title: Comparison of [(177)Lu-DOTA(0),Tyr(3)]octreotate and [(177)Lu-DOTA(0),Tyr(3)]octreotide: which peptide is preferable for PRRT?
abstract: OBJECTIVE
  Patients with somatostatin receptor subtype 2-positive metastasised neuroendocrine tumours can be treated with [(177)Lu-DOTA(0),Tyr(3)]octreotate. Some use octreotide as the peptide for peptide receptor radionuclide therapy (PRRT). We compared in seven patients [(177)Lu-DOTA(0),Tyr(3)]octreotide ((177)Lu-DOTATOC) and [(177)Lu-DOTA(0),Tyr(3)]octreotate ((177)Lu-DOTATATE), to see which peptide should be preferred for PRRT with (177)Lu.
  
  
  METHODS
  In the same patients, 3,700 MBq (177)Lu-DOTATOC and 3,700 MBq (177)Lu-DOTATATE was administered in separate therapy sessions. Amino acids were co-administered. Whole-body scanning was performed on days 1, 4 and 7 post therapy. Blood and urine samples were collected. We calculated residence times for tumours, spleen and kidneys.
  
  
  RESULTS
  All patients had longer residence times in spleen, kidneys and tumours after use of (177)Lu-DOTATATE (p=0.016 in each case). Comparing (177)Lu-DOTATATE with (177)Lu-DOTATOC, the mean residence time ratio was 2.1 for tumour, 1.5 for spleen and 1.4 for kidneys. Dose-limiting factors for PRRT are bone marrow and/or kidney dose. Although the residence time for kidneys was longer when using (177)Lu-DOTATATE, the mean administered dose to tumours would still be advantageous by a factor of 1.5, assuming a fixed maximum kidney dose is reached. Plasma radioactivity after (177)Lu-DOTATATE was comparable to that after (177)Lu-DOTATOC. Urinary excretion of radioactivity was comparable during the first 6 h; thereafter there was a significant advantage for (177)Lu-DOTATOC.
  
  
  CONCLUSIONS
  (177)Lu-DOTATATE had a longer tumour residence time than (177)Lu-DOTATOC. Despite a longer residence time in kidneys after (177)Lu-DOTATATE, tumour dose will always be higher. Therefore, we conclude that the better peptide for PRRT is octreotate.
authors.affiliation: Department of Nuclear Medicine, Erasmus MC Rotterdam, The Netherlands. J.Esser@ziekenhuis-mst.nl
authors.forename: J P
authors.initials: JP
authors.lastname: Esser
authors.forename: E P
authors.initials: EP
authors.lastname: Krenning
authors.forename: J J M
authors.initials: JJ
authors.lastname: Teunissen
authors.forename: P P M
authors.initials: PP
authors.lastname: Kooij
authors.forename: A L H
authors.initials: AL
authors.lastname: van Gameren
authors.forename: W H
authors.initials: WH
authors.lastname: Bakker
authors.forename: D J
authors.initials: DJ
authors.lastname: Kwekkeboom
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000378:metabolism* / Q000532:radiotherapy*; D015282:Octreotide / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use; D009928:Organ Specificity; D009942:Organometallic Compounds / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics / Q000627:therapeutic use; D014018:Tissue Distribution
chemical_list: C504257:177Lu-octreotide, DOTA(0)-Tyr(3)-; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; C447941:lutetium Lu 177 dotatate; D015282:Octreotide