Preclinical efficacy of the camptothecin-polymer conjugate IT-101 in multiple cancer models

Nanomedicines for Malaria Chemotherapy: Encapsulation vs. Polymer Therapeutics

Malaria is one of the oldest infectious diseases that afflict humans and its history extends back for millennia. It was once prevalent throughout the globe but today it is mainly endemic to tropical regions like sub-Saharan Africa and South-east Asia. Ironically, treatment for malaria has existed for centuries yet it still exerts an enormous death toll. This contradiction is attributed in part to the rapid development of resistance by the malaria parasite to chemotherapeutic drugs. In turn, resistance has been fuelled by poor patient compliance to the relatively toxic antimalarial drugs. While drug toxicity and poor pharmacological potentials have been addressed or ameliorated with various nanomedicine drug delivery systems in diseases like cancer, no clinically significant success story has been reported for malaria. There have been several reviews on the application of nanomedicine technologies, especially drug encapsulation, to malaria treatment. Here we extend the scope of the collation of the nanomedicine research literature to polymer therapeutics technology. We first discuss the history of the disease and how a flurry of scientific breakthroughs in the latter part of the nineteenth century provided scientific understanding of the disease. This is followed by a review of the disease biology and the major antimalarial chemotherapy. The achievements of nanomedicine in cancer and other infectious diseases are discussed to draw parallels with malaria. A review of the current state of the research into malaria nanomedicines, both encapsulation and polymer therapeutics polymer-drug conjugation technologies, is covered and we conclude with a consideration of the opportunities and challenges offered by both technologies.

Cooperativity Principles in Self-Assembled Nanomedicine

Nanomedicine is a discipline that applies nanoscience and nanotechnology principles to the prevention, diagnosis, and treatment of human diseases. Self-assembly of molecular components is becoming a common strategy in the design and syntheses of nanomaterials for biomedical applications. In both natural and synthetic self-assembled nanostructures, molecular cooperativity is emerging as an important hallmark. In many cases, interplay of many types of noncovalent interactions leads to dynamic nanosystems with emergent properties where the whole is bigger than the sum of the parts. In this review, we provide a comprehensive analysis of the cooperativity principles in multiple self-assembled nanostructures. We discuss the molecular origin and quantitative modeling of cooperative behaviors. In selected systems, we describe the examples on how to leverage molecular cooperativity to design nanomedicine with improved diagnostic precision and therapeutic efficacy in medicine.

Improved anticancer efficacy of epirubicin by magnetic mesoporous silica nanoparticles: in vitro and in vivo studies

The development of magnetic nanoparticles as delivery carriers to magnetically accumulate anticancer drug in cancer tissue has attracted immense interest. In the present study, magnetic mesoporous silica nanoparticles (MMSNs) with magnetite core and silica shell were synthesized. The obtained MMSNs were characterized by DLS, XRD, FT-IR, TEM and VSM in order to investigate the nanoparticle characteristics. With the focus on in vivo validation of such magnetic drug delivery systems, we selected epirubicin (EPI) as the drug. The anticancer properties of EPI-loaded MMSNs were evaluated in a C-26 colon carcinoma model. Alongside monitoring of drug in the tissues with animal imaging system, the tissue distribution was also determined quantitavely. The average size of MMSNs determined with TEM images was about 18.68 ± 2.31 nm. The cellular uptake test indicated that geometric mean fluorescence intensity (MFI) of cells treated with MMSN + EPI in presence of external magnetic field was increasing 27% compared with free EPI. In addition, treatment with drug-loaded MMSNs with the aid of external magnetic gradient had significantly higher inhibition efficacy towards tumor growth than the free EPI treated mice. The targeted drug delivery through external magnet-attraction using EPI-loaded MMSNs resulted in high tumor cell uptake, which leads to elimination of cancer cells effectively.

Liposomal CpG-ODN: An in vitro and in vivo study on macrophage subtypes responses, biodistribution and subsequent therapeutic efficacy in mice models of cancers

CpG oligodeoxynucleotides (CpG-ODN), a common immune stimulator and vaccine adjuvant, was reported to switch Tumor Associated Macrophages (TAMs) from M2 to M1 phenotype inducing anti-tumor responses. Liposomes are of the successfully applied carriers for CpG-ODN. The aim of present study was design and preparation of a liposomal formulation containing phosphodiester CpG-ODN, evaluation of its effect on macrophages responses, and subsequent antitumor responses in mice. Liposomal formulations containing phosphodiester CpG-ODN or non-CpG-ODN were prepared and characterized. MTT reduction assay in four different cell lines, uptake, arginase and iNOS activity evaluation in macrophage cell lines, biodistribution study and therapeutic anti-tumor effects of formulations in mice bearing C26 colon carcinoma or B16F0 melanoma were carried out. The size of liposomes containing CpG-ODN was ~200 nm with the encapsulation efficiency of 33%. The iNOS activity assay showed high nitric oxide (NO) level in M2 phenotype of macrophage cell lines treated by liposomes containing CpG-ODN. In mice which received liposomes containing CpG-ODN as a monotherapy, maximum tumor growth delay with remarkable survival improvement was observed compared to control groups. Biodistribution study showed the accumulation of liposomal formulation in tumor micro-environment. In conclusion, considerable anti-tumor responses observed by liposomes containing CpG-ODN was due to enhanced delivery of CpG-ODN to immune cells and subsequent initiation of anti-tumoral immune responses.

