Targeted Brush up Fri rm 340 up...

1

On the Development of Targeted -Therapy

Martin W. Brechbiel, Ph.D.Radioimmune & Inorganic Chemistry Section

Radiation Oncology BranchNational Cancer Institute

Disclosures

• Martin Brechbiel declares no conflicts of interest, real or apparent, and no financial interests in any company, product, or service mentioned in this program, including grants, employment, gifts, stock holdings, and honoraria.

The American Pharmacists Association is accredited by the Accreditation Council for Pharmacy Education as a provider of continuing pharmacy education.

Learning Objectives

• Review the possible emitters suitable for therapy applications

• Discuss the basic chelation and conjugation chemistry related to targeted alpha therapy

• Convey the value of using targeted alpha therapy within the proper disease context combined with chemotherapy

What are the possible emitters suitable for targeted radiation therapy applications

A. 225Ac

B. 213Bi

C. 212Pb(212Bi)

D. 211At

E. 227Th

F. 223Ra

What are the design considerations for the creation and development of novel bifunctional chelating agents for targeted radiation therapy?A. Ionic Radius

B. Charge

C. Donor characteristic (Hard vs. Soft)

D. Cavity Size

E. Coordination number

What are the means for evaluating novel bifunctional chelating agents for targeted radiation therapy?

A. Acid catalysed dissociation rates

B. Challenge experiments (cysteine, hydroxyapatite)

C. Serum Stability

D. In vivo evaluation (PK & PD)

E. In vivo evaluation (Biodistribution Studies)

2

How does one choose the “right” -emitting radionuclide for a therapy study / application?

• Availability / Economics

• Logistics

• Matching T½ to targeting vector T½ for appropriate disease presentation / access.

How does one determine the most efficacious order of administration of an -emitting radionuclide combined

with chemotherapeutic?

• Empirically through animal tumor model therapy studies

(1) The chelate must form a metal complex which has sufficient thermodynamic and kinetic stability to prevent loss of radionuclide in vivo;

(2) Conjugation must not alter mAb specificity;(3) Conjugation must not alter the rate of mAb catabolism;

Minimal Criteria For Successful mAb Conjugation

Milenic, Brady, and Brechbiel Nature Rev Drug Disc 2004

Periodic Table of the Elements

Milenic, Brady, and Brechbiel Nature Rev Drug Disc 2004

vs -Particle Radioimmunotherapy

-Particle50-80 m range5-8 MeV

-Particle1-10 mm range0.1-2.2 MeV

Milenic, DE, Brady, ED, and Brechbiel, MW Nature Rev. Drug Disc. 2004, 3, 488.

Particles vs. -Particles

The track of the particle in thes cloud chamber photo is obviously shorter and denser than the low energy electron.

3

Initial - Activity Required to Produce a Cure Probability of 0.9 at the Optimal Tumor Size – What --emitter is best?

1mm 2 3 4 5 10 20 30

177Lu 7.92 MBq/g

67Cu 10.1 MBq/g

131I 6.37 MBq/g

166Ho 4.83 MBq/g186Re 4.97 MBq/g 90Y 2.43 MBq/g

40mm

Choice of -emitter is dependent on disease presentation and scale!

-emitters are not effective against “small” disease; -emitters fill this niche!

O’Donoghue, JA et al J. Nucl. Med. 1995, 36, 1902

225Ac

Chelating Agents for 225Ac

211At

Generally treated as a halogen, but…………

212Bi, 213Bi

Chelating Agents with 212Bi and 213Bi

4

Comparison of Bi(III) Complex Formation RatesThe Reaction of BiI4

- with DOTA is Very SlowThe Reaction of BiI4

- with CHX-DTPA is Fast

Formation t1/2 of Bi(DOTA) is 31 min!

Reaction Conditions: BiI4

- + DOTA = Bi(DOTA)- + I-

(Bi)T = 5.0 x 10-6 M(DOTA) = 5.0 x 10-5 M

0.1 M NaI, pH 4.0, T = 25oC

Reaction Conditions:BiI4

- + CHX-DTPA = Bi(CHX-DTPA) + I-

Same as Above

Formation t1/2 of Bi(CHX-DTPA) is 0.27 sec!!!

