Targeted Combination Treatment for Glioblastoma Multiforme (GBM) Using Polymeric Nanoparticle

Glioblastoma Multiforme (GBM) is an aggressive cancer that originates from astrocytes and spreads to spinal cord and other parts of the brain. Increase in replication of glial cells leads to advantageous mutations in the tumor. In 2015 about 15,320 deaths were reported due to GBM. Five-year survival is less than 5% making GBM a dreadful cancer. Current treatment involves complex invasive surgery, followed by chemotherapy and radiation. There is a desperate unmet need for a targeted treatment of GBM with minimum damage to the surrounding normal tissue. Combination treatments are increasingly being used to target multiple hallmarks of cancer. The goal of this study is to develop a combination therapy to treat GBM using Poly (lactic-co-glycolic acid) (PLGA) nanoparticles encapsulated with three different drugs namely gefitinib, temozolomide (TMZ) and GSK461364 each with a unique target. Nanoparticles facilitate combination of multiple drugs for simultaneous delivery to cancer cells in a single nano-sized platform. Gefitinib is a Tyrosine Kinase inhibitor, which competes for ATP-binding site of EGFR-TK. TMZ methylates DNA of tumor cells, resulting in apoptosis. GSK461364 is a Polo-like Kinase (PLK-1) inhibitor that blocks the G2/M transition in tumor cell cycle. These three distinct hydrophobic drugs are tested on U-87 MG (human malignant glioma) and MDA-MB-231 (triple negative breast cancer) cell lines. PLGA is attached to Polyethylene glycol (PEG), which is conjugated to transferrin receptor (TfR) binding peptide for targeting TfR overexpression, common in GBM. PEG is known to increase the circulation half-life in vivo and improves colloidal stability of nanoparticles. These transferrin peptides bind to TfR (or CD71) and enable the entry of PLGA across Blood Brain Barrier (BBB). Results of characterization, in vitro drug release profiles, stability at 37C and 4C, cytotoxicity assay, electron micrographs of nanoparticles containing drugs and fluorescent imaging will be presented

Building Better Tumor Models In Vitro: An Investigation into the Improvement of 3D Cell Culture Techniques

In cancer drug discovery, 3D cell culture is a segue between monolayer cell culture and animal testing, offering better predictive modelling of drug performance before animal testing commences. However, even though cell spheroids in 3D cultures superficially resemble tumors, they typically lack the complexity and scale of tumors formed in vivo. Spheroids typically consist of a single cell type whereas tumors contain a whole ecosystem of cells. Also, most 3D protocols stop at day 10, where the spheroids are roughly 500-600 μm in diameter at the largest, whereas tumors that develop in the body are, on average, 7.5 cm in diameter. This study investigates the effects of coculturing cell lines in 3D cultures, the effect of growth factors like Epidermal Growth Factor (EGF) on spheroids, and works on developing methods to increase the size of spheroids to more macroscopic levels. Applications for use of these 3D culture models for imaging and treatment with drug-encapsulating nanoparticles will also be presented

GSK461364A, a Polo-Like Kinase-1 Inhibitor Encapsulated in Polymeric Nanoparticles for the Treatment of Glioblastoma Multiforme (GBM)

Glioblastoma Multiforme (GBM) is a common primary brain cancer with a poor prognosis and a median survival of less than 14 months. Current modes of treatment are associated with deleterious side effects that reduce the life span of the patients. Nanomedicine enables site-specific delivery of active pharmaceutical ingredients and facilitates entrapment inside the tumor. Polo-like kinase 1 (PLK-1) inhibitors have shown promising results in tumor cells. GSK461364A (GSK) is one such targeted inhibitor with reported toxicity issues in phase 1 clinical trials. We have demonstrated in our study that the action of GSK is time dependent across all concentrations. There is a distinct 15−20% decrease in cell viability via apoptosis in U87-MG cells dosed with GSK at low concentrations (within the nanomolar and lower micromolar range) compared to higher concentrations of the drug. Additionally, we have confirmed that PLGA-PEG nanoparticles (NPs) containing GSK have shown significant reduction in cell viability of tumor cells compared to their free equivalents. Thus, this polymeric nanoconstruct encapsulating GSK can be effective even at low concentrations and could improve the effectiveness of the drug while reducing side effects at the lower effective dose. This is the first study to report a PLK-1 inhibitor (GSK) encapsulated in a nanocarrier for cancer applications

