18 F 110 min 634 kev. 68 Ga 68 min 1899 kev generator. 89 Zr 78.4 hrs 897 kev

Transcription

1 utline General aspects Fluor- chemistry and applications Carbon- chemistry and applications Radiopharmaceutical chemistry. Part 1. Zirconium- chemistry and applications Tracer development Bert Windhorst PET Isotopes adressed General aspects Nuclide Half life Emax positron Production C 20 min 960 kev 14 N(p,a) C F 0 min 634 kev (p,n) F 68 Ga 68 min 99 kev generator Zr 78.4 hrs 7 kev Y(p,n) Zr Short half lives Cyclotron production Create complicated logistics: chemistry, QC and transport n-site nuclide production required: cyclotrons Require fast methods: chemistry, purification and formulation Require high starting amounts of radioactivity: >30 GBq Cause strong safety regulations: radiation safety officers peration in hotcels is a must: automation volt between D s 300 circles, 600 accelerations of volt = MeV Handouts page 1

2 (%) (%) Cyclotron: animation IBA /9 Reaction speed and yield F : 2,3 ml H 2 in nuobium C : 60 ml N 2 + 0,5% 2 in aluminium 13 N : 2,3 ml H 2 /Ethanol in nuobium 15 : 60 ml N 2 in aluminium time (min) time (min) Specific activity Labelled compound = Mixture of compounds with stable isotopes and radioactive isotopes Unit = GBq/µmol Specific activity The maximum theoretical specific activity for C is 3409 GBq/μmol. 80 GBq of [ C]carbon dioxide = 0.23 nmol In practice 80 GBq of [ C]carbon dioxide at EB corresponds to nmol nly a tiny fraction of the [ C]carbon dioxide is really C- substituted! Especially for receptor studies a high specific activity is required In practice SA>.5 GBq/µmol EB = End f Bombardment (end of radionuclide production) Handouts page 2

3 Why fluor- It has an good half life: not too short, not too long Low positron energy: enables high resolution scanning Can be produced in high amount as [ F]fluoride Fluor- chemistry Can be obtained easily in high specific activity Drawbacks: Difficult chemistry Limited application in bio-active compounds utline F Fluoride production F targetry and radiochemistry F work up Typical reaction conditions Purification Nuclear reaction (p,n) F, obtained as Fluoride in water Proton energy from 10 MeV Side reaction 16 (p,a) 13 N, obtained as nitrates in water Enriched water F substitution reactions H 2 needed : (p,n) F Nucleophilic: Nuclear side reaction : 16 (p,a) 13 N High enrichement, high F yields Recycling H 2 via oxidation and distillation Electrophilic: Handouts page 3

4 Most important: [ F]FDG F nucleophilic substitution Aliphatic : at primary or secondary C atoms Typical S N 2 mechanism [ F]FDG Leaving group: Halogens, sulphonate esters F nucleophilic substitution F nucleophilic substitution Aliphatic : secondary C atoms Case Competeting base catalyzed Elimination reaction [ F]FP-b-CIT UV Propene-CIT FP-ß-CIT Act [ F]FP-ß -CIT Handouts page 4

5 F nucleophilic substitution F Work up Aromatic : Extract F from H 2 Anion exchange : Biorad AG1-X8 in C 3 2- form More practical Seppak QMA or MN PS-HC 3 - Leaving group: Nitro, trimethylammonium Ew : nitro, amide, nitril, aldehyde (one at ortho or para position) Elute F from ion exchange column with C 3 2- solution in water or mixture of CH 3 CN/water with PTC and K 2 C 3 F Work up Typical reaction conditions No fluorination in presence of water Azeotropic distillation with Acetonitril naked fluoride impossible in organic solvent : Phase transfer catalyst, PTC PTC : crown-ether or Ammoniumsalt Crownether: Counter ion needed, K + Kryptofix[2.2.2] optimal : Typical reaction conditions Typical reaction conditions (n-butyl) 4 NHC 3 made from (n-butyl) 4 NH and C 2 Advantage : ph = 6-7 Solvents : aprotic and dry Acetonitril, THF, DMS, dioxane, (chloro)benzene (DMF) Temperatures : 80-0 C Handouts page 5