The therapeutic potential of human adipose-derived mesenchymal stem cells producing CXCL10 in a mouse melanoma lung metastasis model

Interferon γ-induced protein 10 kDa (IP-10) is a potent chemoattractant and has been suggested to enhance antitumor activity and mediate tumor regression through multiple mechanisms of action. Multiple lines of evidence have indicated that genetically-modified adult stem cells represent a potential source for cell-based cancer therapy. In the current study, we assessed therapeutic potential of human adipose derived mesenchymal stem cells (hADSC) genetically-modified to express IP-10 for the treatment of lung metastasis in an immunocompetent mouse model of metastatic melanoma. A Piggybac vector encoding IP-10 was employed to transfect hADSC ex vivo. Expression and bioactivity of the transgenic protein from hADSCs expressing IP-10 were confirmed prior to in vivo studies. Our results indicated that hADSCs expressing IP-10 could inhibit the growth of B16F10 melanoma cells and significantly prolonged survival. Immunohistochemistry analysis, TUNEL assay and western blot analysis indicated that hADSCs expressing IP-10 inhibited tumor cell growth, hindered tumor infiltration of Tregs, restricted angiogenesis and significantly prolonged survival. In conclusion, our results demonstrated that targeting metastatic tumor sites by hADSC expressing IP-10 could reduce melanoma tumor growth and lung metastasis.

Polysaccharide-Based Controlled Release Systems for Therapeutics Delivery and Tissue Engineering: From Bench to Bedside

Polysaccharides or polymeric carbohydrate molecules are long chains of monosaccharides that are linked by glycosidic bonds. The naturally based structural materials are widely applied in biomedical applications. This article covers four different types of polysaccharides (i.e., alginate, chitosan, hyaluronic acid, and dextran) and emphasizes their chemical modification, preparation approaches, preclinical studies, and clinical translations. Different cargo fabrication techniques are also presented in the third section. Recent progresses in preclinical applications are then discussed, including tissue engineering and treatment of diseases in both therapeutic and monitoring aspects. Finally, clinical translational studies with ongoing clinical trials are summarized and reviewed. The promise of new development in nanotechnology and polysaccharide chemistry helps clinical translation of polysaccharide-based drug delivery systems.

Preclinical effects of CRLX101, an investigational camptothecin-containing nanoparticle drug conjugate, on treating glioblastoma multiforme via apoptosis and antiangiogenesis

Malignant gliomas are difficult to treat in clinical practice. This study was aimed to investigate the preclinical efficacy of CRLX101, an investigational nanoparticle-drug conjugate developed by conjugating camptothecin (CPT) with cyclodextrin-polyethylene glycol, against gliomas. CPT fluorescence was detected across tight-junction barriers and in mouse plasma and brain. Following CRLX101 treatment, CPT was distributed in the cytoplasm of human U87 MG glioma cells. U87 MG cell viability was decreased by CRLX101 and CPT. Moreover, CRLX101 induced less cytotoxicity to human astrocytes compared to CPT. Exposure of U87 MG cells to CRLX101 induced G₂/M cell cycle arrest and apoptosis. Administration of CRLX101 induced apoptosis in mice brain tumor tissues and prolonged the survival rate of mice. In addition, CRLX101 inhibited hypoxia and angiogenesis by suppressing the expression of carbonic anhydrase IX, vascular endothelial growth factor, and CD31 in tumor sections. Taken together, this preclinical study showed that CRLX101 possesses antitumor abilities by inducing cell cycle arrest and apoptosis in glioma cells and inhibiting tumor angiogenesis, thereby prolonging the lifespan of mice bearing intracranial gliomas. These data support further research of CRLX101 in patients with brain tumors.

Current Challenges of Cancer Anti-angiogenic Therapy and the Promise of Nanotherapeutics

With growing interest in cancer therapeutics, anti-angiogenic therapy has received considerable attention and is widely administered in several types of human cancers. Nonetheless, this type of therapy may induce multiple signaling pathways compared with cytotoxics and lead to worse outcomes in terms of resistance, invasion, metastasis, and overall survival (OS). Moreover, there are important challenges that limit the translation of promising biomarkers into clinical practice to monitor the efficiency of anti-angiogenic therapy. These pitfalls emphasize the urgent need for discovering alternative angiogenic inhibitors that target multiple angiogenic factors or developing a new drug delivery system for the current inhibitors. The great advantages of nanoparticles are their ability to offer effective routes that target the biological system and regulate different vital processes based on their unique features. Limited studies so far have addressed the effectiveness of nanoparticles in the normalization of the delicate balance between stimulating (pro-angiogenic) and inhibiting (anti-angiogenic) factors. In this review, we shed light on tumor vessels and their microenvironment and consider the current directions of anti-angiogenic and nanotherapeutic treatments. To the best of our knowledge, we consider an important effort in the understanding of anti-angiogenic agents (often a small volume of metals, nonmetallic molecules, or polymers) that can control the growth of new vessels.

5TR1 aptamer-PEGylated liposomal doxorubicin enhances cellular uptake and suppresses tumour growth by targeting MUC1 on the surface of cancer cells

Employing targeting ligands with high affinity to tumour receptors is an important strategy to increase treatment efficacy. The use of aptamers as targeting agent is increasingly prevalent in drug delivery systems. Mucin1 (MUC1) is a glycoprotein that is over-expressed on the surface of several cancer cells and plays an important role in metastasis and invasion. 5TR1-aptamer is a DNA aptamer, which targets MUC1 receptors. The present study investigated the anti-tumour activity and therapeutic effectiveness of 5TR1-aptamer-PEGylated liposomal doxorubicin (PLD) delivery system in C26 tumour-bearing mice. The in vitro experiments demonstrated enhanced cytotoxicity and cellular uptake of PLD at the presence of 5TR1 aptamer into MUC1⁺C26 cell line. Biodistribution study indicated that aptamer conjugation increased tumour accumulation of PLDs. Pharmacokinetic analysis showed despite higher clearance rate, selective delivery of doxorubicin to tumour tissue was increased in the 5TR1-Doxil group. In C26-bearing tumour mice, treatment with 5TR1-Doxil exhibited significant deceleration in tumour growth and enhanced survival. The results suggested that 5TR1 aptamer is promising ligand for active targeting which improves therapeutic efficiency of PLD in cancer therapy.

