A comparative study of folate receptor-targeted doxorubicin delivery systems: Dosing regimens and therapeutic index

Cancer nanomedicine from a clinician-scientist perspective: Lessons and prospects

The nanomedicine field has progressed enormously in the last couple of decades. From a loose group of liposomologists, polymer scientists, chemical engineers, and experts in metal nanoparticles, mesoporous silica, and other nanomaterials, the field has gradually consolidated and has generated vast amounts of research and clinical data, but, until the development of lipid nanoparticle (LNP)-based vaccinations for Covid-19, has remained with low visibility in the clinic. Applications in the cancer field are the most frequently sought projects in nanomedicine. For the last 45 years, my clinical career has mingled with my research career focusing on ways to formulate drugs in liposomes to improve their safety and efficacy in cancer therapy. In this review, I will discuss my contribution to the development of pegylated liposomal doxorubicin and other cancer nanomedicines from my privileged position as a clinician and scientist.

Trends in the research and development of peptide drug conjugates: artificial intelligence aided design

Peptide-drug conjugates (PDCs) represent an emerging class of targeted therapeutic agents that consist of small molecular drugs coupled to multifunctional peptides through cleavable or non-cleavable linkers. The principal advantage of PDCs lies in their capacity to deliver drugs to diseased tissues at increased local concentrations, thereby reducing toxicity and mitigating adverse effects by limiting damage to non-diseased tissues. Despite the increasing number of PDCs being developed for various diseases, their advancements remain relatively slow due to several development constraints, which include limited available peptides and linkers, narrow therapeutic applications, and incomplete evaluation and information platforms for PDCs. Marked by the recent Nobel Prize awarded to artificial intelligence (AI) and de novo protein design for "protein design and structure prediction," AI is playing an increasingly important role in drug discovery and development. In this review, we summarize the recent developments and limitations of PDCs, highlights the potential of AI in revolutionizing the design and evaluation of PDC.

The anti-glypican 1 AT101 antibody as targeting agent to effectively deliver chitosan nanobubbles to glioblastoma cells

BACKGROUND

Recently, we developed AT101, an IgM-class mouse monoclonal antibody directed against glypican-1 (GPC1), a proteoglycan that can be considered as useful target for glioblastoma multiforme (GBM) treatment being specifically and highly expressed on GBM cell surface. Here, we proposed the use of AT101 as targeting agent in a drug delivery nanoplatfom to effectively deliver chitosan nanobubbles (NBs) for GBM treatment.

METHODS

Chitosan NBs were prepared and conjugated with AT101 or left unconjugated as control.

RESULTS

The ability of AT101 to bind the GPC1 protein was demonstrated by flow cytometry and immunofluorescence analysis in the "GBM-like" GPC1-expressing cell lines U-87 MG and T98G. AT101 was shown to bind GPC1-expressing GBM tumor samples by immunofluorescence. In-vivo experiments in the U-87 MG xenograft model showed that AT101 was able to bind GPC1 on cell surface and accumulate in U-87 MG tumor masses (p = 0.0002 respect to control). Moreover, in-vivo experiments showed that AT101 is able to target GPC1 when conjugated to chitosan NBs, thus increasing their specific deliver to GPC1-expressing cells of U-87 MG tumor, as compared to chitosan NBs not conjugated to AT101 (p = 0.02).

CONCLUSIONS

AT101 is an useful targeting agent for the development of drug delivery nanoplatforms for GBM treatment.

Preparation of double-loaded bitter ginseng derivative B21-DOX liposomes co-modified with SP94 and BR2 ligand and its in vitro anti-hepatocarcinogenic effect

AIM

To construct a novel liposomal drug delivery system co-modified with SP94 and BR2 ligands, encapsulating both the bitter ginseng derivative B21 and doxorubicin (DOX), to achieve superior anti-tumour efficacy and reduced toxic side effects.

METHODS

Liposomes were prepared using an organic phase reaction method, with B21 encapsulated in the lipid phase and DOX in the aqueous phase. The liposomes were further modified with SP94 and BR2 peptides. The characterisations, cytotoxicity, and in vitro targeting effects were assessed through various methods including ultraviolet spectrophotometry, high-performance liquid chromatography, nano-size analysis, ultrafiltration centrifugation, dialysis, transmission electron microscopy, flow cytometry, Methylthiazolyldiphenyl-tetrazolium bromide assay, confocal laser scanning microscopy, transwell assay, and tumorsphere assay.

RESULTS

SP94/BR2-B21/DOX-LP liposomes were spherical with an average diameter of 120.87 ± 1.00 nm, a polydispersity index (PDI) of 0.223 ± 0.006, and a surface charge of -23.1 ± 1.27 mV. The encapsulation efficiencies for B21 and DOX were greater than 85% and 97% (mg/mg), respectively. The results indicated that SP94/BR2-B21/DOX-LP exhibited enhanced targeting and cytotoxicity compared to single-ligand modified and unmodified liposomes, with the combined encapsulation of B21 and DOX showing synergistic anti-hepatocarcinogenic effects.

CONCLUSION

SP94/BR2-B21/DOX-LP liposomes represent a promising targeted drug delivery system for hepatocellular carcinoma, offering improved membrane penetration, enhanced therapeutic efficacy, and reduced systemic toxicity.

Interaction mechanism of novel fluorescent antifolates targeted with folate receptors α and β via molecular docking and molecular dynamic simulations

Eight novel fluorescent antifolates were designed and docked with folate receptors FRα and FRβ. The structures of the complexes were further calculated by molecular dynamic (MD) simulations. The binding energies were calculated by molecular docking and molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) studies. The binding energy differences between FRα and FRβ (|E_bα|-|E_bβ|) values for compounds 3 and 8 were 1.3 and 1.1 kcal/mol calculated by molecular docking, and 13.9 and 10.4 kcal/mol by MM-PBSA simulation, respectively. The results indicated that compounds 3 and 8 may be the best candidates for targeted drug delivery to FRα. The binding structures, interaction residues, negatively charged pocket volume, and surface area were analyzed for all the complexes. We further calculated the root mean square displacement and secondary structural elements of the bound complexes using molecular dynamics simulations. The purpose of this study is to design novel antifolates targeted to FRα and FRβ, and to further distinguish between cancer cells and inflammation.