212PbChelating Agents used with 212Pb

223RaAlpharadin (223Ra chloride) - Algeta ASA partnered with Bayer Schering

Pharma AG

FDA approval 2013

Structure of chelating agents…

5

227Th

Chelators for 227Th

232Th1.41010 y

228Ac6.13 h

228Ra5.75 y

224Ra3.66 d

228Th1.91 y

220Rn55.6 s

216Po0.15 s

212Pb10.6 h

208Tl3.1 m

212Po0.3 s

212Bi60.6 m

208Pbstable

232U70 y

36%

64%

233U1.6105 y

229Th7340 y

213Po4.2 s

225Ra14.8 d

221Fr4.9 m

209Tl2.20 m

209Pb3.25 h

213Bi45.6 m

209Bistable

217At32.3 ms

217Rn0.54 ms

225Ac10.0 d

99.99%

0.01%

2.2%

97.8%

212Pb 212Bi E= 0.3 MeVE= 239 keV

212Bi 212Po E= 2.3 MeVE= 727 keV

212Bi 208Tl E= 6.1 MeV212Po 208Pb E= 8.8 MeV208Tl 208Pb E= 1.8 MeV

E= 2615 keV213Bi 213Po E= 1.4 MeV

E= 440 keV213Bi 209Tl E= 5.9 MeV213Po 209Pb E= 8.4 MeV209Tl 209Pb E= 1.8 MeV

E= 465 keVE= 1566 keV

209Pb 209Bi E= 0.6 MeV

228Th and 229Th Decay Chains Producing 212Pb, 212Bi, or 213Bi

The HotCell

Choosing a Chelating AgentCriteria to Consider:

• Cavity Size vs. Ionic Radius

• Denticity

• Donor Group Character

• Formation Kinetics

• Dissociation Rates

Stability Constants

6

Choosing a Chelating Agent:But now, is it any Good ?

• Thermodynamic Stability Constants (Transchelation & “Challenge”)

• Acid Catalyzed Dissociation

• Serum Stability (Predictive of Failure)

• Biodistribution Studies (In vivo) 101.3093.01.875.05.0DTPA

97.6087.12.368.45.7CDTA

46.70.543.70.936.55.3EDTA

24 hr

Plasma Urine

8 hr

Plasma Urine

4 hr

Plasma Urine

Ligand

Plasma Level and Cumulative Urinary Excretion ofYttrium Chelates

* Percentage of the administered dose in total plasma volume.# Percentage of the administered dose.

Kroll, H., et al. Nature 1957, 180, 919-920.

In vitro screening cannot be used as a predictor of therapeutic activity of

macromolecular conjugates in vivo

Duncan et. al., Anti-Cancer Drugs 1992, 3, 175.

Biodistribution Studies

Backbone-Substituted DTPA LigandsU.S. Patent 4,831,175

Rationale for the CHX-DTPA Ligand(s)

EDTA Me-EDTA CHX-EDTA DTPA CHX-DTPA

Y(III) 18.09 18.78 19.85 22.13 ?????

In(III) 24.9 ------ 28.8 29.0 ?????

Bi(III) 27.8 ------ 32.4 35.6 ?????

Martell and Smith: Critical Stability Constants

7

Synthesis of 2-p-SCN-Bz-CHX-DTPASynthesis of 2-p-SCN-Bz-CHX-DTPA

0

5

10

15

20

25

0 5 10 15 20

CHX-B

CHX-A

CHX-A"

CHX-A'

CHX-B"

CHX-B'

Serum Stability of CHX-DTPA 88Y Complexes

Act

ivit

y of

88Y

-R

elea

sed

Fro

m C

hel

ates

(%

)

Incubation Time (Days)

0

5

10

15

20

25

0 24 48 72 96 120 144 168

Cortex Uptake of 88Y-B3-CHX-DTPA in Normal Mice

CHX-A'

CHX-A"

CHX-B'

CHX-B"

