Development of Degradable Stealth Nanospheres for Controlled Delivery of Anticancer Drugs

Transcription

1 Development of Degradable Stealth Nanospheres for Controlled Delivery of Anticancer Drugs Emmanuel. Akala, R.Ph., Ph.D. Department of Pharmaceutical Sciences School of Pharmacy

2 First Generation Polymeric Nanoparticles Following I. V. injection, nanoparticles are rapidly cleared from the blood stream by the normal reticuloendothelial (MPS) defence mechanism irrespective of composition and morphology Studies have shown that the liver Kupffer cells are the major sites for cell accumulation. ne application of the first generation polymeric nanoparticles is the treatment of liver metastasis using biodegradable polyalkycyanoacrylate nanoparticles loaded with doxorubicin with a dramatic reduction in the number of metatasis in the histiosarcoma experimental cancer (Kupffer cells play the role of a drug reservoir) The same concept has been used for the treatment of intracellular infections using nanoparticles loaded with antibiotics (Salmonella typhimurium infection in mice)

3 Second Generation Stealth Polymeric Nanoparticles The second generation of nanoparticles is for long blood circulation (stealth nanoparticles) and passive targeting Rapid and massive recognition of the first generation polymeric nanoparticles by the mononuclear phargocytic system (reticuloendothelial system) such as liver, spleen and bone marrow limits their usefulness. Consequently, the concept of stealth ploymeric nanoparticles was developed: they are invisible to macrophages by virtue of the cloud of hydrophillic polymer chains at the particle surface which repels plasma proteins (reduces opsonization) They serve as reservoir systems and can penetrate into sites such as solid tumors. The stealth nanoparticles are capable of increasing t 1/2 of drugs (peptides and proteins) and can enter cells by EPR mechanism due to structural changes in the vasculature of tumors.

4 Research Efforts in Dr. Akala s Laboratory on Stealth Polymeric Nanoparticles Development of stealth nanospheres for the delivery of anticancer drugs =C( ) + C NH C =C( ) A =C( ) + =C( ) C C B ( ) n C AIBN ( -C) ( -C) y x C C ( ) n ( -C ) ( -C ) x C C y -C( )- C NH C -C( )- A = N,-dimethacryloylhydroxylamine B = Methymethacrylate C = Polyethyleneglycol monomethylether monomethacrylate D = Crosslinked polymer ( ) n D

5 Structure and Hydrolysis of Nanospheres R R C NH C R R R R R hydrolysis TEM of Drug-Loaded Nanosphere R C--NH-C R R= --C- R = -( - ) n -C- Hydrolyzable network R C - ( -C) ( -C) y x C C ( ) n NH 3 + Hydrolysis segments

6 SEM of Crosslinked Poly(ethylene Glycol-co Methyl Methacrylate) (PE-MMA) Nanospheres Prepared by Dispersion Polymerization

7 Typical Particle Size Distribution Graphs for PEG-PMMA Nanospheres Size distribution(s) Size distribution(s) % in class 15 % in class Diameter (nm) Diameter (nm)

8 Response Surface Plot of the Dependence of Nanosphere Particle Size on Methymethacrylate (MMA) and Crosslinker Concentration (Described by a Cubic Model btained by Nonlinear Regression Analysis). Size Design points above predicted value Design points below predicted value X1 = A: Crosslinker X2 = B: MMA Size nm B: MMA mmol A: Crosslinker (mmol%)

9 Effect of Varying Monomer (MMA) Amount (mmol) and Crosslinker Concentration (mmol %) on Particle Size (nm) 500 Particle Size (nm) Amount of MMA (mmol) 4 mmol % 3 mmol % 2 mmol % Crosslinker 1 mmol % Concentration (mmol %) 1 mmol % 2 mmol % 3 mmol % 4 mmol %

10 In vitro Release Isotherms for Paclitaxeland Zapp88-Loaded Nanospheres Fabricated Using Different Initiators Cummulative amount released (%) PEG-PMMA (ZDL)a PEG-PMMA (ZDL)r PEG-PMMA (PDL)a PEG-PMMA (PDL)r Time (hrs)

