Preparation, Pharmacokinetic Profile, and Tissue Distribution Studies of a Liposome-Based Formulation of SN-38 Using an UPLC-MS/MS Method

Recent advances in SN-38 drug delivery system

DNA topoisomerase I plays a key role in lubricatingthe wheels of DNA replication or RNA transcription through breaking and reconnecting DNA single-strand. It is widely known that camptothecin and its derivatives (CPTs) have inhibitory effects on topoisomerases I, and have obtained some clinical benefits in cancer treatment. The potent cytotoxicity makes 7-ethyl-10-hydroxycamptothecin (SN-38) become a brilliant star among these derivatives. However, some undesirable physical and chemical properties of this compound, including poor solubility and stability, seriously hinder its effective delivery to tumor sites. In recent years, strategies to alleviate these defects have aroused extensive research interest. By focusing on the loading mechanism, basic nanodrug delivery systems with SN-38 loaded, like nanoparticles, liposomes and micelles, are demonstrated here. Additionally, functionalized nanodrug delivery systems of SN-38 including prodrug and active targeted nanodrug delivery systems and delivery systems designed to overcome drug resistance are also reviewed. At last, challenges for future research in formulation development and clinical translation of SN-38 drug delivery system are discussed.

Application of Biocompatible Drug Delivery Nanosystems for the Treatment of Naturally Occurring Cancer in Dogs

Background: Cancer is a common disease in dogs, with a growing incidence related to the age of the animal. Nanotechnology is being employed in the veterinary field in the same manner as in human therapy. Aim: This review focuses on the application of biocompatible nanocarriers for the treatment of canine cancer, paying attention to the experimental studies performed on dogs with spontaneously occurring cancer. Methods: The most important experimental investigations based on the use of lipid and non-lipid nanosystems proposed for the treatment of canine cancer, such as liposomes and polymeric nanoparticles containing doxorubicin, paclitaxel and cisplatin, are described and their in vivo fate and antitumor features discussed. Conclusions: Dogs affected by spontaneous cancers are useful models for evaluating the efficacy of drug delivery systems containing antitumor compounds.

In vitro and in vivo Evaluation of a Novel Estrogen-Targeted PEGylated Oxaliplatin Liposome for Gastric Cancer

Background

Chemotherapy is still the main first-line treatment for advanced metastatic gastric cancer, but it has the limitations of serious side effects and drug resistance. Conventional liposome has been substantially used as drug carriers, but they lack targeting character with lower drug bioavailability in tumor tissues. Based on the above problems, a novel estrogen-targeted PEGylated liposome loaded with oxaliplatin (ES-SSL-OXA) was prepared to further improve the metabolic behavior, the safety profile, and the anti-tumor efficacy of oxaliplatin.

Methods

Four kinds of oxaliplatin (OXA) liposomes were prepared by film hydration method. The obtained formulations were characterized in terms of entrapment efficiency (EE), particle size, and so on by HPLC and DLS (dynamic light scanning). The morphology of ES-SSL-OXA was detected by transmission electron microscope (TEM). The in vitro and in vivo targeting effect of ES-SSL-OXA was verified by fluorescence microscopy and in vivo imaging system in gastric cancer cells (SGC-7901) and tumor-bearing athymic mice. The in vitro and in vivo antitumor efficacies of ES-SSL-OXA were investigated on SGC-7901 cells and athymic tumor-bearing mice. Pharmacokinetic, biodistribution, and acute toxicity tests of ES-SSL-OXA were performed on ICR mice.

Results

The ES-SSL-OXA exhibited an average particle size of about 153.37 nm with an encapsulation efficiency of 46.20% and low leakage rates at 4°C and 25°C. In vivo and in vitro targeting study confirmed that ES-SSL-OXA could effectively target the tumor site. The antitumor activity demonstrated the strongest inhibition in tumor growth of ES-SSL-OXA. Pharmacokinetics and acute toxicity study showed that ES-SSL-OXA could significantly improve the metabolic behavior and toxicity profile of oxaliplatin.

Conclusion

In this study, a novel estrogen-targeted long-acting liposomal formulation of OXA was successfully prepared. ES fragment effectively targeted the delivery system to tumor tissues which highly express estrogen receptor, providing a promising therapeutic method for gastric cancer in clinic.

