Engineered Protein Nanoparticles as Therapeutics for Gliomas

Abstract

Gliomas are the most common malignant type of central nervous system tumor for which treatment options are usually limited to maximal safe surgical resection, radiotherapy, and chemotherapy. Protein-based nanoparticles are promising therapeutic candidates as they leverage the advantages of nanoparticles-mediated delivery while exploiting protein’s selectivity, low immunogenicity, versatility, and biodegradability. Recently, therapeutic efficacy was achieved in a glioma model using synthetic protein nanoparticles (SPNPs), which were produced through electrohydrodynamic (EHD) (co) jetting. This thesis sought to expand the utility of these SPNPs for glioma therapy. Nanoparticle-mediated delivery of small molecules is often explored for glioma therapy since the majority of small molecules are excluded from the brain, however using SPNPs has yet to be described. In the first part of this thesis, the hydrophobic small molecule, paclitaxel, was solubilized into albumin through high pressure homogenization then subjected to EHD jetting to form paclitaxel SPNPs. The paclitaxel SPNPs showed favorable morphology, release kinetics, stability, and retained paclitaxel’s toxicity in vitro. For the first time, a hydrophobic small molecule was loaded into an EHD-produced SPNPs, which sets foundation for hydrophobic small molecule-loaded SPNPs. Next, bicompartmental SPNPs were fabricated to contain two therapeutics of differing size, solubility, and function: STAT3 siRNA and paclitaxel. Nanoparticle combination therapy is the cornerstone of advanced therapy as it allows two or more therapeutics to be delivered while exploiting the advantages of combination therapy. These STAT3i/paclitaxel bicompartmental SPNPs released siRNA and paclitaxel over time, exhibited stability, and showed anti-glioma activity in glioblastoma IDH wild-type (grade 4) glioma cell cultures. Finally, an SPNP containing siRNA against an autophagy related gene, ATG7, was fabricated to re-sensitize mutant IDH astrocytoma (grade 2) to radiotherapy. When combined with radiotherapy, long term survival was achieved in a mutant IDH astrocytoma (grade 2) model. Long term survivors were rechallenged with a second tumor and achieved 100% survival, despite not receiving additional treatment suggesting immunological memory. While the work described in this thesis only represents a fraction of the capabilities possible with EHD-jetted SPNPs for glioma therapy, it lays the groundwork for future SPNP exploration, whether in glioma or with other loaded molecules.