% I

. D. /

g

Time (Hours)

Bifunctional chelating and linking agents for therapy and imaging

111In, 90/86Y, 177Lu, 213Bi 212Pb

211At

8

Targeted Radiation – Clinical translation summation

ChemistryCHX-A’’*

1B4M-DTPA*TCMC

N-Me-SAPS

*Commercial productsZevalin

Pre-clinical trials @ NCIHER2 / EGFR

213Bi, 212Pb, 211At111In, 86Y

Extramural Clinical trials 90Y CD19 // 90Y CD45

806 Antigen // Lewis-Y // CMD-193

212Pb Clinical trial @ UABAREVA

Clinical trials @ NIH90Y/111In daclizumab

111In trastuzumab

Primary model system(s)

LS-174T i.p. tumors Therapy @ 3 d tumor burden. Controls die at ~ 14-21 d. Both mAbs bind to this tumor.

Imagingtrials

Treatment of disseminated intraperitoneal disease with trastuzumab, panitumumab (HER2/EGFR) targeted -

emitter radiation therapy (212Pb, 213Bi, 211At)

Validation - 111In & 86Y imaging

Survival of Athymic Mice Bearing 3 Day Human Colon Carcinoma Xenografts (LS-174T; i.p.) Following Singlei.p. Treatment with 212Pb-TCMC-Labeled Trastuzumab

Days Post Tumor Implantation

0 20 40 60 150 200

Per

cen

t S

urv

ivin

g

0102030405060708090

100110

PBSCold Trastuzumab (50 g) 10 Ci Trastuzumab 10 Ci HuIgG

Survival of Mice Bearing 5 Day Human Colon Carcinoma Xenografts (LS-174T; i.p.) Following i.p. Treatment with

212Pb-TCMC-Labeled Trastuzumab

0

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0 10 20 30 40 50 60 70

Days Post mAb Treatment

Per

cen

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Control (n=8)Trastuzumab 7 Ci (n=4)Trastuzumab 13 Ci (n=4)Trastuzumab 20 Ci (n=4)Trastuzumab 40 Ci (n=4)Trastuzumab 60 Ci (n=3)HuIgG 20 Ci (n=3)HuIgG 60 Ci (n=3)HuIgG 100 Ci (n=3)

RIT-3

Milenic, D. E., et. al., Cancer Biother. Radiopharm. 2005, 20, 557.

Gemcitabine (difluorodeoxycytidine)

(Gemzar)2’-deoxy-2’,2’-difluorocytidine

• Radiosensitizer (Lawrence et al., Sem. Oncol. 1997, 24, 24)• DNA / RNA anti-metabolite• Therapy for pancreatic and non-small cell lung cancer• Topoisomerase I poison (Pommier et al., Clin. Cancer Res. 2002, 8, 2499)

Effect of Gemcitabine on Survival of Athymic Mice Bearing i.p.LS-174T Xenografts Following Administration of 212Pb-Labeled

Trastuzumab i.p.

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0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90


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Fra

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RIT-13

GEMmAb

Untreated

n = 8

GEM Only

10 Ci HuIgG

10 Ci Trastuzumab 10 Ci Trastuzumab & GEM

10 Ci HuIgG & GEM

Milenic, D. E., et. al., Clin. Cancer Res. 2007, 13, 1926.

9

Treatment Schedule for Combination Modality of Radioimmunotherapy andChemotherapy Protocol: 212Pb-Trastuzumab & GEMZAR {23 n=10 groups}

= 10 Ci 212Pb-Trastuzumab or HuIgG = 1 mg GEMZARDays

Gro

ups

11 / 19

10 / 18

9 / 17

8 / 16

4

0 5 10 15 20 25 30 35 40 45

15 / 23

14 / 22

13 / 21

12 / 20

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Fractionated Radioimmunotherapy (212Pb-Herceptin)/ Gemcitabine Excerpt: 23 Groups (n=10) Athymic Mice Bearing i.p. LS-174T

