.::VOLUME 15 (XV), LESSON 2::. Evolution of PET Radiochemistry: Synthesis and Clinical Application of Radiopharmaceuticals Continuing Education for Nuclear Pharmacists And Nuclear Medicine Professionals By Shankar Vallabhajosula, Ph.D. Professor of Radiochemistry and Radiopharmacy Weill Cornell Medical College, Cornell University Citigroup Biomedical Imaging Center (CBIC) The University of New Mexico Health Sciences Center College of Pharmacy is accredited by the Accreditation Council for Pharmacy Education as a provider of continuing pharmacy education. Program No. 039-000-09-153- H04-P 2.0 Contact Hours or .2 CEUs. Initial release date: 4/6/2011 -Page 1 of 23- -- Intentionally left blank -- -Page 2 of 23- Instructions: Upon purchase of this Lesson, you will have gained access to the online site where this lesson and the corresponding assessment are located. http://hsc.unm.edu/pharmacy/radiopharmacyCE/ To receive a Statement of Credit you must: 1. Review content 2. Complete assessment, submit answers online and pass with a 70% (you will have 2 chances to pass) 3. Complete lesson evaluation Once all requirements are met, a Statement of Credit will be available in your workspace. At any time you may "View the Certificate" and use the print command of your web browser to print the completion certificate for your records. NOTE: Please be aware that we can not provide you with the correct answers to questions you got wrong. This would violate the rules and regulations for accreditation by ACPE. We can however, tell you which questions you did receive wrong. You may contact the CE Administrator to request this information. Disclosure: The Author does not hold a vested interest in or affiliation with any corporateorganization offering financial support or grant monies for this continuing education activity, or any affiliation with an organization whose philosophy could potentially bias the presentation. -Page 3 of 23- The Evolution of PET Radiochemistry: Synthesis and Clincial Application of Radiopharmaceuticals By Shankar Vallabhajosula, Ph.D. Editor, CENP Jeffrey Norenberg, MS, PharmD, BCNP, FASHP, FAPhA UNM College of Pharmacy Editorial Board Stephen Dragotakes, RPh, BCNP, FAPhA Neil Petry, RPh, MS, BCNP, FAPhA James Ponto, MS, RPh, BCNP, FAPhA Tim Quinton, PharmD, MS, FAPhA S. Duann Vanderslice, RPh, BCNP, FAPhA John Yuen, PharmD, BCNP Advisory Board Dave Abbott, RPh, BCNP Mark Gurgone, BS, RPh Vivian Loveless, PharmD, BCNP, FAPhA Lisa Marmon, RPh, BCNP Michael Mosley, RPh, BCNP Janet Robertson, BS, RPh, BCNP Brantley Strickland, BCNP Scott Knishka, RPh, BCNP Dave Engstrom, PharmD, BCNP Brigette Nelson, MS, PharmD, BCNP Samuel Ernesto, RPh, MBA Director, CENP Administrator, CE & Web Publisher Kristina Wittstrom, RPh, FAPhA, BCNP Christina Muñoz, B.S. UNM College of Pharmacy UNM College of Pharmacy While the advice and information in this publication are believed to be true and accurate at the time of press, the author(s), editors, or the publisher cannot accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, expressed or implied, with respect to the material contained herein. Copyright 2009 University of New Mexico Health Sciences Center Pharmacy Continuing Education Albuquerque, New Mexico -Page 4 of 23- EVOLUTION OF PET RADIOCHEMISTRY: SYNTHESIS AND CLINICAL APPLICATION OF RADIOPHARMACEUTICALS STATEMENT OF LEARNING OBJECTIVES: 1. Describe the principle of molecular imaging and the characteristics of PET radiopharmaceuticals 2. Describe the basic concepts involved in the synthesis of 18F and 11C labeled radiotracers 68Ga and 64Cu labeled peptides and Antibodies 3. Describe the application of automated synthesis modules in the routine production of PET radiopharmaceuticals 4. Describe the potential clinical applications of new PET radiopharmaceuticals Page 5 of 23 COURSE OUTLINE INTRODUCTION ....................................................................................................................................................... 7 RADIONUCLIDES FOR PET ................................................................................................................................... 8 CHEMISTRY OF 18F .................................................................................................................................................. 9 FLUORINATION REACTIONS: .................................................................................................................................... 10 18 SYNTHESIS OF 2-DEOXY-2-[ F]FLUORO-D-GLUCOSE (FDG) .................................................................................. 11 18 SYNTHESIS OF [ F]-3’-DEOXY-3’-FLUOROTHYMIDNE (FLT) ................................................................................. 