A new immune-nanoplatform for promoting adaptive antitumor immune response.

Immunoliposomes (ILs), obtained with monoclonal antibodies (mAbs) decorating the liposome surface, are used for cancer treatment. These mAbs provide the recognition of molecules upregulated in cancer cells, like Programmed Death-Ligand 1 (PD-L1), an immune-checkpoint involved in tumor resistance, forming a complex that blocks this molecule and thereby, induces antitumor immune response. This mechanism introduces a new concept for ILs. ILs coupled to anti-PD-L1 or its Fab' fragment have been developed and in vitro/in vivo characterized. Factors such as coupling methods, PEG density and ligand size were optimized. In vitro data showed that Fab'-ILs displayed the highest PD-L1 cell interaction, correlating with a higher in vivo tumor accumulation and an increase of effector cytotoxic CD8+ T cells, providing tumor shrinkage and total regression in 20% of mice. Therefore, a novel immune-nanoplatform able to modulate the immune system has been developed, allowing the encapsulation of several agents for combinatorial therapies.