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Radiopharmaceuticals Labeled with Bromine Radionuclides

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Radiopharmaceuticals Labeled with Bromine Radionuclides Powered By Docstoc
					Applications of 76Br Radiochemistry


          Robert H. Mach, Ph.D.

      Division of Radiological Sciences
   Washington University School of Medicine
                St. Louis, MO



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                   Disclosure

•   US Patent 6,113,877
•   US Patent 6,676,925
•   US Patent 6,669,925
•   US Patent 7,390,902
•   US Patent Application # 2008/107599A1
•   Isotrace Technologies, Inc.
•   Bayer Schering Pharma AG



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                Issues Associated with 76Br

1.   Production

     -Solid target: Cu2Se   76Se(p,n)76Br


     -Dry distillation



2.   Properties of Radioactive Decay

     -High energy positron

     -High energy gammas



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CS-15 Cyclotron and Target Stations




      Beam current: 5 μA                    Washington
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Halogen Radionuclides Process Summary (cont’d)

  Dry Distillation
 • Start Argon gas flow in the quartz tube located in the furnace
 • Place target face-up in the center of the quartz tube
 • Turn furnace ON and heat up to 1080°C for approximately 40 min to
   preheat + 50 min to release Br and I isotopes from target. Then furnace is
   turned OFF.

  Recovery
 • Activity is carried over by the Argon gas stream and settled over ~ 4 cm
   on the quartz tube wall (smaller Ø side)
 • Recover the activity using a total ~ 900µL of 0.6M NH4OH
50 – 80% recovery from distillation; 10 – 20 mCi in final collection vial
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Radionuclide Properties


                         76Br              18F            11C

  Nuclear                               18O (p,n)
                  76Se   (p,n)   76Br               14N   (p,α) 11C
  Reaction                                 18F


  T1/2               16.2 hr            109.8 min    20.4 min

  % β+ Decay         57% β+             >99% β+       97% β+

  Eβ+ avg (kEv)          1,180            250             386

  Eβ+ max (kEv)          3,980            640             960


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 Fortuitous coincidences from cascade gamma rays

                      16.2 h, Emax= 3941 keV

3352           8.6%         76Br

3160            6%

3070           20%

2951      12.3%

1689
                3%
1216
               26%
559
               6%
  0
       76Se
                                               With 2 cascades γ rays, there are 6
       76Br: 3.35 gamma/decay                           possible LORs.
        86Y; 4.55 gamma/decay                  Only the annihilation pair is good
       60Cu; 4.00 gamma/decay                           for imaging !!!
       61Cu; 2.18 gamma /decay
  Sphere Phantom imaged with Br-76

MAP β = 0.05, 30 iterations
Without range correction




MAP β = 0.01, 30 iterations
With range correction
            76Br-nanostructure   (RGD conjugated)

           OSEM-2D                   MAPR, β = 0.01, 30iter




           Maximum Intensity Projection images

mmr0613f
   Example 1:
Cell Proliferation




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                          O
            76
             Br                        BrdU
                              NH


                          N        O           Br-
   HO
                  O
            H         H
        H                 H
            OH        H

[76Br]Bromodeoxyurine ([76Br]BUdR)




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         18F-Labeled                 Thymidine Analogs                                 18F-Labeled   Sigma-2 Radiotracer
                                                                      O
                            O
                                                                          CH3
                                     CH3                                                                                   OCH3
                                                            HN                  18
                   HN                                                            F
                                                                                       O     O
                                                                                                               N
                                                        O             N
              O             N                                                                    N                         OCH3
                                                                                                 H
                                           HO
HO                                                                                                    [18F]ISO-1
                                                            O                          CH3
                  O
                                                    H           18F
          H             H
                                                H                     H
     H                      H                       OH           H
         18
          F             H

                  [18F]FLT                      [18F]FMAU




                                       M
                                G2
                                                                                                                    P:Q Ratio:
                                                    G1                                       G0                    Important for
                                     Ki-67                                                                          Treatment
                      S
                                                                                        Ki-67 (-)                    Planning
                                 DNA



