Synthesis and stability of [ 77 Br]-m-Bromobenzylguanidine ( 77 Br-MBBG)

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1 Synthesis and stability of [ 77 Br]-m-Bromobenzylguanidine ( 77 Br-MBBG) Shigeki Watanabe 1 [ watanabe.shigeki@jaea.go.jp ] Noriko S. Ishioka 1, Ji Xin Liang 1, Hirofumi Hanaoka 2, Yasuhiko iida 2,3, Keigo Endo 3,4 1. Plant Positron Imaging Group, Japan Atomic Energy Agency (JAEA) 2. Bioimaging Information Analysis, Gunma University Graduate School of Medicine 3. 21st century COE program, Gunma University 4. Diagnostic Radiology and Nuclear Medicine, Gunma University Graduate School of Medicine

2 2 Table of Contents 1. Introduction 2. Synthesis of 77 Br-MBBG Production of 77 Br Synthesis of precursor and 77 Br-MBBG 3. Stability of 77 Br-MBBG in serum 4. Biodistribution of 77 Br-MBBG in normal mice 5. Summary and Future Plans

3 3 MIBG (m-iodobenzylguanidine) ; norepinephrine function analogue Imaging agent Introduction Myocardial function, Neuroendcrine tumor (Pheochromocytoma, Neuroblastoma etc.), Radionuclide ; I-123 or 131 for SPECT Our Goal ; Tumor imaging by PET X = I ; MIBG X = Br ; MBBG 76 Br-MBBG In this study ; stability, biodistribution of MBBG Half-life Decay mode Eγ (kev) 76 Br 16.1 h β + (57%), EC 520, Br 57.0 h β + (1%), EC Br-MBBG as a prototype compound

4 4 Production of 77 Br Cu 2 nat Se Irradiation Separation 77 Br Irradiation Nuclear reaction ; nat Se(p,xn) 77 Br Target ; Cu nat 2 Se pellet 600 mg Irradiation of proton beam Energy ; 20 MeV Current ; 5 μa Time ; 6 h. Separation Dry distillation method (1) Results Yield of 77 Br ; 10.0 MBq (E.O.B.) Other nuclides ; radio-bromine (1) V. Tolmachev et al., Appl. Radiat. Isot., 49, (1998)

5 5 Synthesis of 77 Br-MBBG Reaction scheme of 77 Br-MBBG (1) NH NH I NH 2 NH 2 CN N H NH 2 77 Br, Cu + AcOH I (Halogen exchange) 77 Br N H NH 2 Results Precursor 77 Br-MBBG Synthesis of Precursor Yield ; 840 mg ( 58% ) m.p. ; 167 ~ 168 o C (lit (2) 164 ~ 165 o C) Characterization ; 1 H, 13 C NMR, FT-IR Synthesis of 77 Br-MBBG Yield ; 192 kbq (38%, Total) Radiochemical purity ; >97% (1) C. Loc h et al., Nucl. Med. Biol., 21, (1994) (2) D. M. Wieland et al., J. Nucl. Med., 21, (1980)

6 6 Characterization of 77 Br-MBBG TLC analysis Plate ; Reverse phase C-18 Solvent ; 30% MeCN in 10 mm H 3 PO 4 aq. R f = 0.25 (cold MBBG = 0.28) 77 Br-MBBG HPLC analysis Column ; μbond-pak C18 ( Waters, 300 x 7.8 mm i.d.) Solvent ; 15% MeCN in 10 mm NaH 2 PO 4 aq. Detector ; gamma detector Retention time (t R ) = 33 min. (cold MBBG = 33 min.) counts Time (min.) Analytical HPLC of 77 Br-MBBG

7 7 Stability of 77 Br-MBBG in serum Method 77 Br-MBBG was incubated at 37 o C for 1, 3, 6, and 24 h. Detection = HPLC Column ; μbond-pak C18 ( Waters, 300 x 7.8 mm i.d.) Solvent ; 15% MeCN in 10 mm NaH 2 PO 4 aq. Detector ; ganma detector Counts Abs. 77 Br - 3h 1h Retention time (min.) Analytical HPLC of 77 Br-MBBG 77 Br-MBBG 24 h 6h 77 Br-MBBG is stable in serum (>97%) within 24 hours.

