Standardization of Procedures for the Preparation of ¹⁷⁷Lu- and ⁹⁰Y-labeled DOTA-Rituximab Based on the Freeze-dried Kit Formulation

Title:Standardization of Procedures for the Preparation of ¹⁷⁷Lu- and ⁹⁰Y-labeled DOTA-Rituximab Based on the Freeze-dried Kit Formulation

Volume: 8 Issue: 1

Author(s): Wioletta Wojdowska, Urszula Karczmarczyk, Michal Maurin, Piotr Garnuszek and Renata Mikolajczak

Affiliation:

Keywords: anti-CD20, dried kit, Lutetium-177, radiolabeling, Rituximab, Yttrium-90.

Abstract: Rituximab when radiolabelled with ¹⁷⁷Lu or ⁹⁰Y has been investigated for the treatment of patients with Non-Hodgkin’s Lymphoma. In this study, we optimized the preparation of antibody conjugates with chelating agent in the freeze-dried kit. It shortens procedures needed for the successful radiolabeling with lutetium-177 and yttrium-90 and assures reproducible labelling yields. Various molar ratios of Rituximab:DOTA (from 1:5 to 1:100) were used at the conjugation step and different purification method to remove unbound DOTA were investigated (size-exclusion chromatography, dialysis, ultrafiltration). The final monoclonal antibody concentration was quantified by Bradford method, and the number of DOTA molecules was determined by radiolabeling assay using ⁶⁴Cu. The specific activity of ¹⁷⁷Lu-DOTA-Rituximab and ⁹⁰Y-DOTA-Rituximab were optimized using various amounts of radiometal. Quality control (SE-HPLC, ITLC) and stability study were performed. An average of 4.2 ± 0.8 p-SCN-Bz-DOTA molecules could be randomly conjugated to a single molecule of Rituximab. The ultrafiltration system was the most efficient for purification and resulted in the highest recovery efficiency (77.2%). At optimized conditions the ¹⁷⁷Lu-DOTARituximab and ⁹⁰Y-DOTA-Rituximab were obtained with radiochemical purity >99% and specific activity ca. 600 MBq/mg. The radioimmunoconjugates were stable in human serum and 0.9% NaCl. After 72 h of incubation the radiochemical purity of ¹⁷⁷Lu-DOTA-Rituximab decreased to 94% but it was still more than 88% for ⁹⁰Y-DOTA-Rituximab. The radioimmunoconjugate showed stability after six months storage at 2 - 8⁰C, as a lyophilized formulation. Our study shows that Rituximab-DOTA can be efficiently radiolabeled with ¹⁷⁷Lu and ⁹⁰Y via p-SCN-Bn-DOTA using a freezedried kit.

Cite this article as:

Wojdowska Wioletta, Karczmarczyk Urszula, Maurin Michal, Garnuszek Piotr and Mikolajczak Renata, Standardization of Procedures for the Preparation of ¹⁷⁷Lu- and ⁹⁰Y-labeled DOTA-Rituximab Based on the Freeze-dried Kit Formulation, Current Radiopharmaceuticals 2015; 8 (1) . https://dx.doi.org/10.2174/1874471008666141215151253