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

Yi Liu,1 David Quintanar Guerrero,2 David Lechuga-Ballesteros,3 Mingdian Tan,1 Faiz Ahmad,1 Bilal Aleiwi,4 Edmund Lee Ellsworth,4 Bin Chen,4 Mei-Sze Chua,1 Samuel So1 1Department of Surgery, School of Medicine, Stanford University, Stanford, CA, USA; 2Laboratorio de Investigación y Posgrado en Tecnologías Farmacéuticas, Facultad de Estudios Superiores Cuautitlán, Universidad Nacional Autónoma de México, Cuautitlán Izcalli, CP, 54745, Mexico; 3AstraZeneca Pharmaceuticals, Ltd. 4222 Emperor Boulevard, Durham, NC, USA; 4Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USACorrespondence: Mei-Sze Chua, Email [email protected]: 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 Cmax 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 carcinom

Physical characterization of Tobramycin Inhalation Powder: II. State Diagram of an Amorphous Engineered Particle

Tobramycin Inhalation Powder (TIP) is a spray-dried engineered particle formulation used in TOBI® Podhaler™, a drug/device combination for treatment of cystic fibrosis. A TIP particle consists of two phases: amorphous, glassy tobramycin sulfate and a gel-phase phospholipid (DSPC). The objective of this work was to characterize both the amorphous and gel phases following exposure of TIP to a broad range of relative humidity and temperature. Because changes in either particle morphology or the solid-state form of the drug could affect drug delivery or biopharmaceutical properties, understanding physical stability was critical to development and registration of this product. This characterization included morphological assessments of particles, thermal analysis to measure the gel-to-liquid crystalline phase transition (Tm) and the glass transition temperature (Tg), enthalpy relaxation measurements to determine structural relaxation times, and gravimetric vapor sorption to measure moisture sorption isotherms of TIP and its components. Collectively, these data enabled development of a state diagram for TIP, a map of the environmental conditions under which physical stability can be expected. This diagram shows that, under long-term storage conditions, TIP is at least 50°C below the Tg of the amorphous phase and at least 40°C below the Tm of the gel phase. Enthalpy relaxation measurements demonstrate that the characteristic structural relaxation times under these storage conditions are many orders of magnitude greater than that at Tg. These data, along with long-term physicochemical stability studies conducted during product development, demonstrate that TIP is physically stable, remaining as a mechanical solid over timescales and conditions relevant to a pharmaceutical product. This met a key design goal in the development of TIP: a room-temperature-stable formulation (three years at room temperature) that obviates the need for refrigeration for long-term storage. This has enabled development of TOBI® Podhaler™ - an approved inhaled drug product that meaningfully reduces the treatment burden of cystic fibrosis patients worldwide