Preclinical evaluations of norcantharidin-loaded intravenous lipid microspheres with low toxicity

Review targeted drug delivery systems for norcantharidin in cancer therapy

Norcantharidin (NCTD) is a demethylated derivative of cantharidin (CTD), the main anticancer active ingredient isolated from traditional Chinese medicine Mylabris. NCTD has been approved by the State Food and Drug Administration for the treatment of various solid tumors, especially liver cancer. Although NCTD greatly reduces the toxicity of CTD, there is still a certain degree of urinary toxicity and organ toxicity, and the poor solubility, short half-life, fast metabolism, as well as high venous irritation and weak tumor targeting ability limit its widespread application in the clinic. To reduce its toxicity and improve its efficacy, design of targeted drug delivery systems based on biomaterials and nanomaterials is one of the most feasible strategies. Therefore, this review focused on the studies of targeted drug delivery systems combined with NCTD in recent years, including passive and active targeted drug delivery systems, and physicochemical targeted drug delivery systems for improving drug bioavailability and enhancing its efficacy, as well as increasing drug targeting ability and reducing its adverse effects.

Graphical Abstract

Strategies for Solubility and Bioavailability Enhancement and Toxicity Reduction of Norcantharidin

Cantharidin (CTD) is the main active ingredient isolated from Mylabris, and norcantharidin (NCTD) is a demethylated derivative of CTD, which has similar antitumor activity to CTD and lower toxicity than CTD. However, the clinical use of NCTD is limited due to its poor solubility, low bioavailability, and toxic effects on normal cells. To overcome these shortcomings, researchers have explored a number of strategies, such as chemical structural modifications, microsphere dispersion systems, and nanodrug delivery systems. This review summarizes the structure-activity relationship of NCTD and novel strategies to improve the solubility and bioavailability of NCTD as well as reduce the toxicity. This review can provide evidence for further research of NCTD.

Illuminating the hepatotoxic mechanism of norcantharidin in rats using metabolomics analysis

Background

Norcantharidin (NCTD) has multiple antitumor effects. However, NCTD can induce significant hepatotoxicity and the mechanism of hepatotoxicity is not clear for now.

Objective

This study aimed to explore the hepatotoxicity of NCTD in rat by ultra-performance liquid chromatography (UPLC) quadrupole time-of-flight (Q-TOF)-MS (UPLC/Q-TOF-MS) metabolomics.

Results

Serum biochemical indices including alanine aminotransferase (ALT) and total bilirubin (T-BIL) were significantly increased. Histopathological and ultrastructure results revealed that hepatocytes were damaged. Furthermore, the metabolomics results showed that 11 metabolites in serum and 8 metabolites in liver were differential metabolites for NCTD hepatotoxicity. Four metabolic pathways including the sphingolipid metabolism, purine metabolism, arachidonic acid metabolism, and glycerophospholipid metabolism were the key metabolic pathways related to NCTD hepatotoxicity.

Conclusion

The metabolomics analysis in this study reveal new clues on the hepatotoxicity mechanism of NCTD in rats. These findings have potential applications in the toxicity study of NCTD.

Preclinical evaluations of Norcantharidin liposome and emulsion hybrid delivery system with improved encapsulation efficiency and enhanced antitumor activity

BACKGROUND

Norcantharidin (NCTD) has a certain degree of hydrophilicity and poor lipophilicity, and has some side-effects, including short t_1/2, vascular irritation, cardiotoxicity and nephrotoxicity, which bring difficulties for formulation research. In this study, we aim to develop a novel nanocarrier to improve encapsulation efficiency, increase sterilization stability and enhance antitumor activity.

METHODS

Phospholipid complexes methods were used for increasing the lipophilicity of norcantharidin (NCTD), then NCTD phospholipid complexes were not only loaded in the oil phase and oil-water interface surface, but also encapsulated in phospholipid bilayers to obtain NCTD liposome-emulsion hybrid (NLEH) delivery system. The in vitro cytotoxicity and apoptosis, in vivo tissue distribution, tumor penetration, heterotopic and orthotopic antitumor studies were conducted to evaluate therapeutic effect.

RESULTS

NLEH exhibited an improved encapsulation efficiency (89.3%) and a better sterilization stability, compared to NCTD liposomes and NCTD emulsions. NLEH can achieve a better antitumor activity by promoting absorption (1.93-fold), prolonging blood circulation (2.08-fold), enhancing tumor-targeting accumulation (1.19 times), improving tumor penetration, and increasing antitumor immunity.

CONCLUSIONS

The liposome-emulsion hybrid (LEH) delivery system was potential carrier for NCTD delivery, and LEH could open opportunities for delivery of poorly soluble anticancer drugs, especially drugs that are more hydrophilicity than lipophilicity.

