Development of synthetic peptide-modified liposomes with LDL receptor targeting capacity and improved anticancer activity

Advances in Drug Delivery Systems for the Treatment of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a common and catastrophic hematological neoplasm with high mortality rates. Conventional therapies, including chemotherapy, hematopoietic stem cell transplantation (HSCT), immune therapy, and targeted agents, have unsatisfactory outcomes for AML patients due to drug toxicity, off-target effects, drug resistance, drug side effects, and AML relapse and refractoriness. These intrinsic limitations of current treatments have promoted the development and application of nanomedicine for more effective and safer leukemia therapy. In this review, the classification of nanoparticles applied in AML therapy, including liposomes, polymersomes, micelles, dendrimers, and inorganic nanoparticles, is reviewed. In addition, various strategies for enhancing therapeutic targetability in nanomedicine, including the use of conjugating ligands, biomimetic-nanotechnology, and bone marrow targeting, which indicates the potential to reverse drug resistance, are discussed. The application of nanomedicine for assisting immunotherapy is also involved. Finally, the advantages and possible challenges of nanomedicine for the transition from the preclinical phase to the clinical phase are discussed.

Effects of Surface IR783 Density on the In Vivo Behavior and Imaging Performance of Liposomes

Background: Nanoparticles conjugated with fluorescent probes have versatile applications, serving not only for targeted fluorescent imaging but also for evaluating the in vivo profiles of designed nanoparticles. However, the relationship between fluorophore density and nanoparticle behavior remains unexplored. Methods: The IR783-modified liposomes (IR783-sLip) were prepared through a modified ethanol injection and extrusion method. The cellular uptake efficiency of IR783-sLip was characterized by flow cytometry and fluorescence microscope imaging. The effects of IR783 density on liposomal in vivo behavior were investigated by pharmacokinetic studies, biodistribution studies, and in vivo imaging. The constitution of protein corona was analyzed by the Western blot assay. Results: Dense IR783 modification improved cellular uptake of liposomes in vitro but hindered their blood retention and tumor imaging performance in vivo. We found a correlation between IR783 density and protein corona absorption, particularly IgM, which significantly impacted the liposome performance. Meanwhile, we observed that increasing IR783 density did not consistently improve the effectiveness of tumor imaging. Conclusions: Increasing the density of modified IR783 on liposomes is not always beneficial for tumor near-infrared (NIR) imaging yield. It is not advisable to prematurely evaluate novel nanomaterials through fluorescence dye conjugation without carefully optimizing the density of the modifications.

Multifunctional targetable liposomal drug delivery system in the management of leukemia: Potential, opportunities, and emerging strategies

The concern impeding the success of chemotherapy in leukemia treatment is descending efficacy of drugs because of multiple drug resistance (MDR). The previous failure of traditional treatment methods is primarily responsible for the present era of innovative agents to treat leukemia effectively. The treatment option is a chemotherapeutic agent in most available treatment strategies, which unfortunately leads to high unavoidable toxicities. As a result of the recent surge in marketed products, theranostic nanoparticles, i.e., multifunctional targetable liposomes (MFTL), have been approved for improved and more successful leukemia treatment that blends therapeutic and diagnostic characteristics. Since they broadly offer the required characteristics to get past the traditional/previous limitations, such as the absence of site-specific anti-cancer therapeutic delivery and ongoing real-time surveillance of the leukemia target sites while administering therapeutic activities. To prepare MFTL, suitable targeting ligands or tumor-specific antibodies are required to attach to the surface of the liposomes. This review exhaustively covered and summarized the liposomal-based formulation in leukemia treatment, emphasizing leukemia types; regulatory considerations, patents, and clinical portfolios to overcome clinical translation hurdles have all been explored.

Recent Development of LDL-Based Nanoparticles for Cancer Therapy

Low-density lipoprotein (LDL), a natural lipoprotein transporting cholesterol in the circulatory system, has been a possible drug carrier for targeted delivery. LDL can bind to the LDL receptor (LDLR) with its outside apolipoprotein B-100 and then enter the cell via LDLR-mediated endocytosis. This targeting function inspires researchers to modify LDL to deliver different therapeutic drugs. Drugs can be loaded in the surficial phospholipids, hydrophobic core, or apolipoprotein for the structure of LDL. In addition, LDL-like synthetic nanoparticles carrying therapeutic drugs are also under investigation for the scarcity of natural LDL. In addition to being a carrier, LDL can also be a targeting molecule, decorated to the surface of synthetic nanoparticles loaded with cytotoxic compounds. This review summarizes the properties of LDL and the different kinds of LDL-based delivery nanoparticles, their loading strategies, and the achievements of the recent anti-tumor advancement.

