The objective of this dissertation is to develop multiple novel lipid-based nanoparticle formulations for therapeutic active compounds with different identities, including small molecular drugs with specific functional ligands or chemical functional groups, small molecular drugs with highly lipophilic properties, or co-encapsulation of hydrophobic agents along with antisense oligonucleotides or nucleic acid substances, and the efficacy evaluation and activity enhancement on antineoplastic therapeutics.
Lipid-based nanoparticles, including liposomes, lipid nanoemulsions, and lipid nanoparticles for nucleic acid delivery, have been favored by numerous scientists and the pharmaceutical industry for decades. Since the FDA approval of Doxil in 1997, the popularity of nanoparticle formulations in biomedical sciences has skyrocketed due to the extinct properties that nanoparticles can provide and the ability to alter the drug pharmacokinetic/pharmacodynamic (PK/PD) profiles. Many commercialized products utilize nanoparticle formulations to achieve sustained release, prolong systemic circulation, and protect vulnerable active substances. Moreover, lipid nanoparticle applications in nucleic acid delivery have made considerable success these years, including Onpattro (or Patisiran, from Alnylam Pharmaceuticals, the first approved lipid nanoparticle formulation for siRNA delivery against hATTR amyloidosis), Comirnaty (from BioNTech & Pfizer, lipid nanoparticles delivering SARS-CoV2 spike protein mRNA), and Spikevax (from Moderna Therapeutics, lipid nanoparticles delivering SARS-CoV2 spike protein mRNA). Those novel lipid nanoparticles have been shown to enhance the delivery of nucleic acid substances to target cells with high delivery efficiency and to achieve outstanding therapeutic responses or immunization. Hence, more and more ongoing research, utilizing nanoparticles but not limited to lipid-based nanoparticles, has been shown to achieve promising results for not only the delivery of nucleic acid substances but also the repurposing the use of current clinical small molecular drugs.
In Chapter 2, we proposed a novel liposomal formulation to deliver an anti-multiple myeloma (MM) agent, Bortezomib through prodrug conjugation chemistry. Bortezomib is a successful drug in treating MM patients, but it experiences narrow therapeutic windows, accumulative toxicity, and resistance that may lead to severe side effects. The novel ascorbyl palmitate-bortezomib (AP-BTZ) conjugate liposomal bortezomib exhibited higher MTD and formulation stability by applying the ion-pairing concept to the constructs to adjust the conjugate stability/dissociation rate by modifying the surface pH, which was critical for the boronic ester reaction.
In Chapter 3, a lipid nanoemulsion platform was developed to assist the delivery of an epigenetic anticancer drug AZD5153 to the liver compartment in treating HCC. Both subcutaneous and orthotopic murine xenograft models were tested, and the single-agent AZD5153, a bivalent BRD4 inhibitor, worked efficiently in suppressing the tumor growth at lower doses compared with the first generation BRD4 inhibitor JQ-1. The pharmacological mechanism and combination therapies of AZD5153 were explored and examined as well. AZD5153 could induce cancer cell apoptosis through the inhibition of BRD4 downstream signaling of multiple oncogenes, such as c-MYC and YAP1. We also demonstrated that AZD5153 could disrupt NAD+ homeostasis by inhibiting the function of a crucial enzyme NAPRT, which led to the examination of the combination therapy of AZD5153 and FK866, a NAMPT inhibitor, in treating HCC.
In Chapter 4, multiple constructs and combinations of toll-like receptor (TLR) agonists, tumor-associated antigen peptides, and anti-PDL1 antisense oligonucleotides (anti-PDL1 ASO) were tested in vitro and in vivo to evaluate the anticancer efficacy through the immune system activation, known as cancer vaccines. Squalene-based nanoemulsions and the derivatives (pH-sensitive nanoemulsions, or PSNE) were used as the main delivery platform to co-encapsulate hydrophobic substances and nucleic acid cargos. Co-delivery of TLR agonists along with tumor-associated antigen peptides was shown to have the ability to trigger cancer-specific immunity, and the protective immunity was able to delay the onset of tumor rechallenge. Also, the combination of TLR agonists and anti-PDL1 antisense oligonucleotides were tested in vitro and in vivo utilizing the first-gen PSNE and the next-gen PSNE for anticancer treatments. The combination of SD-101 and anti-PDL1 LNA ASO demonstrated promising performance in delaying cancer progression by fine-tuning the tumor microenvironment and immune system activation. However, due to the nature of lipid nanoparticle biodistribution, the intravenous injection of the next-gen PSNE encapsulated with anti-PDL1 ASO was accumulated in liver. It showed substantial downregulation of the target gene in liver instead of in spleen or tumor compartments. This suggested that the next-gen PSNE could work efficiently as a gene delivery platform for nucleic acids and the overall construct of the next-gen PSNE/anti-PDL1 ASO could be repurposed for treating autoimmune diseases by downregulating the PD-L1 expression in liver.
In summary, in this dissertation, we successfully demonstrated several strategies to encapsulate or reformulate not only small molecular drugs but also nucleic acid substances into lipid-based nanoparticles to enhance the treatment efficacy for cancers. Optimization can be done to match the specific needs in cancer treatments, and the delivery platform can be repurposed for different therapeutic applications such as gene therapy and gene editing.