In Vitro and In Vivo Evaluation of SP94 Modified Liposomes Loaded with N-14NCTDA, a Norcantharimide Derivative for Hepatocellular Carcinoma-Targeting

The purpose of this research is to develop a liposomal drug delivery system, which can selectively target hepatocellular carcinoma (HCC) to deliver the antitumor agent N-14NCTDA, a C₁₄ alkyl chain norcantharimide derivative of norcantharidin. N-14NCTDA-loaded liposomes were successfully prepared by lipid membrane hydration and extrusion methods. SP94, a targeting peptide for HCC cells, was attached to the liposomes loaded with N-14NCTDA by the post-insertion method to obtain SP94 modified liposomes (SP94-LPs). SP94-LPs had a significant cytotoxicity against Hep G2 cells with the IC₅₀ of 15.395 ± 0.89 μg/mL, which is lower than that of NCTD-S (IC₅₀ = 20.863 ± 0.56 μg/mL) and GAL-LPs (IC₅₀ = 24.589 ± 1.02 μg/mL). Compared with conventional liposomes (Con-LPs), SP94-LPs showed greater cellular uptake in Hep G2 cells. Likewise, significant tumor suppression was achieved in H22 tumor-bearing mice which were treated with SP94-LPs. The tumor inhibition rate (IRw) of SP94-LPs was 82 ± 0.98%, obviously higher than that of GAL-LPs (69 ± 1.39%), Con-LPs (60 ± 2.78%), and NCTD-S (51 ± 3.67%). SP94-LPs exhibited a significant hepatocellular carcinoma-targeting activity in vitro and in vivo, which will provide a new alternative for hepatocellular carcinoma treatment in future. Graphical Abstract.

Contribution of p38 MAPK Pathway to Norcantharidin-Induced Programmed Cell Death in Human Oral Squamous Cell Carcinoma

Norcantharidin (NCTD), a demethylated analog of cantharidin isolated from blister beetles, has been used as a promising anticancer agent; however, the underlying function of NCTD against human oral squamous cell carcinoma (OSCC) has not been fully understood. Here, this study was aimed to investigate the apoptotic effect and molecular targets of NCTD in human OSCC in vitro and in vivo. The anticancer effects of NCTD and its related molecular mechanisms were evaluated by trypan blue exclusion assay, live/dead assay, western blotting, 4-6-Diamidino-2-Phenylindole (DAPI) staining, flow cytometric analysis, Terminal Deoxynucleotidyl Transferase dUTP Nick end Labeling (TUNEL) assay, and immunohistochemistry. NCTD significantly inhibited cell growth and increased the number of dead cells in HSC-3 and HN22 cell lines. It induced the following apoptotic phenomena: (1) the cleavages of poly (ADP-ribose) polymerase and casepase-3; (2) increase in apoptotic morphological changes (nuclear condensation and fragmentation); (3) increase in annexin V-positive cells or sub-G₁ population of cells. NCTD significantly activated the p38 mitogen-activated protein kinase (MAPK) pathway but inactivated the signal transducer and activator of transcription (STAT)3 pathway. A p38 MAPK inhibitor (SB203580) partially attenuated NCTD-induced programmed cell death (apoptosis) in both cell lines, whereas ectopic overexpression of STAT3 did not affect it. NCTD strongly suppressed tumor growth in the tumor xenograft bearing HSC-3 cells, and the number of TUNEL-positive cells increased in NCTD-treated tumor tissues. In addition, NCTD did not cause any histopathological changes in the liver nor the kidney. NCTD induced programmed cell death via the activation of p38 MAPK in OSCC. Therefore, these results suggest that NCTD could be a potential anticancer drug candidate for the treatment of OSCC.

PEGylated lipid microspheres loaded with cabazitaxel for intravenous administration: stability, bioavailability, antitumor efficacy, and toxicity

This paper aimed to develop a novel lipid microsphere delivering cabazitaxel (CTX) using phosphatidylcholine combined with DSPE-PEG2000 as emulsifier, and evaluate its stability, pharmacokinetics, antitumor efficacy, and toxicity. The pegylated cabazitaxel-loaded lipid microspheres (CTX-PLMs) were prepared by high-pressure homogenization methods; the biological samples were analyzed by the UPLC-MS/MS method. CTX-PLMs had a drug concentration of 1.2 mg/ml and a mean particle size of 180.0 ± 51.119 nm. CTX-PLMs showed a superior physical stability as it could remain nearly intact after 1-year storage. The AUC_0-t of the CTX-PLMs was 1562.6 ± 520.1 μg h L^-1 compared with the CTX-solution of 860.734 ± 312.4 μg h L^-1. CTX-PLMs exhibited a strong antitumor efficacy against NCI-N87 and DU145 tumor models with tumor growth inhibition rates of 93.5 and 88.5%, respectively. The LD50 of CTX-PLMs in rats was 20.89 mg/kg. As for the long-term toxicity, the thymus, mesenteric lymph nodes, and bone marrow were the main toxic target organs and systemic toxicity induced by CTX-PLMs was alleviated relative to that of the CTX-solution. Safety assessment studies including hemolysis test, dermal sensitization test, systemic anaphylaxis, and vascular stimulation test indicated that CTX-PLMs is safe enough for intravenous administration. In a word, CTX-PLMs are a promising carrier for intravenous administration with satisfactory stability, stronger tumor inhibition, and superior safety profile.

