MPL nano-liposomal vaccine containing P5 HER2/neu-derived peptide pulsed PADRE as an effective vaccine in a mice TUBO model of breast cancer

Doxil chemotherapy plus liposomal P5 immunotherapy decreased myeloid-derived suppressor cells in murine model of breast cancer

Myeloid-derived suppressor cells (MDSCs) play a pivotal role in cancer. To overcome the problem of the MDSCs in the tumor microenvironment in this study, a combination of immunotherapy and chemotherapy was used. For this purpose, a liposomal formulation of P5 peptide and PEGylated liposomal doxorubicin (Doxil®) was utilized to treat mice bearing HER2⁺ tumor model. The results revealed that Doxil® administration before immunotherapy had not only reduced the population and functions of the MDSCs in the spleen (P < 0.001) and the tumor microenvironment (P < 0.05) but had also supported further immunotherapy including enhanced CD4⁺ (P < 0.01) and CD8⁺ lymphocyte (P < 0.001) population and IFN-γ production (P < 0.001). This effect was also more pronounced with a liposomal P5 and Doxil® compared with free peptide and doxorubicin. In conclusion, the results demonstrated that Doxil® plus liposomal P5 could have a decreasing effect on MDSCs and tumor growth, and it could be beneficial in breast cancer treatment.

Cell cytotoxicity, immunostimulatory and antitumor effects of lipid content of liposomal delivery platforms in cancer immunotherapies. A comprehensive in-vivo and in-vitro study

Liposome is one of the promising technologies for antigen delivery in cancer immunotherapies. It seems that the phospholipid content of liposomes can act as immunostimulatory molecules in cancer immunotherapy. In the present study, the immunological properties of different phospholipid content of liposomal antigen delivery platforms were investigated. To this aim, F1 to F4 naïve liposomes (without tumor-specific loaded antigens) of positively charged DOTAP/Cholesterol/DOPE (4/4/4 mol ratio), negatively charged DMPC/DMPG/Cholesterol/DOPE (15/2/3/5), negatively charged DSPC/DSPG/Cholesterol/DOPE (15/2/3/5) and PEGylated HSPC/mPEG2000-DSPE/Cholesterol (13/110) liposomal compositions were administered in mice bearing C26 colon carcinoma to assess tumor therapy. Moreover, In-vitro studies were conducted, including cytotoxicity assay, serum cytokines measurements, IFN-γ and IL-4 ELISpot assay, T cells subpopulation frequencies assay. The liposomes containing DOTAP and DOPE (F1 liposomes) were able to stimulate cytotoxic T lymphocytes signals such as IFN-γ secretions. In parallel, the aforementioned phospholipids stimulated secretion of IL-4 and IL-17 cytokines from T helper cells. However, these liposomes did not improve survival indices in mice. As conclusion, DOTAP and DOPE contained liposomes (F1 liposomes) stimulate a mixture of Th1 and Th2 immune responses in a tumor-specific antigens-free manner in mice bearing C26 colon carcinoma. Therefore, phospholipid composition of liposomes merits consideration in designing antigen-containing liposomes for cancer immunotherapy.