Cancer is the second leading cause of death and is responsible for approximately 9.6 million deaths worldwide in 2018. Among all oncological diseases, lung cancer claims the highest mortality (male: 23.5%; female: 22%) and the second most new cases (male: 13%; female: 12%) in the US. Approximately 40% of newly diagnosed lung cancer patients are in the advanced stage IV, for which platinum-based chemotherapy is the first-line treatment, either by itself or in combination with surgery or radiotherapy. Cisplatin, the first-generation platinum-based anticancer chemotherapeutic agent, has the highest potency against lung cancer but carries many severe adverse effects. Cisplatin also induces drug resistance during long-term chemotherapy. Many more platinum complexes have been investigated as better alternatives, which led to the approval of carboplatin and oxaliplatin by Food and Drug Administration (FDA). In addition, miriplatin suspended in iodolipds (lipiodolization) was approved in Japan for the treatment of hepatocellular carcinoma (HCC) in 2009. Miriplatin has the same non-leaving group as oxaliplatin but different leaving groups of two myristate chains, which make it highly lipophilic. Several characteristics of solid tumors in lung cancer constitute a physiochemical barrier to the homogenous distribution and deep penetration of chemotherapy agents. Nanocarriers provide a promising platform to overcome the physiochemical barrier and to reduce the systemic toxicity of anticancer chemotherapy. In this study, miriplatin is formulated with various lipid-based nanocarriers including micelles and solid lipid nanoparticles (SLNs) thanks to its highly lipophilic structure. The goal of this thesis is to develop and evaluate miriplatin-loaded nano formulations against lung cancer. Miriplatin-loaded formulations were prepared by different methods, including thin film hydration and several scale-up methods including chloroform dripping, chloroform injection, chloroform evaporation, co-solvent evaporation, chloroform slow evaporation and co-solvent slow evaporation. Between the two types of nano formulations under this study, micelles were much smaller (~10 nm in diameter) and more homogeneous (PDI < 0.3), while SLNs were bigger (~ 100 nm in diameter) and more heterogeneous (PDI ~0.8). A quantification method of miriplatin was established using inductively coupled plasma-optical emission spectrometry (ICP-OES). The quantification of platinum recovery from different miriplatin-loaded nano formulations was facilitated by digestion with 70% nitric acid and heating. The co-solvent slow evaporation method to prepare miriplatin-loaded nano formulations improved the platinum recovery prominently from 10% to 70%. Thus, co-solvent slow evaporation has been established as a pharmaceutically viable scale-up method to prepare nano formulations of miriplatin. Miriplatin-loaded nano formulations of different compositions were negatively stained with uranyl acetate and then imaged by transmission electron microscopy (TEM), which showed the formulations’ size and morphology that were consistent with the size and PDI data from dynamic light scattering studies by the Malvern Zetasizer. In the TEM studies, micelles showed a morphology of spherical dots at around 10 nm in diameter while SLNs showed both spherical and rod structures with a size distribution from 50 to 150 nm. A three-dimensional multicellular spheroid (3D MCS) model of A549-iRFP cells was used for in vitro evaluation of the nano formulations’ activity against lung cancer. A549-iRFP cells were engineered from the common lung cancer cell line A549 to stably express the near-infrared fluorescent protein (iRFP). The viability of A549-iRFP 3D MCS after exposure to cisplatin or nano formulations was similar to A549 3D MCS. The anticancer activity of miriplatin-loaded nano formulations against 3D MCS was positively associated with the platinum recovery as quantified by ICP-OES. The miriplatin-loaded nano formulations that had been prepared by the co-solvent slow evaporation method showed substantial anticancer activities against A549 3D MCS and A549-iRFP 3D MCS, which were comparable to cisplatin. Taken together, miriplatin-loaded nano formulations were successfully prepared by co-solvent slow evaporation. The formulations were developed to carry favorable physiochemical properties to enhance the activities of platinum drugs against lung cancer.

Solid tumors possess biological features that are different from those in healthy tissues, which provides opportunities of anticancer treatment by nanomedicines. Due to the presence of the fenestrated tumor vasculatures, nanomedicines can selectively accumulate in tumor tissues by the enhanced permeability and retention (EPR) effect. The acidic pH in tumor interstitium (pH 6.0-7.0) also provides a promising mechanism to trigger the nanomedicines to promote the cellular uptake of cargo drugs. The previously reported stealth liposomes coated with PEG are known to accumulate in tumors owing to their prolonged circulation time. The PEG coating on liposomes can hinder serum protein adsorption and thus prevent rapid elimination by the reticuloendothelial system, thus increasing the liposome circulation time. However, liposomal interaction with cancer cells can also be hindered by the PEG coating. In order to improve the anticancer activity of stealth liposomes, novel synthetic imidazole-based lipids were introduced to the composition of stealth liposomes to develop the pH-sensitive imidazole-based convertible liposomes (ICL). At acidic pH, the imidazole-based lipids would protonate to acquire positive charges, thus clustering with the negatively charged PEGylated lipids. Such lipid-lipid electrostatic interaction would induce phase separation of the bilayer to generate a PEG-free domain that displays excess positive charges. Such newly converted, cationic liposomes at acidic pH in tumor interstitium would have better interaction with negatively charged cancer cells and/or enhanced drug release, therefore overcoming the drawback of traditional stealth liposomes. After synthesizing the imidazole-based lipids DHI, DHMI and DHDMI, we constructed doxorubicin (DOX)-loaded ICL formulations. The physicochemical properties of ICL were characterized, and factors influencing such properties were explored. The pH-triggered acquisition of positive charges of ICL was confirmed by the elevation of ζ- potentials and aggregation with negatively charged model liposomes that mimic bio-membranes at acidic pH 6.0-7.0. Acidic pH-triggered release of ICL was confirmed by drug release assays. It was also found that although the incorporation of cholesterol can remarkably reduce the size and increase the encapsulation efficiency (EE) of ICL, it also hinders the pH-sensitivity of ICL. The morphology of ICL at both pH 7.4 and pH 6.0 was characterized under transmission electron microscopy (TEM), which showed morphological changes in response to acidic pH 6.0, which further supported the proposed pH-sensitivity of ICL. Cytotoxicity assays on 3D MCS of HeLa, A549, MDA-MB-231 and MDA-MB-468 cell lines were conducted to evaluate the anticancer activity of ICL formulations. ICL formulations without cholesterol showed considerably enhanced anticancer activities against MCS compared with the non-sensitive stealth liposomes (NSL). However, incorporation of cholesterol decreased such activities. The IC50 values of cholesterol-free ICL and ICL with cholesterol against MCS strongly suggested that the pH-sensitivity introduced by the imidazole-based lipids would enhance the anticancer activity of stealth liposomes, while the hindrance of the pH-sensitivity by cholesterol would reduce such activities. Taken together, ICL’s pH-sensitivity is correlated with their enhanced anticancer activity than non-sensitive stealth liposomes.