              Proliferating Tumor Cell (P)                                      Quiescent Tumor Cell (Q)
              Sigma-2 Receptor Imaging Agent: [76Br]3

                                             OCH3                                               OCH3
  H311CO           O                                       H3CO       O

                                    N                                                   N
                       N                     OCH3                         N                     OCH3
                       H                                                  H

                               1                                                  2
             CH3        σ1 = 3,078 nM                                     σ1 = >1,000 nM
                        σ2 = 10.3 nM                              F
                                                                           σ2 = 21.8 nM
                       σ1:σ2 ratio = 300                                  σ1:σ2 ratio = >46
                         Log P = 2.84



                                                      F

                                             OCH3                                             OCH3
       H3CO        O                                       O      O
H3CO                                 N              H3CO                            N
                       N                     OCH3                     N                       OCH3
                       H                                              H
                                3                                            4
             Br         σ1 = 12,900 nM                     Br         σ1 = 15,300 nM
                          σ2 = 8.2 nM                                  σ2 = 386 nM
                       σ1:σ2 ratio = 1,575                            σ1:σ2 ratio = 40
                          Log P = 3.33                                 Log P = 3.56


        76
             Br



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                                    OCH3                                                                               OCH3
       OCH3 O                                                                OCH3 O
                                                  [76Br]NH4Br        H3CO                         N
H3CO                     N                                                            N                                OCH3
                N                   OCH3                                              H
                H
                                           5% Peracetic Acid:Acetic Acid
                                           Milli-Q and EtOH                 76
                                                                                 Br
       Sn(C4H9)3                                                                          ~60%



                             EMT-6 Mouse Mammary Adenocarcinoma




  Tumor                                              Tumor


       Liver                                                                                              Liver
                      Non-block                                              Block
                                                  2 hour
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                    Rowland et al., J. Nucl. Med. 47: 1041 – 1048 (2006)                         MIR         Mallinckrodt Institute
                                                                                                             of Radiology
                                    OCH3                                                                                                         OCH3
       OCH3 O                                                                         OCH3 O
                                                  [76Br]NH4Br        H3CO                                                 N
H3CO                     N                                                                       N                                               OCH3
                N                   OCH3                                                         H
                H
                                           5% Peracetic Acid:Acetic Acid
                                           Milli-Q and EtOH                     76
                                                                                      Br
       Sn(C4H9)3                                                                                        ~60%



                                                                                                            76 Br]1
                                                                                           [18 F]FLT vs. [ [76Br]3
                                                                               12.5



                                                                                 10




                                                                       Ratio
                                                                                7.5
                                                                                                                                                 [18F]FLT

                                                                                  5                                                               76Br]3
                                                                                                                                                  76
                                                                                                                                                 [[ Br]1


                                                                                2.5



                                                                                  0


                                            [76Br]3




                                                                                                            e




                                                                                                                                       e
                                                                                                                     at
                                                                                              od



                                                                                                            cl




                                                                                                                                   on
                                                                                                                     :F
                                                                                            lo



                                                                                                        us




                                                                                                                                  :B
                                                                                                                 or
                                                                                           :B



                                                                                                       :M




                                                                                                                              or
                                                                                                                 m
                                                                                        or




                                                                                                             Tu
                                                                                                     or




                                                                                                                              m
                                                                                       m




                                                                                                                          Tu
                                                                                                   m
                                                                                      Tu



                                                                                                 Tu
          1 hour                           2 hours


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                    Rowland et al., J. Nucl. Med. 47: 1041 – 1048 (2006)                                                  MIR          Mallinckrodt Institute
                                                                                                                                       of Radiology
                                                OCH3
MsO
           O     O                                            [18F]Fluoride
                                      N
                     N                          OCH3      104oC/10 min
                     H

           CH3

                                                       OCH3
      18
       F
                 O       O
                                            N                  Yield: 50%
                             N                     OCH3
                             H
                                  [18F]ISO-1
                 CH3
                                 σ1 = 330 nM
                                 σ2 = 6.95 nM
                                  Ratio = 48
                                 Log P = 3.06



