Stability of protein-based drugs: Herceptin a case study

There is a lack of stability data for in-use parenteral drugs. Manufacturers state a shelf-life of 24 hours for infusions based on microbiological contamination. The lack of data is of particular significance with protein-based drugs where action is determined by their complex structure. A range of techniques are required to assess stability, including biological assessment to support other data. There has been an increase in published data but often the few studies that address in-use stability are incomplete as they do not employ biological assessment to assess potency. Trastuzumab is an antibody-based drug used to treat cancers where the Epidermal Growth Factor Receptor 2 (HER2) is over expressed or over abundant on the cell surface. Trastuzumab infusions have been assigned by the manufacturer to be stable for 24 hours at temperatures not exceeding 30 oC. If stability is shown beyond this point it would enable extended storage and administration. To this end, methods were selected and developed with biological assessment central to the approach to assess clinically relevant infusion concentrations (0.5 mg/mL and 6.0 mg/mL) and a sub-clinical infusion concentration (0.1 mg/mL). This may enhance instability and provide opportunity to study degradation. A Cell Counting Kit CCK8 (Sigma Aldrich) was ultimately adopted as a basis for a colorimetric assay to assess cell viability. Attenuated Total Reflectance Infra-Red Spectroscopy and Size Exclusion Chromatography methods were developed to evaluate secondary structure and aggregation respectively. These methods were applied to a shelf-life study (43 days) as a collaboration with Quality Control North West (NHS) and Clatterbridge Centre for Oncology NHS Foundation Trust, Clatterbridge Hospital. There was no evidence of degradation and no loss efficacy for clinically relevant infusions (0.5 mg/mL and 6.0 mg/mL) over 43 days, whilst the sub-clinical infusions (0.1 mg/mL) developed particles after 7 days of storage between 2 oC and 8 oC. Furthermore, evidence of stability at day 119 gave increased confidence for the data from earlier time points. This work assisted in the shelf-life being recommended to be extended to 28 days for Trastuzumab stored in polyolefin IV bags at concentrations between 0.5 mg/mL and 6.0 mg/mL with 0.9% saline between 2 oC and 8 oC. However, infusions with concentrations below 0.5 mg/mL were not recommended for storage.