Targeted Polymeric Nanoparticles~drug delivery~

Literature Seminar
May 21, 2012
Soichi Ito (M1)1

Contents
I. Introduction
II. Topics
1. Passive vs Active targeting
2. Preparation of targeted polymeric NPs
3. Targeting ligands
4. Optimal biophysicochemical characteristics
III.Perspective

2

Historical timeline of clinical-stage
nanoparticle technologies

3
JINJUN SHI et al. ACCOUNTS OF CHEMICAL RESEARCH, 2011, 44(10), 1123–1134.

• Polymeric NPs have the capability to
1. release drugs at an experimentally predetermined
rate over a prolonged period of time,
2. release drugs preferentially at target sites with thepossibility of controlled release rates,
3. maintain drug concentrations within therapeuticallyappropriate ranges in circulation and within tissues,
4. protect drugs from hepatic inactivation, enzymatic
degradation and rapid clearance in vivo.
4

Targeted polymeric NPs

5

JINJUN SHI et al. ACCOUNTS OF CHEMICAL RESEARCH, 2011, 44(10), 1123–1134.

Targeted NPs in clinical development

Nazila Kamaly et al. Chem. Soc. Rev., 2012, 41, 2971–3010.6

What is the targeted polymeric NPs?

poly(lactic-co-glycolic acid) (PLGA), poly(ethylene glycol) (PEG)
Nazila Kamaly et al. Chem. Soc. Rev., 2012, 41, 2971–3010. 7

Biodegradable polymers“Controlled Drug Release”

poly(lactic acid) (PLA), poly(glycolic acid) (PGA),
poly(lactic-co-glycolic acid) (PLGA), poly(caprolactone) (PCL)
Nazila Kamaly et al. Chem. Soc. Rev., 2012, 41, 2971–3010.

8

Drug release mechanisms

a. Diffusion from polymer
matrixb. Surface erosion/degradationof polymer matrix
c. Biodegradation of polymer
matrix due to hydrolyticdegradation

9Nazila Kamaly et al. Chem. Soc. Rev., 2012, 41, 2971–3010.

“Stealth” Nanopartile
The non-specific binding of plasma proteins onto
the surface of NPs, also known as opsonization,leads to enhanced blood clearance by the cellsof mononulear phagocytic system (MPS).

By decorating the surfaces of NPs with PEG
polymers, the circulation times can be prolonged.
10

Contents
I. Introduction
II. Topics
1. Passive vs Active targeting
2. Preparation of targeted polymeric NPs
3. Targeting ligands
4. Optimal biophysicochemical characteristics
III.Perspective11

EPR effect (Passive targeting)“Enhanced Permeation and Retention” effectPavan P. Adiseshaiah et al. WIREs Nanomed Nanobiotechnol 2009, 2, 99–112.

12

Limitations of Passive targeting• Passively targeted NPs end up releasing their
therapeutic payload into the tumor milieu rather
than within cancer cells. (“PEG dilemma”)• For drugs that are not readily retained in tumors or
macromolecular drugs that are not readily taken up
by cancer cells, this extracellular drug release may
be less effective at maintaining a differentially hightumor drug concentration over an extended periodof time.
13

Passive vs active targeting

Omid C. Farokhzad et al. ACS Nano, 2009, 3 (1), 16–20.

14

Active targeting• Targeted NPs facilitate receptor-mediatedendocytosis(RME), releasing therapeutic agentsinside target cell.
Higher therapeutic efficacy
Lower toxicity

15

Contents
I. Introduction
II. Topics
1. Passive vs Active targeting
2. Preparation of targeted polymeric NPs
3. Targeting ligands
4. Optimal biophysicochemical characteristics
III.Perspective16

NP Formulation Method
“Bottom-up” (self-assembly)Bulk synthesis• Nanoprecipitation• Oil-in-water emulsification-solvent evaporation• Water-in-oil-in-water emulsification-solvent
evaporation, etc.
Microfluidic synthesis

“Top-down”
PRINT(Particle Replication In Non-wetting Templates)

17

Nanoprecipitation

 Difficulty in complete removal of the organic solvent after selfassembly.
Pegi Ahlin Grabnar et al. Journal of Microencapsulation 2011, 28(4), 323–335. 18

Single emulsion• This method results in higher drug loading andencapsulation efficiency compared to nanoprecipitation,
as well as achieving complete solvent removal.
• Obtained NPs are often larger than those obtained
through nanoprecipitation.
19

Double emulsion

Guilin Wang et al. Expert Opin. Drug Deliv. 2008, 5(5), 499-515.