           EMT-6 Mouse Mammary Tumors




 MicroPET                           Merged                            MicroCT
                 J. Med. Chem. 50: 3194 (2007)
    MicroPET/CT: Murine Mammary Cancer (66)
                                                      T
                                      T
[18F]ISO-1



                                      T
[18F]FLT                                                    T




                                          T
                                                            T
[18F]FMAU


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                             Example 2: PPARγ Antagonists
                                  Co-activator
             Co-activator          complex
               protein                                      Plays a role in a variety of tumor
   PPAR                 RXR
ligands                             Target gene
                                                            development, inflammation, Type
                                   transcription
                                                            II diabetes, neurodegenerative and
          Response element
                                                            cardiac diseases
  Ligand-dependent transcriptional
  activation

            PPARγ Antagonists


                                   O               N                 O

               O2N                                          O2N
                                        N                                 N
                                        H                                 H

                                                                     Cl               18
                                   Cl                  18
                                                        F                              F


                               T0070907                                   GW9662

                             PPARα: 850 nM                           PPARα: 39 nM
                             PPARγ: 1.0 nM                           PPARγ: 5.4 nM
                            PPARδ: 1,800 nM                         PPARδ: 1,200 nM              Washington
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PPARγ Antagonists
                                                O
                                                                 Y
                     O2N
                                                       N
                                                       H


                                                X



 Compound            X        Y      IC50 (nM)       Compound   X    Y   IC50(nM)

       1            Br        C          1.8               4    Br   N        2.8

  GW9662            Cl        C         13.9         T0070907   Cl   N     148.3

       3             F        C        264.8               6    F    N     155.3
  Reported values: IC50 GW9662=5.4±0.6 nM
  Leesnitzer L., et al. Biochemistry 2002, 41, 6640-6650

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       Copper-assisted Halogen Exchange

        O                                                O
O2 N                         [76Br]NH4Br       O2N
             N                                                   N
             H                                                   H
                       0.04 M CuSO4/DMSO
        Cl
                            150oC/2 hr
                                                         76
                                                          Br


                                                              [76Br]1
                    Radiolabeling yield: 60-70%
                 Specific activity: > 1,000 mCi/μmole

       % [76Br]1      5 min.       30 min.    120 min.

       Plasma           54            27         13

        Whole
                        15            8           9
        blood
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                                                  Second Generation Analogs
                                                                                                                                    O
                                    O                                                                                                                           X
                                                                                                            O2N
             O2N                                                                                                                         N
                                         N                                                                                               H
                                         H
                                                                                                                                    Cl
                                    Cl
                                                                                                                         SL-12        SL-13
                             GW9662                                                                                   X = CH2CH2F X = OCH2CH2F
                     reported PPARγ = 5.4 nM                                                                          IC50 = 30 nM IC50 = 48 nM
                           IC50 = 144 nM                                                                               RBA = 900    RBA = 700


                           [18F] 12                                                                          [18F] 13
             5                                                                                 5
                                                            TG/C heart                                                                             TG/C heart
             4                                              TG/C brain                         4                                                   TG/C brain
                                                            TG/C heart blocking                                                                    TG/C heart blocking

                                                                                  TG/C ratio
TG/C ratio




             3                                              TG/C brain blocking                3                                                   TG/C brain blocking

             2                                                                                 2

             1                                                                                 1

             0                                                                                 0
                 0    10   20       30       40   50   60                                          0   10   20       30       40   50    60
                                Time (min)                                                                       Time (min)


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                   Conclusion #1
•76Br-labeled Radiotracers are useful as imaging agents
provided that there isn’t a 18F-labeled version that works as
well

•Question: When should Br-76 be used in radiotracer
development?