6 F Fluorine production F Fluorine targets Target material : Nickel, Monel or Aluminium Nuclear reaction 20 Ne(d,a) F or (p,n) F deuterons from 7 MeV protons from 10 MeV Side reaction - 1 st irradiation : F fluorine deposit on target wall Empty target, fill with Neon % F 2 Irradiate Yields [ F]F 2 in Neon F Fluorine specific activity Electrophilic substitution Addition of F 2 is essential, but decreases specific radioactivity F-DPA Typically : less then 1 GBq/µmol Gives problems for receptor studies, however for F-DPA no problem New developments Just recently: Fluor- as fluoride, react with Pd complex after which Fluor- reacts as electrophile Carbon- chemistry [ F]ALF, F labeled aluminium fluoride and DTA for peptide labeling Handouts page 6

7 Why carbon- utline Low dose to the patient All molecules contain carbon Large diversity in chemical methods for carbon- labeling Can be produced easily in high amounts Characteristics of carbon- labeling Major carbon- labeling methods Purification Drawbacks: Limited half life Difficult to obtain in high specific activity Characteristics C labeling Equipment for C labelling Remote controlled, automated synthesis devices Short reaction times (normally < 10 min, often 1-5 minutes) Divers chemistry rganic chemistry in small scale Various techniques: Gas phase and solution chemistry n column & on-line procedures ne-pot reactions Miniaturized scale Position specific labelling Attention to specific activity Specialized facilitates - Automated / remote controlled synthesis equipment Radiation protection / monitoring Radiopharmaceutical manufacturing - GMP Some possibilities of carbon- C-Methylation reactions Zn 400 C C 2 LiAlH 4, 20 C The methylation is generally carried out on N-, and S nucleophiles, CHCl 3 C Cl 2, CuCl C H 2 NNH 2 KH, 60 C Ni, H C Pt, NH C CH 4 H CN I 2 (g) 720 C CH 3 I LiAlH 4-40 C CH 2 CH 3 H HI 130 C CH 3 I [ C]methyl iodide [ C]methyl triflate R 2 [ C]CH 3I R2 base R 1 N H R 1 N * CH 3 R SH R S * CH 3 R H R * CH 3 R H * CH 3 R CH 2 N 2 ften simple, fast and reasonable high yielding reactions. Handouts page 7

8 [undefined] [undefined] CH 3 I [ C]raclopride: D 2 receptor Flumazenil PK195 Verapamil Raclopride SCH23390 DASB Deprenyl PIB [ C]PK195: inflammation [ C]PIB: b-amyloid control Rheumatoid arthritis Traumatic brain injury patient Grignard reaction C 2 and Grignard reactions R 1 H SCl 2 Base RMgBr + [ C]C 2 R * MgBr R * Cl R * R 1 R 2 H N R 1 R6301 WAY R 2 H N R 1 microwave heating R 1 R * N R 2 NaBH 4 * R 1 R N R 2 Taxotere Acetic acid Handouts page 8

9 [ C]Acetic acid [ C]R6301 [ C]C 2 + CH 3 MgCl CH 3 [ C]CH Rate of [ C]acetate uptake in the heart correlates to blood flow. Clearance rate correlates to oxygen consumption [ C]R6301 [ C]R6301 PET Zirconium- Why zirconium- Zr production Ideal half life (78.4 hrs) for labeled monoclonal antibodies Versatile labeling method available Long half life: commercially available 25 mm Drawbacks: High energy gamma s: need to be compensated in PET camera set-up Dosimetry relatively high Handouts page 9

