How to develop novel, more effective radiopharmaceuticals at various facilities, such as research reactors and accelerators, was the main question 450 participants from 94 countries discussed at the IAEA International Symposium on Trends in Radiopharmaceuticals in Vienna earlier this month.
More than 80% of all nuclear medicine Single Photon Emission Computerized Tomography (SPECT) scans used each year to detect diseases like cancer and cardiovascular require Technetium-99m (Tc-99m) – the most widely used radioisotope in radiopharmaceuticals. Tc-99m is the decay product of Molybdenum-99 (Mo-99), which is mainly generated in research reactors. Although research reactors are cost-effective and very well suited for commercial, large-scale Mo-99 production, many of them are reaching the end of their lifespan, urging experts to look into alternatives for medical radioisotope production.
“When it comes to Mo-99 production, accelerators can provide a good alternative to research reactors by offering many advantages, such as less radioactive waste and cheaper operating and decommissioning costs,” said Valeriia Starovoitova, Radiation Technology Coordination Officer at the IAEA.
Experts at the symposium also discussed the production of new radioisotopes with longer half-life, an indication of the length of time for which a substance is radioactive, such as Zirconium-89 (Zr-89). Tc-99m has a very short half-life, which means that it must be used quickly after production and be generated constantly to meet demand. Radioisotopes with a longer half-life would allow producers to deliver to a broader area and more medical facilities.
Furthermore, they would enable antibody-based imaging diagnostics, which can provide medical professionals with even more information on the stage and exact location of cancer cells in a patient’s body. Zr-89, with a half-life 13 times longer than that of Tc-99m, can be attached to antibodies to create specific biomarkers, making them useful in nuclear medicine for high-fidelity imaging.
“In the future, important nuclear medicine techniques, such as Positron Emission Tomography (PET), could rely on Zr-89 for diagnosis and therapy planning for various types of cancer,” said Amir Jalilian, Radiopharmaceutical-Radioisotope Chemist at the IAEA.
Bringing the ‘Big Guns’ for Destroying Cancer Cells
Radiopharmaceuticals are used to detect tumors and diagnose other health conditions. They can also be used to eliminate cancer cells. In recent years, significant improvements in therapeutic radiopharmaceutical applications have been made, thereby playing an increasingly essential role in the fight against cancer, experts at the symposium said.
Radioisotopes emitting beta particles – high-energy electrons – are a commonly used form of radionuclide therapy for more than half a century. However, new research and clinical trials have recently demonstrated that the application of alpha particles – a Helium atom core of two protons and two neutrons – can be more efficient in destroying cancer cells, thanks to their higher charge and mass, while sparing healthy tissue.
“There is a very distinctive trend in therapeutic radioisotopes, which are clearly moving from beta minus emitters to alpha emitters, such as Ac-225 and Bi-213,” said Joao Osso Junior, Head of the IAEA Section on Radioisotope Products and Radiation Technology.
In addition, Auger electron emitters show promising preclinical results for Auger therapy - a form of radiation therapy, which relies on a large number of low-energy electrons that can damage cells over a very short range, allowing highly-targeted therapy.
Closing the Gender Gap and Involving Gen Z in Nuclear
As part of the symposium, the IAEA hosted the 2019 World Nuclear University Olympiad. Four teams of students presented their research on how nuclear technology and radiopharmaceuticals are perceived in their home countries and what factors influence the public perception of radiopharmacy.
The IAEA, in cooperation with Women in Nuclear Global, launched the first ever network for women in radiopharmaceutical sciences at an event during the symposium titled “Women in Radiopharmaceutical Sciences: Challenges and Opportunities”.
“We hope that this network will give an opportunity to women from all over the world to connect, exchange expertise and foster mentorship,” said Aruna Korde, Radiopharmaceutical Scientist at the IAEA and coordinator of the new network.
Browsing through the World of Medical Isotopes
At the symposium, the IAEA also launched two new online applications: the Medical Isotope Browser and the Database of Medical Cyclotrons Used for Radioisotope Production, which bring data directly to professionals in radiopharmaceutical research and industry.
The Symposium also highlighted a series of success stories on the transfer of technology related to radiopharmaceutical sciences through the IAEA Technical Cooperation Programme, for example the production and application of Tc-99m radiopharmaceuticals for SPECT diagnostic imaging applications in Cuba and Kazakhstan, as well as successful implementation of IAEA supported projects on various PET radiopharmaceuticals in Argentina.
