Graduation Year

2020

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Medical Sciences

Major Professor

Subhra Mohapatra, Ph.D.

Committee Member

Shyam S. Mohapatra, Ph.D.

Committee Member

Daniel J. Denmark, Ph.D.

Keywords

Dual Drug Delivery, Targeted Therapy, Chemotherapeutic Resistance, Nanotechnology, Nanoparticles

Abstract

Background: According to the American Cancer Society, lung cancer was accountable for over 142,000 deaths in the USA in 2019. Common mutations related to lung cancer mainly occur in TP53, EGFR, and KRAS genes. Lapatinib is a small molecule tyrosine kinase inhibitor which acts reversibly on both epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2). Overexpression of EGFR leads to increased production and signaling of proteins that cause upregulation of cellular proliferation, cholesterol synthesis and resistance to apoptosis. Ketoconazole is an imidazole antifungal agent which works principally by inhibiting the enzyme cytochrome P450 14α-demethylase (CYP51A1) in the fungal cell membrane. A recent study showed that ketoconazole can reduce cholesterol synthesis in the mitochondria of lapatinib resistant lung cancer cells. The use of lapatinib in combination with ketoconazole has shown promises to work against therapeutic resistance in that study but as these drugs have limited oral bioavailability, the clinical applicability of this therapeutic approach is highly questionable. So, there is a need to explore a suitable delivery strategy for this combination therapy to achieve its full potential.

Methods: Both lapatinib and ketoconazole are poorly water soluble, which is responsible for their variable oral absorption. Large daily doses of lapatinib limit its clinical usage significantly due to the occurrence of various side effects. Nanoparticle based formulations offer remarkable promise in delivering hydrophobic drugs and enhancing their permeability and retention (EPR) inside tumors. In this study, a PEGylated hyaluronic acid (PEG - Polyethylene glycol) coated lipid micellar nanoparticle has been developed using a thin film hydration procedure for combined delivery of lapatinib and ketoconazole in cancer cells. Characterization of the particles including, in vitro drug release, cellular uptake, and cell viability studies have been performed to assess their functionality as a cancer drug delivery vehicle.

Results: Size and zeta potential of the particles were 170 nm and 16 mV respectively with a narrow size distribution which also exhibited good colloidal stability over a month. Drug loading data obtained using HPLC revealed 70% loading efficiency for lapatinib and 100% for ketoconazole. In vitro data showed augmented cellular toxicity of this lipid particle compared to free drugs in H1650 and LLC1 cells. Besides drug release study performed at pH 7 and 5 in the presence and absence of hyaluronidase (HAase) and cellular uptake of the particles studied using H1650 cells also have been found to be satisfactory. Particle showed an initial burst release of drugs in presence of HAase which is desirable for chemotherapeutic drug delivery in tumor site which is rich in HAase.

Conclusion: HA coated lipid micellar nanoparticle can be a promising tool for delivery of lipophilic drugs like lapatinib in combating drug resistance.

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