• This method is generally used for encapsulation of hydrophilic drugs• This method normally yields NPs with larger size thannanoprecipitaion or O/W methods, with moderate drug loading andencapsulation efficiency.
20

Microfluidic methods

21

Rohit Karnik et al. Nano Lett. 2008, 8(9), 2906-2912.

MARY E. NAPIER et al. Polymer Reviews, 2007, 47, 321–327.

22

Jin Wang et al. small, 2011, 7, No. 14, 1919–1931.

23

Drug loading methods

Encapsulation method is the most common technique in this field.
*The drug is entrapped in the polymer matrix during preparation of NPs.
24

Incorporation of targeting ligands on NPs

Coupling chemistry shouldnot lead to undesirable products or side reactions
be produced on large-scales in a reproducible manner25

Post-synthesis NP surface modification method• Amide bond formation• Maleimide coupling with thiols• “Bioorthogonal” reactions such as Cu-free click reactions
 [4+2] cycloadditon reaction

W. Russ Algar et al. Bioconjugate Chem. 2011, 22, 825–858.
Mariagrazia Di Marco et al. International Journal of Nanomedicine, 2010, 5, 37–49.
John C. Jewett et al. Chem. Soc. Rev., 2010, 39, 1272–1279.

26

Targeted NPs through polymer self-assembly• It is difficult to control the stoichiometry of functional biomoleculeson the surface of NPs via coupling chemistries.
• Self-assembly of pre-functionalized triblock copolymers allows
for the reproducible creation of optimal targeted NPs.

Frank Gu et al. PNAS, 2008, 105, 2586-2591.

27Precisely controlled aptamer density

28

The effect of Apt surface density on NP
in vivo vs in vitro

29

Solubility of ligands

30

Pedro M. Valencia et al. Biomaterials, 2011, 32, 6226-6233.

Contents
I. Introduction
II. Topics
1. Passive vs Active targeting
2. Preparation of targeted polymeric NPs
3. Targeting ligands
4. Optimal biophysicochemical characteristics
III.Perspective

31

Targeting ligands
Antibodies and their fragments
Proteins
Peptides
Aptamers (Nucleic acid lidands)
Small molecules (folic acid, carbohydrate etc.)32

Antibodies and their fragments

Dan Peer et al. nature nanotechnology, 2007, 2, 751-760.
TypeMW/kDa

Diameter/nm

Whole antibodies

150

15-20

Fab’

50

5-10

ScFv

25

3-5

Nanobody

15

2-3

33

Proteins• Endogenous proteins that selectively bind to specificmembrane-bound receptors on cells can be used.
 Transferrin, Epidermal Growth Factor,
Nerve Growth Factor, etc.
The receptors of Tf and EGF are overexpressed oncancer cells.

 Demerits
Commonly immunogenic, off-target adverse effects
Ulrich E. Schaible et al. NATURE REVIEWS, 2004, 2, 946-953.

34

Peptides• Small size, relatively low immunogenicity, highstability, and ease of conjugation to NP surfaces
RGD (Arg-Gly-Asp) sequence binds to αvβ3
integrin receptors which are highly upregurated on
both tumor cells and angiogenic endothelial cells.
Cell-penetrating peptides such as Tat peptide
 Tat peptide derives from the HIV-1 virus.
Peptides with R/KXXR/K motif such as iRGD
iRGD homes to tumors and penetrates into them.
35

Kazuki N. Sugahara et al. Cancer Cell, 2009, 16, 510–520.

36http://www.creative-biolabs.com/phagedisplay1.htm

37

Aptamers• Single-strand of DNA or RNA oligonucleotides• Small size, reproducible synthesis, low immunity
Type

MW/kDaDiameter/nm

Whole antibodies

150

15-20

Nanobody

15

2-3

Aptamers DNA/RNA

10-30

2-3

 The high specificity of Apts against targets is theirsecondary structure, but the secondary structure
may be affected by heat, exonuclease orendonuclease degradation.
38

“cell-uptake selection”

Z. Xiao et al. ACS Nano, 2012, 6, 696–704. 39

Small molecules• The availability of a range of facile couplingchemistries for their conjugation• The availability of a wide range of targeting ligandswith variable solubilities and functional groups
Folic acid (or folate)Folate receptors (FRs) are frequently over-expressedin a range of cancer
FRs are expressed not only in tumor tissue but innormal epithelia.
40