12 CHEMISTRY OF 11C................................................................................................................................................ 13 11 SYNTHESIS OF [O-METHYL- C]RACLOPRIDE .......................................................................................................... 14 CHEMISTRY OF RADIOMETALS ....................................................................................................................... 15 68 CHEMISTRY OF GA ................................................................................................................................................ 16 64 CHEMISTRY OF CU ................................................................................................................................................ 18 NEW PET RADIOPHARMACEUTICALS ............................................................................................................ 19 SUMMARY ................................................................................................................................................................ 20 REFERENCES .......................................................................................................................................................... 21 ASSESSMENT QUESTIONS ................................................................................................................................... 23 Page 6 of 23 Presented at 2009 Annual APhA Meeting EVOLUTION OF PET RADIOCHEMISTRY: SYNTHESIS AND CLINICAL APPLICATION OF RADIOPHARMACEUTICALS Shankar Vallabhajosula, Ph.D. Professor of Radiochemistry and Radiopharmacy Weill Cornell Medical College, Cornell University Citigroup Biomedical Imaging Center (CBIC) INTRODUCTION Georg de Hevesy in 1920s coined the term radioindicator or radiotracer and introduced the tracer principle in biomedical sciences. A radiotracer can be defined as a specific radiolabeled molecule (or probe) that resembles or traces the in vivo behavior of a natural molecule and can be used to provide information about a specific biological process. The degree of similarity between radiotracer and the natural substance, however, may vary depending on the particular radiotracer. For example, [11C]glucose and [14C]glucose are true tracers of glucose since they are chemically identical to natural glucose, while [18F]fluorodeoxyglucose (FDG), an analog of glucose, also traces glucose, but does not behave identically to glucose since it is chemically different. One of the most important characteristics of a true radiotracer, however, is the ability to study the components of a homeostatic system without disturbing their function. Occasionally, the term radioligand is also used in the context of imaging studies. All radiolabeled compounds or substances used for the purpose of diagnosis or therapy have been defined as radioactive drugs or radiopharmaceuticals (RP) by the U.S. food & Drug Association (FDA). In the early 1970’s Michael Phelps and his colleagues at the Washington University in St. Louis built the first PET camera for clinical studies and demonstrated the potential clinical utility of positron tracers such as [11C]glucose, [13N]ammonia and [15O]water. Following the development of FDG synthesis by Dr. Walter Wolf and his colleagues at Brookhaven National Laboratory, the first FDG-PET imaging studies were performed at UCLA in 1977. In the last 3 decades, several hundred positron emitting radiotracers have been developed for PET. Page 7 of 23 RADIONUCLIDES FOR PET The most important radionuclides useful for the development of PET radiopharmaceuticals are listed in Table 1. The physical half-life (T½) and the theoretical specific activity (SA) are important for radiotracer development and synthesis. The β+ abundance, energy and the associated gammas determine the imaging characteristics such as resolution, sensitivity, and radiation dosimetry of the PET radiopharmaceutical. Among the radionuclides listed in Table-1, we have three groups: organic nuclides (11C, 13N), halogens (18F, 124I) and metals (68Ga, 64Cu, 62Cu, 89Zr and 82Rb). Developing a specific RP involves careful design of the structural requirements in a molecule in order to optimize target specificity and at the same time optimize the pharmacokinetic and pharmacodynamic behavior of the probe to meet the demand of the imaging technique. The physicochemical properties of the RP such as size, charge, solubility, lipophilicity, and specific activity are very important criteria and must be addressed in designing the structural features of the molecule. Factors such as rapid metabolism and plasma protein binding and non-specific binding in non-target tissues are not desirable for optimal in vivo behavior.