Redox responsive 7-ethyl-10-hydroxycamptothecin (SN38) lysophospholipid conjugate: synthesis, assembly and anticancer evaluation

7-Ethyl-10-hydroxycamptothecin (SN38), a potent camptothecin derivative specifically targeting DNA topoisomerase I cleavage complexes, has shown great potential in the treatment of solid tumors. Because of its poor solubility and chemical and metabolic stability, the clinical application of SN38 is highly limited. To address these problems, a novel redox-responsive SN38 conjugate based liposomal formulation is developed in this report. First, SN38 was conjugated with lysophospholipid by using a cleavable disulfide bond linker. After that, the conjugate (SN38-SS-PC) was assembled into liposomes by thin film method. Dynamic lightscattering(DLS) characterization indicated that SN38-SS-PC liposomes possessed a narrow size distribution (172.8 ± 10.5 nm) and negative charged zeta potential (-8.9 ± 0.3 mV). The results of storage and physiological stabilities showed that SN38-SS-PC liposomes was stable under different conditions. More importantly, a reduction responsive release of parent drug SN38 was observed in the medium containing glutathione (GSH). In addition, SN38-SS-PC liposomes had a much more rapid cellular uptake behavior against cancer cells. The enhanced anti-cancer efficacy of SN38-SS-PC liposomes was further demonstrated by in vitro cytotoxicity assay against MCF-7 and A549 cells. Under in vivo evaluation in 4 T1 xenograft tumor model, SN38-SS-PC liposomes were observed to have lower systemic toxicity and higher tumor inhibition rate of 53.3% compared with the commercialized SN38 prodrug Irinotecan (Ir). In summary, SN38-SS-PC liposomes could be a promising redox responsive delivery system of SN38 for cancer therapy.

Folate Receptor Targeting and Cathepsin B-Sensitive Drug Delivery System for Selective Cancer Cell Death and Imaging

In this work, a folate receptor (FR)-mediated dual-targeting drug delivery system was synthesized to improve the tumor-killing efficiency and inhibit the side effects of anticancer drugs. We designed and synthesized an FR-mediated fluorescence probe (FA-Rho) and FR-mediated cathepsin B-sensitive drug delivery system (FA-GFLG-SN38). FA-GFLG-SN38 is composed of the FR ligand (folic acid, FA), the tetrapeptide substrate for cathepsin B (GFLG), and an anticancer drug (SN38). The rhodamine B (Rho)-labeled probe FA-Rho is suitable for specific fluorescence imaging of SK-Hep-1 cells overexpressing FR and inactive in FR-negative A549 and 16-HBE cells. FA-GFLG-SN38 exhibited strong cytotoxicity against FR-overexpressing SK-Hep-1, HeLa, and Siha cells, with IC₅₀ values of 2-3 μM, but had no effect on FR-negative A549 and 16-HBE cells. The experimental results show that the FA-CFLG-SN38 drug delivery system proposed by us can effectively inhibit tumor proliferation in vitro, and it can be adopted for the diagnostics of tumor tissues and provide a basis for effective tumor therapy.

MicroRNA Biogenesis is Enhanced by Liposome-Encapsulated Pin1 Inhibitor in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is in an urgent need of new, effective therapies to reduce morbidity and mortality. We have previously demonstrated that peptidyl-prolyl cis/trans isomerase Pin1 is a potential target for HCC therapy, due to its pivotal role in HCC development through regulating miRNA biogenesis, and discovered the small molecule API-1 as a novel and specific Pin1 inhibitor. Despite its significant anti-HCC activity, the low water solubility and in vivo bioavailability of API-1 limit its clinical application. To address these issues, we herein developed a liposomal formulation of API-1 to improve API-1 delivery and enhance its anti-HCC efficacy. Methods: We designed and developed a nanoscale liposomal formulation of API-1, named as API-LP. Subsequently, the mean diameter, polydispersity, zeta potential, encapsulation efficiency and thermal properties of the optimization API-LP were characterized. The enhanced anti-HCC activity and the molecular mechanism of API-LP were investigated both in vitro and in vivo. Finally, the safety and pharmacokinetic property of API-LP were evaluated systematically. Results: API-LP had good formulation characteristics and exhibited an enhanced in vitro activity of suppressing proliferation and migration of HCC cells when compared with free API-1. The mechanism study showed that API-LP upregulated miRNA biogenesis via inhibiting Pin1 activity followed by restoring the nucleus-to-cytoplasm export of XPO5. Because of the increased delivery efficiency, API-LP displayed a stronger ability to promote miRNA biogenesis than free API-1. Importantly, API-LP displayed higher systemic exposure than free API-1 in mice without apparent toxicity, resulting in an enhanced tumor inhibition in xenograft mice. Conclusion: The development and assessment of API-LP provide an attractive and safe anti-HCC agent, highlighting the miRNA-based treatment for human cancers.

