daisuke kanoh, 1 shoji tachikawa, 1 shinichi sato, 2 hiroyuki nakamura*,2 1)department of chemistry,...
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Daisuke Kanoh,1 Shoji Tachikawa,1 Shinichi Sato,2
Hiroyuki Nakamura*,2
1) Department of Chemistry, Faculty of Science, Gakushuin University, Japan
2) Synthetic Organic Division, Chemical Resources LaboratoryTokyo Institute of Technology, Japan
Development of Albumin-bound closo-Dodecaborate and its Promising Boron
Delivery Efficacy to Tumor
>25 ppm 10B in Tumor, T/B and T/N >2.5
Large amount administration is required! ⇒ Significantly low toxic
Different approach is needed in comparison with conventional antitumor drug design
How can we deliver a large amount of 10B to tumor?
Use of Nanocarriers (Micelles, Liposomes…)
In the clinical study: L-BPA (500 mg/kg) 1 hr before irradiation ⇒ Total dose: 30 g /person (60 kg body weight)
Requirements for Efficient BNCT
Nano Carrier Drug Delivery System (DDS)
Tumor tissue
-Enhanced permeability and retention (EPR) effect → particle size of 100 nm- Escape from Reticulo-endothelial-system (RES) → PEG-conjugation
Tumor blood vessel
Tumorcells
Abnormal architectureswithout tight
junction
Liposome
10BLigand
Ligand Ligand
Ligand
10B
Liposomal Boron Agents for BNCT
1991-H. Yanagie, et alBoronated anti-CEA immunoliposome
2002-R. J. Lee, et alFA-PEG-Liposome
2003-E. B. Kullberg, et alEGF-PEG-Liposome
2004-H. Nakamura, et alBoron Lipid Liposome
1992-M. F. Hawthorne, et alBoronated DSPC Liposome
2004-K. Maruyama, et alTF-PEG-Liposome
PEG
Boron lipidsNaH
O O
OH
O
OO
OS
2
O
O
2013H. Nakamura, et alHigh Boron Content Liposome
10B
DSBL
Total lipid dose147 mg/kg
Total lipid dose743 mg/kg
30 ppm (15 mgB/kg)
82 ppm (30 mgB/kg)
143 ppm (50 mgB/kg)
Boron conc. in tumor
H. Koganei, et. al., Bioconjugate Chem. 2013, 24, 124.
100 nm
2009-K, Tomizawa, H. Matsui et alAnti-EGFR-antibody-Liposome
5
Antibody-conjugates
Biopolymer-Based Boron Delivery
BSD
MoAb IB16-6(B16-BL6 melanoma)
4.8 x 104 ~ 2.5 x 105 / cell
R. F. Barth, et al, Bioconjugate Chem. 1994, 5, 58-66
CetuximabBSD
~1100 boron atoms/BSD
R. F. Barth, et al, Bioconjugate Chem. 2004, 15, 185-194
Growth factor-conjugatesEGF (53 aminoacid residues)
BSD
BSD-EGF
BNCT effect
Rolf. F. Barth, et al, Cancer Res. 2002, 62, 3159.
F98 glioma-bearing rats
6
Biopolymer-Based Boron Delivery
12,000 17,000 29,00068,000 (8 nm) 150,000 (15 nm)
EPR Effect was observed in the proteins with the MW over 68,000
Accumulation of Evans blue-stained albumin complex in tumor
blood
tumor
skin
Albumin as a Biopolymer DDS Vehicle
Abraxane® (an albumin-paclitaxel nanoparticle)- FDA approval in 2005- Treatment of Breast cancer, non-small cell lung cancer, stomach cancer, and adenocarcinoma of the pancreas
Structure of Abraxane A 130 nm albumin-bound particle form of paclitaxel
Uptake of abraxane is presumably mediated by the EPR effect and the gp60 transcytosis.
F. Kratz, B. Elsadek, J. Control. Release 161 (2012) 429–445
Albumin, a major plasma protein constituent, is composed approximately 55% of the human plasma protein, and has been extensively investigated as a versatile carrier for therapeutic and diagnostic agents.