11 Current Efforts on Third Generation Multifunctional Nanoparticles with Molecular Recognition (Active Targeting)

12 Current Efforts on Multifunctional Nanoparticles

13 Current Efforts on Multifunctional Nanoparticles

14 The Ultimate Goal: To Develop Multifunctional Nanoparticles for Cancer Chemotherapy But The Attainment f The Goal Will Be In Phases With ne Phase Building n The Previous Phase Development of biodegradable stealth paclitaxel-loaded nanopsheres for long blood circulation and passive targeting to tumor by enhanced permeability and retention effect (EPR) (Already Achieved). In Vitro Testing Using Appropriate Cancer Cell Lines (e.g. BT-20 human breast carcinoma cell line). In Vivo Testing: Tumor propagation in nude mice using a suspension of MDA-MB-435S.luc cells and the administration of paclitaxel loaded nanoparticles to the mice to determine the biodistribution and efficacy in human breast cancer xenograftbearing nude mice.

15 The Ultimate Goal: To Develop Multifunctional Nanoparticles for Cancer Chemotherapy But The Attainment of the Goal Will Be In Phases With ne Phase Building n The Previous Phase Development of biodegradable stealth paclitaxel-loaded and non-invasive imaging agent (paramagnetic oxide) loaded nanopsheres capable of long blood circulation, molecular recognition (active targeting), and imaging of breast primary cancer and cancer metastases. Targeting of nanoparticles to surface receptors or antigens on cancer cells (to prevent untoward effects on healthy cells and to facilitate the uptake of the nanoparticulate drug delivery system via receptor mediated endocytosis). Fluid-phase endocytosis and adsorptive endocytosis (nonspecific adsorption based on hydrophobic interactions or charges) Receptor mediated endocytosis involves interaction of nanoparticles with cell surface surface receptors or antigens: Peptide receptors (luteinizing hormone-releasing hormone receptor: LHRH gene is over expressed in human ovarian, breast and prostate cancer cells); gastrinreleasing peptide receptor; neuropeptide receptor); Antigens expressed on cancer cells can be targeted using antibodies or their antigen recognition fragments; Folate receptors which are upregulated in many cancers; Vascular Targeting to cause shutdown of blood supply (EFFR antagonists (anti-angiogenic agents which inhibit EGFR)

16 The Ultimate Goal: To Develop Multifunctional Nanoparticles for Cancer Chemotherapy But The Attainment of the Goal Will Be In Phases With ne Phase Building n The Previous Phase Suppression of Pump and Non-pump Anticancer Drug Resistance Multi-drug resistance caused by transmembrane transporters (e.g. P-glycoprotein) function as pumps to remove cytotoxic agents from cells (antisense oligonucleotides can be targeted against genes encoding drug efflux pump or sirna can be used to silence the gene encoding for drug efflux pump). Non-pump resistance by encouraging cancer cell proliferation (e.g. altered protein kinase C-α (PKC- α) expression promotes carcinogenesis & its expression can be inhibited by selective antisense oligonucleotide or sirna); the expression of proteins responsible for cellular detoxification mechanisms can be selectively shut down by sirna sirna delivery is promising as a therapeutic approach because of the specific gene knockdown that can be achieved and the ability to silence previously un-drugable targets. Nanoparticles internalized by receptor mediated endocytosis can facilitate the delivery to the cytoplasm.

17 The Ultimate Goal: To Develop Multifunctional Nanoparticles for Cancer Chemotherapy But The Attainment of the Goal Will Be In Phases With ne Phase Building n The Previous Phase Combination therapy It has been postulated that the simultaneous use of anticancer drugs and RNAi could provide strategies to inactivate essential genes promoting tumor growth Paclitaxel plus transtuzumab (antibody) in advanced cancer diseases The delivery system will be: LHRH-surfacemodified-nanoparticles containing SPIN, sirna, antibody or gemcitabine and paclitaxel.

18 Collaborators Emmanuel. Akala, R.Ph., Ph.D. (PI) Yomi kunola, MS Simeon Adesina, MS Seun gunwuyi, BS ladapo Bakare, Ph.D. Wusheng Yin, Ph.D. Tamara Minko, Ph.D.