Design and evaluation of folate-modified liposomes for pulmonary administration in lung cancer therapy

Pulmonary drug administration for the treatment of lung cancer is useful because the drug is directly delivered to the lung tissues with minimal invasiveness and higher efficiency compared to other conventional methods. However, it is critical to enhance drug accumulation in the lung cancer tissues to achieve sufficient therapeutic efficacy. The submicron-sized liposome (ssLip) preparation is one of the most promising approaches to enhance drug accumulation in the lungs; however, ssLips prepared for conventional inhalation do not have tumour selectivity. Therefore, in this study, we prepared folate (FA)-modified ssLip (FA-ssLip) to enhance drug accumulation in folate receptor (FR)-expressing lung cancer cells, and evaluated its physicochemical properties and potential as a drug carrier in pulmonary administration. In addition, we prepared rapamycin (RM-an autophagy-inducing anticancer drug)-loaded FA-ssLip (RM/FA-ssLip) and investigated its anti-tumour effect. FA-ssLip showed excellent nanoparticle properties with submicron size (approximately 120 nm) and high lung accumulation in lung cancer mouse model-bearing LL2 cells-a mouse Lewis lung carcinoma cell line. RM/FA-ssLip showed significant cytotoxic activity in FR-expressing cancer cells. In addition, pulmonary administration of RM/FA-ssLip extended the survival of LL2 cell tumour-bearing mice. Taken together, our results suggest the potential of FA-ssLip as a pulmonary drug carrier for the efficient treatment of lung cancer.

Co-Delivery of Paclitaxel and shMCL-1 by Folic Acid-Modified Nonviral Vector to Overcome Cancer Chemotherapy Resistance

Acquired chemoresistance presents a major clinical impediment, which is an urgent problem to be solved. Interestingly, myeloma cell leukemia-1 (MCL-1) and folate receptor expression levels are higher in chemotherapy-resistant patients than in pretreatment patients. In this study, a multifunctional folic acid (FA)-targeting core-shell structure is presented for simultaneous delivery of shMCL-1 and paclitaxel (PTX). The transfection efficiency of shMCL-1 with the FA-targeting delivery system is higher than with a nontargeting delivery system in Skov3 and A2780T cells. The FA-targeting system significantly inhibits cell growth, blocks cell cycles, and promotes apoptosis of cancer cells in vitro. The mechanisms involved in inhibiting growth are related to Bcl-2/Bax and cdc2/Cyclin B1 pathways. An analysis of RNA sequencing suggests that shMCL-1 reverses chemoresistance through regulating genes such as regulator of chromosome condensation 2 (RCC2). The synergetic effect of shMCL-1 and PTX effectively inhibits tumor growth in both PTX-resistant and normal cancer models by inducing tumor apoptosis, inhibiting proliferation, and limiting tumor angiogenesis. The study results indicate that a FA-targeting delivery system combining shMCL-1 with PTX can simultaneously target tumor sites and restore the sensitivity of chemotherapy-resistant cancer to PTX. These findings have important implications for patients with normal or PTX-resistant cancer.

Developing Actively Targeted Nanoparticles to Fight Cancer: Focus on Italian Research

Active targeting is a valuable and promising approach with which to enhance the therapeutic efficacy of nanodelivery systems, and the development of tumor-targeted nanoparticles has therefore attracted much research attention. In this field, the research carried out in Italian Pharmaceutical Technology academic groups has been focused on the development of actively targeted nanosystems using a multidisciplinary approach. To highlight these efforts, this review reports a thorough description of the last 10 years of Italian research results on the development of actively targeted nanoparticles to direct drugs towards different receptors that are overexpressed on cancer cells or in the tumor microenvironment. In particular, the review discusses polymeric nanocarriers, liposomes, lipoplexes, niosomes, solid lipid nanoparticles, squalene nanoassemblies and nanobubbles. For each nanocarrier, the main ligands, conjugation strategies and target receptors are described. The literature indicates that polymeric nanoparticles and liposomes stand out as key tools for improving specific drug delivery to the site of action. In addition, solid lipid nanoparticles, squalene nanoparticles and nanobubbles have also been successfully proposed. Taken together, these strategies all offer many platforms for the design of nanocarriers that are suitable for future clinical translation.

Meet me halfway: Are in vitro 3D cancer models on the way to replace in vivo models for nanomedicine development?

The complexity and diversity of the biochemical processes that occur during tumorigenesis and metastasis are frequently over-simplified in the traditional in vitro cell cultures. Two-dimensional cultures limit researchers' experimental observations and frequently give rise to misleading and contradictory results. Therefore, in order to overcome the limitations of in vitro studies and bridge the translational gap to in vivo applications, 3D models of cancer were developed in the last decades. The three dimensions of the tumor, including its cellular and extracellular microenvironment, are recreated by combining co-cultures of cancer and stromal cells in 3D hydrogel-based growth factors-inclusive scaffolds. More complex 3D cultures, containing functional blood vasculature, can integrate in the system external stimuli (e.g. oxygen and nutrient deprivation, cytokines, growth factors) along with drugs, or other therapeutic compounds. In this scenario, cell signaling pathways, metastatic cascade steps, cell differentiation and self-renewal, tumor-microenvironment interactions, and precision and personalized medicine, are among the wide range of biological applications that can be studied. Here, we discuss a broad variety of strategies exploited by scientists to create in vitro 3D cancer models that resemble as much as possible the biology and patho-physiology of in vivo tumors and predict faithfully the treatment outcome.

Screening of chemical linkers for development of pullulan bioconjugates for intravitreal ocular applications

The treatment of posterior segment disorders of the eye requires therapeutic strategies to achieve drug effects over prolonged times. Innovative colloidal delivery systems can be designed to deliver drugs to the retina and prolong their intravitreal permanence. In order to exploit pullulan (Pull) as polymeric drug carrier for intravitreal drug delivery, derivatives of hydrophobic model molecule rhodamine B (RhB) were conjugated to the pullulan backbone through linkers with different stability, namely ether (Et), hydrazone (Hy) or ester (Es) bond to obtain Pull-Et-RhB, Pull-Hy-RhB and Pull-Es-RhB, respectively. Dynamic light scattering and transmission electron microscopy analyses showed that the polymer conjugates self-assembled into 20-25 nm particles. Pull-Et-RhB was fairly stable at all tested pH values. At the vitreal pH of 7.4, 50% of RhB was released from Pull-Hy-RhB and Pull-Es-RhB in 11 and 6 days, respectively. At endosomal pH (5.5), 50% of RhB was released from Pull-Hy-RhB and Pull-Es-RhB in 4 and 1 days, respectively. Multiple particle tracking analyses in ex vivo porcine eye model showed that the diffusivity of the bioconjugates in the vitreous was about 10³ times lower than in water. Flow cytometry and confocal microscopy analyses showed that bioconjugates are remarkably taken up by the retinal RPE cells. In vivo studies showed that after intravitreal injection to mice, the bioconjugates localize in the ganglion cell layer and in the inner and outer plexiform layers. Pull-Hy-RhB particles were detected also inside the retinal blood vessels. These results demonstrate that pullulan with tailored linkers for drug conjugation is a promising vehicle for long-acting intravitreal injectables that are capable to permeate to the retina.