Polymeric Nanoparticles for Targeted Combination Treatment of Temozolomide Resistant Glioblastoma Multiforme (GBM)

Glioblastoma Multiforme (GBM) is an aggressive cancer that originates from astrocytes and spreads to spinal cord and other parts of the brain. Increase in replication of glial cells leads to advantageous mutations in the tumor. According to the cancer statistics from 2015 about 15,320 deaths were reported due to GBM. Five-year survival is less than 5% making GBM a dreadful form of cancer. Current treatment involves complex invasive surgery, followed by chemotherapy and radiation. The goal of this study is to develop a combination therapy to treat GBM using Poly (lactic-co-glycolic acid) (PLGA) nanoparticles encapsulated with two drugs namely gefitinib and GSK461364, each with a unique target. Gefitinib is a Tyrosine Kinase inhibitor, which competes for ATP-binding site of EGFR-TK. GSK461364 is a Polo-like Kinase (PLK-1) inhibitor that blocks the G2/M transition in tumor cell cycle. These distinct hydrophobic drugs are tested on U-87 MG (human malignant glioma) cell line. PLGA is attached to Polyethylene glycol (PEG), which is conjugated to transferrin receptor binding peptide. These transferrin peptides bind to transferrin receptors (TfR) or CD71 and enable the entry of PLGA-PEG nanoparticles across the Blood Brain Barrier (BBB). Results of characterization, TEM, SEM images, in vitro drug release profiles, stability, cytotoxicity assay, flow cytometry data of uptake of the nanoparticles will be presented

GSK461364A, a Polo-Like Kinase-1 Inhibitor Encapsulated in Polymeric Nanoparticles for the Treatment of Glioblastoma Multiforme (GBM)

Glioblastoma Multiforme (GBM) is a common primary brain cancer with a poor prognosis and a median survival of less than 14 months. Current modes of treatment are associated with deleterious side effects that reduce the life span of the patients. Nanomedicine enables site-specific delivery of active pharmaceutical ingredients and facilitates entrapment inside the tumor. Polo-like kinase 1 (PLK-1) inhibitors have shown promising results in tumor cells. GSK461364A (GSK) is one such targeted inhibitor with reported toxicity issues in phase 1 clinical trials. We have demonstrated in our study that the action of GSK is time dependent across all concentrations. There is a distinct 15−20% decrease in cell viability via apoptosis in U87-MG cells dosed with GSK at low concentrations (within the nanomolar and lower micromolar range) compared to higher concentrations of the drug. Additionally, we have confirmed that PLGA-PEG nanoparticles (NPs) containing GSK have shown significant reduction in cell viability of tumor cells compared to their free equivalents. Thus, this polymeric nanoconstruct encapsulating GSK can be effective even at low concentrations and could improve the effectiveness of the drug while reducing side effects at the lower effective dose. This is the first study to report a PLK-1 inhibitor (GSK) encapsulated in a nanocarrier for cancer applications

Targeting Strategies for the Combination Treatment of Cancer Using Drug Delivery Systems

Cancer cells have characteristics of acquired and intrinsic resistances to chemotherapy treatment—due to the hostile tumor microenvironment—that create a significant challenge for effective therapeutic regimens. Multidrug resistance, collateral toxicity to normal cells, and detrimental systemic side effects present significant obstacles, necessitating alternative and safer treatment strategies. Traditional administration of chemotherapeutics has demonstrated minimal success due to the non-specificity of action, uptake and rapid clearance by the immune system, and subsequent metabolic alteration and poor tumor penetration. Nanomedicine can provide a more effective approach to targeting cancer by focusing on the vascular, tissue, and cellular characteristics that are unique to solid tumors. Targeted methods of treatment using nanoparticles can decrease the likelihood of resistant clonal populations of cancerous cells. Dual encapsulation of chemotherapeutic drug allows simultaneous targeting of more than one characteristic of the tumor. Several first-generation, non-targeted nanomedicines have received clinical approval starting with Doxil® in 1995. However, more than two decades later, second-generation or targeted nanomedicines have yet to be approved for treatment despite promising results in pre-clinical studies. This review highlights recent studies using targeted nanoparticles for cancer treatment focusing on approaches that target either the tumor vasculature (referred to as ‘vascular targeting’), the tumor microenvironment (‘tissue targeting’) or the individual cancer cells (‘cellular targeting’). Recent studies combining these different targeting methods are also discussed in this review. Finally, this review summarizes some of the reasons for the lack of clinical success in the field of targeted nanomedicines