Delivery strategies in treatments of leukemia

Leukemia is a hematological malignancy associated with the uncontrolled proliferation of mutant progenitors, suppressing the production of normal blood cells. Current treatments, including chemotherapy, radiotherapy, and immunotherapy, still lead to unsatisfactory results with a 5 year survival rate of only 30-50%. The poor prognosis is related to both disease relapse and treatment-associated toxicity. Delivery strategies can improve the in vivo pharmacokinetics of drugs, navigating the therapeutics to target cells or the tumor microenvironment and reversing drug resistance, which maximizes tumor elimination and alleviates systematic adverse effects. This review discusses available FDA-approved anti-leukemia drugs and therapies with a focus on the advances in the development of anti-leukemia drug delivery systems. Additionally, challenges in clinical translation of the delivery strategies and future research opportunities in leukemia treatment are also included.

Peptide-functionalized liposomes as therapeutic and diagnostic tools for cancer treatment

Clinically efficacious medication in anticancer therapy has been successfully designed with liposome-based nanomedicine. The liposomal formulation in cancer drug delivery can be facilitated with a functionalized peptide that mediates the specific drug delivery opportunities with increased drug penetrability, specific accumulation in the targeted site, and enhanced therapeutic efficacy. This review aims to focus on recent advances in peptide-functionalized liposomal formulation techniques in cancer diagnosis and treatment regarding recently published literature. It also will highlight different aspects of novel liposomal formulation techniques that incorporate surface functionalization with peptides for better anticancer effect and current challenges in peptide-functionalized liposomal drug formulation.

Enhanced cytotoxicity of highly water-soluble gold nanoparticle-cyclopeptide conjugates in cancer cells

Conjugation of cytostatic drugs to nanomaterials seeks to improve their low bioavailability and selectivity to overcome the important associated side effects. In this work, we aimed to synthesize water-soluble gold nanoparticles as transporters for synthetic cyclic peptides with a potential anticancer activity but with a limited bioavailability. The highly water-soluble nanoparticles (2.5 nm diameter gold core) are coated with a mixture of polyethylene glycol linkers, one bearing a terminal hydroxyl group for increasing dispersibility in water, and the second bearing a carboxylic acid group for peptide conjugation through amide bond formation. Peptide-functionalized particles have a 9.7 ± 1.8 nm hydrodynamic diameter and are highly water-soluble and stable in solution for at least one year. The morphology of the gold cores as well as their organic coating was studied using Transmission Electron Microscopy, showing that the attachment of a limited number of peptides per nanoparticle leads to a uneven organic coating of two different thicknesses, one of 2.0 ± 0.6 nm formed by polyethylene glycol linkers, and a second of 3.6 ± 0.5 nm which includes the peptide. GNP significantly enhance the internalization of the cyclic peptide BPC734 in cells as compared to peptide in solution, with improved uptake in cancerous HT29 cells. Cytotoxicity studies show that peptide BPC734 in solution is toxic in the micromolar range, whereas peptide-functionalized particles are toxic at nanomolar peptide concentrations and with a significantly higher toxicity for cancerous cells. All these results, besides the stability and expected passive tumor targeting, make these particles a promising option for improving the bioavailability, efficacy, and selectivity in cancer therapy.

Redox-sensitive dimeric camptothecin phosphatidylcholines-based liposomes for improved anticancer efficacy

Aim: A redox-triggered camptothecin (CPT) liposomal system was developed for an improved clinical potential in tumor therapy. Materials & methods: CPT–phosphorylcholine conjugates (CPT–SS–GPCs: CPT–SS–3–GPC and CPT–SS–11–GPC) were synthesized by conjugating CPT to glycerylphosphorylcholine via disulfide bond linker. CPT–SS–GPCs could be assembled into liposomes. Different in vitro and in vivo analyses were used to evaluate the anticancer activities of CPT–SS–GPCs. Results: CPT–SS–GPCs liposomes exhibited extremely high drug loading and uniform size of 150–200 nm. Moreover, the rapid release of parent CPT in reductive condition and high cellular uptake of CPT–SS–GPCs liposomes were observed. At last, in vitro and in vivo anticancer assay showed the enhanced efficacy of CPT–SS–GPCs liposomes. Conclusion: Redox-triggered CPT–SS–GPC liposomes have great potential in tumor therapy.

Surface engineering of nanomaterials with phospholipid-polyethylene glycol-derived functional conjugates for molecular imaging and targeted therapy

In recent years, phospholipid-polyethylene glycol-derived functional conjugates have been widely employed to decorate different nanomaterials, due to their excellent biocompatibility, long blood circulation characteristics, and specific targeting capability. Numerous in vivo studies have demonstrated that nanomedicines peripherally engineered with phospholipid-polyethylene glycol-derived functional conjugates show significantly increased selective and efficient internalization by target cells/tissues. Targeting moieties including small-molecule ligands, peptides, proteins, and antibodies are generally conjugated onto PEGylated phospholipids to decorate liposomes, micelles, hybrid nanoparticles, nanocomplexes, and nanoemulsions for targeted delivery of diagnostic and therapeutic agents to diseased sites. In this review, the synthesis methods of phospholipid-polyethylene glycol-derived functional conjugates, biophysicochemical properties of nanomedicines decorated with these conjugates, factors dominating their targeting efficiency, as well as their applications for in vivo molecular imaging and targeted therapy were summarized and discussed.