8 8 Biodistribution of 77 Br-MBBG in normal mice Procedures 1 kbq of 77 Br-MBBG was injected in the tail vein. Three mice were sacrificed at 10 min., 30 min., 1 h., 3 h., and 6 h after injection. Blood, liver, kidney, intestine, heart, muscle, and brain were removed and weighed. Radioactivity of the samples was measured in a well-type gamma counter and concentration (%dose/g) was determined.

9 9 Biodistribution of 77 Br-MBBG in normal mice Heart ; Higher uptake (8.5 %dose/g after 10 min.) Rapid clearance from blood (0.7 %dose/g after 10 min.) %dose/g Blood Liver Kidney Intestine Heart Muscle Brain Time (h) Application to imaging of neuroendcrine tumor

10 10 Summary and Future Plans 77 Br was produced via the nat Se(p,xn) 77 Br reaction 77 Br-MBBG was synthesized via halogen exchange reaction using Cu + 77 Br-MBBG is stable in serum within 24 hours. 77 Br-MBBG has higher uptake to heart and rapid clearance from blood. Application to imaging of neuroendocrine tumor. We will synthesize 76 Br-MBBG and apply to tumor imaging by PET We will also investigate on novel synthesis methods of MBBG under milder condition.

11 11 Thank you for kind attention

12 12 Halogen exchange reaction Under sealed condition with high pressure ; Explosion? Separation is difficult (Precursor and MBBG have to separate using HPLC) Substitution with oxidized agent such as ChloraminT? Electrophilic or radical reaction using bromination agent? Nucleophilic introduction using activated bromide anion? We will investigate novel synthesis method on MBBG.

13 Introduction 76 Br is β + (57%) EC (43%) 76 34 Se 16.1 h 76 35 Br Longer half-life ; Compare to other PET nuclides ( 11 C, 18 F etc.

13 13 Introduction 76 Br is β + (57%) EC (43%) Se 16.1 h Br Longer half-life ; Compare to other PET nuclides ( 11 C, 18 F etc.) Halogen nuclide ; Stronger covalent-bond than iodine Production of 76 Br in JAEA By AVF cyclotron Nuclear reaction ; 76 Se(p,n) 76 Br Target ; Enriched-Cu 76 2 Se 76 Br-labeled radiopharmaceuticals antibodies, peptides, small molecule, with Gunma University (Prof. K. Endo) AVF Cyclotron in JAEA

14 14 Dry distillation of 77 Br from the target Irradiated Cu 2 Se target Quartz tube PTFE tube Ar Flow meter 30 ml/min. Electromuffle I. (Extraction) at 1030 o C Electromuffle II. (Trap of impurity) at 200 o C Trap (H 2 O)

15 15 Basic Characterization of cold MBBG 1 H NMR ( 300 MHz, CD 3 OD ) δ (ppm) ; 4.4 (s, 2H), (m, 2H), (m, 2H). MBBG 13 C NMR ( 300 MHz, CD 3 OD ) δ (ppm) ; 43.4, 122.1, 125.5, 129.6, 130.1, 130.3, 139.2, ( C-Br ; 122 ppm / C-I ; 93.9 ppm ) Abs FT-IR C-Br bond cm -1 (NH), 1668, 1617 cm -1 (C=N) Guanidine group Retention time (min.) HPLC profile of cold MBBG HPLC analysis t R = 33 min. (MIBG = 21 min.)

16 16 in saline Radiochemical purity (%) Time (h) Method Synthesized 77 Br-MBBG was incubated in saline at 35 o C for 1, 3, 6, and 24 h, respectively. Detection By TLC analysis (C18 plate, 30% MeCN in 1mM H 3 PO 4 solution) Ratio of Br-MBBG was determined from bio-imaging analyzer system 77 Br-MBBG is stable (>95%) in saline until 24 hours.

17 17 Accumulation mechanism of MIBG 123/131I-[MIBG] heart Adrenal

18 18

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