Pilot trial of CRLX101 in patients with advanced, chemotherapy-refractory gastroesophageal cancer

Background

CRLX101 is an investigational nanoparticle-drug conjugate with a camptothecin payload. Preclinical evidence indicated preferential uptake in tumors, and tumor xenograft models demonstrate superiority of CRLX101 over irinotecan. A pilot trial was conducted at recommended phase 2 dosing (RP2D) using the bimonthly schedule to assess preferential uptake of CRLX101 in tumor vs. adjacent normal tissue in endoscopically accessible tumors in chemotherapy-refractory gastroesophageal cancer. Results from the biopsies were previously reported and herein we present the clinical outcomes.

Methods

Patients initiated CRLX101 dosed at RP2D (15 mg/m²) on days 1 and 15 of a 28-day cycle. Detection of preferential CRLX101 tumor uptake was the primary endpoint and objective response rate (ORR) was a secondary endpoint. With a sample size of ten patients, the study had 90% power to detect ≥1 responder if the true response rate is ≥21%.

Results

Between Dec. 2012 and Dec. 2014, ten patients with chemotherapy-refractory (median 2 prior lines of therapy, range 1-4) gastric adenocarcinoma were enrolled. The median time-to-progression was 1.7 months. Best response was seen in one patient with stable disease (SD) for 8 cycles. Only ≥ grade 3 drug-related toxicity occurred in one patient with grade 3 cardiac chest pain who was able to resume therapy after CRLX101 was reduced to 12 mg/m².

Conclusions

Bimonthly CRLX101 demonstrated minimal activity with SD as best response in this heavily pretreated population. Future efforts with CRLX101 in gastric cancer should focus on combination and more dose-intensive strategies given its favorable toxicity profile and evidence of preferential tumor uptake.

A nano-liposome vaccine carrying E75, a HER-2/neu-derived peptide, exhibits significant antitumour activity in mice

E75 (HER-2/neu-369-377), is an immunogenic peptide which is highly expressed in breast cancer patients. The purpose of this study was to develop an effective vaccine delivery/adjuvant system by attachment of this peptide to the surface of liposomes consisting of phospholipids including distearoylphosphocholine (DSPC) and distearoyl phosphoglycerol (DSPG) with high transition temperature (Tm) and dioleoylphosphatidylethanolamine (DOPE) (a pH-sensitive lipid for cytosolic antigen delivery) to improve antitumour immune activity against the E75 peptide. For this purpose, the E75 peptide was incorporated into liposomes consisting of DSPC/DSPG/cholesterol (Chol)/DOPE (15/2/3/5 molar ratio) through conjugation with distearoylphosphoethanolamine-N-[maleimide(polyethylene glycol)-2000] (maleimide-PEG₂₀₀₀-DSPE). Immunization of BALB/c mice was performed three times with different forms of liposomal formulations at 2-week intervals and antitumour immunity responses were evaluated. Results of ELISpot and flow cytometry analysis showed that mice vaccinated with DSPC/DSPG/Chol/DOPE/E75 have significantly enhanced the antigen-specific IFN-γ response of CD8⁺ T cells and generated cytotoxic T lymphocytes (CTL) antitumour responses. CTL responses induced by this formulation resulted in inhibition of tumour progression and longer survival time in the mice TUBO tumour model. The results revealed that the liposomes consist of DSPC/DSPG/Chol/DOPE could be suitable candidates for vaccine delivery of E75 peptide for the prevention and therapy of HER2-positive breast cancer and merit further investigation.

Therapeutic Efficacy of Cisplatin Thermosensitive Liposomes upon Mild Hyperthermia in C26 Tumor Bearing BALB/c Mice

This study reports on the activity of thermosensitive liposomes (TSLs) incorporating different HSPC ratios in DPPC/MSPC/PEG₂₀₀₀-DSPE matrix (90/10/4) plus mild hyperthermia (HT) (42 °C). TSLs were loaded with a poorly membrane permeable anticancer drug, cisplatin, through the passive equilibration method. The addition of HSPC to the corresponding DPPC lipid matrix increased the transition temperature. In vitro data demonstrated >90% cisplatin leakage from nanosized DPPC 90-lyso-TSL (LTSL) within 10 min at 42 °C, while other TSLs bearing HSPC showed greater stability. The plasma kinetics of cisplatin demonstrated higher cisplatin leakage from DPPC 90-LTSL in the first 4 h (from 17.4 to 0.4 μg/mL) compared to other formulations. Indeed, increasing HSPC fraction in liposome bilayers significantly improved drug retention in blood. Though DPPC 90-LTSL plus one-step HT was expected to provide a unique drug release, the premature drug leakage as well as the likely wash-back of a great portion of drug into the blood circulation resulted in reduced survival. On the other hand, stabilized DPPC 30/HSPC 60/MSPC 10/PEG₂₀₀₀-DSPE 4 liposomes plus two-step HT greatly enhanced the survival of animals. In particular, the improved delivery of cisplatin through stabilized DPPC 30/HSPC 60/MSPC 10/PEG₂₀₀₀-DSPE 4 liposomes in two-step mild HT enhanced antitumor efficacy compared to other formulations. Thus, prolonged exposure of cancer cells to cisplatin through stabilized liposomes would be an efficient approach in improving the survival of animals.