Preparation and Characterization of Syringic Acid-Loaded TPGS Liposome with Enhanced Oral Bioavailability and In Vivo Antioxidant Efficiency

In this study, syringic acid-loaded TPGS liposome (SA-TPGS-Ls) was successfully prepared to improve oral bioavailability of syringic acid (SA). SA is a natural and notable antioxidant activity compound with its limited bioavailability ascribable to its poor aqueous solubility and fast elimination. Recently, TPGS has become a perfect molecular biomaterial in developing several carrier systems with sustained, controlled, and targeted the drug delivery. SA-TPGS-Ls was prepared via thin-film dispersion method and characterized in terms of particle size, stability, morphology, and encapsulation efficiency (EE). The results showed that SA-TPGS-Ls had regular spherical-shaped nanoparticles with EE of 96.48 ± 0.76%. The pharmacokinetic studies demonstrated a delayed MRT and prolonged t_1/2, while relative oral bioavailability increased by 2.8 times. Tissue distribution showed that SA-TPGS-Ls maintained liver drug concentration while delayed elimination was also observed in the kidney. In CCl₄-induced hepatotoxicity study, the activities of hepatic T-AOC, GSH-Px, CAT, GSH, and SOD were greatly elevated, while serum biological markers ALT, AST, and AKP were reduced after treatment of mice with SA-TPGS-Ls. Histopathological studies confirmed that SA-TPGS-Ls could remarkably improve the status of hepatic tissues. Collectively, SA-TPGS-Ls significantly improved the drug encapsulation efficiency, stability coupled with bioavailability of SA, hence increasing in vivo antioxidant activity of the drug.

Developments in drug delivery of bioactive alkaloids derived from traditional Chinese medicine

The bioactive alkaloids (e.g. vincristine, hydroxycamptothecin, ligustrazine, and so on) from traditional Chinese medicine (TCM) have exerted potent efficacies (e.g. anti-tumor, anti-inflammation, immunosuppression, etc.). However, a series of undesirable physicochemical properties (like low solubility and weak stability) and baneful pharmacokinetic (PK) profiles (e.g. low bioavailability, short half time, rapid clearance, etc.) have severely restricted their applications in clinic. In addition, some side effects (like cumulative toxicities caused by high-frequency administration and their own toxicities) have recently been reported and also confined their clinical uses. Therefore, developments in drug delivery of such alkaloids are of significance in improving their drug-like properties and, thus, treatment efficiencies in clinic. Strategies, including (i) specific delivery via liposomes; (ii) sustained delivery via nanoparticles, gels, and emulsions; and (iii) transdermal delivery via ethosomes, solid lipid nanoparticles, and penetrating enhancers, have been reported to improve the pharmacokinetic and physicochemical characters of problematic TCM alkaloids, decline their adverse effects, and thus, boost their curative efficacies. In this review, the recent reports in this field were comprehensively summarized with the aim of providing an informative reference for relevant readers.

Liposome-encapsulated chemotherapy: Current evidence for its use in companion animals

