Fig. 3. A, a pH sensitive polymer (MGlu-HPG) modified cationic liposomes (TRX) for efficient antigen delivery and activation of dendritic cells [52]. B, the drug is released when exceeded the liposome phase transition temperature [54].
To grasp the particularity of tumor environment or immune cells, it is helpful to establish an efficient immune induction system or drug delivery system by modifying different targeted ligands on liposomes. Sakurai et al. established a new drug delivery system for malignant pleural mesothelioma (MPM) cells with high expression and high affinity with HA receptor CD44 for the treatment of MPM [55]. The drug delivery system connects cationic liposomes and HA derivatives through the reductive amination of carboxyl and amino groups, which improves the targeting effect of drug therapy. DC-SIGN is known to be pathogen-associated molecular patterns (PAMPs) receptor and the C-type lectin receptor that can recognize and combine mannose structure and fucose structure. Martine et al. generated a liposome containing the glycan Lewis (Le)X to target DC with tumor antigen [56]. The glycol-liposome increased the targeting of the drug to DC-SIGN, enhanced the uptake of liposome antigen conjugate by DC, and ensured the presentation of tumor antigen in MHC molecule.