Lipid-Based Self-Microemulsion of Niclosamide Achieved Enhanced Oral Delivery and Anti-Tumor Efficacy in Orthotopic Patient-Derived Xenograft of Hepatocellular Carcinoma in Mice

Abstract

Introduction

We previously identified niclosamide as a promising repurposed drug candidate for hepatocellular carcinoma (HCC) treatment. However, it is poorly water soluble, limiting its tissue bioavailability and clinical application. To overcome these challenges, we developed an orally bioavailable self-microemulsifying drug delivery system encapsulating niclosamide (Nic-SMEDDS).

Methods

Nic-SMEDDS was synthesized and characterized for its physicochemical properties, in vivo pharmacokinetics and absorption mechanisms, and in vivo therapeutic efficacy in an orthotopic patient-derived xenograft (PDX)-HCC mouse model. Niclosamide ethanolamine salt (NEN), with superior water solubility, was used as a positive control.

Results

Nic-SMEDDS (5.6% drug load) displayed favorable physicochemical properties and drug release profiles in vitro. In vivo, Nic-SMEDDS displayed prolonged retention time and plasma release profile compared to niclosamide or NEN. Oral administration of Nic-SMEDDS to non-tumor bearing mice improved niclosamide bioavailability and C_max by 4.1- and 1.8-fold, respectively, compared to oral niclosamide. Cycloheximide pre-treatment blocked niclosamide absorption from orally administered Nic-SMEDDS, suggesting that its absorption was facilitated through the chylomicron pathway. Nic-SMEDDS (100 mg/kg, bid) showed greater anti-tumor efficacy compared to NEN (200 mg/kg, qd); this correlated with higher levels (p < 0.01) of niclosamide, increased caspase-3, and decreased Ki-67 in the harvested PDX tissues when Nic-SMEDDS was given. Biochemical analysis at the treatment end-point indicated that Nic-SMEDDS elevated lipid levels in treated mice.

Conclusion

We successfully developed an orally bioavailable formulation of niclosamide, which significantly enhanced oral bioavailability and anti-tumor efficacy in an HCC PDX mouse model. Our data support its clinical translation for the treatment of solid tumors.

Keywords:

• niclosamide
• self-microemulsifying drug delivery system
• SMEDDS
• oral bioavailability
• drug repurposing
• hepatocellular carcinoma

Acknowledgments

The authors would like to thank Stanford Center for Innovation in In vivo Imaging (SCi3) for providing the facilities and resources for executing this study; specifically, they thank Dr. Frezghi Habte, Dr. Laura J. Pisani, and Dr. Edwin Chan for their technical support with animal imaging and histological slides scanning. The authors would like to thank the Histology Service at the Department of Pathology, Dr. Pauline Chu, and Dr. Ferda Filiz for the preparation of histology slides and histological analysis of the stained slides.

Disclosure

The authors declare no potential conflicts of interest in this work.

Additional information

Funding

This work was supported by CJ Huang Foundation, the TS Kwok Liver Foundation, and the Lui HM Foundation (Y.L., M.T., F.A., M.-S.C., and S.S.), and NIH NIGMS R01GM134307 (B.C., S.S., M.T., M.-S.C.).