The colder, the better? Sustainability in frozen storage of a monoclonal antibody drug substance.

This study investigates the long-term stability of a monoclonal antibody (mAb) in selected formulations containing histidine buffer, sucrose, and 2-hydroxypropyl-β-cyclodextrin (HPβCD). Samples were stored for up to 24 months at -80 °C, -40 °C, and - 10 °C to assess whether more energy-efficient storage temperatures can maintain drug quality. We analyzed key physical stability attributes by monitoring high-molecular-weight species, subvisible particles, and optical density, while chemical stability was assessed by monitoring methionine oxidation. A primary focus was evaluating whether physical stability in the frozen state correlates with the formulation's glass transition temperature (Tg') as an indicator of matrix mobility. We report that storage at -40 °C and, in many cases, even at -10 °C, offers stability comparable to -80 °C, making these temperatures viable and more sustainable long-term storage options. Formulations containing HPβCD as a novel approach for freeze-thaw and frozen storage demonstrated the best stability, likely due to its combined cryoprotective and interfacial-shielding properties, which reduce both aggregation and particle formation. Data demonstrate a drastic stability change at Tg', with substantially increased stability below Tg'. However, above and below Tg', the temperature difference relative to Tg' had only minor influence compared to formulation effects. We therefore hypothesize that the sharp change in matrix mobility primarily governs frozen-state stability. The observation that several formulations remained stable at -10 °C highlights that formulation-dependent mechanisms can compensate for increased matrix mobility, offering promising potential for more flexible, sustainable frozen storage conditions.