Improved tumor accumulation and therapeutic efficacy of CTLA-4-blocking antibody using liposome-encapsulated antibody: In vitro and in vivo studies

One approach to address the obstacles of cancer therapy is the use of liposomes. The aim of the present study was to evaluate the therapeutic effect of liposomes containing CTLA-4-blocking antibodies. Biodistribution and treatment studies, and flow cytometry analysis of immune cells of the tumor site and lymph nodes were performed on mice bearing C26 colon carcinoma tumors by PEGylated and non-PEGylated liposomes. The biodistribution study showed that the PEGylated liposomes had prolonged blood half-lives and accumulated remarkably more than non-PEGylated liposomes and free CTLA-4-blocking antibodies in the tumor area. The lowest tumor volumes and highest survival times were seen in mice that received PEGylated liposomes. In conclusion, antibodies in PEGylated liposomal formulations containing anti CTLA-4 antibody are delivered to tumor sites more efficiently and have a greater effect on anti-tumor immune responses than free antibodies alone.290