Background and Importance Pembrolizumab (Keytruda^®) is a human IgG4 monoclonal antibody (mAb) from the group of immunomodulators, which binds to programmed death receptor 1 (PD-1). Given its structural complexity, physical aggregation and chemical degradation can occur throughout its life, and even modest environmental stresses can cause extensive damage which may affect the safety and efficacy of the medicine.¹

Aim and Objectives To assess the impact of agitation on pembrolizumab (Keytruda^®, 25 mg/mL) safety and efficacy through the study of aggregation and functionality when mishandling in real hospital conditions.

Material and Methods Pembrolizumab (Keytruda^®, 25 mg/mL) fresh opened vials were used. Agitation stress was carried out in a mechanical laboratory shaker (300 rounds/min, 24h, 25°C) and gentle agitation was performed manually (1 min, 25°C). Aggregation was assessed by Dynamic Light Scattering (DLS) and Size–Exclusion Ultra–High–Performance Liquid Chromatography (SE/UHPLC–UV). Pembrolizumab functionality was evaluated by Enzyme-Linked Immunosorbent Assay (ELISA).

Results Pembrolizumab control sample (25 mg/mL) showed a single particulate population with hydrodynamic diameter (HD) of 9.5 ± 2.8 nm corresponding to pembrolizumab monomers. SE/UHPLC–UV chromatograms of the control sample revealed a main chromatographic peak assigned to pembrolizumab monomers and a small one assigned to native dimers. DLS and SE/UHPLC–UV showed that agitation stress did not promote increase in aggregation. However, pembrolizumab functionality was affected after applying agitation stress since ELISA revealed a significant loss of functionality. As a consequence, a gentle agitation of pembrolizumab was performed in order to investigate if this loss of functionality could also happen in less stressful conditions. As a result, ELISA also revealed a significant loss of functionality in gently agitated pembrolizumab.

Conclusion and Relevance The exposure to agitation stress did not induce aggregate formation in pembrolizumab. Nevertheless, both agitation stress and gentle agitation led to a loss of its functionality not related to agitation. Thus, we recommend preventing pembrolizumab from agitation when handling in hospitals.

Reference

1. M.R. Nejadnik et al. J.Pharm.Sc.107(2018)2013-2019.

Acknowledgements Funded by projects P20-01029 (Junta de Andalucía, Spain) and B-FQM-308-UGR20 (Universidad de Granada, FEDER 2020). A.T-L grants a FPU predoctoral contract (FPU18/03131, Ministry of Universities, Spain). J.H benefits a research contract (P20_01029, Junta de Andalucía and European Regional Development Funds). R.P-R holds a postdoctoral position (DOC-01694, Junta de Andalucía, Spain).

Conflict of Interest No conflict of interest