Graduation Date

Spring 5-4-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Programs

Pharmacology and Experimental Neuroscience

First Advisor

Dr. Howard E. Gendelman

Abstract

Dolutegravir (DTG) is a potent human immunodeficiency virus type 1 (HIV-1) integrase strand-transfer inhibitor (INSTI) with a high barrier to viral drug resistance. However, opportunities to improve its profile abound. These include extending the drug’s apparent half-life, increasing penetrance to “putative” viral reservoirs, and reducing inherent toxicities. These highlight, in part, the need for long-acting, slow effective release antiretroviral therapy (LASER ART) delivery schemes. A long-acting (LA) DTG was made by synthesizing a hydrophobic and lipophilic prodrug encased with poloxamer (P407) surfactant. This modified DTG (MDTG) reduced systemic metabolism and polarity, increased lipophilicity and membrane permeability, improved encapsulation, and formed stable nanoparticles upon formulation. MDTG was synthesized through esterification of DTG with myristic acid. Poloxamer encasement was prepared for native and modified DTG (NDTG and NMDTG, respectively) with thorough characterization. NMDTG was characterized morphologically by uniform rod-shaped particles. It was taken up and retained avidly in human monocyte-derived macrophages (MDM) for > 30 days with no demonstrable cytotoxicity. Protection against viral infection was recorded for > 30 days against HIV-1ADA challenge as determined by HIV-1 reverse transcriptase (RT) activity in culture fluids and cell-based HIV-1p24 staining. Parallel native DTG responses were operative for one day. Pharmacokinetics (PK) testing in mice showed that drug apparent half-life was increased from 62 to 330 hours for NDTG and NMDTG, respectively, with drug levels of the latter above the protein-adjusted 90% inhibitory concentration (PA-IC90) of 64 ng/mL > 8 weeks following a single intramuscular (IM) dose. At day 28, NMDTG had > 100-fold higher tissue drug levels than NDTG and were still demonstrable at day 56. NMDTG protected humanized mice from parenteral challenge of HIV-1ADA for two weeks. Further PK testing in three rhesus macaques demonstrated that a single IM injection of NMDTG can provide plasma drug levels above the PA-IC90 for one month and can greatly extend drug apparent half-life (467 h). Taken together, these results are a first-step towards producing a potent, long-acting, slow-release DTG for the treatment and prevention of HIV-1 in humans by affecting drug apparent half-life, cell and tissue drug penetration, and antiretroviral potency.

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