Photodegradation of human growth hormone: a novel backbone cleavage between Glu-88 and Pro-89

Photo-Oxidation of Therapeutic Protein Formulations: From Radical Formation to Analytical Techniques

UV and ambient light-induced modifications and related degradation of therapeutic proteins are observed during manufacturing and storage. Therefore, to ensure product quality, protein formulations need to be analyzed with respect to photo-degradation processes and eventually protected from light exposure. This task usually demands the application and combination of various analytical methods. This review addresses analytical aspects of investigating photo-oxidation products and related mediators such as reactive oxygen species generated via UV and ambient light with well-established and novel techniques.

Thiyl Radical Reactions in the Chemical Degradation of Pharmaceutical Proteins

Free radical pathways play a major role in the degradation of protein pharmaceuticals. Inspired by biochemical reactions carried out by thiyl radicals in various enzymatic processes, this review focuses on the role of thiyl radicals in pharmaceutical protein degradation through hydrogen atom transfer, electron transfer, and addition reactions. These processes can lead to the epimerization of amino acids, as well as the formation of various cleavage products and cross-links. Examples are presented for human insulin, human and mouse growth hormone, and monoclonal antibodies.

The Effects of Light-Accelerated Degradation on the Aggregation of Marketed Therapeutic Monoclonal Antibodies Evaluated by Size-Exclusion Chromatography With Diode Array Detection

Research into the effects that exposure to light can have on therapeutic proteins is essential for ensuring the quality and safety of the medicines in which they are used. It is important to understand the effects of light on aggregation to help avoid undesirable colloidal instabilities, both in the original medicines and in the formats in which they are finally administered. In this study, 5 marketed therapeutic mAbs, namely bevacizumab, cetuximab, infliximab, rituximab, and trastuzumab, were investigated for this purpose. The medicines and 2 diluted preparations in 0.9 NaCl (2 mg/mL and 5 mg/mL)-commonly used in clinical practice-were subjected to controlled light-accelerated degradation. The formation of aggregates was monitored by size-exclusion chromatography. The results indicated that light induced protein aggregation. This process of protein damage was influenced above all by mAb concentration, although the particular characteristics of each mAb were also important. Photodegradation also produced the fragmentation of the mAbs. The damage caused to the mAbs as a result of light-induced aggregation and/or fragmentation was demonstrated both in the medicines and in the diluted preparation forms. These findings should be carefully considered when handling the medicines for administration and when recommending beyond-use dates in normal hospital conditions.