Folic acid-modified celastrol nanoparticles: synthesis, characterization, anticancer activity in 2D and 3D breast cancer models

Celastrol is used in traditional Chinese medicine for treating cancers. However, its low water solubility and poor tumour selection represent major pitfalls for clinical application. In the present study, gold nanoparticle (AuNP) firstly was conjugated with PVP-co-2-dimethylaminoethyl methacrylate (Polymer) and celastrol then modified by folic acid. The as-prepared folate receptor-targeted celastrol AuNP (FCA) was characterized using attenuated total reflection Fourier transform infrared spectroscopy, UV-Vis spectrometry, transmission electron microscope, and inductively coupled plasma mass spectrometry. The physical properties of FCA were also determined in solubility, drug encapsulation and in vitro drug release. Its anticancer activities were assessed in the 2D and 3D breast cancer models. The results showed that FCA was synthesized successfully with good solubility, high encapsulation efficiency and loading content. FCA showed the optimal cumulative release at pH 5.0 and high cellular uptake and exhibited significant inhibition on breast cancer cells. FCA also induced more significant apoptosis either in 2D and 3D breast cancer model than the celastrol AuNP and celastrol alone. These findings demonstrate that FCA improves water solubility of celastrol and enhances its anticancer activities against breast cancer. FCA might be a potential candidate of anticancer drug for breast cancer in the future if further development.

Rational Design of Polyglutamic Acid Delivering an Optimized Combination of Drugs Targeting Mutated BRAF and MEK in Melanoma

Targeted therapies against cancer can relieve symptoms and induce remission, however, they often present limited duration of disease control, cause side effects and often induce acquired resistance. Therefore, there is a great motivation to develop a unique delivery system, targeted to the tumor, in which we can combine several active entities, increase the therapeutic index by reducing systemic exposure, and enhance their synergistic activity. To meet these goals, we chose the biocompatible and biodegradable poly(α,L-glutamic acid) (PGA) as a nanocarrier that facilitates extravasation-dependent tumor targeting delivery. The RAS/RAF/MEK/ERK pathway when aberrantly activated in melanoma, can lead to uncontrolled cell proliferation, induced invasion, and reduced apoptosis. Here, we selected two drugs targeting this pathway; a MEK1/2 inhibitor (selumetinib; SLM) and a modified BRAF inhibitor (modified dabrafenib; mDBF), that exhibited synergism in vitro. We synthesized and characterized our nanomedicine of PGA conjugated to SLM and mDBF (PGA-SLM-mDBF). PGA-SLM-mDBF inhibited the proliferation of melanoma cells and decreased their migratory and sprouting abilities without inducing a hemolytic effect. Moreover, the polymer-2-drugs conjugate exhibited superior anti-tumor activity in comparison with the two separate polymer-drug conjugates in vitro and with free drugs in a mouse model of primary melanoma and prolonged survival at a lower dose.

Type and size effect of functional groups on the novel antifolate target recognition folate receptors α and β: Docking, molecular dynamics and MM/PBSA study

A series of novel antifolates (32 compounds) were used to study the interactions with folate receptors α and β. The compounds had different sizes of methyl (-CH₃), carboxyl (-COOH), hydroxyl (-OH), and amino groups (-NH₂). The binding properties of the complexes were studied by molecular docking, molecular dynamic (MD) simulations, and MM/PBSA free energy calculations. The docked binding energies and modes were analyzed to identify compounds with good recognition of FRα from FRβ. The stable conformers, root mean square displacement, root mean square fluctuation free binding energy, and contribution of residues to the binding energy of the complexes were further analyzed to illustrate the interactions between the novel compounds and folate receptors. The data show that introducing long functional groups in folate will increase the binding affinity with FRα but will decrease the binding affinity with FRβ. The results provide a strategy for the design of novel antifolates targeted to FRα.

Targeted uptake of folic acid-functionalized polymeric nanoparticles loading glycoalkaloidic extract in vitro and in vivo assays

Solanum lycocarpum fruits contain two major glycoalkaloids (GAs), solamargine (SM) and solasonine (SS). These compounds are reported as cytotoxic. However, they have poor water solubility and low bioavailability. To overcome these disadvantages and getting an efficient formulation the current study aimed to develop, characterize, and test the effectiveness of a nanotechnology-based strategy using poly(D,L-lactide) (PLA) nanoparticles functionalized with folate as delivery system of glycoalkaloidic extract (AE) for bladder cancer therapy. The strategic of adding folic acid into nanoformulations can increase the selectivity of the compounds to the cancer cells reducing the side effects. Our results revealed the successful preparation of AE-loaded folate-targeted nanoparticles (NP-F-AE) with particle size around 177 nm, negative zeta potential, polydispersity index <0.20, and higher efficiency of encapsulation for both GAs present in the extract (>85 %). To investigate the cellular uptake, the fluorescent dye coumarin-6 was encapsulated into the nanoparticle (NP-F-C6). The cell studies showed high uptake of nanoparticles by breast (MDA-MB-231) and bladder (RT4) cancer cells, but not for normal keratinocytes cells (HaCaT) indicating the target uptake to cancer cells. The cytotoxicity of nanoparticles was evaluated on RT4 2D culture model showing 2.16-fold lower IC50 than the free AE. Furthermore, the IC50 increased on the RT4 spheroids compared to 2D model. The nanoparticles penetrated homogeneously into the urotheliumof porcine bladder. These results showed that folate-conjugated polymeric nanoparticles are potential carriers for targeted glycoalkaloidic extract delivery to bladder cancer cells.

