ABSTRACT
Objectives: The present work describes the automated radiochemical synthesis of different PET tracers like [68Ga]Ga-Pentixafor, [68Ga]Ga-FAPI-4 and [68Ga]Ga-DOTATATE using optimized single protocol in the non-cassette based Eckert & Ziegler (EZ) Modular Lab (fixed tubing system) without any modification in the inbuilt human machine interface (HMI) software. Recently, PET agents viz. [68Ga]Ga-Pentixafor and [68Ga]Ga-FAPI-4 are gaining prominence for the diagnosis of overexpressed Chemokine Receptor-4 (CXCR4) and Fibroblast Activation Protein (FAP) receptor, respectively, in the microenvironment of numerous cancer types. The promising results observed with the clinical usage of [68Ga]Ga-DOTATATE produced using the automated protocol, provided impetus for the clinical translation of [68Ga]Ga-Pentixafor and [68Ga]Ga-FAPI-4 using the in-house developed automated radiolabeling protocol. Methods: Herein we report a single radiolabeling protocol for the automated preparation of [68Ga]Ga-Pentixafor and [68Ga]Ga-FAPI-4 in the non-cassette based EZ Modular-Lab Standard radiochemistry module, without any changes in schematic, graphical user interface (GUI) software and time list, from that used for routine production of [68Ga]Ga-DOTATATE in our centre, since 2015. Physico-chemical quality control and in-vitro stability analyses were carried out using radio-TLC and radio-HPLC. Results: The automated protocol yielded reliable and consistent non-decay corrected (ndc) radiochemical yield (RCY) of (84.4%±0.9%) and (85.5%±1.4%) respectively, for [68Ga]Ga-Pentixafor and [68Ga]Ga-FAPI-4, with RCP>98%, which are comparable to the RCY of (84.4%±1.2%) and RCP (99.1%±0.3%) for [68Ga]Ga-DOTATATE. The biological quality control studies confirmed the formulations to be of ready-to-use pharmaceutical grade. Conclusion: The consistent and reliable RCY and RCP of multiple 68Ga-labeled PET tracers by single automated radiochemistry protocol exhibits the versatility of the EZ Modular Lab.
ABSTRACT
Background: The overexpression of human epidermal growth factor receptor 2 (HER2) is commonly associated with metastatic breast cancer and epithelial ovarian cancer. The U.S. Food and Drug Administration (FDA) has approved Trastuzumab as an anti-HER2 agent for the metastatic breast and epithelial ovarian cancer. However, Trastuzumab has severe limitations in the treatment of metastatic breast cancer associated with ligand-dependent dimerization of HER2 receptor at the extracellular domain-II (ECD-II) region. The therapeutic approach in combination of pertuzumab and trastuzumab is found to be effective in preventing HER2 dimerization at the ECD-II region. The radioimmunotherapeutic approach, utilizing both these anti-HER2 agents (trastuzumab/pertuzumab), radiolabeled with [177Lu]Lu3+, has proved to be clinically efficacious with promising potential. Toward this, the formulation for clinical doses of [177Lu]Lu-DOTA-pertuzumab has been optimized using medium specific activity (0.81 GBq/µg) [177Lu]LuCl3. Materials and Methods: Preconcentrated pertuzumab was conjugated with p-NCS-benzyl-DOTA. Purified DOTA-benzyl-pertuzumab conjugate was radiolabeled with carrier-added [177Lu]LuCl3. Quality control parameters were evaluated for the [177Lu]Lu-DOTA-pertuzumab. In vivo biodistribution was carried out at different time points postadministration. Specific cell binding, immunoreactivity, and internalization were investigated by using SKOV3 and SKBR3 cells. Results: In this study, the authors reported a consistent and reproducible protocol for clinical dose formulations of [177Lu]Lu-DOTA-pertuzumab, with a radiochemical yield of 86.67% ± 1.03% and radiochemical purity (RCP) of 99.36% ± 0.36% (n = 10). Preclinical cell binding studies of [177Lu]Lu-DOTA-pertuzumab revealed specific binding with SKOV3 and SKBR3 cells up to 24.4% ± 1.4% and 23.2% ± 0.8%, respectively. The uptakes in SKOV3- and SKBR3-xenografted tumor in severe combined immunodeficiency mice were observed to be 25.9% ± 0.8% and 25.2% ± 1.2% ID/g at 48 and 120 h postinjection, respectively. Conclusions: A protocol was optimized for the preparation of ready-to-use clinical dose of [177Lu]Lu-DOTA-pertuzumab, in hospital radiopharmacy settings. The retention of RCP of the radiopharmaceutical, on storage in saline and serum, at -20°C, up to 120 h postradiolabeling, confirmed its in vitro stability.