Applied Radiation and Isotopes 65 (2007) 301–308 On the preparation of a therapeutic dose of 177 Lu-labeled DOTA–TATE using indigenously produced 177 Lu in medium flux reactor Tapas Das, Sudipta Chakraborty, Sharmila Banerjee , Meera Venkatesh Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai-400085, India Received 26 June 2006; received in revised form 1 September 2006; accepted 29 September 2006 Abstract 177 Lu could be produced with a specific activity of 23,000 mCi/mg (850 GBq/mg) by neutron activation using enriched 176 Lu (64.3%) target when irradiation was carried out at a thermal neutron flux of 1 10 14 n/cm 2 /s for 21 d. 177 Lu–DOTA–TATE could be prepared in high radiochemical yield (99%) and adequate stability using the 177 Lu produced indigenously. The average level of radionuclidic impurity burden in 177 Lu due to 177m Lu was found to be 250 nCiof 177m Lu/1 mCi of 177 Lu (9.25 kBq/37 MBq) at the end of bombardment, which corresponds to 0.025% of the totalactivity produced. The maximum specific activity achievable via careful optimizationof the irradiationparameterswas found to be adequatefor the preparationof a therapeuticdoseof the radiopharmaceutical. The in-house preparation of this agent using 25 mg (17.41 nmole) of DOTA–TATE and indigenously prod 177 Lu (0.8 mg, 4.52 nmole), corresponding to peptide/Lu ratio of 3.85 yielded 98.7% complexation. Allowing possibility of d transportation to users, it has been possible to demonstrate that at our end, a single patient dose of 150–200 mCi (5.55–7 prepared by using 250–333 mg of DOTA–TATE conjugate. This amount compares well with 177 Lu–DOTA–TATE prepared for a typical peptide receptor radionuclide therapy (PRRT) procedure which makes use of 100 mg of the DOTA–TATE conjugate, which i 50 mCi(1.85 GBq) of 177 Lu activity,thereby implying that in order to achieve a single patient dose of 150–200 mCi (5.55–7.40 GBq), 300–400 mg of the conjugate needs to be used. r 2006 Elsevier Ltd. All rights reserved. Keywords: PRRT; 177 Lu; DOTA–TATE; Somatostatin receptors 1. Introduction Radiometallated peptides which exhibit high specificity for cognate receptors over-expressed on cancerous lesions, offer importantpotentialas site-directed diagnostic and therapeutic radiopharmaceuticals (Boerman etal., 2000; Breeman et al., 2001; Britton, 1997; Eckelman and Gibson, 1993).The highly specificbiochemical and physiologic binding capabilities of the receptor-avid peptides can be exploited for using these agents as a vehicle to target the delivery ofthe radioactivity to the cells over-expressing similar type ofreceptors after radiolabeling the peptides with the radionuclide ofinterest.Such peptide analogs when labeled with therapeutic radionuclidesare being actively investigated as agents for use in peptide recepto radionuclide therapy (PRRT) (Kwekkeboom et al., 2000, 2003a, 2005; de Jong et al., 2005). Among the severalclassesof radiolabeled peptides, radiolabeled somatostatin analogs have been proved to b the most promising.Octreotide,a metabolically stable analog of native somatostatin (Pauwels et al., 1998),has been radiolabeled with 111 In using a bifunctional chelating agent and the resultant radiolabeled peptide, 111 In–DTPA- Octreotide (commonly known as OctreoScan s ) has been successfully employed in clinical diagnosis of somatostat receptor positive tumors (Pauwels et al., 1998; Krenning et al. 1992, 1993). Efforts are being made to develop suit therapeutic analogs having the potential to eradicate the cancerous lesions over-expressing somatostation recepto ARTICLE IN PRESS www.elsevier.com/locate/apradiso 0969-8043/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.apradiso.2006.09.011 Corresponding author. Tel.: +91 22 2559 0616; fax: +91 22 2550 5345. E-mail address: sharmila@barc.gov.in (S. Banerjee).