Folic acid-modified nonionic surfactant vesicles for gambogenic acid targeting: Preparation, characterization, and in vitro and in vivo evaluation

The aim of present study was to develop folic acid (FA)-modified nonionic surfactant vesicles (NISVs, niosomes) as carrier systems for targeted delivery of gambogenic acid (GNA). The FA-GNA-NISVs exhibited a mean particle size of 180.77 ± 2.41 nm with a narrow poly dispersion index of 0.147 ± 0.08 determined by dynamic light scattering. Transmission electron microscopy also revealed that the FA-GNA-NISVs were spherical with double-layer structure. Entrapment efficiency (EE%) and zeta potential of the optimal FA-GNA-NISVs were 87.84 ± 1.06% and -37.33 ± 0.33 mV, respectively. Differential scanning calorimetry demonstrated that the GNA was in a molecular or amorphous state inside the FA-NISVs in vitro release profiles suggested that FA-GNA-NISVs could release GNA at a sustained manner, and less than 60% of GNA was released from the FA-NISVs within 12 hours of dialysis. in vivo pharmacokinetic results illustrated that FA-GNA-NISVs had considerably higher C_max , area under curve (AUC_0 - t ) and accumulation in lung. The cell proliferation study shown that the FA-GNA-NISVs significantly enhanced the in vitro cytotoxicity against A549 cells. Flow cytometry and fluorescence microscopy further demonstrated that the FA-GNA-NISVs increased apoptosis compared with nonmodified GNA-NISVs and free GNA. Moreover, FA-GNA-NISVs induced A549 cell apoptosis in a dose-dependent manner. In addition, cellular uptake assays showed a higher uptake of FA-GNA-NISVs than GNA-NISVs as well as free GNA. Taken together, it could be concluded that FA-GNA-NISVs were proposed as a novel targeting carriers for efficient delivering of GNA to cancers cells.

Improvement in the Anti-Tumor Efficacy of Doxorubicin Nanosponges in In Vitro and in Mice Bearing Breast Tumor Models

Doxorubicin (DOX) is an anthracycline widely used in cancer therapy and in particular in breast cancer treatment. The treatment with DOX appears successful, but it is limited by a severe cardiotoxicity. This work evaluated the in vitro and in vivo anticancer effect of a new formulation of β-cyclodextrin nanosponges containing DOX (BNS-DOX). The BNS-DOX effectiveness was evaluated in human and mouse breast cancer cell lines in vitro in terms of effect on cell growth, cell cycle distribution, and apoptosis induction; and in vivo in BALB-neuT mice developing spontaneous breast cancer in terms of biodistribution, cancer growth inhibition, and heart toxicity. BNS-DOX significantly inhibited cancer cell proliferation, through the induction of apoptosis, with higher efficiency than free DOX. The breast cancer growth in BALB-neuT mice was inhibited by 60% by a BNS-DOX dose five times lower than the DOX therapeutic dose, with substantial reduction of tumor neoangiogenesis and lymphangiogenesis. Biodistribution after BNS-DOX treatment revealed a high accumulation of DOX in the tumor site and a low accumulation in the hearts of mice. Results indicated that use of BNS may be an efficient strategy to deliver DOX in the treatment of breast cancer, since it improves the anti-cancer effectiveness and reduces cardiotoxicity.

Chitosan-based advanced materials for docetaxel and paclitaxel delivery: Recent advances and future directions in cancer theranostics

Paclitaxel (PTX) and docetaxel (DTX) are key members of taxanes with high anti-tumor activity against various cancer cells. These chemotherapeutic agents suffer from a number of drawbacks and it seems that low solubility in water is the most important one. Although much effort has been made in improving the bioavailability of PTX and DTX, the low bioavailability and minimal accumulation at tumor sites are still the challenges faced in PTX and DTX therapy. As a consequence, bio-based nanoparticles (NPs) have attracted much attention due to unique properties. Among them, chitosan (CS) is of interest due to its great biocompatibility. CS is a positively charged polysaccharide with the capability of interaction with negatively charged biomolecules. Besides, it can be processed into the sheet, micro/nano-particles, scaffold, and is dissolvable in mildly acidic pH similar to the pH of the tumor microenvironment. Keeping in mind the different applications of CS in the preparation of nanocarriers for delivery of PTX and DTX, in the present review, we demonstrate that how CS functionalized-nanocarriers and CS modification can be beneficial in enhancing the bioavailability of PTX and DTX, targeted delivery at tumor site, image-guided delivery and co-delivery with other anti-tumor drugs or genes.

Interacted mechanism of functional groups in ligand targeted with folate receptor via docking, molecular dynamic and MM/PBSA

Twenty novel compounds with different functional groups (-COOH, -OH, -NH2 and -CH3) were designed to study the interaction mechanism of ligands with folate receptors (FRs). The optimized structure and the dipole moment of the novel compounds were calculated by a density functional tight-binding method (DFTB). The binding mechanism of the compounds with FRs was studied by molecular docking, molecular dynamic (MD) simulations and MM/PBSA free energy calculations. The binding energies, root mean square displacement and root mean square fluctuation of the complexes were analyzed to further illustrate the effect of the functional groups. The functional groups play important roles in stabilizing the bound complexes. Compared to other groups, -OH is more stably linked with the compound. These data provide a theoretical basis for the design of novel compounds targeted with FRs.

Amphiphilic Polymeric Micelles Based on Deoxycholic Acid and Folic Acid Modified Chitosan for the Delivery of Paclitaxel

The present investigation aimed to develop a tumor-targeting drug delivery system for paclitaxel (PTX). The hydrophobic deoxycholic acid (DA) and active targeting ligand folic acid (FA) were used to modify water-soluble chitosan (CS). As an amphiphilic polymer, the conjugate FA-CS-DA was synthesized and characterized by Proton nuclear magnetic resonance (¹H-NMR) and Fourier-transform infrared spectroscopy (FTIR) analysis. The degree of substitutions of DA and FA were calculated as 15.8% and 8.0%, respectively. In aqueous medium, the conjugate could self-assemble into micelles with the critical micelle concentration of 6.6 × 10⁻³ mg/mL. Under a transmission electron microscope (TEM), the PTX-loaded micelles exhibited a spherical shape. The particle size determined by dynamic light scattering was 126 nm, and the zeta potential was +19.3 mV. The drug loading efficiency and entrapment efficiency were 9.1% and 81.2%, respectively. X-Ray Diffraction (XRD) analysis showed that the PTX was encapsulated in the micelles in a molecular or amorphous state. In vitro and in vivo antitumor evaluations demonstrated the excellent antitumor activity of PTX-loaded micelles. It was suggested that FA-CS-DA was a safe and effective carrier for the intravenous delivery of paclitaxel.