Contents
I. Introduction
II. Topics
1. Passive vs Active targeting
2. Preparation of targeted polymeric NPs
3. Targeting ligands
4. Optimal biophysicochemical characteristicsIII.Perspective

41

Influence of particle size
• The generally accepted diameter of nanomedicine
for cancer is in the range of 10-100 nm.
The lower limit is determined by an interaction
with renal filtration in the kidney.
The upper limit is determined by an interaction
with RES (immune system) in the spleen and liver.
(particles larger than 200 nm must compensate by deformability)

For the purpose of tumor accumulation, the upper
limit for extravasation into solid tumors have beensuggested at ~400 nm.
42• Influence of NP shapeSpheres vs Rods on cellular uptake?
Further investigations are required.

• Influence of NP surface charge
NP surface charge is a major factor contributing
to the non-specific binding of NPs to cells.
Charged NPs will inevitably have short half-lives
and high non-specific cellular uptakes due tointeraction with blood proteins and complement
activation.
Neutral particles would be good.
43

Influence of NP PEGylation“mushroom”

Optimal PEG coverage?

“brush”
Donald E. Owens III et al. International Journal of Pharmaceutics, 2006, 307, 93–102.44

Contents
I. Introduction
II. Topics
1. Passive vs Active targeting
2. Preparation of targeted polymeric NPs
3. Targeting ligands
4. Optimal biophysicochemical characteristics
III.Perspective45

“A new class of therapeutics”• Delivering therapeutics in a more controlled andspecific mannerImproved drug safety and efficacy• Protecting drugs from rapid metabolism andinactivation; improving drug solubility, PK, BD,and target tissue exposureAdditional degrees of freedom to medical chemistry46

Co-delivering of multiple drugs

N. Kolishetti et al. Proc. Natl. Acad. Sci. U. S. A., 2010, 107, 17939–17944.

47

Challenges
Insufficient understanding of events at the nano-bio
interface in vitro and in vivo
Inadequate knowledge of the fate of NPs at the body,organ, and cellular levels
Difficulty in achieving reproducible and controlled
synthesis of NPs at scales suitable for clinicaldevelopment and commercialization
Overreliance on the EPR effect (This phenomenon
may not be a universal property of all tumors.)
There are too many “on a case-by-case basis”.
Is it possible for a reasonable strategy to exist?
48

Reference•••••••••••••••••Nazila Kamaly et al. Chem. Soc. Rev., 2012, 41, 2971–3010.
JINJUN SHI et al. ACCOUNTS OF CHEMICAL RESEARCH, 2011, 44(10), 1123–1134.
Pavan P. Adiseshaiah et al. WIREs Nanomed Nanobiotechnol 2009, 2, 99–112.
Omid C. Farokhzad et al. ACS Nano, 2009, 3 (1), 16–20.
Pegi Ahlin Grabnar et al. Journal of Microencapsulation 2011, 28(4), 323–335.
Guilin Wang et al. Expert Opin. Drug Deliv. 2008, 5(5), 499-515.
Rohit Karnik et al. Nano Lett. 2008, 8(9), 2906-2912.
MARY E. NAPIER et al. Polymer Reviews, 2007, 47, 321–327.
Jin Wang et al. small, 2011, 7, No. 14, 1919–1931.
Mariagrazia Di Marco et al. International Journal of Nanomedicine, 2010, 5, 37–49.
John C. Jewett et al. Chem. Soc. Rev., 2010, 39, 1272–1279.
Frank Gu et al. PNAS, 2008, 105, 2586-2591.
Pedro M. Valencia et al. Biomaterials, 2011, 32, 6226-6233.
Dan Peer et al. nature nanotechnology, 2007, 2, 751-760.
Ulrich E. Schaible et al. Nature Reviews Microbiology 2004, 2, 946-953.
Kazuki N. Sugahara et al. Cancer Cell 2009, 16, 510–520.
W. Russ Algar et al. Bioconjugate Chem. 2011, 22, 825–858.

•••

Z. Xiao et al. ACS Nano, 2012, 6, 696–704.
Donald E. Owens III et al. International Journal of Pharmaceutics, 2006, 307, 93–102.
N. Kolishetti et al. Proc. Natl. Acad. Sci. U. S. A., 2010, 107, 17939–17944.

••

http://www.creative-biolabs.com/phagedisplay1.htm
wikipedia49