Validation of 64Cu-DOTA-rituximab injection preparation under good manufacturing practices: a PET tracer for imaging of B-cell non-Hodgkin lymphoma

Abstract

Manufacturing of 64Cu-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-rituximab injection under good manufacturing practices (GMP) was validated for imaging of patients with CD20+ B-cell non-Hodgkin lymphoma. Rituximab was purified by size exclusion high performance liquid chromatography (HPLC) and conjugated to DOTA-mono-(N-hydroxysuccinimidyl) ester. 64CuCl2, buffers, reagents, and other raw materials were obtained as high-grade quality. Following a semi-automated synthesis of 64Cu-DOTA-rituximab, a series of quality control tests was performed. The product was further tested in vivo using micro-positron emission tomography/computed tomography (PET/CT) to assess targeting ability towards human CD20 in transgenic mice. Three batches of 64Cu-DOTA-rituximab final product were prepared as per GMP specifications. The radiolabeling yield from these batches was 93.1 ± 5.8%; these provided final product with radiopharmaceutical yield, purity, and specific activity of 59.2 ± 5.1% (0.9 ± 0.1 GBq of 64Cu), > 95% (by HPLC and radio-thin layer chromatography), and 229.4 ± 43.3 GBq/µmol (or 1.5 ± 0.3 MBq/µg), respectively. The doses passed apyrogenicity and human serum stability specifications, were sterile up to 14 days, and retained > 60% immunoreactivity. In vivo micro-PET/CT mouse images at 24 hours postinjection showed that the tracer targeted the intended sites of human CD20 expression. Thus, we have validated the manufacturing of GMP grade 64Cu-DOTA-rituximab for injection in the clinical setting.