Xenografts

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Su

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2X GEM

10 Ci Trastuzumab

10 uCi HuIgG

10 Ci HuIgG & 2X GEM

mAb

Gem10 Ci Trastuzumab & 2X GEM


Taxol (paclitaxel)(2aR,4S,4aS,6R,9S,11S,12S,12aR,12bS)-1,2a,3,4,4a,6,9,10,11,12,12a,12b-

Dodecahydro-4,6,9,11,12,12b-hexahydroxy-4a,8,13,13-tetramethyl-7,11-methano-5H-cyclodeca(3,4)benz(1,2-b)oxet-5-one 6,12b-diacetate,

12-benzoate, 9-ester with (2R,3S)-N-benzoyl-3-phenylisoserine

• Radiosensitizer (Steren et al., Gyn. Oncol.1993, 48, 252)

• Induces and stabilizes assembly of tubulininto microtubules to disrupt mitosis

• Therapy for advanced ovarian cancer

Survival of Athymic Mice Bearing Human Colon CarcinomaXenografts ( LS-174T; i.p.) Following a Sequential Administration

of 212Pb Labeled mAb and 600 g Taxol 24 hr pre-RIT

Days Post-Tumor Implantation0 20 40 60 80 100 120 140 160 180 200

0

20

40

60

80

100

% S

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ice

Control 600 g Taxol

600 g Taxol

600 g Taxol

10 Ci Trastuzumab

10 Ci Trastuzumab

10 Ci HuIgG

10 Ci HuIgG


Combination Therapy: 213Bi-Labeled Herceptin / Taxol213Bi-Labeled Herceptin plus 600 g Taxol 24 hr post-RIT:Survival of Athymic Mice Bearing i.p. LS-174T Xenografts

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Days Post-Tumor Implantation

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500 Ci Herceptin

600 g Taxol

500 Ci HuIgG

500 Ci HuIgG / 600 g Taxol

500 Ci Herceptin / 600 g Taxol

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Untreated

3X Paclitaxel

Trastuzumab

Paclitaxel/Trastuzumab/Paclitaxel 2XHuIgG

Paclitaxel/HuIgG/Paclitaxel 2X

Survival of Athymic Mice Bearing Human Colon Carcinoma Xenografts (LS-174T; i.p.) Following One Cycle of paclitaxel and

212Pb-Labeled Trastuzumab


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Per

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trastuzumab

cetuximabpanitumumab

HuIgG

Survival of Athymic Mice Bearing Human Colon Carcinoma Xenografts (LS-174T; i.p.) Following a Single 10 Ci

Administration of 212Pb

Milenic, D. E., et. al., in preparation

trastuzumab – studies with 212Pb• Single i.p. Dose MTD Median Survivals

• 212Pb (10 Ci) Established 56 d

• Combination Therapy

• Single i.p. Dose MTD• 212Pb ( 10 Ci) Established 145 d• 212Pb (10 Ci) Established >200 d

• Combination Therapy

• 212Pb @ 10 Ci + gemcitabine 70 d • 212Pb @ 10 Ci + gemcitabine; multi-dosing 197 d• 212Pb @ 10 Ci + paclitaxel – dosing & admin. order 180 d• 212Pb @ 10 Ci + paclitaxel; multi-dosing >300 d• 212Pb @ 10 Ci + carboplatin 160 d

