Stephen W. Burgess

Improved Oral Delivery of N-(4-Hydroxyphenyl)Retinamide with a Novel LYM-X-SORB Organized Lipid Complex

Purpose: Fenretinide [N-(4-hydroxyphenyl)retinamide (4-HPR)] is a cytotoxic retinoid that suffers from a wide interpatient variation in bioavailability when delivered orally in a corn oil capsule. The poor bioavailability of the capsule formulation may have limited responses in clinical trials, and the large capsules are not suitable for young children. To support the hypothesis that a novel organized lipid matrix, LYM-X-SORB, can increase the oral bioavailability of fenretinide, fenretinide in LYM-X-SORB matrix and in a powderized LYM-X-SORB formulation was delivered to mice. Experimental Design: Fenretinide was delivered orally to mice as the contents of the corn oil capsule, in LYM-X-SORB matrix (4-HPR/LYM-X-SORB matrix) or in a LYM-X-SORB matrix powderized with sugar and flour (4-HPR/LYM-X-SORB oral powder). Levels of 4-HPR, and its principal metabolite, N-(4-methoxyphenyl)retinamide, were assayed in plasma and tissues. Results: In a dose-responsive manner, from 120 to 360 mg/kg/d, delivery to mice of 4-HPR in LYM-X-SORB matrix, or as 4-HPR/LYM-X-SORB oral powder, increased 4-HPR plasma levels up to 4-fold (P < 0.01) and increased tissue levels up to 7-fold (P < 0.01) compared with similar doses of 4-HPR delivered using capsule contents. Metabolite [N-(4-methoxyphenyl)retinamide] levels mirrored 4-HPR levels. Two human neuroblastoma murine xenograft models showed increased survival (P < 0.03), when treated with 4-HPR/LYM-X-SORB oral powder, confirming the bioactivity of the formulation. Conclusions: 4-HPR/LYM-X-SORB oral powder is a novel, oral drug delivery formulation, suitable for pediatric use, which warrants further development for the delivery of fenretinide in the treatment of cancer. A phase I clinical trial in pediatric neuroblastoma is in progress.

Avanti lipid tools: connecting lipids, technology, and cell biology.

Lipid research is challenging owing to the complexity and diversity of the lipidome. Here we review a set of experimental tools developed for the seasoned lipid researcher, as well as, those who are new to the field of lipid research. Novel tools for probing protein-lipid interactions, applications for lipid binding antibodies, enhanced systems for the cellular delivery of lipids, improved visualization of lipid membranes using gold-labeled lipids, and advances in mass spectrometric analysis techniques will be discussed. Because lipid mediators are known to participate in a host of signal transduction and trafficking pathways within the cell, a comprehensive lipid toolbox that aids the science of lipidomics research is essential to better understand the molecular mechanisms of interactions between cellular components. This article is part of a Special Issue entitled Tools to study lipid functions.

Abstract 2610: Identifying a lead compound for mitigation of drug-induced PQTS

In addition to 170 approved therapeutic drugs whose adverse effects include QT prolongation, a prevalence of 1:2500 subjects in the US are genetically susceptible, or have a diabetic syndrome with increased risk of QT prolongation, torsade de pointes, and sudden death. To address this risk we determined the mitigating effect of a liposome and its components administered intravenously and orally on clinically approved QT-prolonging anticancer drugs, crizotinib and nilotinib, and an antibiotic moxifloxacin (MF) in vitro and in vivo in rats and guinea pigs. Intravenous MF at 20 mg/kg caused a statistically significant QTc prolongation of 35ms in guinea pigs. This observation is in line with peer-reviewed literature in which an oral dose of 400 mg (or approximately 6.1 mg/kg) in humans caused the FDA to black-label MF for causing QT interval prolongation in patients. The mitigating effect of a liposome consisting of dimyristoyl phosphatidylcholine (DMPC) and dimyristoyl phosphatidylglycerol (DMPG) on curcumin, a compound that inhibits the IKr (hERG) current, was initially discovered during preclinical testing with Lipocurc™. Additional patch-clamp studies with DMPC, DMPG, their metabolites myristoyl lysophosphatidylcholine (14:0 LPC) and myristoyl lysophosphatidylglycerol (14:0 LPG), and a synthetic compound, myristoyl ethyleneglycolphosphatidylglycerol (EGPG), revealed mitigation of crizotinib- and nilotinib-induced inhibition of the IKr current. Formulation of 14:0 LPG in a eutectic mixture with a monoglyceride and myristic acid (EU8120) given orally to both normal and diabetic rats prior to challenge with intravenous nilotinib resulted in significantly reduced QT prolongation. We quantified and compared the conduction delays on QT intervals in guinea pigs induced by MF alone with those of MF preceded by oral administration of EU8120, 14:0 LPG, 16:0 LPG, EGPG and DMPG. Three ratios of phospholipids:MF were tested for mitigation of conduction delays: 3:1, 1:1 and 0.3:1. At the 3:1 ratio, all the compounds tested mitigated MF-induced prolongation of QT intervals. While EGPG induced the most protection it caused bradycardia which limited its beneficial effects at that dose level. DMPG was the least potent. At lower ratios of 1:1 and 0.3:1 the mitigating effects of EU8120, EGPG and DMPG were maintained with equal potency. Lipid:MF ratios of 0.1:1 and 0.03:1 are currently being tested and will identify a lead compound for drug development, and offer insight into its mechanism of action. Citation Format: Lawrence Helson, Walter A. Shaw, Stephen W. Burgess, George Shopp, Annie Bouchard, Dany Savail, Muhammed Majeed. Identifying a lead compound for mitigation of drug-induced PQTS. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2610. doi:10.1158/1538-7445.AM2015-2610

Preparation of Surfactant and Lipid Vectors for Delivery of Proteins and Genes to Tissue

Gene therapy, the newest and mostly unexplored frontier of medical research, offers the promise of treatment and perhaps cures for many dreadful afflictions of humanity, many of which are inflicted upon the most innocent of victims, infants and children who are powerless to defend themselves from the devastating effects of disease and illness. While the technology exists to determine the affected gene and manufacture a replacement, a suitable delivery vehicle for the genetic material which allows incorporation into the cell and utilization by the cellular machinery to manufacture the gene product has yet to be developed. Currently there are two approaches to this problem, commonly grouped into the classes referred to as viral vectors, modified viral particles capable of infecting cells and delivering genetic material, and non-viral vectors, primarily cationic amphiphilic lipid-like molecules which complex naked genetic material and facilitate its transport across the cell membrane. Viral vectors, while successful at delivering genetic material to cells, presents a number of severe limitations. Many of these limitations can be circumvented by the use of non-viral vectors, although the efficiency of gene delivery is dramatically decreased. This article will concentrate on discussing the factors affecting the handling and use of surfactant and lipid vectors, as well as the preparation of lipid suspensions for the delivery of proteins and genetic material to cells. We will conclude with a brief discussion of an alternative to the classical approaches to protein and gene delivery.