Studies towards purification of Auger electron emitter 165Er – a possible radiolanthanide for cancer treatment Master’s thesis Salla Tapio Department of Chemistry University of Helsinki 30 November 2018 Tiedekunta – Fakultet – Faculty Koulutusohjelma – Utbildningsprogram – Degree programme Matemaattis-luonnontieteellinen tiedekunta Kemia Tekijä – Författare – Author Salla Tapio Työn nimi – Arbetets titel – Title Studies towards purification of Auger electron emitter 165Er – a possible radiolanthanide for cancer treatment Työn laji – Arbetets art – Level Aika – Datum – Month and year Sivumäärä – Sidoantal – Number of pages Pro Gradu -työ 11/2018 87 Tiivistelmä – Referat – Abstract Syöpä on maailmanlaajuisesti yksi yleisimmistä kuolinsyistä ja syöpäkuolemien määrän odotetaan yhä nousevan johtuen väestönkasvusta sekä elämäntavoista, jotka lisäävät syöpäriskiä. Vaikka useita hoitomuotoja on tarjolla, tarvitaan jatkuvasti uusia, entistä tehokkaampia vaihtoehtoja. Kohdennettu radionukliditerapia on sisäisen sädehoidon muoto, jossa sädehoito voidaan kohdistaa selektiivisesti syöpäsoluihin käyttäen radiolääkeaineita. Radiolääkeaineet ovat molekyylejä, jotka sisältävät sekä sädehoitoon sopivan radionuklidin että biomolekyyliosan, joka sitoutua syöpäsolun pinnan proteiineihin. Uusia tapoja tuottaa ja puhdistaa sisäiseen sädehoitoon sopivia radionuklideja tutkitaan jatkuvasti. Hoidon kohdentamiseen käytettävien biomolekyylien leimaamiseen tarvitaan kemiallisesti ja radionuklidisesti puhtaita radionuklidiprekursoreita. Radionuklideja tuotetaan usein pommittamalla stabiilia kohtiomateriaalia protoneilla, joten kiinnostuksen kohteena olevan radioisotoopin erottaminen kohtiomateriaalista on erityisen tärkeä osa nuklidituotantoa. Auger elektroneja emittoiva Erbium-165 on potentiaalinen radiolantanidi syöpähoitoon. Sen tuottaminen vaatii Erbiumin kemiallista erottamista joko Holmiumista tai Tuliumista. LN hartsit ovat ekstraktiokromatografiahartseja, jotka on kehitetty erityisesti lantanidierotuksia varten. Tässä työssä tutkittiin niiden sopivuutta Holmium/Erbium ja Erbium/Tulium –erotuksiin. Erotusmahdollisuuksien arvioimiseksi, näiden kolmen lantanidin pidättymiskapasiteetit määritettiin jokaisessa LN hartsissa. Lisäksi suoritettiin pylväserotuskokeita. Avainsanat – Nyckelord – Keywords Sisäinen sädehoito, Auger emitteri, radiolantanidi, LN hartsi Säilytyspaikka – Förvaringställe – Where deposited E-thesis Muita tietoja – Övriga uppgifter – Additional information Tiedekunta – Fakultet – Faculty Koulutusohjelma – Utbildningsprogram – Degree programme Faculty of science Chemistry Tekijä – Författare – Author Salla Tapio Työn nimi – Arbetets titel – Title Studies towards purification of Auger electron emitter 165Er – a possible radiolanthanide for cancer treatment Työn laji – Arbetets art – Level Aika – Datum – Month and year Sivumäärä – Sidoantal – Number of pages Master’s thesis 11/2018 87 Tiivistelmä – Referat – Abstract Cancer is one of the most common causes of death worldwide and the amount of cancer deaths is expected to increase due to population growth and lifestyle choices that increase cancer risk. Even though there is a great variety of treatment approaches available, new and more efficient options are in high demand. Targeted radionuclide therapy is a form of internal radiation therapy that can be used to selectively target cancer cells. It utilizes radiopharmaceuticals, molecules that contain a radionuclide and a targeting vector part (biomolecule) which can bind to certain entities expressed on cancer cell surfaces. Ways to produce and purify new radionuclides suitable for cancer therapy are constantly investigated. Radionuclide precursors of high chemical and radionuclidic purity are needed for radiolabelling of the biomolecules used as targeting vectors. Radionuclides are often produced by proton irradiation of stable target material and separation of the radioisotope of interest from the target material is a vital part of nuclide production. Auger electron emitter Erbium-165 is a potential radiolanthanide for cancer treatment. Its production would require separation of Erbium from either Holmium or Thulium, adjacent lanthanides to Erbium. LN resins are extraction chromatography resins developed especially for lanthanide separations. In this work, the suitability of these resins for Holmium/Erbium and Erbium/Thulium separations was investigated. In order to assess the possibility of separating the lanthanides of interest on LN resins, the retention capacities of the lanthanide were determined on each resin. In addition, column separation experiments were performed. Avainsanat – Nyckelord – Keywords TRNT, Auger electron emitter, radiolanthanide, LN resin Säilytyspaikka – Förvaringställe – Where deposited E-thesis Muita