Nanoformulations of doxorubicin: how far have we come and where do we go from here?

Nanotechnology, focused on discovery and development of new pharmaceutical products is known as nanopharmacology, and one research area this branch is engaged in are nanopharmaceuticals. The importance of being nano has been particularly emphasized in scientific areas dealing with nanomedicine and nanopharmaceuticals. Nanopharmaceuticals, their routes of administration, obstacles and solutions concerning their improved application and enhanced efficacy have been briefly yet comprehensively described. Cancer is one of the leading causes of death worldwide and evergrowing number of scientific research on the topic only confirms that the needs have not been completed yet and that there is a wide platform for improvement. This is undoubtedly true for nanoformulations of an anticancer drug doxorubicin, where various nanocarrriers were given an important role to reduce the drug toxicity, while the efficacy of the drug was supposed to be retained or preferably enhanced. Therefore, we present an interdisciplinary comprehensive overview of interdisciplinary nature on nanopharmaceuticals based on doxorubicin and its nanoformulations with valuable information concerning trends, obstacles and prospective of nanopharmaceuticals development, mode of activity of sole drug doxorubicin and its nanoformulations based on different nanocarriers, their brief descriptions of biological activity through assessing in vitro and in vivo behavior.

Liposome-chaperoned cell-free synthesis for the design of proteoliposomes: Implications for therapeutic delivery

Cell-free (CF) protein synthesis has emerged as a powerful technique platform for efficient protein production in vitro. Liposomes have been widely studied as therapeutic carriers due to their biocompatibility, biodegradability, low toxicity, flexible surface manipulation, easy preparation, and higher cargo encapsulation capability. However, rapid immune clearance, insufficient targeting capacity, and poor cytoplasmic delivery efficiency substantially restrict their clinical application. The incorporation of functional membrane proteins (MPs) or peptides allows the transfer of biological properties to liposomes and imparts them with improved circulation, increased targeting, and efficient intracellular delivery. Liposome-chaperoned CF synthesis enables production of proteoliposomes in one-step reaction, which not only substantially simplifies the production procedure but also keeps protein functionality intact. Building off these observations, proteoliposomes with integrated MPs represent an excellent candidate for therapeutic delivery. In this review, we describe recent advances in CF synthesis with emphasis on detailing key factors for improving CF expression efficiency. Furthermore, we provide insights into strategies for rational design of proteoliposomal nanodelivery systems via CF synthesis.

STATEMENT OF SIGNIFICANCE

Liposome-chaperoned CF synthesis has emerged as a powerful approach for the design of recombinant proteoliposomes in one-step reaction. The incorporation of bioactive MPs or peptides into liposomes via CF synthesis can facilitate the development of proteoliposomal nanodelivery systems with improved circulation, increased targeting, and enhanced cellular delivery capacity. Moreover, by adapting lessons learned from natural delivery vehicles, novel bio-inspired proteoliposomes with enhanced delivery properties could be produced in CF systems. In this review, we first give an overview of CF synthesis with focus on enhancing protein expression in liposome-chaperoned CF systems. Furthermore, we intend to provide insight into harnessing CF-synthesized proteoliposomes for efficient therapeutic delivery.

Novel fluorescent antifolates that target folate receptors α and β: Molecular dynamics and density functional theory study

Nine novel fluorescent antifolates, 1-9, were designed and docked with FRα and FRβ. The binding energies of the bound complexes were determined by molecular docking and MM-PBSA studies. The structural properties of the complexes FR-FOL, FR-7, FR-8 and FR-9 were analyzed in detail via molecular docking and molecular dynamics studies. We further calculated the root mean square displacement and root mean square fluctuation of the bound complexes using molecular dynamics simulations. Since compounds 7, 8 and 9 are promising candidate in distinguishing FRα from FRβ, the hydrogen bond properties of complexes FRα-7, FRα-8 and FRα-9 were studied by a dispersion complemented density functional tight-binding method. The purpose of this study is to provide a rationale for the design of novel fluorescent antifolates targeted with FRα and FRβ.

Folate receptor-mediated celastrol and irinotecan combination delivery using liposomes for effective chemotherapy

Drug targeting using functionalized nanoparticles provides a new standard in anticancer therapy. Liposomes, safe and effective drug delivery carriers, can incorporate both hydrophilic and hydrophobic drugs for combination chemotherapy treatment of cancers. The objectives of the current study were to synthesize and test the effectiveness of a nanotechnology-based strategy utilizing folic acid (FA)-conjugated liposomes that incorporate both celastrol (Cs) and irinotecan (Ir) for targeted breast cancer therapy. Our results revealed the successful preparation of Cs and Ir-loaded folate-targeted liposomes (Lipo/Cs/Ir-FA) with a small particle size (∼190 nm) and polydispersity index (∼0.10). The formulation exhibited higher drug release profiles for both Ir and Cs at pH 5.0 compared to those at physiological pH, favoring cancer cell-targeted release. Furthermore, in vitro cell studies showed high uptake and enhanced apoptosis in folate receptor-positive breast cancer cells (MCF-7 and MDA-MB-231), but not in folate receptor-negative lung cancer cells (A549). Moreover, an in vivo study in a mouse tumor model using MDA-MB-231 xenografts supported effective drug delivery behavior of the folate-conjugated liposomes by selective targeting of tumor tissue and minimizing systemic adverse effects. Therefore, our formulation could provide an effective therapy for targeted cancer treatment.