Preparation and characterization of norcantharidin liposomes modified with stearyl glycyrrhetinate

In the current study, norcantharidin (NCTD)-loaded liposomes (LIPs) modified with stearyl glycyrrhetinate (SG; SG-NCTD-LIP) were prepared by the ethanol injection method. To increase the drug encapsulation efficiency (EE), the formulation of NCTD-LIP was optimized by single factor test and orthogonal design. The release of NCTD in vitro from SG-NCTD-LIP was evaluated by equilibrium dialysis. The cytotoxicity of SG-NCTD-LIP in HepG2 was investigated by MTT assay. The results revealed that the EE of liposomes was ~27.80%, the average SG-NCTD-LIP was 87.5 nm, the in vitro NCTD release from SG-NCTD-LIP was delayed compared with NCTD in solution and the drug-release kinetic followed a first-order model. MTT assays revealed increased cytotoxicity activity against HepG2 cells for SG-NCTD-LIP compared with free NCTD. In conclusion, SG-NCTD-LIP prepared in the present study may be a promising liposomal drug delivery system for anticancer drugs in liver-targeting therapy.

Folate receptor-targeted liposomes loaded with a diacid metabolite of norcantharidin enhance antitumor potency for H22 hepatocellular carcinoma both in vitro and in vivo

The diacid metabolite of norcantharidin (DM-NCTD) is clinically effective against hepatocellular carcinoma (HCC), but is limited by its short half-life and high incidence of adverse effects at high doses. We developed a DM-NCTD-loaded, folic acid (FA)-modified, polyethylene glycolated (DM-NCTD/FA-PEG) liposome system to enhance the targeting effect and antitumor potency for HCC at a moderate dose based on our previous study. The DM-NCTD/FA-PEG liposome system produced liposomes with regular spherical morphology, with mean particle size approximately 200 nm, and an encapsulation efficiency >80%. MTT cytotoxicity assays demonstrated that the DM-NCTD/FA-PEG liposomes showed significantly stronger cytotoxicity effects on the H22 hepatoma cell line than did PEG liposomes without the FA modification (P<0.01). We used liquid chromatography–mass spectrometry for determination of DM-NCTD in tissues and tumors, and found it to be sensitive, rapid, and reliable. In addition, the biodistribution study showed that DM-NCTD liposomes improved tumor-targeting efficiency, and DM-NCTD/FA-PEG liposomes exhibited the highest efficiency of the treatments (P<0.01). Meanwhile, the results indicated that although the active liposome group had an apparently increased tumor-targeting efficiency of DM-NCTD, the risk to the kidney was higher than in the normal liposome group. With regard to in vivo antitumor activity, DM-NCTD/FA-PEG liposomes inhibited tumors in H22 tumor-bearing mice better than either free DM-NCTD or DM-NCTD/PEG liposomes (P<0.01), and induced considerably more significant cellular apoptosis in the tumors, with no obvious toxicity to the tissues of model mice or the liver tissue of normal mice, as shown by histopathological examination. All these results demonstrate that DM-NCTD-loaded FA-modified liposomes might have potential application for HCC-targeting therapy.

Determination and pharmacokinetic study of the diacid metabolite of norcantharidin in beagle plasma by use of liquid chromatography-tandem mass spectrometry

Because norcantharidin (NCTD) is unstable and subject to ring opening and hydrolysis, the diacid metabolite of norcantharidin (DM-NCTD) is the stable form of NCTD found in normal saline solution. Conversion of NCTD to DM-NCTD is almost 100%, making it possible to determine and investigate the pharmacokinetics of DM-NCTD converted from NCTD. In this paper, a sensitive, simple and selective liquid chromatographic-tandem mass spectrometric method was developed and validated for determination of DM-NCTD in beagle plasma. DM-NCTD was detected in multiple-reaction monitoring (MRM) mode by using the dehydrated ion 169.3 as precursor ion and its product ion 123.1 as the detected ion. Ribavirin was used as internal standard and detected in MRM mode by use of precursor ions, resulting in a product ion transition of m/z 267.1 → 135.1. This method was successfully used for a pharmacokinetic study of DM-NCTD in beagles after intravenous administration of DM-NCTD in normal saline solution at doses of 0.39, 0.78, and 1.6 mg kg(-1). DM-NCTD had dose-dependent kinetics across the dosage range investigated, with enhanced T(1/2α) and AUC(0-12) and apparently decreasing V(d) and CL with increasing dosage. After single-dose administration, T(1/2α) ranged from 0.20 to 0.55 h, AUC(0-12) from 1.81 to 43.6 μg mL(-1) h(-1), V(d) from 228 to 55.9 mL kg(-1), and CL from 220 to 36.5 mL kg(-1) h(-1) (P < 0.01). The results indicated nonlinear pharmacokinetic behavior of DM-NCTD in beagles, suggesting that the risk of DM-NCTD in normal saline solution intoxication may be non-proportionally increased at higher doses.