantly reduced the expression of ATG7 and BECN1 (p < 0.01). Moreover, the expression of XBP-1s, HSPA5, CASP9, CASP12, BAX and ATG7 in pristine ZnO NP-exposed co-culture was significantly lower than that in hydrophobic ZnO NP-exposed co-culture (p < 0.05). In conclusion, hydrophobic surface coating might influence the colloidal aspects of ZnO NPs and alter ER stress-apoptosis-autophagy gene expression pattern by pristine ZnO NPs in A549-macrophage co-culture.

Albumin enhances PTX delivery ability of dextran NPs and therapeutic efficacy of PTX for colorectal cancer

The nanoassemblies of Dex_6k–BSA–PTX and the pH-responsive drug release for anti-tumor applications in vivo.

Targeted chemotherapy for subcutaneous and orthotopic non-small cell lung tumors with cyclic RGD-functionalized and disulfide-crosslinked polymersomal doxorubicin

Lung cancer, with its high mortality and increasing morbidity, has become one of the most lethal malignancies worldwide. Here, we developed cyclic RGD peptide-directed and disulfide-crosslinked polymersomal doxorubicin (cRGD-PS-Dox) as a targeted chemotherapy for human non-small cell lung cancer (NSCLC). Notably, cRGD-PS-Dox exhibited a high Dox loading (15.2 wt.%), small hydrodynamic diameter (96 nm), superb stability, prominent targetability to α_vβ₃ integrin overexpressing A549 human lung cancer cells, and rapid release of the drug into nuclei, leading to a significantly improved antitumor activity compared with the control groups, i.e., PS-Dox and Lipo-Dox (a liposome injection employed in clinical settings). The pharmacokinetic and biodistribution results for cRGD-PS-Dox revealed similar elimination half-lives but two-fold enhanced tumor accumulation compared with PS-Dox and Lipo-Dox. Intriguingly, cRGD-PS-Dox effectively suppressed the growth of A549 lung tumors in both subcutaneous and orthotopic models with minimal adverse effects at a Dox dose of 12 mg/kg, leading to significant survival benefits compared with PS-Dox and Lipo-Dox. This α_vβ₃ integrin-targeting multifunctional polymersomal doxorubicin is highly promising for targeted chemotherapy of human NSCLC.

When wrapped in an engineered vesicle and augmented with cancer-targeting peptides, chemotherapy drug doxorubicin shows increased efficacy in a preclinical study. Zhiyuan Zhong, from China’s Soochow University, and his team developed the therapeutic (cRGD-PS-Dox) that targets cancer cells that overexpress a specific protein (α_vβ₃ integrin), such as those of non-small cell lung cancer. In vitro assays showed that cRGD-PS-Dox specifically targeted and inhibited cancer cells, and inhibited the growth and metastasis of human tumor grafts in mice. In vivo imaging confirmed a desirable drug stability profile and accumulation within tumors. These results showed clear advantages over non-targeted doxorubicin treatment controls. Mice treated with cRGD-PS-Dox also survived significantly longer than control-treated mice. The preferential attributes of the therapy make it a promising agent for further study into tumors that overexpress α_vβ₃ integrin.

Revival of a potent therapeutic maytansinoid agent using a strategy that combines covalent drug conjugation with sequential nanoparticle assembly

Maytansine and its related analogues are a class of highly potent anti-proliferation agents that have failed to be exploited as clinical drugs for human therapy due to unacceptable systemic toxicity. Here, we delineate a novel strategy that combines rational drug conjugation with subsequent nanoparticle assembly to systemically deliver this highly potent and toxic drug. To demonstrate this concept, we covalently coupled the thiolated maytansine derivative, the DM1 agent, to amphiphilic block co-polymers, polyethylene glycol (PEG)-block-polylactide (PLA), in varying molecular weights to generate two prodrug constructs (i.e., PEG_2K-PLA_2K-DM1 and PEG_2K-PLA_4K-DM1) via the maleimide-thiol reaction. The resulting two constructs are amenable to self-assembly in aqueous solutions and are systemically injectable for preclinical studies. In vivo evaluations indicate that PEG-PLA-DM1 conjugate-assembled nanoparticles (NPs) display substantially reduced drug toxicity compared to the free drug forms and NPs that physically encapsulate DM1. Furthermore, following systemic administration, these nanodrugs produced superior therapeutic efficacy over free DM1 in a colon tumor xenograft-bearing mouse model. Therefore, this study provides evidence that the conjugation of toxic drugs to assembling copolymers enables the alleviation of cancer drug toxicity and effective delivery of anticancer drugs. Thus, this DM1-formulated platform represents a new generation of nanotherapeutics that are available for further clinical evaluation.