Synergistic tumor microenvironment targeting and blood-brain barrier penetration via a pH-responsive dual-ligand strategy for enhanced breast cancer and brain metastasis therapy

Cancer associated fibroblasts (CAFs) which shape the tumor microenvironment (TME) and the presence of blood brain barrier (BBB) remain great challenges in targeting breast cancer and its brain metastasis. Herein, we reported a strategy using PTX-loaded liposome co-modified with acid-cleavable folic acid (FA) and BBB transmigrating cell penetrating peptide dNP2 peptide (cFd-Lip/PTX) for enhanced delivery to orthotopic breast cancer and its brain metastasis. Compared with single ligand or non-cleavable Fd modified liposomes, cFd-Lip exhibited synergistic TME targeting and BBB transmigration. Moreover, upon arrival at the TME, the acid-cleavable cFd-Lip/PTX showed sensitive cleavage of FA, which reduced the hindrance effect and maximized the function of both FA and dNP2 peptide. Consequently, efficient targeting of folate receptor (FR)-positive tumor cells and FR-negative CAFs was achieved, leading to enhanced anti-tumor activity. This strategy provides a feasible approach to the cascade targeting of TME and BBB transmigration in orthotopic and metastatic cancer treatment.

Selective Cell Penetrating Peptide-Functionalized Polymersomes Mediate Efficient and Targeted Delivery of Methotrexate Disodium to Human Lung Cancer In Vivo

It is a long challenge to develop nanomedicines that simultaneously possess tumor cell selectivity and penetration functions. Here, it is reported that selective cell penetrating peptide (RLWMRWYSPRTRAYGC)-functionalized polymersomes (SCPP-PS) mediate efficient and targeted delivery of methotrexate disodium (MTX) to human lung cancer in vivo. SCPP-PS with an SCPP density of 18.7% is self-crosslinked, has a small size (63-65 nm), and high MTX loading (up to 19.4 wt%), shows selective uptake and fast penetration into A549 lung cancer cells, and efficiently releases MTX intracellularly. Interestingly, MTX-loaded SCPP-PS (MTX-SCPP-PS) displays much lower IC₅₀ than those of MTX-PS and free MTX. Installing SCPP to polymersomes has no detrimental effect to their long blood circulation time but significantly increases drug accumulation in A549 tumor (5.3% injected dose per gram at 8 h post injection). Remarkably, SCPP-PS exhibits deep penetration in to A549 tumors. MTX-SCPP-PS completely inhibits tumor progression and significantly improves survival rates in mice bearing A549 lung tumor xenografts as compared to MTX-PS and free MTX groups (median survival time: 75 vs 45 and 38 d, respectively), without causing noticeable adverse effects. These results highlight that functionalization of nanomedicines with SCPP is a feasible strategy to achieve efficient and targeted tumor therapy.

PEGylated dendritic polyglycerol conjugate targeting NCAM-expressing neuroblastoma: Limitations and challenges

Neural cell adhesion molecule (NCAM) is found to be a stem-cell marker in several tumor types and its overexpression is known to correlate with increased metastatic capacity. To combine extravasation- and ligand-dependent targeting to NCAM overexpressing-cells in the tumor microenvironment, we developed a PEGylated NCAM-targeted dendritic polyglycerol (PG) conjugate. Here, we describe the synthesis, physico-chemical characterization and biological evaluation of a PG conjugate bearing the mitotic inhibitor paclitaxel (PTX) and an NCAM-targeting peptide (NTP). PG-NTP-PTX-PEG was evaluated for its ability to inhibit neuroblastoma progression in vitro and in vivo as compared to non-targeted derivatives and free drug. NCAM-targeted conjugate inhibited the migration of proliferating endothelial cells, suggesting it would be able to inhibit tumor angiogenesis. The targeting conjugate provided an improved binding and uptake on IMR-32 cells compared to non-targeted control. However, these results did not translate to our in vivo model on orthotopic neuroblastoma bearing mice.

Integrated Multifunctional Micelles Co-Self-Assembled from Polypeptides Conjugated with Natural Ferulic Acid and Lipoic Acid for Doxorubicin Delivery

The development of safe, easily accessible, and multifunctional nanocarriers is a big topic in nanomedicine research. Here, integrated multifunctional micelles (IMM) were developed by co-self-assembly of poly(ethylene glycol)-b-poly(l-lysine) derivatives with natural ferulic acid (FA) or lipoic acid (LA). FA confers IMM with intrinsic antitumor activity, improved loading of doxorubicin (DOX) through π-π stacking, and reduced DOX cardiotoxicity. LA provides IMM with reversible crosslinking property, which leads to a high colloidal stability with inhibited drug leakage and triggered intracellular DOX release. Notably, our results showed that cRGD-decorated IMM (cRGD-IMM) had a small size (≈56 nm) and superior loading of DOX (27.1 wt. %). Blank cRGD-IMM, though nontoxic to normal cells, exhibited obvious antiproliferative activity against cancer cells including B16F10 and HCT-116 cells at 150 μg FA equiv. mL^-1 . DOX-loaded cRGD-IMM displayed enhanced growth inhibition of α_v β₃ -positive B16F10 and HCT-116 cells, a long elimination half-life of 3.85 h, and a high maximum-tolerated dose of over 100 mg DOX equiv. kg^-1 . Histological analysis revealed that DOX-loaded cRGD-IMM at 100 mg DOX equiv. kg^-1 caused negligible cardiotoxicity, which is a major issue for the clinical use of DOX. These integrated multifunctional micelles with excellent safety and accessibility have emerged as a new platform for targeted cancer chemotherapy.

Targeting tumor microenvironment to curb chemoresistance via novel drug delivery strategies

INTRODUCTION

Tumor is a heterogeneous mass of malignant cells co-existing with non-malignant cells. This co-existence evolves from the initial developmental stages of the tumor and is one of the hallmarks of cancer providing a protumorigenic niche known as tumor microenvironment (TME). Proliferation, invasiveness, metastatic potential and maintenance of stemness through cross-talk between tumors and its stroma forms the basis of TME.

AREAS COVERED

The article highlights the developmental phases of a tumor from dysplasia to the formation of clinically detectable tumors. The authors discuss the mechanistic stages involved in the formation of TME and its contribution in tumor outgrowth and chemoresistance. The authors have reviewed various approaches for targeting TME and its hallmarks along with their advantages and pitfalls. The authors also highlight cancer stem cells (CSCs) that are resistant to chemotherapeutics and thus a primary reason for tumor recurrence thereby, posing a challenge for the oncologists.

EXPERT OPINION

Recent understanding of the cellular and molecular mechanisms involved in acquired chemoresistance has enabled scientists to target the tumor niche and TME and modulate and/or disrupt this communication leading to the transformation from a tumor-supportive niche environment to a tumor-non-supporting environment and give synergistic results towards an effective management of cancer.

