The present invention provides novel and inventive drug delivery systems with higher loading capability, a capacity to sequester high tumors levels of both hydrophobic and hydrophilic agents simultaneously, and longer release profiles. Some aspects of these delivery systems include compositions including stabilized multilamellar lipid vesicles having crosslinked lipid bilayers (referred to herein as inter-bilayer-crosslinked multilamellar vesicles or ICMV) covalently conjugated to an agent (e.g., an antigen).