Bioresponsive polymer coated drug nanorods for breast cancer treatment

Ineffective drug release at the target site is among the top challenges for cancer treatment. This reflects the facts that interaction with the physiological condition can denature active ingredients of drugs, and low delivery to the disease microenvironment leads to poor therapeutic outcomes. We hypothesize that depositing a thin layer of bioresponsive polymer on the surface of drug nanoparticles would not only protect drugs from degradation but also allow the release of drugs at the target site. Here, we report a one-step process to prepare bioresponsive polymer coated drug nanorods (NRs) from liquid precursors using the solvent diffusion method. A thin layer (10.3 ± 1.4 nm) of poly(ε-caprolactone) (PCL) polymer coating was deposited on the surface of camptothecin (CPT) anti-cancer drug NRs. The mean size of PCL-coated CPT NRs was 500.9 ± 91.3 nm length × 122.7 ± 10.1 nm width. The PCL polymer coating was biodegradable at acidic pH 6 as determined by Fourier transform infrared spectroscopy. CPT drugs were released up to 51.5% when PCL coating dissolved into non-toxic carboxyl and hydroxyl groups. Trastuzumab (TTZ), a humanized IgG monoclonal antibody, was conjugated to the NR surface for breast cancer cell targeting. Combination treatments using CPT and TTZ decreased the HER-2 positive BT-474 breast cancer cell growth by 66.9 ± 5.3% in vitro. These results suggest effective combination treatments of breast cancer cells using bioresponsive polymer coated drug delivery.

Safe approaches for camptothecin delivery: Structural analogues and nanomedicines

Twenty-(S)-camptothecin is a strongly cytotoxic molecule with excellent antitumor activity over a wide spectrum of human cancers. However, the direct formulation is limited by its poor water solubility, low plasmatic stability and severe toxicity, which currently limits its clinical use. As a consequence, two strategies have been developed in order to achieve safe and efficient delivery of camptothecin to target cells: structural analogues and nanomedicines. In this review, we summarize recent advances in the design, synthesis and development of camptothecin molecular derivatives and supramolecular vehicles, following a systematic classification according to structure-activity relationships (structural analogues) or chemical nature (nanomedicines). A series of organic, inorganic and hybrid materials are presented as nanoplatforms to overcome camptothecin restrictions in administration, biodistribution, pharmacokinetics and toxicity. Nanocarriers which respond to a variety of stimuli endogenously (e.g., pH, redox potential, enzyme activity) or exogenously (e.g., magnetic field, light, temperature, ultrasound) seem the best positioned therapeutic materials for optimal spatial and temporal control over drug release. The main goal of this review is to be used as a source of relevant literature for others interested in the field of camptothecin-based therapeutics. To this end, final remarks on the most important formulations currently under clinical trial are provided.

Cyclodextrin-based supramolecular nanoparticles for biomedical applications

Supramolecular host-guest interactions are ideal for engineering supramolecular nanoparticles (SNPs), because their modular character offers the possibility of using the same basic SNPs made of very similar building blocks in a variety of applications. The most widely used host is cyclodextrin (CD), therefore, this review will focus on SNPs involving CD as the host entity. In the first part, particle formation and size control are described, and the forces that induce the assembly between the different components and, therefore, result in the formation of stable and controllable nanoparticles. In the second part, the use of CD-based SNPs for diagnostics and therapeutics is described. Here, the emphasis is on how the therapeutic agent/imaging component is included in the system and how it is released at the target site. CD-based SNPs provide great possibilities for the formulation of nanoparticles for biomedical applications because of their high flexibility, stability, modular character, and biocompatibility.

Priming nanoparticle-guided diagnostics and therapeutics towards human organs-on-chips microphysiological system

Nanotechnology and bioengineering have converged over the past decades, by which the application of multi-functional nanoparticles (NPs) has been emerged in clinical and biomedical fields. The NPs primed to detect disease-specific biomarkers or to deliver biopharmaceutical compounds have beena validated in conventional in vitro culture models including two dimensional (2D) cell cultures or 3D organoid models. However, a lack of experimental models that have strong human physiological relevance has hampered accurate validation of the safety and functionality of NPs. Alternatively, biomimetic human "Organs-on-Chips" microphysiological systems have recapitulated the mechanically dynamic 3D tissue interface of human organ microenvironment, in which the transport, cytotoxicity, biocompatibility, and therapeutic efficacy of NPs and their conjugates may be more accurately validated. Finally, integration of NP-guided diagnostic detection and targeted nanotherapeutics in conjunction with human organs-on-chips can provide a novel avenue to accelerate the NP-based drug development process as well as the rapid detection of cellular secretomes associated with pathophysiological processes.

