TY - JOUR T1 - Biodistribution and Dosimetry Results from a Phase 1 Trial of Therapy with the Antibody–Radionuclide Conjugate <sup>177</sup>Lu-Lilotomab Satetraxetan JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 704 LP - 710 DO - 10.2967/jnumed.117.195347 VL - 59 IS - 4 AU - Johan Blakkisrud AU - Jon Erik Holtedahl AU - Ayca Løndalen AU - Jostein Dahle AU - Tore Bach-Gansmo AU - Harald Holte AU - Stine Nygaard AU - Arne Kolstad AU - Caroline Stokke Y1 - 2018/04/01 UR - http://jnm.snmjournals.org/content/59/4/704.abstract N2 - 177Lu-lilotomab satetraxetan is a novel antibody–radionuclide conjugate currently in a phase 1/2a first-in-humans dose escalation trial for patients with relapsed CD37-positive indolent non-Hodgkin lymphoma. The aim of this study was to investigate biodistribution and absorbed doses to organs at risk. Methods: In total, 7 patients treated with 177Lu-lilotomab satetraxetan were included for dosimetry. Patients were grouped on the basis of 2 different predosing regimens (with and without predosing with 40 mg of lilotomab) and were treated with different levels of activity per body weight (10, 15, and 20 MBq/kg). All patients were pretreated with rituximab. Serial planar and SPECT/CT images were used to determine time–activity curves and patient-specific masses for organs with 177Lu-lilotomab satetraxetan uptake. Doses were calculated with OLINDA/EXM. Results: The organs (other than red bone marrow and tumors) with distinct uptake of 177Lu-lilotomab satetraxetan were the liver, spleen, and kidneys. The highest uptake was found in the spleen, with doses ranging from 1.54 to 3.60 mGy/MBq. The liver received 0.70–1.15 mGy/MBq. The kidneys received the lowest dose of the source organs investigated, 0.16–0.79 mGy/MBq. No statistically significant differences in soft-tissue absorbed doses were found between the two predosing regimens. The whole-body dose ranged from 0.08 to 0.17 mGy/MBq. Conclusion: The biodistribution study for patients treated with 177Lu-lilotomab satetraxetan revealed the highest physiologic uptake to be in the liver and spleen (besides the red marrow). For all treatment levels investigated, the absorbed doses were found to be modest when compared with commonly assumed tolerance limits. ER -