title: Nephrotoxicity profiles and threshold dose values for [177Lu]-DOTATATE in nude mice.
abstract: BACKGROUND
  In peptide receptor radionuclide therapy for neuroendocrine tumors the main dose-limiting tissue is found in the kidneys because of tubular reabsorption and retention of radioactivity. The aim of this study was to quantify late effects in renal cortex of nude mice exposed to high amounts of [(177)Lu]-DOTA-Tyr(3)-octreotate ([(177)Lu]-DOTATATE), and to determine whether a threshold dose value exists for these findings.
  
  
  METHODS
  Nude mice were exposed to 90, 120 or 150 MBq of [(177)Lu]-DOTATATE. Renal toxicity was evaluated up to 6 months after injection. Blood samples were collected to examine renal functional markers, and after sacrifice at 6 months changes in renal morphology were explored. Tissue damage was estimated by quantifying the relative area of the different subunits in the renal cortex using point counting. Additional morphological signs of radiation damage were also noted. The absorbed doses to the kidneys were estimated by previously determined kidney pharmacokinetics and Monte Carlo simulations for different assumptions regarding the activity distribution.
  
  
  RESULTS
  Increased serum creatinine and urea values indicated long-term renal toxicity. The tissue area occupied by proximal tubules decreased with increasing doses of [(177)Lu]-DOTATATE, whereas the other subunits in cortex slightly increased. The mean absorbed dose in the renal cortex for [(177)Lu]-DOTATATE was estimated to be 35-58 Gy for the different groups of animals. A dose-response relationship was observed for proximal tubular damage, and a threshold dose value of 24 Gy (BED 37 Gy) was determined.
  
  
  CONCLUSIONS
  Selective morphological changes in kidney cortex of nude mice were quantified and appeared in a dose dependent manner after injection of high amounts of [(177)Lu]-DOTATATE.
authors.affiliation: Department of Oncology, The Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden. johanna.svensson@oncology.gu.se
authors.forename: Johanna
authors.initials: J
authors.lastname: Svensson
authors.forename: Johan
authors.initials: J
authors.lastname: Mölne
authors.forename: Eva
authors.initials: E
authors.lastname: Forssell-Aronsson
authors.forename: Mark
authors.initials: M
authors.lastname: Konijnenberg
authors.forename: Peter
authors.initials: P
authors.lastname: Bernhardt
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001835:Body Weight / Q000528:radiation effects; D001853:Bone Marrow / Q000528:radiation effects; D005260:Female; D007267:Injections; D007668:Kidney / Q000166:cytology / Q000378:metabolism / Q000502:physiology / Q000528:radiation effects*; D007672:Kidney Cortex / Q000166:cytology / Q000378:metabolism / Q000502:physiology / Q000528:radiation effects; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000378:metabolism / Q000502:physiology / Q000528:radiation effects; D051379:Mice; D008819:Mice, Nude; D015282:Octreotide / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000633:toxicity; D009942:Organometallic Compounds / Q000008:administration & dosage / Q000633:toxicity*; D011829:Radiation Dosage; D011874:Radiometry; D018675:Toxicity Tests
chemical_list: D015415:Biomarkers; D009942:Organometallic Compounds; C447941:lutetium Lu 177 dotatate; D015282:Octreotide