Clinical Dose Preparation of [Lu]Lu-DOTA-Pertuzumab Using Medium Specific Activity [Lu]LuCl for Radioimmunotherapy of Breast and Epithelial Ovarian Cancers, with HER2 Receptor Overexpression.

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 [Lu]Lu, has proved to be clinically efficacious with promising potential. Toward this, the formulation for clinical doses of [Lu]Lu-DOTA-pertuzumab has been optimized using medium specific activity (0.81 GBq/μg) [Lu]LuCl. Preconcentrated pertuzumab was conjugated with -NCS-benzyl-DOTA. Purified DOTA-benzyl-pertuzumab conjugate was radiolabeled with carrier-added [Lu]LuCl. Quality control parameters were evaluated for the [Lu]Lu-DOTA-pertuzumab. biodistribution was carried out at different time points postadministration. Specific cell binding, immunoreactivity, and internalization were investigated by using SKOV3 and SKBR3 cells. In this study, the authors reported a consistent and reproducible protocol for clinical dose formulations of [Lu]Lu-DOTA-pertuzumab, with a radiochemical yield of 86.67% ± 1.03% and radiochemical purity (RCP) of 99.36% ± 0.36% ( = 10). Preclinical cell binding studies of [Lu]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. A protocol was optimized for the preparation of ready-to-use clinical dose of [Lu]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 stability.