Cytotoxic drugs encapsulated into liposomes were originally designed to increase the anticancer response, while minimizing off-target adverse effects. The first liposomal chemotherapeutic drug was approved for use in humans more than 20 years ago, and the first publication regarding its use in a canine cancer patient was published shortly thereafter. Regardless, no general application for liposomal cytotoxic drugs has been established in veterinary oncology till now. Due to the popularity of canines as experimental models for pharmacokinetic analyses and toxicity studies, multiple publications exist describing various liposomal drugs in healthy dogs. Also, some evidence for its use in veterinary cancer patients exists, especially in canine lymphoma, canine splenic hemangiosarcoma and feline soft tissue sarcoma, however, the results have not been overwhelming. Reasons for this may be related to inherent issues with the enhanced permeability and retention effect, the tumour phenomenon which liposomal drugs exploit. This effect seems very heterogeneously distributed in the tumour. Also, it is potentially not as ubiquitously occurring as once thought, and it may prove important to select patients for liposomal therapy on an individual, non-histology-oriented, basis. Concurrently, new developments with active-release modified liposomes in experimental models and humans will likely be relevant for veterinary patients as well, and holds the potential to improve the therapeutic response. It, however, does not resolve the other challenges that liposomal chemotherapy faces, and more work still needs to be done to determine which veterinary patients may benefit the most from liposomal chemotherapy.

Novel Curcumin Liposome Modified with Hyaluronan Targeting CD44 Plays an Anti-Leukemic Role in Acute Myeloid Leukemia in Vitro and in Vivo

Curcumin has been widely used as a food additive for centuries and has been recently explored for its anti-inflammatory and antitumor properties. Although curcumin is pharmacologically safe and efficacious to certain cancers, its role against acute myeloid leukemia (AML) still remains unclear, and it lacks clinical application due to low water solubility and low in vivo bioavailability. To address these issues, we developed a novel curcumin liposome modified with hyaluronan (HA-Cur-LPs) to specifically deliver curcumin to AML by targeting CD44 on AML cell surface. When compared with free curcumin and nontargeted liposome (Cur-LPs), the HA-Cur-LPs exhibited good stability, high affinity to CD44, increased cellular uptake, and more potent activity on inhibiting AML cell proliferation. The KG-1 cell implanted AML mice had significantly delayed, or even prevented, AML progression following treatment with 50 mg/kg of curcumin dose in the HA-Cur-LPs every 2 days for 2 weeks. Mechanistically, the anti-AML effects of HA-Cur-LPs were achieved by inhibiting Akt/ERK pathways and activating caspase-dependent apoptosis. Moreover, HA-Cur-LPs played a critical role in downregulation of DNMT1 expression in AML, leading to DNA hypomethylation and reactivation of tumor suppressor genes such as miR-223. The development and assessment of the HA-Cur-LPs in this study provide another potential choice for AML therapy, using HA-Cur-LPs as either a single treatment agent or in combination with other treatments.

One-pot polyglycidol nanogels via liposome master templates for dual drug delivery

Polyglycidol-based nanohydrogels (nHGs) have been prepared by optimizing the use of liposome master templates resulting in a high-yielding and more practical one-pot process to provide materials capable of carrying drugs of adverse chemical nature. The nanogels prepared with the one-pot method showed favorable kinetics for the release of either Nile Red (NR) or lysozyme (LYS), loaded with gel precursors such as semi-branched poly(glycidol allylglycidyl ether), PEG dithiol (1KDa), a free radical initiator and liposomal lipids at the liposome formation step. This process is superior to a comparable step-wise traditional approach and circumvents loading of the gel precursors with the hydrophilic drug into preformed liposome templates. A thiol-ene crosslinking reaction accomplishes the formation of the nanonetwork resulting in nHGs prepared in the traditional step-wise (nHG-SW) approach and the one-pot (nHG-OP) process. Both nanogel networks were characterized in terms of particle size and zeta (ζ) potential with average values of 148nm±39nm and -25.9mV±9.2 for the nHG-SW and 132nm±32 and -23.1mV±9.7 for the nHG-OPs. Loading efficiency for both of the nanogels with NR was determined by spectrophotometry to be 28% (nHP-SW) and 31% (nHP-OP). The LYS loading was based on the target loading of 10μg/mg for both nanogels found to be 84% and 86% for the nHG-SW and nHP-OP, respectively. As proof of concept for combination drug delivery, the in vitro release of both drug mimics, NR and LYS, were monitored under physiologically relevant conditions by an optimized dialysis method. The implementation of the multi-functional and semi-branched polyglycidol is recognized as the main contributor for the observed highly controlled release of proteins that are otherwise rapidly released from common PEG-based nanogel networks. Furthermore, the one-pot process led to be the most favorable drug delivery system based on the release kinetics pointing to a denser polymer network.