Combination therapy of paclitaxel and cyclopamine polymer-drug conjugates to treat advanced prostate cancer

Repeated treatments with chemotherapeutic agent(s) fail due to cancer stem cells (CSCs) and chemoresistance regulated by microRNAs (miRNA) whose expression alters owing to dysfunctional signaling pathways including Hedgehog (Hh) signaling. We previously demonstrated the combination of Hh inhibitor cyclopamine (CYP) and paclitaxel (PTX) effectively inhibit PTX-resistant cells and side population, a cell fraction rich in CSCs. In this study, we synthesized mPEG-b-PCC-g-PTX-g-DC (P-PTX) and mPEG-b-PCC-g-CYP-g-DC (P-CYP) polymer-drug conjugates, which they self-assembled into micelles. The combination of P-PTX and P-CYP alleviated PTX resistance and suppressed tumor colony formation. Further, combination therapy inhibited Hh signaling and up-regulated tumor suppressor miRNAs. We established orthotopic prostate tumor in nude mice and there was significant tumor growth inhibition in the group treated with the combination therapy of P-PTX and P-CYP compared with monotherapy. In conclusion, this combination therapy of P-PTX and P-CYP has the potential to treat chemoresistant prostate cancer.

Poly (I:C)-DOTAP cationic nanoliposome containing multi-epitope HER2-derived peptide promotes vaccine-elicited anti-tumor immunity in a murine model

In the current study we aimed at developing a vaccine delivery/adjuvant system to enhance anti-tumor immunity against the natural multi-epitope HER2/Neu-derived P5 peptide. Polyriboinosinic: polyribocytidylic acid [Poly (I:C)] is a strong immunoadjuvant able to enhance specific antitumor immunity induced by peptide-based vaccines. Nevertheless, delivering the peptide and adjuvant intracellularly into their target site remains a challenging issue. We hypothesized this barrier could be overcome through the use of a cationic nanoliposome carrier system which can carry and protect the antigen and adjuvant in the extracellular environment and augment the induction of antitumor immunity. P5 was encapsulated in cationic nanoliposomes composed of 1,2-dioleoyl-3-trimethylammonium propane (DOTAP)-Cholesterol either alone or complexed with Poly (I:C). Immunocompetent BALB/c mice were immunized with the formulations 3 times in two-week intervals and the efficiency and type of immune response were then evaluated both in vitro and in vivo. The groups immunized with Lip-P5+PIC (DOTAP-Cholestrol-P5+Poly (I:C)) and Lip+PIC (DOTAP-Cholestrol+Poly (I:C)) enhanced the release of Interferon (IFN)-γ in comparison with other groups. Flow cytometry analysis revealed that Lip-P5+PIC formulation induced the highest level of IFN-γ in CD8(+) lymphocytes. Lip-P5+PIC, Lip+PIC and Lip-P5 (DOTAP-Cholestrol-P5) provided some extent of protection in terms of tumor regression in TUBO tumor mice model during the first 65days post tumor challenge but at the end only the tumors of mice immunized with Lip-P5+PIC were significantly smaller than all other groups. Furthermore, tumors of mice receiving Lip-P5+PIC grew at a significantly slower rate throughout the observation period. Our results showed that the combination of Poly (I:C) and DOTAP with the tumor antigen and without applying additional T-helper epitope induced strong antitumor responses. The observations presented here are of great interest for future vaccine studies.

Improved drug delivery and therapeutic efficacy of PEgylated liposomal doxorubicin by targeting anti-HER2 peptide in murine breast tumor model

Targeted cancer therapy is a powerful therapeutic strategy to management of cancer. HER2 as an anticancer target has long been studied. Its overexpression plays an important role in the pathogenesis and progressiveness of breast and other cancers. To establish efficient and reliable drug delivery to HER2-overexpressing cells, the authors of this study have developed anti-HER2 (ErbB2) peptide-liposomal formulations of doxorubicin (DOX) by an engineered breast tumor-targeting peptide ligand, AHNP, Anti-HER2/neu peptide, (FCDGFYACYADV) with three glycine amino acids as spacer before its original sequencing. Towards this goal, PEGylated liposome doxorubicin (PLD) bearing different ligand densities of AHNP was prepared and characterized for their size, zeta potential and peptide conjugation. The AHNP functionalization and density effects on breast tumor cell uptake, selective cytotoxicity, prevention of tumor growth and the tissue biodistribution of encapsulated DOX were studied in mice bearing TUBO breast cancer tumor model. The findings demonstrated that increasing the ligand density of AHNP increases cytotoxicity and cell-uptake in SKBR3 and TUBO cells which overexpress HER2 but not in MDA-MB-231with low HER2 expression profile. The anticancer activity was also superior for targeted liposomal DOX with more AHNP densities. Overall, the results showed that optimum AHNP density functionalization of PLD can significantly improve selectivity and the therapeutic index of liposomal DOX in the treatment of HER2 positive breast cancer and merits further investigation.

Improved therapeutic activity of HER2 Affibody-targeted cisplatin liposomes in HER2-expressing breast tumor models

OBJECTIVES

The purpose of this study was to investigate whether the conjugation of anti-HER2-Affibody to cisplatin PEGylated liposome can efficiently enhance the therapeutic effectiveness of the targeted liposome.

METHODS

First, Affibody molecules were incubated with Mal-PEG2000-DSPE micelle to afford formation of a maleimide-mediated thioether coupling to the COOH-terminal cysteine of Affibody. Cisplatin-loaded liposomes composed of hydrogenated soy phosphatidylcholine/ cholesterol/mPEG2000-DSPE (56.5:38.5:5 molar ratio) (150 mM) were prepared and characterized by their physicochemical properties. Affibody-conjugated micelles were then transferred into preformed liposomes by means of post insertion. The cytotoxicity and cellular uptake of Affibody-targeted (affisome) and nontargeted liposomes were tested in HER2(+) SK-BR-3, and the in vivo therapeutic activity was evaluated in TUBO breast cancer models.