Resveratrol-loaded PLGA nanoparticles: enhanced stability, solubility and bioactivity of resveratrol for non-alcoholic fatty liver disease therapy

Resveratrol (3, 4', 5-trihydroxy-trans-stilbene, RSV), a nutraceutical, has recently attracted lots of attention because of its outstanding pharmacological potential. The effects of RSV on non-alcoholic fatty liver disease (NAFLD) remain inconclusive, although a wealth of research has been done. The major obstacle presented was RSV's poor bioavailability due to its poor aqueous solubility, chemical instability and intestinal metabolism. In this study, nanotechnology was used to encapsulate RSV to enhance its stability, water solubility and bioactivity, which can be used to treat NAFLD by HepG2 hepatocytes-induced in vitro. RSV-loaded poly (d, l-lactide-co-glycolide acid) (PLGA) nanoparticles (RSV-PLGA-NPs) were prepared according to an oil/water (O/W) emulsion technique. The RSV-PLGA-NPs were of spherical morphology with an average size of 176.1 nm and a negative charge of -22.6 mV. These nanoparticles exhibited remarkable encapsulation efficiency (EE%) (97.25%) and drug loading (14.9%) for RSV. A sustained RSV release from RSV-PLGA-NPs could be achieved especially in acidic conditions when simulating transporting through the gastrointestinal tract. In addition, these nanoparticles were stable enough to store at 4°C for a least six months with unchanged EE%. Moreover, RSV-PLGA-NPs were more efficient in alleviating lipogenesis, promoting lipolysis and reducing hepatocellular proliferation than free RSV due to its improved stability, water solubility and bioactivity. These findings indicated that the RSV-PLGA-NPs provided superb and stable drug delivery with small particle size, high capsulation efficiency, well-controlled drug release, which greatly enhanced the stability, water solubility and bioactivity. Besides, the discovery that the inhibitory effect of RSV-PLGA-NPs on hepatocellular proliferation and lipid accumulation in steatotic HepG2 cells may provide a new way to study the mechanism of NAFLD. Therefore, RSV-PLGA-NPs have a promising potential for NAFLD therapy.

Doxorubicin-loaded protease-activated near-infrared fluorescent polymeric nanoparticles for imaging and therapy of cancer

INTRODUCTION

Despite significant progress in the field of oncology, cancer remains one of the leading causes of death. Chemotherapy is one of the most common treatment options for cancer patients but is well known to result in off-target toxicity. Theranostic nanomedicines that integrate diagnostic and therapeutic functions within an all-in-one platform can increase tumor selectivity for more effective chemotherapy and aid in diagnosis and monitoring of therapeutic responses.

MATERIAL AND METHODS

In this work, theranostic nanoparticles were synthesized with commonly used biocompatible and biodegradable polymers and used as cancer contrast and therapeutic agents for optical imaging and treatment of breast cancer. These core-shell nanoparticles were prepared by nanoprecipitation of blends of the biodegradable and biocompatible amphiphilic copolymers poly(lactic-co-glycolic acid)-b-poly-l-lysine and poly(lactic acid)-b-poly(ethylene glycol). Poly-l-lysine in the first copolymer was covalently decorated with near-infrared fluorescent Alexa Fluor 750 molecules.

RESULTS

The spherical nanoparticles had an average size of 60-80 nm. The chemotherapeutic drug doxorubicin was encapsulated in the core of nanoparticles at a loading of 3% (w:w) and controllably released over a period of 30 days. A 33-fold increase in near-infrared fluorescence, mediated by protease-mediated cleavage of the Alexa Fluor 750-labeled poly-l-lysine on the surface of the nanoparticles, was observed upon interaction with the model protease trypsin. The cytocompatibility of drug-free nanoparticles and growth inhibition of drug-loaded nanoparticles on MDA-MB-231 breast cancer cells were investigated with a luminescence cell-viability assay. Drug-free nanoparticles were found to cause minimal toxicity, even at high concentrations (0.2-2,000 µg/mL), while doxorubicin-loaded nanoparticles significantly reduced cell viability at drug concentrations >10 µM. Finally, the interaction of the nanoparticles with breast cancer cells was studied utilizing fluorescence microscopy, demonstrating the potential of the nanoparticles to act as near-infrared fluorescence optical imaging agents and drug-delivery carriers.

CONCLUSION

Doxorubicin-loaded, enzymatically activatable nanoparticles of less than 100 nm were prepared successfully by nanoprecipitation of copolymer blends. These nanoparticles were found to be suitable as controlled drug delivery systems and contrast agents for imaging of cancer cells.

In situ construction of nanonetworks from transformable nanoparticles for anti-angiogenic therapy

Tumor metastasis as the most common reason of death from cancer has always been a great challenge in both clinical and scientific research, where angiogenesis plays a necessary role. Herein, we report an extracellularly transformable nanomaterial for in situ construction of defensive networks on interaction with vascular endothelial growth factor (VEGF) for anti-angiogenic therapy of tumor. The fibrous networks exhibit transformation-enhanced accumulation and retention (TEAR) effects (over 72 h), and bind and intercept cell-secreted VEGF over particulate and molecular anti-angiogenic agents with high efficiency, leading to anti-angiogenesis. This study demonstrates that angiogenesis is positively related to tumor growth as well as tumor metastasis; the anti-angiogenic therapy inhibits tumor metastasis with an inhibition rate of 65.9%. In addition, this extracellular strategy of transformation may be utilized to bind huge amounts of cell-secreted biomolecules/factors or receptors on cell surfaces and inhibit their functionalities for cancer therapy.