cetuximab; panitumumab – current & ongoing studies with 212Pb

• 212Pb @ 10 Ci + Gemcitabine > 200 d

Targeted -emitter radiation therapy – 212Pb

Progression of 212Pb translation to clinical evaluation – Phase 1 Trial

DOTA complex DOTA chemistry

HER2 therapy

TCMC complex

212Pb/Gemcitabine

212Pb/paclitaxel

212Pb dual targeting

212Pb Mech

212Pb Gemcitabine Mech212Pb Paclitaxel Mech

1st 212Pb ip therapy study

1991 1996 1997 2000 2005 2007 2008 2010 20132012

DOTA complex DOTA chemistry

HER2 therapy

TCMC complex

212Pb/Gemcitabine

212Pb/paclitaxel

212Pb dual targeting

212Pb Mech

1st Contact 1/07 AREVAJDC presentation 4/26Relocate to UAB 9/19

Team Meeting France 5/18CRADA Approved 6/04Pre-IND 7/28

Pre-vial testing 6-7/2009GMP vialed 9/2009

IND approved 1/24Tubiana Site Open 6/2011Trial open 7/28

1st Patient treated

Oct 2014 – Phase 1 Trial Completed

212Pb Gemcitabine Mech212Pb Paclitaxel Mech

1st 212Pb ip therapy study

1991 1996 1997 2000 2005 2007 2008

2007 2008 2009

2010

2010 2011

20132012

2012 2014

Toxicity Studies @ NCI07/2009 - 08/2010

Mechanistic Studies – 212Pb-TCMC-trastuzumab

• ds breaks

• Repair mechanisms

• Apoptosis

• Chromatin remodeling

• etc….

Studies need to be performed in vivo –> tumor bearing animal model!

More mice…..

• Mice bearing human colon cancer LS-174T intraperitoneal (i.p.) xenografts were treated with 212Pb-TCMC-trastuzumab and compared with non-specific controls:– 212Pb-TCMC-HuIgG– Trastuzumab– HuIgG

• Tumor tissue was harvested from mice treated with 212Pb-TCMC-trastuzumab and the non-specific controls at:– 0, 6, 24, 48, 72, 96, 120 h

Mechanistic Studies – 212Pb-TCMC-trastuzumab

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Induction of Apoptosis by 212Pb-TCMC- trastuzumab in LS-174T ip Xenografts

A TUNEL DAPI

Untreated

HuIgG

Trastuzumab

212Pb-HuIgG

212Pb-Trastuzumab

The presence of apoptotic bodies on tumor sections was determined at 24 h using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) system. TUNEL staining; left, DAPI counterstaining; right (40x).

A clear induction of apoptosis was observed in tumors upon 212Pb-TCMC-trastuzumab treatment vs. controls.

Yong, K. J., et. al., Mol. Cancer Therap. 2012, 11, 640.

HuIgG

Trastuzumab212Pb-HuIgG212Pb-Trastuzumab

212Pb-TCMC-trastuzumab treatment significantly increased in apoptotic rates (P <0.05) based on morphologic criteria (isolated distribution, fragmentation of nuclei, etc).

Apoptotic bodies were scored using IHC and H&E staining at the indicated times.


Induction of Apoptosis by 212Pb-TCMC- trastuzumab in LS-174T ip Xenografts

Comet

γH2AX

A B

212Pb-HuIgGUntreated 212Pb-Trastuzumab

212Pb-HuIgGTrastuzumab

212Pb-Trastuzumab

HuIgG

212Pb-TCMC-trastuzumab induced DNA damage and repair delay in LS-174T i.p. xenografts

Induction of DNA DSB damage was evident as measured by IHC staining for γH2AX (Top).

Comet assay shows physical DNA strand damage (Bottom).

Enhancement and specificity of fluorescence intensity of the tail was observed for 212Pb-TCMC-trastuzumab vs. 212Pb-TCMC-HuIgG.

To determine impact on DNA damage repair, DNA content in the tails was compared by comet assay. DNA repair inhibition was more pronounced in the mice treated with 212Pb-TCMC-trastuzumab as indicated by the persistently higher % DNA in the comet tail at all time points (p < 0.001) which exhibited a greater specific effect from 212Pb -TCMC-trastuzumab.


Rad 51c-Caspase 3

0.0

0.2

0.4

0.6

Rel

ativ

e d

ensi

ty

GAPDHGAPDH

DNA-PKcs

212Pb-TCMC-trastuzumab induced DNA damage and repair delay in LS-174T i.p. xenografts: Western Blot Analysis

Rad51 and DNA-PKcs, essential for HR and NHEJ, respectively,.

At 24 h, Rad51 was significantly down-regulated by 212Pb -TCMC-trastuzumab while DNA-PKcs was not affected, suggesting Rad51 may be responsible for the delayed DNA damage repair.