RESULTS

Anti-HER2 affisome demonstrated a higher amount of platinum intracellularly, and affected HER2(+)-SK-BR-3 cell death was at lower concentrations compared with its liposome counterparts. Further, cisplatin-affisome showed greater therapeutic efficiency than nontargeted liposome in HER2(+)-TUBO models. Equally promising, the affisome-treated mice did extend the survival of animals by several days and even left one tumor-free survivor.

CONCLUSIONS

Affibody-targeting endowed cisplatin liposomes with significantly enhanced, albeit modest, therapeutic activity in HER2-overexpressing tumor model; however, further values are yet to be determined to advance clinical translation of these targeted nanoparticulates.

Improvement in the drug delivery and anti-tumor efficacy of PEGylated liposomal doxorubicin by targeting RNA aptamers in mice bearing breast tumor model

Targeted delivery by ligands such as aptamers, is a promising method to increase the efficiency of PEGylated-liposomal doxorubicin (PL-Dox). In this study, we have successfully conjugated our recently developed anti-breast cancer RNA aptamer (TSA14) to the surface of PL-Dox and characterized for their size, zeta potential, Dox percent encapsulation and release properties in the presence of fetal bovine serum. In vitro experiments showed that aptamer could improve cellular uptake and cytotoxicity of PL-Dox in TUBO breast cell line. In mice bearing TUBO breast tumor, although, the doxorubicin plasma level of liposomal doxorubicin did not significantly change after modification of nanoparticles with aptamer, however, much higher tumor accumulation of Dox as compared with non-targeted liposomes proved the tumor-targeting capability of aptamers. In the same way, aptamer-PL-Dox improved anti-tumor efficiency of liposomes in TUBO breast tumor in mice compared to non-targeted liposomes. Overall, the results showed that aptamer decoration of PL-Dox could significantly improve selectivity and the therapeutic efficacy of liposomal DOX and merits further investigation.

Optimizing the therapeutic efficacy of cisplatin PEGylated liposomes via incorporation of different DPPG ratios: In vitro and in vivo studies

The anionic lipid DPPG is known to enhance the cellular uptake of liposomes by forming phase boundaries of high fusogenic potentials in vesicular membranes. The focus of this study is to optimize DPPG concentrations to improve the therapeutic efficacy of cisplatin-loaded liposomes. First, cisplatin liposomes composed of HSPC, mPEG2000-DSPE and cholesterol with increasing amounts of DPPG (10, 20 and 30% mol) were prepared by ethanol injection. Liposomes were then characterized by their size, zeta potential and cytotoxicity against C26 colon carcinoma cells. In an experimental system, based upon C26 tumor bearing BALB/c, mice were treated with administering i.v. doses of different formulations, once weekly for total of three weeks. Although with the highest DPPG ratio (30% mol) liposomes exhibited the highest toxicity in vitro, at 10% DPPG better stability of the encapsulated drug was obtained in the presence of serum. In addition, survival of animals was substantially improved at 10% DPPG compared to the higher DPPG contents. It is thus presumable that the high density of negatively charged residues of DPPG gave rise to repulsive forces between phospholipids in concentric lipid bilayers, which resulted in the instability of lipid structure and the subsequent premature drug leakage. Results indicated that cisplatin liposome fabricated with the inclusion of 10% DPPG, maintains the stability while in circulation, and improves therapeutic efficacy due to fusogenic properties; therefore might serve as an effective and stable formulation of cisplatin. However, further investigations are required to confirm the potential anti-tumor effects of cisplatin anionic nanoliposomes in various tumor types.

Targeting CD44 expressing cancer cells with anti-CD44 monoclonal antibody improves cellular uptake and antitumor efficacy of liposomal doxorubicin

Although liposomes improve the safety and pharmacokinetic properties of free drugs, they have not sufficiently enhanced the therapeutic efficacy compared to them. To address this problem, targeted therapy of tumor cells holds great promise to further enhance therapeutic index and decreases off-target effects compared with non-targeted liposomes. In the context of antibody-mediated targeted cancer therapy, we evaluated the anti-tumor activity and therapeutic efficacy of Doxil, and that of Doxil modified with a monoclonal antibody (mAb) against CD44, which is one of the most well-known surface markers associated with Cancer Stem Cells (CSCs). Flow cytometry analyses and confocal laser scanning microscopy results showed significant enhanced cellular uptake of CD44-targeted Doxil (CD44-Doxil) in CD44-positive C-26 cells compared to Doxil. However, CD44-negative NIH-3T3 cells showed a similar uptake and in vitro cytotoxicity with both CD44-Doxil and non-targeted Doxil. In BALB/c mice bearing C-26 murine carcinoma, CD44-Doxil groups exhibited significantly higher doxorubicin concentration (than Doxil) inside the tumor cells, while their circulation time and distribution profile remained comparable. CD44-Doxil at doses of either 10 or 15 mg/kg resulted in superior tumor growth inhibition and higher inclination to tumor, indicating the potential of anti-CD44 mAb targeting in therapeutic efficacy improvement. This study provides proof-of-principle for actively tumor-targeting concept and merits further investigations.

