TY - JOUR T1 - Biodistribution and Radiation Dosimetry of the Anti-HER2 Affibody Molecule <sup>68</sup>Ga-ABY-025 in Breast Cancer Patients JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 867 LP - 871 DO - 10.2967/jnumed.115.169342 VL - 57 IS - 6 AU - Mattias Sandström AU - Karolina Lindskog AU - Irina Velikyan AU - Anders Wennborg AU - Joachim Feldwisch AU - Dan Sandberg AU - Vladimir Tolmachev AU - Anna Orlova AU - Jens Sörensen AU - Jörgen Carlsson AU - Henrik Lindman AU - Mark Lubberink Y1 - 2016/06/01 UR - http://jnm.snmjournals.org/content/57/6/867.abstract N2 - 68Ga-ABY-025 is a radiolabeled Affibody molecule for in vivo diagnosis of human epidermal growth factor receptor 2 (HER2)–positive breast cancer tumors with PET. The aim of the present work was to measure the biodistribution and estimate the radiation dosimetry of 68Ga-ABY-025 for 2 different peptide mass doses in a single group of patients using dynamic and serial whole-body PET/CT. Methods: Eight patients with metastatic breast cancer were included. Each patient underwent an abdominal 45-min dynamic and 3 whole-body PET/CT scans at 1, 2, and 4 h after injection of a low peptide dose (LD) and a high peptide dose (HD), with approximately the same amount of radioactivity, in separate investigations 1 wk apart. As input to the absorbed dose calculations, volumes of interest were drawn on all clearly identifiable source organs: liver, kidneys, spleen, descending aorta, and upper large intestine. Absorbed doses were calculated using OLINDA/EXM, version 1.1. Results: Of the major organs, the highest radionuclide uptake at 1, 2, and 4 h after injection was observed in the kidneys and liver. The highest absorbed organ doses were seen in the kidneys, followed by the liver for both LD and HD 68Ga-ABY-025. Absorbed doses to liver and kidneys were slightly but significantly higher for LD. Total effective dose was 0.030 ± 0.003 mSv/MBq for LD and 0.028 ± 0.002 mSv/MBq for HD. Conclusion: The effective dose for a typical 200-MBq administration of 68Ga-ABY-025 is 6.0 mSv for LD and 5.6 mSv for HD. Therefore, from a radiation dosimetry point of view, HD is preferred for PET/CT evaluation of HER2-expressing breast cancer tumors. These effective doses are somewhat higher than earlier published values for other 68Ga-labeled tracers, such as 0.021 ± 0.003 mSv/MBq for 68Ga-DOTATATE and 68Ga-DOTATOC, mainly because of higher uptake in liver and kidney. ER -