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     Case 1:
Drug candidate
 contains a Br
  H3CO



                             N
   HO                            CH3

  H3CO




  H3CO                  Br

           A-69024
         D1 = 12.6 nM



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                               [76Br]A-69024: Synthesis
H3CO                                              H3CO                         H3CO


                           N                                   N                                             N
 HO                            CH3                 HO                   CH3     HO                                 CH3
                                                                   76
                                                                [ Br]NH4Br
H3CO                                              H3CO                         H3CO
                                     n-BuLi/THF                 Chloramine-T
                                      (Bu)3SnCl

H3CO                  Br                          H3CO     Sn(Bu)3             H3CO                 76
                                                                                                      Br

         A-69024                                                                      [76Br]A-69024
       D1 = 12.6 nM                                                                       70-80%




                               Kassiou et al. Nucl. Med. Biol. 29: 295 – 302 (2002)

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           [76Br]A-69024: In vitro Binding Studies




(+)




(-)



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      Kassiou et al. Nucl. Med. Biol. 29: 295 – 302 (2002)   MIR Mallinckrodt Institute
                                                                 of Radiology
       [76Br]A-69024: PET Studies




Kassiou et al. Nucl. Med. Biol. 29: 295 – 302 (2002)
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            [76Br]BrPH: Synthesis
H                                                H
N                                                N


                                                                         76
                       Cl                                                   Br

                   N                                              N


     Epibatidine                                     [76Br]BrPH



 H
 N
                               [76Br]NH4Br
                            CuSO4/190oC/30 min

                        I

                   N

      IPH



Kassiou et al. Synapse 45: 95 – 104 (2002)
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[76Br]BrPH: Nicotinic Acetylcholine Receptors


                                 KD1 = 8 pM


                                        KD2 = 3 nM




    Kassiou et al. Synapse 45: 95 – 104 (2002)
Kassiou et al. Synapse 45: 95 – 104 (2002)




Displacement Study               Blocking Study
Specific Activity = 48 – 55 GBq/μmol
      (1,300 – 1,500 mCi/μmol)




Specific Activity = 6– 20 GBq/μmol
       (160 – 540 mCi/μmol)
       Case 2:
Compounds with a long
  biological half-life



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         Example 1:

Bromine-76 Labeled Antibodies




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Imaging of tumor vasculature with 76Br-L19-SIP
The extra domain B (ED-B) of               129/sv mouse with F9 tumor imaged at 24 h and 48 h
                                           after administration of 76Br-L19-SIP (ca. 1.4 mg/kg bw,
fibronectin is overexpressed               350 μCi/mouse). In left panel, the animal was slightly
on tumor vasculature and                   offset from full supine position because of the tumor in
normal tissues undergoing                  the hindlimb.
angiogenesis.
                                           24 h p.i.                 48 h p.i.

The human recombinant                                                                                   Max
scFv fragment (L19) has
been sub-nanomolar binding
affinity for ED-B of fibronectin

      Small Immunoprotein
       L19-SIP (~ 75 kDa)



                                                                                                        Min
     VH    VL         VL   VH


          εCH4    εCH4
                                BPO/H2O2
                S-S                                        F9 tumor                    Washington
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          Rossin, et al., J Nucl Med 48: 1172-9 (2007)                           MIR Mallinckrodt Institute
                                                                                     of Radiology
Imaging of tumor vasculature with 76Br-L19-SIP

  5 h p.i.      24 h p.i.     48 h p.i.
                                            SUV               5h          24h             48h p.i.

                                            Tumor         2.4 ± 0.5     2.7 ± 0.1 2.4 ±0.2
                                            Muscle        0.6 ± 0.2     0.6 ± 0.0 0.5 ± 0.0
                                            Stomach          ND         1.9 ± 0.0 1.9 ± 0.0


                                            SUVs for 76Br-L19-SIP from the quantitation of
                                            MicroPET images in F9 tumor bearing mice (n =
                                            4). Data are obtained from averaging 3D regions
                                            of interest in the selected organs, and presented
                                            as mean SUV ± SD.

                                            Coronal microPET projection images of two F9
                                            tumor bearing mice at 5 h (left), 24 h (center), and
                                            48 h (right) p.i. The imaging intensity was decay-
                                            corrected and scaled by max/min frame.

  min                             max
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     Rossin, et al., J Nucl Med 48: 1172-9 (2007)                               MIR Mallinckrodt Institute
                                                                                    of Radiology
              Example 2: Radiolabeled Nanoparticles

 Integrated Nanosystems for Diagnosis and Therapy
Program of Excellence in Nanotechnology (HL080729)