Antiproliferative Activity and VEGF Expression Reduction in MCF7 and PC-3 Cancer Cells by Paclitaxel and Imatinib Co-encapsulation in Folate-Targeted Liposomes

Co-encapsulation of anticancer drugs paclitaxel and imatinib in nanocarriers is a promising strategy to optimize cancer treatment. Aiming to combine the cytotoxic and antiangiogenic properties of the drugs, a liposome formulation targeted to folate receptor co-encapsulating paclitaxel and imatinib was designed in this work. An efficient method was optimized for the synthesis of the lipid anchor DSPE-PEG(2000)-folic acid (FA). The structure of the obtained product was confirmed by RMN, FT-IR, and ESI-MS techniques. A new analytical method was developed and validated for simultaneous quantification of the drugs by liquid chromatography. Liposomes, composed of phosphatidylcholine, cholesterol, and DSPE-mPEG(2000), were prepared by extrusion. Their surface was modified by post-insertion of DSPE-PEG(2000)-FA. Reaction yield for DSPE-PEG(2000)-FA synthesis was 87%. Liposomes had a mean diameter of 122.85 ± 1.48 nm and polydispersity index of 0.19 ± 0.01. Lyophilized formulations remained stable for 60 days in terms of size and drug loading. FA-targeted liposomes had a higher effect on MCF7 cell viability reduction (p < 0.05) when compared with non-targeted liposomes and free paclitaxel. On PC-3 cells, viability reduction was greater (p < 0.01) when cells were exposed to targeted vesicles co-encapsulating both drugs, compared with the non-targeted formulation. VEGF gene expression was reduced in MCF7 and PC-3 cells (p < 0.0001), with targeted vesicles exhibiting better performance than non-targeted liposomes. Our results demonstrate that multifunctional liposomes associating molecular targeting and multidrug co-encapsulation are an interesting strategy to achieve enhanced internalization and accumulation of drugs in targeted cells, combining multiple antitumor strategies.

Control of targeting ligand display by pH-responsive polymers on gold nanoparticles mediates selective entry into cancer cells

Selective targeting of cells for intracellular delivery of therapeutics represents a major challenge for pharmaceutical intervention in disease. Here we show pH-triggered receptor-mediated endocytosis of nanoparticles via surface ligand exposure. Gold nanoparticles were decorated with two polymers: a 2 kDa PEG with a terminal folate targeting ligand, and a di-block copolymer including a pH-responsive and a hydrophilic block. At the normal serum pH of 7.4, the pH-responsive block (apparent pK_a of 7.1) displayed a hydrophilic extended conformation, shielding the PEG-folate ligands, which inhibited cellular uptake of the nanoparticles. Under pH conditions resembling those of the extracellular matrix around solid tumours (pH 6.5), protonation of the pH-responsive polymer triggered a coil-to-globule polymer chain contraction, exposing folate residues on the PEG chains. In line with this, endocytosis of folate-decorated polymer-coated gold nanoparticles in cancer cells overexpressing folate receptor was significantly increased at pH 6.5, compared with pH 7.4. Thus, the tumour acidic environment and high folate receptor expression were effectively exploited to activate cell binding and endocytosis of these nanoparticles. These data provide proof-of-concept for strategies enabling extracellular pH stimuli to selectively enhance cellular uptake of drug delivery vectors and their associated therapeutic cargo.

Folate-targeted polymersomes loaded with both paclitaxel and doxorubicin for the combination chemotherapy of hepatocellular carcinoma

Combination chemotherapy is a promising method of improving cancer treatment, but the distinct pharmacokinetics of combined drugs and non-specific drug distribution slow down the development in the clinic. In this study, folate (FA) receptor-targeted polymersomes with apparent bilayered lamellar structure were successfully developed to co-encapsulate a hydrophobic-hydrophilic chemotherapeutic drug pair (PTX and DOX) in a single vesicle for enhancing the combination chemotherapeutic effect. Hydrophobic PTX was loaded into the thick hydrophobic lamellar membrane by the self-assembly of triblock copolymer PCL₈₀₀₀-PEG₈₀₀₀-PCL₈₀₀₀, while hydrophilic DOX was encapsulated into the hydrophilic reservoir using a trans-membrane ammonium sulfate gradient method. In vitro release study indicated that the drugs were released from the polymersomes in a controlled and sustained manner. Cellular uptake study indicated that FA-targeted Co-PS had higher internalization efficiency in FA receptor-overexpressing BEL-7404 cells than non-targeted Co-PS. In vitro cytotoxicity assay demonstrated that FA-targeted Co-PS exhibited less cytotoxic effect than free drug cocktail, but suppressed the growth of tumor cells more efficiently than non-targeted Co-PS. Ex vivo imaging biodistribution studies revealed that FA-targeted Co-PS led to highly efficient targeting and accumulation in the BEL-7404 xenograft tumor. Furthermore, the in vivo antitumor study showed that the combination chemotherapy of polymersomes to BEL-7404 tumor via intravenous injection was superior to free drug cocktail treatment, and the FA-targeted Co-PS exhibited significantly higher tumor growth inhibition than non-targeted Co-PS group. Therefore, the newly developed FA-targeted co-delivery polymersomes hold great promise for simultaneous delivery of multiple chemotherapeutics and would have great potential in tumor-targeting and combination chemotherapy.

STATEMENT OF SIGNIFICANCE

Combination chemotherapy is a promising method of improving cancer treatment, but the distinct pharmacokinetics of combined drugs and non-specific drug distribution slow down the development in the clinic. In our study, novel folate-targeted co-delivery polymersomes (Co-PS) were successfully developed to encapsulate a hydrophobic-hydrophilic chemotherapeutic drug pair (paclitaxel and doxorubicin) into the different compartments of the vesicle. In vivo studies revealed that the combination chemotherapy of polymersomes to BEL-7404 xenograft tumor via intravenous injection was superior to free drug cocktail treatment, and the FA-targeted Co-PS exhibited significantly higher tumor growth inhibition than non-targeted Co-PS group. Therefore, the newly developed FA-targeted co-delivery polymersomes hold great promise for simultaneous delivery of multiple chemotherapeutics and would have great potential in tumor-targeting and combination chemotherapy.