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Maleimide Doxorubicin Conjugate in situ Binding to Albumin
+
Chemical structure of INNO-206,the (6-maleimidocaproyl)hydrazone derivative of doxorubicin
Tumor targeting based on in situ binding to the circulating albumin after intravenous injection.
C. Unger, B. Haring, M. Medinger, J. Drevs, S. Steinbild, F. Kratz, K. Mross, Clin. Cancer Res. 13 (16) (2007) 4858.
9
Design of Maleimide Boron Cluster Conjugates
2-O
2Na
O
HN
O
N
O
O
Maleimide-closo-dodecaborate conjugate（ B12H12, MID）
Easy to synthesize and low toxic
BSA(bovine serum albumin)
D.S. Wilbur, M. F. Hawthorne, Bioconjugate Chem. 2007, 18, 1226−1240
Maleimide-decaborate conjugate（ B10H10）
(COCl)2
68%
2-
NH
OO
O
O NH
O
N
O
O
2 Et3NH
F(ab’)2
antibody
10
CH2Cl2
TBA-N3
THF
Ph3P, H2O
4
quant87% 2 steps
NaBF4, HCl
1,4-dioxane
321
2-
2 TBA
O
2 TBA
ON3
2-
2-O
2 TBA
ONH2
O
TBA
O-
V. I. Bregadze, Appl.Organometal. Chem., 2007, 21, 98-100
2-O
2 TBA
O
HN
O
N
O
O
5 (MID-TBA)
2-O
2 Na
O
HN
O
N
O
O
MID
THF
4-Maleimidobutyric Acid, BOP, Et3N
77%
2) Na-Amberlite / H2O
1) TMA-Cl / EtOH
89%2 steps
Synthesis of Maleimide-closo-Dodecaborate Conjugate (MID)
11MID is low toxic!
IC50 (mM)
>1
>1
>1
MTT assay (CT26 and B16 cell、 72h)
2-O
2 Na
O
HN
O
N
O
O
MID
2-O
2 Na
ONH2
4
2-SH
2 Na BSH
Cytotoxicity of closo-Dodecaborates
12
The reaction proceeded quantitatively in an hour at rt.
Reaction of MID with Cysteines
2-O
2 TMA
O
HN
O
N
O
O
2-O
2 TMA
O
HN
O
N
O
O
NHRS
OHO
+
6 (MID-TMA)
PBS (pH 7.4)
7a: R = H7b: R = Ac
RHN
HS
O
OH
8a: R = H8b: R = AcMID-2TMA
ESI-negative MSm/z 205.1
8am/z 265.6
8bm/z 286.4
The reaction process was monitored by ESI-TOF MS.
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BSH was detected by the anti-BSH antibody in Western blot analysis.
The intensity of BSH-conjugated BSA bands increased until the mixture of an 1:1 ratio and then became plateau.
Conjugation of MID to BSA in vitro
antibody*
* anti-BSH antibody was kindly donated by Prof. Kirihata (Osaka Prefecture University)
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Cys34
Total number of Cys: 33
Structure of BSA
15
+410
The peptide including Cys34
We could detect the conjugation of MID and the peptide fragment including Cys34 in BSA.
MW 2,845MW 2,835(+48)
2-O
2 TMA
O
HN
O
N
O
O
MID: MW 410
MID : BSA = 1 : 1
MID : BSA = 100 : 1
MID : BSA = 10 : 1
BSA only
Analysis MID-BSA Conjugation by MALDI-TOF-MS
BSA was digested with trypsin and the peptide fragments were analyzed by MALDI-TOF-MS.
CT26-bearing mice (Balb/c/ ; 5 weeks) ♀ i.v.16
• Tumor boron conc. reached 60 ppm in the mice treated with MID-BSA conjugates (10:1, 30 mgB/kg) 12 hours after injection from tail vein.• Boron concentration in other organs was low compared to boron liposomes.
