Nuclear Medecine: an overview

  • Less known than radiology and radiotherapy, nuclear medicine is based on the use of radioactive substances directly injected into the patient.

    These radioactive drugs, - drugs because they are pharmaceuticals definitely needing a market authorization - , have the property to bind specifically to the targeted cells, tissues, organs and they emit radiations from the areas in which they concenter.

    According to the radionuclide properties and so, to the emitted radiation, these radiopharmaceuticals can be used either for the diagnostic (medical imaging based on gamma or positrons emission) or for therapy (killing of cells with alpha or beta radiations).

  • Nuclear Medicine, for what purpose?

    Radio nuclear MedecineSince the first treatment of thyroid cancer patients with radioactive iodine in the forties, the nuclear medicine has considerably evolved benefit exceptional progresses of the technology over the 10 last years, such as the ability to produce industrial scale radionuclides with shorter half-lives by cyclotrons or as the potential of the computing capacities and the discovery of new biological vectors to which radionuclides can be bound enabling to target other tissues than the thyroid.


    On the diagnosis side, cardiology was the first field to benefit on a large scale from molecules based on Techneétium-99m or Thallium-201. A great leap has been reached following the discovery of FDG (fludesoxyglucose), a Fluor-18 labeled molecule which enables to visualize nearly all solid cancers and their metastaseis.

    Following the first therapeutic applications of Iiodine-131 and later Yttrium-90, the new radiotherapeuticy products based on Lutétium-177 or Lead-212 iares close to reach the market.

     

  • Nuclear Medicine, in what area?

    Nowadays, almost any larger hospital is equipped with a nuclear medicine department.

    With the extension of the cyclotrons network able to produce Fluor-18, a radionuclide with a half-life of only two hours, the cancer patients benefit from important information about their cancer conditions but particularly about the efficiency of the treatment in progress and so, the evolution of their disease.

    This Fluor-18 and the associated technology are at the origin of the first molecules of diagnostic marketed in 2013 in the Alzheimer's disease imaging area.

    The so-called metabolic radiotherapy (based on injected substances interfereing with the metabolism, part of nuclear medicine) is different from the external radiotherapy and still must be considered in its early development stages. The centers using these first authorized molecules are still in a limited number.

    With the expected launch of new products on the market by 2018-2020, targeting for example neuroendocrine tumors or prostate cancers, it is very likely that this technology could rise to the same rank than chemotherapy or surgery. The radio-therapeutics are in fact nothing else than chemotherapy products with the toxic effect based on the cells destruction by radioactivity but which remains located where the molecule is anchored.

  • Nuclear Medicine, where and whom?

    Around the world many laboratories are developing new labeled molecules which will allow to diagnose and target different cancers. But the neurology has not been left behind, with new tools enabling to precise the diagnosis of Alzheimer or Parkinson. 

    The development of these molecules follows the same long (7 to 10 years) and expensive (€100 to 300M) paths than those of any conventional drug. The most recent molecules that could be marketed within the next 5 years, have been developed in the USA, but also in Australia or Germany. Actually, the discovery of a new molecule can originate from a small university laboratory with the appropriate infrastructure and authorizations and most of the countries are funding several of those research centers, including Iran, India or South-Korea.

    Laboratory nuclear medecineThe first laboratories were civil nuclear centers that wanted to diversify, and each country with such nuclear equipment has started exploring this new science.

    By transferring the technology to hospitals, these centers specialized in the handlinge of low doses radioactivity for human applications, gained their independence.

     

    The clinical studies necessary to confirm the interest of these molecules for human performed in the nuclear medicine departments of hospitals equipped with SPECT (Single Photon Emission Computed Tomography) or PET (Positron Emission Tomography). cameras. Such studies are taking place all over the world and data are collected in Europe or in Northern America as well as in China, Japan, Singapore or Brazil. Nowadays, only Central Africa has not yet been able to develop this technology.

     

  • Nuclear Medicine, what risks?

    The risk in nuclear medicine drug handling is not relied to the clinical examination by itself but from the rising frequency of these procedures. The benefit/risk ratio of the treatment is definitely in favor of the technology as it translates in several years of survival, if not a total recovery.

    There is an other advantages that the patient undergoing radiotherapeutic treatments discovers in comparison to chemotherapy: side- effects are exceptional – no hair loss, no nausea or vomiting, and very often thea treatment is limited to a single or two injections applied under ambulatory conditions.

    Concerning the risks the professionals of the field are undergoing – operators, nurses, doctors – who handle these substances daily, they are limited to the strict minimum in accordance with applicable regulations. France has played a key role in this area. This is the countries with the most binding nuclear regulation but it became for that reason also a reference in the field.

  • Nuclear Medicine, what links with the civil nuclear applications?

    Civil and medical nuclear applications are not two different worlds. Over the time, the radiopharmaceutical companies became independent and have developed their own radionuclides production tools, including cyclotron networks enabling them to product the most common radionuclides such as Fluorine-18, Thallium-201, Iodine-123 or Indium-111.

    But the radiopharmaceutical industry y largely depends on the reactors, all public, for the access to the longer half-life radionuclides.

    The most common radionuclide, Technetium-99m is produced through a tool named generator, a separation system based on Molybdenum-99, weekly delivered to each NM department. Molybdenum-99 is a product of the decay chain of uranium and is obtained in reactors, together with Iiodine-131.

    Presently, these reactors enable to produce also in industrial amounts, radionuclides such as Lutetium-177, Samarium-153 or Strontium-90. On the other hand, Lead-212 is originally a product extracted from the thorium decay chain, what we commonly call "nuclear waste".

    Before concluding, we should not forget that nuclear medicine has benefited from all the improvements made by the civil nuclear industry in terms of radioprotection, waste management and transport.

  • Who is Richard Zimmermann?

    Richard ZimmermannRichard Zimmermann is a chemical engineer, PhD (Strasbourg), who has spent 15 years of his’ career in the conventional pharmaceutical industry's R&D before joining since 1998 the Nuclear Medicine area as R&D Director at CISbio international (Saclay, CEA). He was in charge of the building of the PET/FDG centers for the European network of the Schering/IBA JV, and VP Radiopharmaceutical development for IBA Molecular. In 2012, he created his consulting company, Chrysalium, specialized in Radiopharmaceutical industrialization and production support.

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