Cytochrome P450 and P-Glycoprotein-Mediated Interactions Involving African Herbs Indicated for Common Noncommunicable Diseases

Herbal remedies are regularly used to complement conventional therapies in the treatment of various illnesses in Africa. This may be because they are relatively cheap and easily accessible and are believed by many to be safe, cause fewer side effects, and are less likely to cause dependency. On the contrary, many herbs have been shown to alter the pharmacokinetics of coadministered allopathic medicines and can either synergize or antagonize therapeutic effects as well as altering the toxicity profiles of these drugs. Current disease burden data point towards epidemiological transitions characterised by increasing urbanization and changing lifestyles, risk factors for chronic diseases like hypertension, diabetes, and cancer which often present as multimorbidities. As a result, we highlight African herb-drug interactions (HDIs) modulated via cytochrome P450 enzyme family (CYP) and P-glycoprotein (P-gp) and the consequences thereof in relation to antihypertensive, antidiabetic, and anticancer drugs. CYPs are enzymes which account for to up to 70% of drug metabolism while P-gp is an efflux pump that extrudes drug substrates out of cells. Consequently, regulation of the relative activity of both CYP and P-gp by African herbs influences the effective drug concentration at the site of action and modifies therapeutic outcomes.

“Click” functionalization of dual stimuli-responsive polymer nanocapsules for drug delivery systems

“Clickable” and dual stimuli-responsive nanocapsules were developed for facile surface functionalizationviathiol–yne click chemistry and employed as drug nano-carriers.

Preclinical Evaluation of an Epidermal Growth Factor Receptor-Targeted Doxorubicin-Peptide Conjugate: Toxicity, Biodistribution, and Efficacy in Mice

Doxorubicin (DOX) is known to induce apoptosis and necrosis in healthy tissue resulting in unwanted toxicities. To improve the ability of DOX to more specifically target tumors and minimize undesirable side effects, conjugation of DOX with epidermal growth factor receptor (EGFR)--binding peptide (DOX-EBP) has been developed to deliver DOX to EGFR-overexpressing neoplastic cells. Here, we investigated whether DOX-EBP was able to reduce toxicity and enhance anticancer efficacy in vivo through receptor-mediated targeted delivery system. Nude mice were treated with DOX or DOX-EBP to estimate general toxicity, normal tissue damage, biodistribution, and antitumor efficacy. In addition, the expression levels of EGFR in tumor tissues and normal organs were investigated by Western blotting, and their mRNA expression was analyzed by reverse transcription PCR. This study demonstrated that DOX-EBP was able to effectively decrease the distribution of DOX in normal tissues without EGFR overexpressing and reduce DOX-induced toxicity. On the other hand, the research also confirmed that DOX-EBP was able to preferentially accumulate DOX in EGFR-overexpressing tumor tissues and showed the enhanced anticancer efficacy over free DOX. DOX-EBP could be used for receptor-targeted chemotherapy with less toxicity and greater efficacy of tumor cells overexpressing EGFR. DOX-EBP conjugate is a good therapeutic agent for cancer treatment.

Bridging the Gap between Macroscale Drug Delivery Systems and Nanomedicines: A Nanoparticle-Assembled Thermosensitive Hydrogel for Peritumoral Chemotherapy

The objective of this study was to investigate the spatiotemporal delivery of nanomedicines by an injectable, thermosensitive, and nanoparticle-self-aggregated hydrogel for peritumoral chemotherapy. Doxorubicin (Dox) was taken as the model medicine, which was encapsulated into poly(ε-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone)-poly(ethylene glycol)-poly(ε-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone) (PECT) nanoparticles (PECT/Dox NPs). Macroscale hydrogel was formed by thermosensitive self-aggregation of PECT/Dox NPs in aqueous solution. Drug release from the hydrogel formulation was dominated by sustained shedding of PECT/Dox NPs and the following drug diffusion from these NPs. The hydrogel retention and release pattern of NPs in vivo was further confirmed by fluorescence resonance energy transfer (FRET) imaging. A single treatment with the hydrogel formulation possessed similar cytotoxicity against HepG2 cells compared to triple administrations of free Dox or PECT/Dox NPs in vitro due to enhanced uptake of PECT/Dox NPs and sustained intracellular drug release. Importantly, single peritumoral injection of drug-encapsulated hydrogel in vivo showed advantages over multiple intravenous administrations of PECT/Dox NPs and free Dox, including preferential and prolonged local drug accumulation and retention in tumors, resulting in superior cancer chemotherapy efficiency. Collectively, such a unique thermosensitive and nanoparticle-shedding hydrogel could effectively combine the advantages of nanomedicines and macroscale drug delivery systems, demonstrating great potential in the local nanodrugs' delivery. It will open a new promising path for cancer chemotherapy with enhanced treatment efficacy and minimized side effects.

Anti-cancer activity of doxorubicin-loaded liposomes co-modified with transferrin and folic acid

Cancer-specific drug delivery represents an attractive approach to prevent undesirable side-effects and increase the accumulation of the drug in the tumor. Surface modification of nanoparticles such as liposomes with targeting moieties specific to the up-regulated receptors on the surface of tumor cells thus represents an effective strategy. Furthermore, since this receptor expression can be heterogeneous, using a dual-combination of targeting moieties may prove advantageous. With this in mind, the anti-cancer activity of PEGylated doxorubicin-loaded liposomes targeted with folic acid (F), transferrin (Tf) or both (F+Tf) was evaluated. The dual-targeted liposomes showed a 7-fold increase in cell association compared to either of the single-ligand targeted ones in human cervical carcinoma (HeLa) cell monolayers. The increased penetration and cell association of the dual-targeted liposomes were also demonstrated using HeLa cell spheroids. The in vitro cytotoxicity of the doxorubicin liposomes (LD) was then evaluated using HeLa and A2780-ADR ovarian carcinoma cell monolayers. In both these cell lines, the (F+Tf) LD showed significantly higher cytotoxic effects than the untargeted, or single-ligand targeted liposomes. In a HeLa xenograft model in nude mice, compared to the untreated group, though the untargeted LD showed 42% tumor growth inhibition, both the (F) LD and (F+Tf) LD showed 75% and 79% tumor growth inhibition respectively. These results thus highlight that though the dual-targeted liposomes represent an effective cytotoxic formulation in the in vitro setting, they were equally effective as the folic acid-targeted liposomes in reducing tumor burden in the more complex in vivo setting in this particular model.