Choline Derivate-Modified Doxorubicin Loaded Micelle for Glioma Therapy

Ligand-mediated polymeric micelles have enormous potential for improving the efficacy of glioma therapy. Linear-dendritic drug-polymer conjugates composed of doxorubicin (DOX) and polyethylene glycol (PEG) were synthesized with or without modification of choline derivate (CD). The resulting MeO-PEG-DOX8 and CD-PEG-DOX8 could self-assemble into polymeric micelles with a nanosized diameter around 30 nm and a high drug loading content up to 40.6 and 32.3%, respectively. The optimized formulation 20% CD-PEG-DOX8 micelles had superior cellular uptake and antitumor activity against MeO-PEG-DOX8 micelles. The subcellular distribution using confocal study revealed that 20% CD-PEG-DOX8 micelles preferentially accumulated in the mitochondria. Pharmacokinetic study showed area under the plasma concentration-time curve (AUC0-t) and Cmax for 20% CD-PEG-DOX8 micelles and DOX solution were 1336.58 ± 179.43 mg/L·h, 96.35 ± 3.32 mg/L and 1.40 ± 0.19 mg/L·h, 1.15 ± 0.25 mg/L, respectively. Biodistribution study showed the DOX concentration of 20% CD-PEG-DOX8 micelles treated group at 48 h was 2.37-fold higher than that of MeO-PEG-DOX8 micelles treated group at 48 h and was 24 fold-higher than that of DOX solution treated group at 24 h. CD-PEG-DOX8 micelles (20%) were well tolerated with reduced cardiotoxicity, as evaluated in the body weight change and HE staining studies, while they induced most significant antitumor activity with longest media survival time in an orthotopic mouse model of U87-luci glioblastoma model as displayed in the bioluminescence imaging and survival curve studies. Our findings consequently indicated that 20% CD-PEG-DOX8 micelles are promising drug delivery system for glioma chemotherapy.

Polymeric Micelle-Mediated Delivery of DNA-Targeting Organometallic Complexes for Resistant Ovarian Cancer Treatment

Three half-sandwich iridium and ruthenium organometallic complexes with high cytotoxicity are synthesized, and their anticancer mechanisms are elucidated. The organometallic complexes can interact with DNA through coordination or intercalation, thereby inducing apoptosis and inhibiting proliferation of resistant cancer cells. The organometallic complexes are then incorporated into polymeric micelles through the polymer-metal coordination between poly(ethylene glycol)-b-poly(glutamic acid) [PEG-b-P(Glu)] and organometallic complexes to further enhance their anticancer effects as a result of the enhanced permeability and retention effect. The micelles with particle sizes of ≈60 nm are more efficiently internalized by cancer cells than the corresponding complexes, and selectively dissociate and release organometallic anticancer agents within late endosomes and lysosomes, thereby enhancing drug delivery to the nuclei of cancer cells and facilitating their interactions with DNA. Thus, the micelles display higher antitumor activity than the organometallic complexes alone with a lack of the systemic toxicity in a mouse xenograft model of cisplatin-resistant human ovarian cancer. These results suggest that the polymeric micelles carrying anticancer organometallic complexes provide a promising platform for the treatment of resistant ovarian cancer and other hard-to-treat solid tumors.

Challenges in SN38 drug delivery: current success and future directions

INTRODUCTION

Clinical use of SN38 is limited by its poor aqueous solubility and hydrolysis of the lactone ring at pH > 6 to inactive carboxylate form. A variety of drug delivery systems have been developed to improve the solubility and stability of SN38, and reduce its toxicity. A few noteworthy formulations with some success in initial phases of clinical trials are reported.

AREAS COVERED

This work aims to provide a comprehensive review on the various techniques and strategies employed (physical, chemical and biological methods) to improve physicochemical properties and to deliver the drug efficiently to the cancer cells. Physical methods such as nanoparticle encapsulation, cyclodextrin complexation; chemical methods such as prodrugs, polymer-, albumin- and immunoconjugates; and enzyme activated prodrug therapy are discussed.

EXPERT OPINION

The challenges in SN38 drug delivery may be overcome by two ways: ensuring multiple layers of protection against degradation and slow but sustained release of therapeutically effective drug concentrations. It may also be achieved by preparing a polymer-drug conjugate and further encapsulating the conjugate in suitable carrier system; tumor-targeted SN38 delivery by using immunoconjugates, enzyme-activated prodrug therapy and antibody-directed nanoparticle delivery. However, selection of a suitable ligand for tumor targeting and use of safe and biocompatible nanoparticle systems play an important role in realizing this goal.

Targeted nanoparticles for image-guided treatment of triple-negative breast cancer: clinical significance and technological advances

Effective treatment of triple-negative breast cancer (TNBC) with its aggressive tumor biology, highly heterogeneous tumor cells, and poor prognosis requires an integrated therapeutic approach that addresses critical issues in cancer therapy. Multifunctional nanoparticles with the abilities of targeted drug delivery and noninvasive imaging for monitoring drug delivery and responses to therapy, such as theranostic nanoparticles, hold great promise toward the development of novel therapeutic approaches for the treatment of TNBC using a single therapeutic platform. The biological and pathological characteristics of TNBC provide insight into several potential molecular targets for current and future nanoparticle-based therapeutics. Extensive tumor stroma, highly proliferative cells, and a high rate of drug resistance are all barriers that must be appropriately addressed in order for these nanotherapeutic platforms to be effective. Utilization of the enhanced permeability and retention effect coupled with active targeting of cell surface receptors expressed by TNBC cells, and tumor-associated endothelial cells, stromal fibroblasts, and macrophages is likely to overcome such barriers to facilitate more effective drug delivery. An in-depth summary of current studies investigating targeted nanoparticles in preclinical TNBC mouse and human xenograft models is presented. This review aims to outline the current status of nanotherapeutic options for TNBC patients, identification of promising molecular targets, challenges associated with the development of targeted nanotherapeutics, the research done by our group as well as by others, and future perspectives on the nanomedicine field and ways to translate current preclinical studies into the clinic.