The level of cleaved caspase-3 was significantly reduced by 212Pb -TCMC-trastuzumab suggesting the induction of apoptosis occurs via a caspase-3 independent mechanism.


Effect on chromatin remodeling by 212Pb-TCMC-trastuzumab

The ChIP assay, using p21 promoter specific primers, was quantified using qPCR to determine whether changes occur in chromatin remodeling following 212Pb-TCMC-trastuzumab treatment. The H3K4 to H3K9 methylation ratio served as a measurement of change (open/close) in chromatin structure.

The abundance of histone modifications identified with transcriptionally activated chromatin states, such as H3 methylated at lysine 4 observed at 48 h with 212Pb-TCMC-HuIgG and 72 h after 212Pb-TCMC-trastuzumab treatment, indicated that the open chromatin structure was delayed until 72 h.


Effect on chromatin remodeling by 212Pb-TCMC-trastuzumab by Western blot


There was significant reduction of p21 at 24h vs. non-specific control, indicating that reduction of p21 expression was specific to 212Pb-TCMC-trastuzumab treatment.

GAPDH

p21

Un

trea

ted

Hu

IgG

Tra

stu

zum

ab

212 P

b-Ig

G

212 P

b-T

rast

uzu

mab

Induction of p21 protein and modification in chromatin structure of p21 in response to 212Pb-TCMC-trastuzumab was investigated.

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Time point (h)

0 6 24 48 72 96 120

None 23.8±1.3

212Pb-Trastuzumab 13.7±1.2 7.3±1.4 2.6±0.7 7.5±0.5 1.1±0.2 1.6±0.3

212Pb-HuIgG 16.4±1.2 8.1±0.9 2.4±0.1 2.8±0.5 4.2±0.4 13.2±0.4

Trastuzumab 15.1±1.0 21.4±1.1 14.8±12.9 27.5±1.5 20.6±1.8 18.2±2.3

HuIgG 15.9±0.8 19.0±0.4 20.7±1.3 23.4±1.1 22.1±0.6 16.7±1.3

Analysis of DNA synthesis in LS-174T tumor xenografts (n=5 mice) following treatment with 212Pb-TCMC-trastuzumab

Values are the average and standard deviation of three analysis.

Mice were injected with 5’-bromo-2’-deoxyuridine (BrdU) 4 h prior to euthanasia. BrdU incorporation decreased by 6 h after specific treatment (13.7±1.2) and remained low throughout the study. Cessation of DNA synthesis is specific to α-radiation and continued depression of DNA synthesis post-120 h was specific to the targeted therapy.


Time point (h)Treatment Phase 0 6 24 48 72 96 120

G1 67.5±2.7S 17.7±2.0

G2-M 14.8±0.7

212Pb-Trastuzumab G1 68.6±3.8 66.9±1.3 67.7±4.0 68.1±1.3 66.6±0.7 73.2±0.1S 14.3±5.4 5.9±0.1 6.3±1.8 7.9±0.7 3.6±0 4.6±1.9

G2-M 17.1±1.6 27.3±1.2 26.1±2.1 23.9±0.6 29.7±0.7 22.2±2.0

212Pb-HuIgG G1 63.9±5.2 65.1±2.3 64.6± 67.1±0.5 63.1±0.3 65.5±2.6S 20.0±5.3 7.4±1.3 5.8± 5.5±0.1 7.8±0.7 17.1±3.6

G2-M 16.0±0.1 27.5±1.0 29.6± 27.4±0.6 29.1±1.0 17.5±0.9

Trastuzumab G1 69.5±2.6 63.3±1.6 68.0±0.1 61.3±1.8 65.1±3.3 73.3±4.3S 21.7±3.4 26.0±3.2 22.0±1.8 28.1±1.6 23.5±4.3 14.8±2.9

G2-M 8.9±0.9 10.7±1.6 10.1±1.7 10.7±3.4 11.5±1.0 11.9±1.4

HuIgG G1 72.3±3.4 70.3±3.4 70.6±2.3 60.6±1.6 73.9±1.0 74.6±2.2S 22.0±3.4 19.8±2.1 20.9±1.9 26.6±1.8 19.6±2.2 18.2±2.3

G2-M 5.7±0 9.8±1.4 8.4±0.4 12.8±0.2 6.6±1.2 7.2±4.5

Cell cycle distribution analysis following treatment with 212Pb-trastuzumab

Values are the average and standard deviation of three analyses. Yong, K. J., et. al., Mol. Cancer Therap. 2012, 11, 640.