Anti-CD123 antibody-modified niosomes for targeted delivery of daunorubicin against acute myeloid leukemia

A novel niosomal delivery system was designed and investigated for the targeted delivery of daunorubicin (DNR) against acute myeloid leukemia (AML). Anti-CD123 antibodies conjugated to Mal-PEG₂₀₀₀-DSPE were incorporated into normal niosomes (NS) via a post insertion method to afford antibody-modified niosomes (CD123-NS). Next, NS was modified with varying densities of antibody (0.5 or 2%, antibody/Span 80, molar ratio), thus providing L-CD123-NS and H-CD123-NS. We studied the effect of antibody density on the uptake efficiency of niosomes in NB4 and THP-1 cells, on which CD123 express differently. Our results demonstrate CD123-NS showed significantly higher uptake efficiency than NS in AML cells, and the uptake efficiency of CD123-NS has been ligand density-dependent. Also, AML cells preincubated with anti-CD123 antibody showed significantly reduced cellular uptake of CD123-NS compared to control. Further study on the uptake mechanism confirmed a receptor-mediated endocytic process. Daunorubicin (DNR)-loaded H-CD123-NS demonstrated a 2.45- and 3.22-fold higher cytotoxicity, compared to DNR-loaded NS in NB4 and THP-1 cells, respectively. Prolonged survival time were observed in leukemic mice treated with DNR-H-CD123-NS. Collectively, these findings support that the CD123-NS represent a promising delivery system for the treatment of AML.

The design of peptide-amphiphiles as functional ligands for liposomal anticancer drug and gene delivery

Liposomal nanomedicine has led to clinically useful cancer therapeutics like Doxil and DaunoXome. In addition, peptide-functionalized liposomes represent an effective drug and gene delivery vehicle with increased cancer cell specificity, enhanced tumor-penetrating ability and high tumor growth inhibition. The goal of this article is to review the recently published literature of the peptide-amphiphiles that were used to functionalize liposomes, to highlight successful designs that improved drug and gene delivery to cancer cells in vitro, and cancer tumors in vivo, and to discuss the current challenges of designing these peptide-decorated liposomes for effective cancer treatment.

Lipoprotein based drug delivery: Potential for pediatric cancer applications

While survival rates for patients with childhood cancers have substantially improved, the quality of life of the survivors is often adversely impacted by the residual effects of chemo and radiation therapy. Because of the existing metabolic and physiological disparities between pediatric and adult patients, the treatment of pediatric cancer patients poses special challenges to oncologists. While numerous clinical trials being conducted, to improve treatment outcomes for pediatric cancer patients, new approaches are required to increase the efficacy and to minimize the drug related toxic side effects. Nanotechnology is a potentially effective tool to overcome barriers to effective cancer therapeutics including poor bioavailability and non-specific targeting. Among the nano-delivery approaches, lipoprotein based formulations have shown particularly strong promise to improve cancer therapeutics. The present article describes the challenges faced in the treatment of pediatric cancers and reviews the potential of lipoprotein-based therapeutics for these malignancies.

Impediments to enhancement of CPT-11 anticancer activity by E. coli directed beta-glucuronidase therapy

CPT-11 is a camptothecin analog used for the clinical treatment of colorectal adenocarcinoma. CPT-11 is converted into the therapeutic anti-cancer agent SN-38 by liver enzymes and can be further metabolized to a non-toxic glucuronide SN-38G, resulting in low SN-38 but high SN-38G concentrations in the circulation. We previously demonstrated that adenoviral expression of membrane-anchored beta-glucuronidase could promote conversion of SN-38G to SN-38 in tumors and increase the anticancer activity of CPT-11. Here, we identified impediments to effective tumor therapy with E. coli that were engineered to constitutively express highly active E. coli beta-glucuronidase intracellularly to enhance the anticancer activity of CPT-11. The engineered bacteria, E. coli (lux/βG), could hydrolyze SN-38G to SN-38, increased the sensitivity of cultured tumor cells to SN-38G by about 100 fold and selectively accumulated in tumors. However, E. coli (lux/βG) did not more effectively increase CPT-11 anticancer activity in human tumor xenografts as compared to non-engineered E. coli. SN-38G conversion to SN-38 by E. coli (lux/βG) appeared to be limited by slow uptake into bacteria as well as by segregation of E. coli in necrotic regions of tumors that may be relatively inaccessible to systemically-administered drug molecules. Studies using a fluorescent glucuronide probe showed that significantly greater glucuronide hydrolysis could be achieved in mice pretreated with E. coli (lux/βG) by direct intratumoral injection of the glucuronide probe or by intratumoral lysis of bacteria to release intracellular beta-glucuronidase. Our study suggests that the distribution of beta-glucuronidase, and possibly other therapeutic proteins, in the tumor microenvironment might be an important barrier for effective bacterial-based tumor therapy. Expression of secreted therapeutic proteins or induction of therapeutic protein release from bacteria might therefore be a promising strategy to enhance anti-tumor activity.