Evaluation of Dynamic Light Scattering as an Effective Quality Control Method for Aggregates in Radiolabeled Antibodies

Radiolabeled antibodies are promising for targeted cancer imaging, but their structural integrity may suffer during bioconjugation and radiolabeling, leading to undetected aggregation. This study evaluates dynamic light scattering (DLS) as a complementary method to size-exclusion high-performance liquid chromatography (SEC-HPLC) for detecting aggregation in radiolabeled antibodies. Trastuzumab was conjugated with a NOTA bifunctional chelator at various ratios, radiolabeled with [⁶⁴Cu]CuCl₂, and analyzed by using DLS and SEC-HPLC before and after purification. DLS revealed significant aggregation during preparation, undetected by SEC-HPLC, and showed reduced aggregates following purification. Tumor-targeting efficacy correlated with intact antibody content, with Pearson's correlations of 0.71 (PET imaging) and 0.75 (biodistribution) in NIH3T6.7 tumor-bearing mice. The findings suggest DLS as a vital quality control tool, offering enhanced detection of antibody aggregation. By adopting DLS, the bioactivity of radiolabeled antibodies can be better predicted, potentially improving the reliability and effectiveness of these radiopharmaceuticals in clinical settings.