title: SELIMETRY-a multicentre I-131 dosimetry trial: a clinical perspective.
abstract: Treatment options for patients with thyroid cancer that is no longer sensitive to iodine therapy are limited. Those treatments which currently exist are associated with significant toxicity. The SELIMETRY trial (EudraCT No 2015-002269-47) aims to investigate the role of the MEK inhibitor Selumetinib in resensitizing advanced iodine refractory differentiated thyroid cancer to radioiodine therapy. Patients deemed to have sufficient iodine uptake in previously iodine refractory lesions after 4 weeks of Selumetinib therapy will be given an empirical activity of 5.5 GBq I-131, and response to therapy will be assessed. The trial presents an opportunity to investigate the dosimetric aspects of radioiodine therapy for advanced thyroid cancer. Patients will undergo serial I-123 single-photon emission CT (SPECT)/CT scans following Selumetinib therapy to determine whether there has been a change in the degree of iodine uptake to justify further I-131 therapy, and to allow dosimetric calculations to predict absorbed dose to target lesions following therapy. Patients receiving I-131 therapy will undergo a further series of post-therapy SPECT/CT scans to allow dosimetric calculations. We describe the challenges in setting up a multicentre trial in a relatively underinvestigated field, describing the work that has been carried out to calibrate and validate measurements to ensure that standardized image data are collected at each site. We hope that this trial will lead to individualization and optimization of therapy for patients with advanced thyroid cancer and that the ground work carried out in setting up a network of centres capable of standardized molecular radiotherapy dosimetry will lead to further clinical trials in this field.
authors.affiliation: 1 Weston Park Hospital, Sheffield, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Wadsley
authors.affiliation: 2 Department of Physics, The Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Gregory
authors.affiliation: 2 Department of Physics, The Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, UK.
authors.forename: Glenn
authors.initials: G
authors.lastname: Flux
authors.affiliation: 3 Royal Marsden Hospital, London, UK.
authors.forename: Kate
authors.initials: K
authors.lastname: Newbold
authors.affiliation: 3 Royal Marsden Hospital, London, UK.
authors.forename: Yong
authors.initials: Y
authors.lastname: Du
authors.affiliation: 4 Velindre Hospital, Cardiff, Wales.
authors.forename: Laura
authors.initials: L
authors.lastname: Moss
authors.affiliation: 5 CTRU, University of Leeds, Leeds, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hall
authors.affiliation: 5 CTRU, University of Leeds, Leeds, UK.
authors.forename: Louise
authors.initials: L
authors.lastname: Flanagan
authors.affiliation: 5 CTRU, University of Leeds, Leeds, UK.
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Brown
mesh_terms: D001562:Benzimidazoles / Q000627:therapeutic use*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D019275:Radiopharmaceuticals / Q000627:therapeutic use*; D011879:Radiotherapy Dosage; D012107:Research Design; D013964:Thyroid Neoplasms / Q000532:radiotherapy*
chemical_list: C517975:AZD 6244; D001562:Benzimidazoles; D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals