Repurposed drug combination via high-throughput screening and dual drug delivery system development for the treatment of retinoblastoma

The goal of retinoblastoma (RB) treatment is to save the child's life, eyes and functional vision, with that order of priority. The management of RB is complex and involves strategically chosen methods of surgical enucleation, external beam radiotherapy, intravenous chemoreduction and focal therapy. Local administration routes of chemotherapy, intra-arterial (IAC) and intravitreal (IVC), have emerged as promising methods to salvage the eyes and vision. New improvements in the chemotherapy of RB are geared towards reducing side effects of the drugs employed. Emerging strategies includes alternative chemotherapeutic agents, drug combinations, and novel drug delivery systems.

Most successful examples of drug repurposing so far have been serendipitous. The systematic approach here was identified candidate drugs by strategic high-throughput screening methods. In this thesis, hit drugs were screened from a drug library of primarily FDA-approved drugs, and the synergistic effect of selected drug combinations was investigated. The hit drug gemcitabine, known to be an effective clinical treatment for non-small cell lung cancers, in combination with carboplatin, was discovered to have the highest cytotoxicity of the hits identified, and appeared as a potential alternative therapeutic agent for RB treatment.

Polymeric nanoparticles (NPs) as an improved drug delivery system were investigated with gemcitabine. The nanoprecipitation synthesis of a poly(lactic-co-glycolic acid), as known as PLGA, nanoparticle was developed for drug encapsulation. The characterization of PLGA NPs within various active pharmaceutical ingredients were studied using dynamic light scattering and scanning electron microscopy, revealing that spherical NPs ranging in size from 150 to 200 nm could be successfully prepared. The tumor cells proliferation inhibition was observed after treatment with this novel nanoformulation. Furthermore, the possibility of a dual drug delivery system was explored. Gemcitabine and carboplatin were encapsulated together in PLGA NPs and found to show a synergistic effect after dual drug release. Additionally, gemcitabine combined with the light-activated agent indocyanine green was prepared, and laser-induced photothermal therapy (PTT) was explored.