 In vivo evaluation of nanoparticles (NPs) for diagnosis and treatment
                                of heart and lung diseases
Contributions from:
 Washington University in Saint Louis School of Medicine
• Michael J. Welch group
• Steven Brody group
• Dana R. Abendschein group
• Carolyn J. Anderson group
 University of California at Berkeley, Department of Chemistry
• Jean Fréchet Group
Washington University in Saint Louis, Department of Chemistry
• Karen L. Wooley                                                      Washington
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 Nanoparticle: Targeted Dendrimer for imaging acute
                   vascular injury
Controlled blood retention time - PEG chains

In vivo evaluation - functionalization with positron emitting radionuclides
76Br-Tyrosine   (T1/2 = 16.2 h, β+ = 57%)

Targeting – the tripeptide Arg-Gly-Asp (RGD) recognized by αvβ3 integrin
which is over-expressed in proliferating vascular smooth muscle cells
after vessel injury




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Biodegradable RGD-dendrimers - synthesis




      Core:
  pentaerythritol
                            MW = 28 kDa




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            Hindlimb ischemia mouse model (HLI)
Male C57BL/6 mice
Double ligation and excision of the femoral artery of the right thigh
Causes ischemia and stimulates angiogenesis (αvβ3 expression) mainly at the
distal area
Sham injury in the left thigh
Studies were preformed 7 days post injury
        day 0                                                   day 7
HLI injury               Sham injury           HLI injury           Sham injury




• Doppler images for blood flow measurements after injury (day 0) and a week later show
  increase from 10% to 50%
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      Biodegradable RGD-dendrimers - HLI
    Male C57BL/6 mice 7 days post injury administered with ca. 80 μCi 76Br-tracer (0.6 - 0.8
    mg/kg mouse body weight)
    Double ligation and excision in right thigh, sham injury in left thigh
    Right mouse RGD-dendrimer, left mouse control dendrimer
    Imaged at 24 hours p.i.
                                                            76Br-tyrosine
       RGD-dendrimer            Control dendrimer




                                                            ~5 RGD
                                                            per molecule


                                                     RGD- dendrimer
                                                     5-10 nm (GPC)
                                                     28 kDa, 2.7 kDa PEG chain
                                                     5.2 RGDs/molecule (NMR)
                                                     IC50 : 0.18 nM (/[NP])

                                                     Control-dendrimer (no peptides)
                                                     IC50 : > 8000 (/[NP])
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Almutairi, A. et al. manuscript in review                                              MIR Mallinckrodt Institute
                                                                                           of Radiology
        Biodegradable RGD-dendrimers - HLI
     Activity ratio between right (injured) and left (sham) muscle at the proximal
     and distal regions (n = 6 – 8) at 24h post injection
                                    Biodistribution                                                 microPET
                            7                      *                                        6                    *
                            6                                                               5
                                                                                                  *
          Right / L ratio




                                                                          Right / L ratio
                            5
                                                          RGD_dendrimer                     4
                   eft




                            4




                                                                                   eft
                            3                             control                           3

                                                                                            2
                            2


      1                     1
                                                           (* P<0.05)
                                                                          1                 1

                            0                                                               0
                                proximal         distal                                         proximal       distal




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Almutairi, A. et al. manuscript in review                                                                            MIR Mallinckrodt Institute
                                                                                                                         of Radiology
      Example 3: Delivery of Nanoparticle to Lungs
   Queston: can polyacrylamide NP deliver therapeutic cargo to lungs?

   Radiolabeling of polyacrylamide based NPs
    Biodistribution study following intra-tracheal adminstration in the lung (125I)
    MicroPET imaging (76Br)

  Polyacrylamide nanoparticles

                           76Br
              76Br
                                                                  JAC-NP
          Chloraime-T




• Note: For BioD studies all NPs were labeled with 125I in Iodogen tubes


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Polyacrylamide based NPs - biodistribution
 Male C57BL/6 mice (n = 3 – 5)
 Injection dose: 1 µCi and 100µg [125I]JAC-NP in 50 µL PBS
 Time points: 1h, 3h & 24h
 Organs collected for activity assay

Intra-tracheal (I.T.) administration
 Anesthesia: intra-peritoneal injection of avertin
 Surgically cut down of tracheal to insert catheter