10 Zr chemistry Zr chemistry Very reliable, broadly applicable, but labour intensive Verel et al, JNM 2003 Verel et al, JNM 2003 Zr chemistry, simplified Zr application preclinical Zr-U36 Targeting CD44v6 tumor xenografts Vosjan et al, Nat Prot 2010 Zr-rituximab Treatment prediction lymphoma : CD20 expression Before treatment 3 months after 1 day p.i. 3 days p.i. 6 days p.i. FDG FDG Zr-rituximab FDG Rituximab? Yes! Collaboration: Muylle, Flamen, Brussels Collaboration: Muylle, Flamen, Brussels Handouts page 10

11 Treatment prediction Zr-cetuximab : targeting EGFR FDG Zr-cetuximab Automation FDG delineated tumor is not targeted by Zr-cetuximab. Collaboration:van Loon, DeRuysscher, Lambin, Maastricht Hotcels Why hotcels Short half lives => high amount of radionuclide at start synthesis, typically > 30 GBq Consequence: automation is a must Commercially available modules standard modules for eg [ F]FDG or [ C]CH 3 I Fully flexible modules, eg E&Z KIT based: eg SYNTHERA, FASTLAB valves and vials: Scintomics, Synthra Microfluidics: Nanotek, Future Chem Modules for [ F]FDG Modules [ C]methyl iodide Synthra FDGtwo Bioscan GE Tracerlab FX-C Tracerlab MX Bioscan FDG-plus Siemens Explora Synthra Veenstra Methylator II Handouts page

12 Flexibility Kit based system Eckert & Ziegler GE Fastlab Eckert & Ziegler 68 Ga Scintomics IBA Synthera Radiosynthesis modules Many options All have their pro s and cons Choice is based on: needs budget lab limitations preferences Quality Control and logistics Specifications [ C]Flumazenil [ C]Flumazenil synthesis Algemeen Eisen Vrijgifte Specificatie Uiterlijk Helder en kleurloze vloeistof Ja ph 5 8 Ja Radiochemische zuiverheid (HPLC) > 98 % Ja Specifieke Activiteit (ART) >,5 GBq/µmol Nee Steriel en pyrogeenvrij Bubblepoint steriel filter > 1 bar Ja Aceton < 50 ppm Nee Acetonitril < 50 ppm Nee Tetrahydrofuraan < 50 ppm Nee Tetrabutylammoniumhydroxide < 50 ppm Nee Dimethylformamide < 50 ppm Nee Ethanol concentratie 5 8 % Nee Halfwaardetijd - 22 minuten Nee Steriliteit Steriel Nee Bacteriele endotoxine gehalte < 2,5 EU/ml (V max = 70 ml) Nee Radionuclidische zuiverheid > 99.9% Nee Radionucliodische Identiteit dmv gammaspectrum 0.5 MeV Nee Radiochemische identiteit R t = 4-6 min (HPLC) Nee Chemische zuiverheid Precursor < 0,1 µm (HPLC) Nee Handouts page 12

13 [ C]Flumazenil purification [ C]Flumazenil QC Datum : P.. nummer : Paraaf : MM Specificatie Eis Resultaat Voldoet Paraaf Ja Nee Uiterlijk Helder, kleurloos k x MM Radiochemische zuiverheid (HPLC) > 98 % >99% x MM Chemische zuiverheid (HPLC) Geen vreemde pieken in het UV signaal k x MM PH 5-8 5,29 x MM Bubble point 0,22 mm filter > 1,0 bar 1,32 bar x MM Logistics PET study Further reading [ C]Flumazenil Hospital Prepare lab Patient arrives Prepare patient Transmission scan Release Injection Blood samples Analysis blood samples Production 08:30 09:15 10:00 10:15 10:25 10:30 10:40 10:45 :45 12:30 Preparations Isotope production Synthesis Purification Formulation Transport Analysis By Shankar Vallabhajosula For this part: Chapters 5, 7, 9, 10.2,.2, 13 Handouts page 13