Biodistribution of MID-BSA Conjugates in tumor-bearing mice
Tumor60 ppm
38 ppm
24 36 48 7220
40
60
80
100
120
140
160
180Tumor
BSH 3000ppm
10%DSBL 3000ppm
10%DSBL 5000ppm
time (h)
Bo
ron
(p
pm
)
Biodistribution of BSH-Boron Lipid Liposomes
B/P = 2.7
24 36 48 720
50
100
150
200
250
300
350
400
Blood BSH 3000ppm10%DSBL 3000ppm10%DSBL 5000ppm
time (h)
Bo
ron
(p
pm
)
24 36 48 720
10
20
30
40
50
60
70
80
KidneyBSH 3000ppm10%DSBL 3000ppm10%DSBL 5000ppm
time (h) 24 36 48 720
20406080
100120140160180200
Spleen BSH 3000ppm10%DSBL 3000ppm
time (h)
BSH-Liposome
10% DSBL
30 and 50 mg B/kg
H. Koganei, M. Ueno, S. Tachikawa, L. Tasaki, H. S. Ban, M. Suzuki, K. Shiraishi, K. Kawano, M. Yokoyama, Y. Maitani, K. Ono, H. Nakamura, Bioconjugate Chem. 2013, 24, 124.
CT26-bearing mice (Balb/c/ ; 5 weeks) ♀ i.v.18
Biodistribution of MID-BSA Conjugates in tumor-bearing mice
Tumor60 ppm
38 ppm
• Tumor boron conc. reached 60 ppm in the mice treated with MID-BSA conjugates (10:1, 30 mgB/kg) 12 hours after injection from tail vein.• Boron concentration in other organs was low compared to boron liposomes.• EPR effect was also observed even in the case of the injection of MID itself, suggesting that the conjugation of MID to serum albumin in circulating blood.
19
MID was treated with the blood of mice for 1 h at 37oC and the MID-conjugated protein was determined by Western blotting analysis using anti-BSH antibody.
The higher accumulation of the MID-BSA (10： 1) conjugate is probably due to in situ binding of MID to circulating albumin after intravenous injection.
Conjugation of MID to Serum Albumin in Blood
Cont
rol
(blo
od o
nly)
MID
+ b
lood
Cont
rol
(blo
od o
nly)
MID
+ b
lood
~60 kDa
(serum albumin)
20
Tumor growth of mice injected with MID-BSA conjugates at a dose range of 7.5-30 mg[B]/kg was suppressed after BNCT, and the tumor of some mice completely disappeared 14 days after neutron irradiation.
BNCT Effect of Mice Injected with MID-BSA (10:1) Conjugates
0 3 6 10 14 170
100
200
300
400
500
600
700
800
900
1000
MID(10:1) 3000 ppm
MID(10:1) 1500 ppm
MID(10:1) 750 ppm
Hot Control
Days after Irradiation
Tum
or v
olum
e (m
m3)
Neutron flux 1.5-2.2 x 1012 n/cm2
Kyoto University Reactor (KUR)
thermalneutron
Collaborated with Prof. M. Suzuki’s group at KUR
30 mg[B]/kg
15 mg[B]/kg
7.5 mg[B]/kg
1. We succeeded in the synthesis of maleimide closo-dodecaborate (MID) for conjugation of boron sources to biopolymers.
2. MID is low toxic.
3. MID readily reacted with cysteines including Cys34 in BSA.
4. MID also reacted with serum albumin in blood of mice.
5. Tumor boron conc. reached 60 ppm in the mice treated with MID-BSA (30 mg[B]/kg) conjugates 12 hours after injection.
6. Tumor growth of mice injected with MID-BSA conjugates was suppressed after BNCT.
21
Conclusion
Acknowledgment
We thank Professor Mitsunori Kirihata (Osaka Prefecture University) for kindly donating anti-BSH antibody and Stella Pharma Co. Ltd. for the supply of 10B12H12.We also thank Professors Suzuki, Kondo, Sakurai, and Tanaka for their kind supports to proceed thermal neutron irradiation experiments at KUR.
9F7F
Thank you very much for your kind attention!