                     Bronchoalveolar lavage
        Particles    (BAL) at 1, 3 and 24h       Activity Assay
                                                                              &
        (I.T)         • Catheter inserted I.T.   (γ-counter)
                      • PBS, 1 mL injected,
                      • Aspirated                                 BAL fluid         Post-BAL lung
                      • 3 x 1mL
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                                                                                  MIR Mallinckrodt Institute
                                                                                      of Radiology
BioD of 125I-labeled JAC-NP
 %ID/organ




                   Activity removed by BAL (%)
                     1h         3h       24h
                    74%        42%       33%


  The decreasing percentage of activity removed by BAL suggested
  endocytosis by lung cells.
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                                                            MIR Mallinckrodt Institute
                                                                of Radiology
MicroPET/CT of 76Br-labeled JAC-NP

                            1h                       16h          High




                                                                   Low


I.T. injection of ca. 25µCi and 100µg 76Br-labeled JAC NP         Washington
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                                                            MIR Mallinckrodt Institute
                                                                of Radiology
  Case 3-
  Targeted
Radiotherapy



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                   of Radiology
                  Effective Range of Auger Electrons

                                             Decay of Bromine-77:Deposition
                                             of 100 eV into a 10-Å sphere
                                             around the decay site in DNA.

                                                                         O
                                                           77
                                                            Br
                                                                             NH

                                   10 Å
                                                                         N        O

                                                  HO

                                                                 O
                                                           H         H
                                                       H                 H
                                                           OH        H




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Kassis et al, Radiation Res. 1982, 90, 362-373.                               MIR Mallinckrodt Institute
                                                                                  of Radiology
Lethality of Bromine-77 (revisited in 2008)

                                   V-79 (ER+)

                                   Compare Br-76, -77 & I-124 (UdR)
                        OH
        ER     MeO
                                   Assess cell killing potential of ER ligands
                             76
                              Br




          HO
                                   Do steroid receptor ligands labeled
                                   with these isotopes have therapeutic
               ?Å                  potential?




                     Yasui et al, Rad. Res. 155; 328 (2001)
                     Hanson, Cur. Pharm. Design 6; 1457-68 (2000)


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                                                              MIR Mallinckrodt Institute
                                                                  of Radiology
                                   Progestin Ligands
                                         O                                                O



                                                RBA: 13                                               RBA: 100
                                                LogPo/w: 3.87                                         LogPo/w:4.05


                 O                                                 O
                          Progesterone                                         R5020

                                         OH                                                  F
                               O                                                  O
                                               RBA: 240                                               RBA: 170
                                                                                                 H
                                     O         LogPo/w: 4.92                            O             LogPo/w: 3.87
                     H                   O                             H                     O
                                                                                                 O
                                                       F
         O                                                     O                   FFNP




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Kochanny, et al. J. Med. Chem. 1993, 36, 1120; Buckman, et al. J. Med. Chem. 1995, 38, 328
                                                                                                     MIR Mallinckrodt Institute
                                                                                                         of Radiology
                           R'
                 O
                                       R:          O           O        O                         S              S
                       O         R
         H                 O                               Br           I   Br         I         Br          I

                                     R' = OH   2          3        4        5          6     7           8
                                     R' = F    1 (FFNP)   9        10       11         12
O                                    R' = CH3CO           13


    Table 1. Progesterone Receptor Relative Binding Affinities (R5020 = 100%)
                  Relative Binding Affinity                                 Relative Binding Affinity
    Compound                                                   Compound
                      Endo                     Exo                                Endo            Exo
        2            53 ± 15                 2.4 ± 0.5         1 (FFNP)          180 ± 40    5.0 ± 0.9
        3             65 ± 6                 2.3 ± 0.3             9              24 ± 4     4.4 ± 1.1
        4             23 ± 3                 2.6 ± 0.2             10             40 ± 6     9.0 ± 0.8
        5             23 ± 4                0.41 ± 0.09            11            3.9 ± 1.7   4.7 ± 0.8
        6        0.81 ± 0.14                 1.8 ± 0.6             12            6.4 ± 1.4       34 ± 4
        7            5.2 ± 0.7               1.7 ± 0.8             13            7.1 ± 0.1   1.4 ± 0.2
        8            3.2 ± 0.7              0.95 ± 0.25
     Log Po/w: 5.09 ± 0.84 (3)
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         Zhou, et al. J. Med. Chem. 2006, 49, 4737.                                          MIR Mallinckrodt Institute
                                                                                                 of Radiology
                  76Br       Labeling Reactions
     SnBu3                            76
                                        Br