tietoja – Övriga uppgifter – Additional information Acknowledgements I would first like to thank Paul Scherrer Institute and group leader Dr. Nick van der Meulen for giving me the opportunity to carry out my Master’s thesis work in the Radionuclide Development Group at PSI and Dr. van der Meulen for his constant guidance and advice during my thesis work. I am grateful to MSc Nadezda Gracheva, the co–supervisor of my thesis work, for sharing her knowledge in the field of study with me and for her patience in guiding me and answering my many questions. I would also like to thank other members of the Radionuclide Development Group, Dr. Zeynep Talip and MSc Roger Hasler, as well as all other colleagues and friends at PSI for their assistance and support. I wish to express my gratitude to my supervisors, Prof. Anu Airaksinen and Dr. Kerttuli Helariutta, and all my friends at the University of Helsinki for their inspiration and support. I would also like to thank Dr. Helariutta for making me believe in myself and encouraging me to pursue a Master’s thesis position abroad. Finally, I would like to thank my family, my spouse, and dear friends who have always given me strength and courage. I am deeply grateful to them for constantly reminding me what is truly important in life. I would not be where I am today without their endless love and support. 4 Contents Part I: Introduction 9 1 Available therapies for cancer treatment 9 2 Application of radionuclides in nuclear medicine: historical overview 12 3 Radiopharmaceuticals in nuclear medicine 13 4 Radionuclides for cancer diagnosis and therapy 15 4.1 Radionuclides for diagnosis . 16 4.1.1 Imaging modalities for diagnosis . 16 4.1.2 Radionuclides for single photon emission computed tomography . 19 4.1.3 Radionuclides for positron emission tomography . 21 4.2 Radionuclides for therapy . 22 4.3 Radionuclides for theranostics . 28 4.4 Possible use of Auger electron emitters in targeted radionuclide therapy . 29 5 Novel Auger electron emitter for radiotherapy, Erbium-165 32 5.1 Decay characteristics of Erbium-165 . 32 5.2 Prospects in production of Erbium-165 . 33 5.3 Chromatographic methods for lanthanide separation and their ap- plication for Er/Tm, Er/Ho separations . 36 5.4 The concept of distribution coefficients . 42 5 6 Aim of Thesis 44 Part II: Experimental 45 7 Materials and methods 45 7.1 Retention capacities . 45 7.1.1 Sample preparation for determination of retention capacities 45 7.1.2 Sample preparation for ICP–OES measurements . 46 7.1.3 Calculations for determination of retention capacities . 47 7.2 Column separation experiments . 48 8 Results and discussion 50 8.1 Retention capacities . 50 8.2 Column separation experiments . 57 8.2.1 Column separation of Ho and Tm . 57 8.2.2 Column separation of Er and Tm . 61 8.2.3 Er concentration experiment . 66 Part III: Conclusions and outlook 67 A Results of inductively coupled plasma optical emission spectroscopy measurements 85 6 List of abbreviations α–HIBA = α-hydroxy-isobutyric acid BBE = Biological bystander effect CT = computed tomography DNA = Deoxyribonucleic acid DOTATATE = DOTA-Tyr3-octreotate DOTMP = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminomethylene phospho- nic acid DTPA = diethylenetriaminepentaacetic acid EC = electron capture EDTMP = ethylenediamine tetra(methylene phosphonic acid) FDA = United States Food and Drug Administration FDG = 2-(F-18)fluoro-2-deoxyglucose HA = hydroxypaptite HDEHP = bis(2-ethyl-1-hexyl)phosphoric acid HEH[EHP] = 2-ethyl-1-hexyl(2-ethyl-1-hexyl)phosphonic acid HMPAO = hexamethylpropyleneamine oxime H[DTMPP] = bis(2,4,4- trimethyl-1-pentyl)phosphinic acid HP = High purity IC = internal conversion 7 ICP–OES = inductively coupled plasma optical emission spectroscopy LET = Linear energy transfer mCRPC = metastatic castration-resistant prostate cancer MIGB = iodine-123 meta-iodobenzylguanidine MRI = magnetic resonance imaging PET = positron emission tomography PM = personalized medicine PRRT = peptride-receptor radionuclide therapy PSI = Paul Scherrer Institute PSMA = prostate-specific membrane antigen RIT = radioimmunotherapy ROS = reactive oxygen species TRNT = targeted radionuclide therapy SPECT = single photon emission computed tomography 8 Part I: Introduction 1 Available therapies for cancer treatment Cancer is caused by a gene change (mutation) that makes the abnormal mutated cells to divide and grow faster than normal cells.1 Cancer is currently one of the most common causes of death worldwide and the burden it produces on society is expected to increase in the future. This is due to population growth and aging as well as lifestyle choices that increase cancer risk. In 2012 the number of new cancer cases and cancer deaths worldwide was estimated at 14.1 million and 8.2