Conclusions212Pb-TCMC-trastuzumab treatment induced significantly more apoptosis and dsb’s.

Rad51 protein expression was down-regulated, indicating delayed DNA double strand damage repair.

212Pb-TCMC-trastuzumab resulted in G2/M arrest, depression of S phase fraction and depressed DNA synthesis persistent > 120 h.

212Pb-TCMC-trastuzumab delayed open chromatin structure and expression of p21 until 72 h.

Result Increased cell killing efficacy in the LS-174T i.p. xenograft model for disseminated intraperitoneal disease.

Targeted -emitter radiation therapy – Summation & Future Plans

212Pb-TrastuzumabDose escalation2

5d tumorEffective Dose Confirmation in 2 models2

LS-174T & PcSwMultiple dosing (4, monthly)2

LS-174 & Pc-SwDetermination of GEM dose with 212Pb4

Multiple doses of GEM & 212Pb4

212Pb with Paclitaxel5

Administration Sequence 212Pb with Carboplatin6

Administration SequenceMechanistic Studies 212Pb7

Mechanistic Studies GEM/212Pb8

Mechanistic Studies Pac/212Pb9

Gene Expression Profiling 212Pb11

Gene Expression Profiling Pac/212Pb12

Gene Expression Profiling Gem/212Pb*

212Pb-PanitumumabDose Escalation

i.p. injectedi.v. injected

GEM/212PbAdministration Sequence

Paclitaxel/212PbAdministration Sequence

Topotecan/212PbAdministration Sequence

Mechanistic Studies 212Pb

212Pb-Panitumumab F(ab’)2

Dose Escalationi.p. injectedi.v. injected

GEM/212PbAdministration Sequence

Paclitaxel/212PbAdministration Sequence

211At-TrastuzumabDose Escalation3d tumor

GEM/211AtAdministration Sequence

Paclitaxel/211AtAdministration Sequence

1 Clin Cancer Res 10: 7834, 20042 Cancer Biother Radiopharm 20: 557, 20053 Cancer 116(S4): 1059, 20104 Clin Cancer Res 13:1926 20075 Clin Cancer Res 14: 5108, 20086 Cancer Biotherap Radiopharm, 28: 441, 20137 Mol. Cancer Therap. 11: 640, 20128 Int. J. Radiat. Oncol. Biol. Phys. 85: 1119, 20139 Br. J. Cancer 108: 2013, 201310 Pharmaceuticals 5: 1, 201211 Cancer Med. 2: 646, 201312 PLOS 1 9: e108511, 2014* SubmittedOngoingFuture studies

177Lu-TrastuzumabDose Escalation10

i.p. injectedMechanistic and Gene Expression

Profiling Studies 177Lu*

Martin Brechbiel, Ph.D. Diane Milenic, MS

Kwamena Baidoo, Ph.D. Young-Seung Kim, PhD.

Radioimmune & Inorganic Chemistry SectionROB, CCR, NCI

2015

What are the possible emitters suitable for targeted radiation therapy applications

A. 225Ac

B. 213Bi

C. 212Pb(212Bi)

D. 211At

E. 227Th

F. 223Ra

13

What are the design considerations for the creation and development of novel bifunctional chelating agents for targeted radiation therapy?A. Ionic Radius

B. Charge

C. Donor characteristic (Hard vs. Soft)

D. Cavity Size

E. Coordination number

What are the means for evaluating novel bifunctional chelating agents for targeted radiation therapy?

A. Acid catalysed dissociation rates

B. Challenge experiments (cysteine, hydroxyapatite)

C. Serum Stability

D. In vivo evaluation (PK & PD)

E. In vivo evaluation (Biodistribution Studies)

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