           2 : 1 H2O2/AcOH                       Premixing Time: 0 30 60 120 240 (Min)
      O                                    O     Yield 15 (Min): 8 30 39 62 84
               NH476Br
                                                 (%) 30 (Min): 11 41 53 70 84
     CHO                                   CHO
     14                                    15

                              OH                                           OH
                         O                                        O

                             OH                                        O
                                   15, HClO4, TEOF, CH2Cl2
           H                  OH                             H             O
                                                                                      O         76
                                                                                                   Br

                                                                      3, Endo : Exo
O                                                 O                       1 : 1     70%

    TEOF: Triethyl orthoformate

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                                                                           MIR Mallinckrodt Institute
                                                                               of Radiology
  Tissue Biodistribution of [76Br] 3 in Estrogen-primed
   Immature Female Rats at 1, 3 and 18 Hours (n = 4)




1 day estradiol pretreatment; ~5µCi/dose; Specific Activity: 1250 Ci/mmol

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                                                                         of Radiology
  Tissue Biodistribution of [76Br] 3 in Estrogen-primed
     Immature Female Rats: Blocking Study (n = 4)




1 day estradiol pretreatment; ~5µCi/dose; Specific Activity: 1250 Ci/mmol
Blocked with 18 µg R5020/dose
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                                                                   MIR Mallinckrodt Institute
                                                                       of Radiology
                        Final Conclusions
•   Br-76 is difficult to make but is a useful radionuclide for a variety of
    in vivo applications;

•   Will never supersede F-18 for imaging studies (i.e., radiotracer with a
    short biological half-life);

•   Valuable radionuclide if drug candidate has Br in its parent structure
    (Scatchard studies, pharmacokinetics);

•   Useful radionuclide for compounds having a long biological half-life
    (e.g., antibodies, nanoparticles);

•   Measuring pharmacokinetics of candidate radiotherapeutic drug that
    can be labeled with Br-77.


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                                                                      MIR Mallinckrodt Institute
                                                                          of Radiology
                      Acknowledgments

                          Michael J. Welch, Ph.D.

Aviv Hagooly, Ph.D.                         Zhude Tu, Ph.D.

Dong Zhou, Ph.D.                            Sharon Lee, Ph.D.

Jason Lewis, Ph.D.

Richard LaForest, Ph.D.                     MicroPET Group

Douglas Rowland, Ph.D.                      Cyclotron Facility

Raffaella Rossin, Ph.D.


                           CA86307
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                                                                 MIR Mallinckrodt Institute
                                                                     of Radiology
                  Synthesis of 11β -Methoxy-16α-
              [77Br]bromoestradiol-17β ([77Br]BMOX

                          OAc                                                     OH
            MeO                                               MeO
                                 77
                                          CH
                                  Br, AcOH, 3CO3H                                       77
                                                                                          Br


                                   LAH, THF, -78 to 0C
                                   HCl
    AcO                                                  HO


                                                              [77Br]BMOX
                                                              ESTROGEN




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Senderoff et al, Appl. Rad. Isot. 1982, 33, 545-551.                  MIR Mallinckrodt Institute
                                                                          of Radiology
       Biodegradable RGD-dendrimers - biodistribution
        Blood                                                         Liver




                                                                         Excretion profile (%ID) at 48h p.i.