Cancer nanotherapeutics in clinical trials

To be legally sold in the United States, all drugs must go through the FDA approval process. This chapter introduces the FDA approval process and describes the clinical trials required for a drug to gain approval. We then look at the different cancer nanotherapeutics and in vivo diagnostics that are currently in clinical trials or have already received approval. These nanotechnologies are catagorized and described based on the delivery vehicle: liposomes, polymer micelles, albumin-bound chemotherapeutics, polymer-bound chemotherapeutics, and inorganic particles.

Redox-sensitive hyaluronic acid–paclitaxel conjugate micelles with high physical drug loading for efficient tumor therapy

Characterization of targeted redox-sensitive micelles self-assembled from polymer–drug conjugates exhibiting conspicuous drug loading capabilities, selective cellular uptake, rapid intracellular disassembly and drug release is presented.

Translational impact of nanoparticle-drug conjugate CRLX101 with or without bevacizumab in advanced ovarian cancer

PURPOSE

Increased tumor hypoxia and hence elevated hypoxia-inducible factor-1α (HIF1α) is thought to limit the efficacy of vascular endothelial growth factor (VEGF) pathway-targeting drugs by upregulating adaptive resistance genes. One strategy to counteract this is to combine antiangiogenic drugs with agents able to suppress HIF1α. One such possibility is the investigational drug CRLX101, a nanoparticle-drug conjugate (NDC) containing the payload camptothecin, a known topoisomerase-I poison.

EXPERIMENTAL DESIGN

CRLX101 was evaluated both as a monotherapy and combination with bevacizumab in a preclinical mouse model of advanced metastatic ovarian cancer. These preclinical studies contributed to the rationale for undertaking a phase II clinical study to evaluate CRLX101 monotherapy in patients with advanced platinum-resistant ovarian cancer.

RESULTS

Preclinically, CRLX101 is highly efficacious as a monotherapy when administered at maximum-tolerated doses. Furthermore, chronic low-dose CRLX101 with bevacizumab reduced bevacizumab-induced HIF1α upregulation and resulted in synergistic efficacy, with minimal toxicity in mice. In parallel, initial data reported here from an ongoing phase II clinical study of CRLX101 monotherapy shows measurable tumor reductions in 74% of patients and a 16% RECIST response rate to date.

CONCLUSIONS

Given these preclinical and initial clinical results, further clinical studies are currently evaluating CRLX101 in combination with bevacizumab in ovarian cancer and warrant the evaluation of this therapy combination in other cancer types where HIF1α is implicated in pathogenesis, as it may potentially be able to improve the efficacy of antiangiogenic drugs.

Engineered nanoparticles for drug delivery in cancer therapy

In medicine, nanotechnology has sparked a rapidly growing interest as it promises to solve a number of issues associated with conventional therapeutic agents, including their poor water solubility (at least, for most anticancer drugs), lack of targeting capability, nonspecific distribution, systemic toxicity, and low therapeutic index. Over the past several decades, remarkable progress has been made in the development and application of engineered nanoparticles to treat cancer more effectively. For example, therapeutic agents have been integrated with nanoparticles engineered with optimal sizes, shapes, and surface properties to increase their solubility, prolong their circulation half-life, improve their biodistribution, and reduce their immunogenicity. Nanoparticles and their payloads have also been favorably delivered into tumors by taking advantage of the pathophysiological conditions, such as the enhanced permeability and retention effect, and the spatial variations in the pH value. Additionally, targeting ligands (e.g., small organic molecules, peptides, antibodies, and nucleic acids) have been added to the surface of nanoparticles to specifically target cancerous cells through selective binding to the receptors overexpressed on their surface. Furthermore, it has been demonstrated that multiple types of therapeutic drugs and/or diagnostic agents (e.g., contrast agents) could be delivered through the same carrier to enable combination therapy with a potential to overcome multidrug resistance, and real-time readout on the treatment efficacy. It is anticipated that precisely engineered nanoparticles will emerge as the next-generation platform for cancer therapy and many other biomedical applications.

The influence of phospholipid on the physicochemical properties and anti-tumor efficacy of liposomes encapsulating cisplatin in mice bearing C26 colon carcinoma

SPI-077, cisplatin stealth liposome, is the best illustration of poor cisplatin release from liposomes and the subsequent negligible therapeutic activity. For this reason, optimizing drug release kinetics is desirable. In this report, cisplatin was encapsulated in liposomes composed of different phosphatidylcholines with various phase transition temperatures (Tm) (HSPC, DPPC, DMPC, soy phosphatidylcholine (SPC)), cholesterol and mPEG2000-DSPE. In vitro cytotoxicity studies indicated that lowering Tm of lipids increases cisplatin release; the highest cytotoxicity was observed in SPCs. Cisplatin plasma concentration was also sensitive to the transition temperature. The highest platinum concentration observed after treatment with HSPC and DPPC liposomes, whilst the lowest was observed with SPC. HSPC and DPPC containing liposomes showed the highest therapeutic efficacy and survival with DPPC exhibited better efficacy in mouse model of C26. It seems that DPPC with Tm (41.5°C) nearly, or close to body temperature maintains good drug retention in blood circulation. Upon extravasation through permeable tumor microvasculature, it gradually releases its payload in the tumor area better than HSPC, with a greater Tm of 55°C. Our data suggests, the choice of Tm for lipid mixture directed to a considerable extent the rate of cisplatin elimination from plasma and therapeutic effects.