Anti-Gd2 Etoposide-Loaded Immunoliposomes For The Treatment Of Gd2 Positive Tumors

Author

Brandon S. Brown, The University of Texas Graduate School of Biomedical Sciences at HoustonFollow

Date of Graduation

5-2014

Document Type

Dissertation (PhD)

Program Affiliation

Neuroscience

Degree Name

Doctor of Philosophy (PhD)

Advisor/Committee Chair

Andrew Bean, Ph.D.

Committee Member

Ennio Tasciotti, Ph.D.

Committee Member

Neal Waxham, Ph.D.

Committee Member

Russel Broaddus, MD, Ph.D.

Committee Member

Diane Bick, Ph.D.

Committee Member

Jack Waymire, Ph.D.

Abstract

Systemic chemotherapeutics remain the standard of care for most malignancies even though they frequently suffer from narrow therapeutic index, poor serum solubility, and off-target effects. Monoclonal antibodies that specifically bind antigens overexpressed on many tumors such as the ganglioside, GD2, can be conjugated to drug-loaded liposomes to create a targeted drug delivery system. In this study, we have encapsulated etoposide, a topoisomerase inhibitor effective against a wide range of cancers, in surface modified liposomes decorated with anti-GD2 antibodies. We characterized the properties of the liposomes using a variety of methods including dynamic light scattering, electron microscopy, and Fourier transformed infrared spectroscopy. We examined whether these immunoliposomes were able to target cell lines expressing varying levels of surface GD2 and affect cellular proliferation. Anti-GD2 liposomes were generally targeted in a manner that correlated with GD2 expression and inhibited proliferation in cell lines to which they were efficiently targeted. The mechanism by which the immunoliposomes entered targeted cells appeared to be via clathrin-dependent uptake as demonstrated using flow cytometry and confocal microscopy. We initiated pilot studies in animals to examine the biodistribution and antitumor effects of immunoliposome mediated etoposide therapy. Fluorescent liposomes were observed at the tumor site with in vivo imaging, warranting further animals studies for antitumor efficacy. These studies suggest that anti-GD2-targeted, etoposide-loaded liposomes represent a potential strategy for more effective delivery of anti-cancer drugs that could be used for GD2 positive tumors.

Keywords

immunoliposome, GD2, etoposide, neuroblastoma, drug delivery, nanomedicine, 3F8