                                                                                       Urine                        Feces
                                                        Mw = 23 kDa (2.7 kDa PEG)     31.8 ± 1.8                   3.2 ± 0.3
                                                        RGD, Mw = 28 kDa (2.7 kDa PEG) 3.9 ± 0.2                   4.4 ± 1.1


• Both particles have high blood uptakes at the first 24h post injection
• RGD-conjugation increases the liver uptake and decreases the urine excretion
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           SD rats (n = 4) administered with ca. 30 μCi 76Br-dendrimer (80-100 μg/kg rat body weight)   MIR Mallinckrodt Institute
                                                                                                            of Radiology
Normalized 18F-dopa and 76Br-FE-CBT uptake in the putamen of patients with early and advanced
                  Parkinson disease (PD) in the less and more affected sides




                                      Ribeiro, M.-J. et al. Arch Neurol 2002;59:580-586.




  Copyright restrictions may apply.
  Comparison of [18F] and [76Br] Labeled 16α,17α-
dioxolane Progestins in Estrogen-primed Female Rats
                                           OH
                                   O

                                       O
                              H            O

                                                              18
                                                               F
                                       18
                         O                  F
                                   O

                                                H
                                       O
                              H            O
                                                O

                         O                 OH
                                   O

                                                H
                                       O
                              H            O
                                                O
                                                    76
                         O                               Br




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                                                                   MIR Mallinckrodt Institute
                                                                       of Radiology
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            Mallinckrodt Institute
MIR         of Radiology
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Uptake of [Br-77]BrUdR in MCF-7 cells

                   Uptake of [Br-77]BrUdR in MCF-7 cells

            100
             80
 % Uptake




             60
             40
             20
              0
                     5        30        60        120      180
                                    Time (mins)


                  Cells harvested at 70% confluence
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                                                                 MIR Mallinckrodt Institute
                                                                     of Radiology
                    Target Compounds
                 OH                                                              OH
                                                             MeO

                                                                                       77
                                                                                         Br


                                           O
           77
O           Br               77
                              Br                        HO
    H                                          NH
    77                                                       [77Br]BMOX
    [ Br]BDHT
                                           N        O        ESTROGEN
    ANDROGEN
                    HO
                                   O
                             H         H
                         H                 H
                             OH        H

                 [77Br]Bromodeoxyurine ([77Br]BUdR)



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                                                                        MIR Mallinckrodt Institute
                                                                            of Radiology
        Synthesis of 7α-iodo-dihydrotestosterone

                   O


               O                                                                    OH


                       NO2
                             1. [124]I-, ACN, 95C


                             2. KOH/MeOH (1%)
                                                                       124
O        OTs                                        O                     I
    H                                                     H



                                                        [124I]IDHT




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                                                              MIR Mallinckrodt Institute
                                                                  of Radiology
                    Example 4: Monitoring Gene Therapy

       [76Br]-FBAU in vivo accumulation in mouse tumor
                    models on MicroPET



            RG2TK+        LoVo         RG2TK+      LoVo

                                 Kidneys

                                 Bladder




                     4 hours                16 hours
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Courtesy of MSKCC                                         MIR Mallinckrodt Institute
                                                              of Radiology
                Rabbit Imaging




18F-FDHT   (0-60 min)     124I-IDHT   (45-90 min)




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                                              MIR Mallinckrodt Institute
                                                  of Radiology
       Cascade distribution is calculated from an estimate of the
      emission image and subtracted from the detected sinogram.

                        Corrected_data(ρ,θ,z) = Emission_data(ρ,θ,z) – α Scatter(ρ,θ,z) – β CC(ρ,θ,z)
                        with
                                                                                                   v                       v
                                                                A ( x , y , z ) exp( − ∫ μ ( r ) d r ) ⋅ exp( −   ∫ μ (r )dr )
                               CC ( ρ , θ , z ) =   ∑
                                                                                      L1                          L2
                                                        x,y,z                                2   2
                                                                                           d d
                                                                                            1    2



                        Where A(x,y,z) is the estimate of the activity distribution , μ(r) is the average
                        attenuation coefficient and α, β are adjustable parameters.




                                                                                     Uniform         1.25cm        1.0cm    0.62cm


R. Laforest, X.Liu, IEEE-NSS MIC 2008
MicroPET Imaging Study in Panc-02 Tumors




           Tumor
                           Tumor            Tumor




[18F]FLT           [18F]FMAU       [18F]ISO-1

				
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