Dry powders for inhalation containing monoclonal antibodies made by thin-film freeze-drying

Thin-film freeze-drying (TFFD) is a rapid freezing and then drying technique used to prepare inhalable dry powders from the liquid form for applications such as drug delivery to the lungs. Herein we report the preparation of aerosolizable dry powders of monoclonal antibodies (mAbs) by TFFD. We first formulated an IgG antibody with lactose/leucine (60:40, w/w) or trehalose/leucine (75:25) and tested their aerosol performance. The IgG 1% (w/w) formulated with lactose/leucine (60:40, w/w) in phosphate buffered saline (PBS) (IgG-1-LL-PBS) and processed by TFFD was found to produce the powder with desirable aerosol properties. We then replaced the IgG with anti-programmed cell death protein (anti-PD-1 mAb), a specific antibody, to prepare a dry powder (anti-PD1-1-LL-PBS), which performed similarly to the IgG-1-LL-PBS powder. The aerosol properties of the anti-PD1-1-LL-PBS dry powder were significantly better when TFFD was used to prepare the powder than when conventional shelf freeze-drying (shelf FD) was used. The TFFD dry powder had a porous structure with nanoaggregates and had a T_g value between 39 and 50 °C. When stored at room temperature, the anti-PD-1 mAb in the TFFD powder was more stable than that of the same formulation stored as a liquid. The addition of polyvinylpyrrolidone K40 in the formulation raised the T_g to 152 °C, which is expected to further increase the storage stability of the mAbs. The PD-1 binding activity of the anti-PD-1 mAbs after TFFD was not different from before TFFD. While protein loss, likely due to protein binding to vials and the thin-film freezing apparatus, was identified, we were able to minimize the loss by increasing the mAb concentration (i.e., from 1% to 13.2%). Micro-flow imaging revealed that the excipients and PBS affected subvisible aggregate formation. More subvisible mAb aggregates were generated when PBS was used, but the mAb content in the dry powders did not significantly affect the total subvisible aggregate count. Powders prepared with mannitol as an excipient showed the least amount of subvisible mAb aggregates. Finally, we showed that anti-TNF-α, another mAb, can also be converted to a dry powder with a similar composition by TFFD. We conclude that TFFD can be applied to produce stable, aerosolizable dry powders of mAbs for pulmonary delivery and that formulations must be optimized to maximize aerosol performance and minimize protein aggregation.