A DRUG DELIVERY SYSTEM (DDS) FOR ADMINISTRATION OF A WATER SOLUBLE, CATIONIC, AND AMPHIPHILIC PHARMACEUTICALLY ACTIVE SUBSTANCE (API) WHICH DDS COMPRISES POORLY WATER SOLUBLE NANOPARTICLES FORMED BY THE API TOGETHER WITH A NA-SALT OF N-ALL-TRANS-RETINOYL CYSTEIC ACID METHYL ESTER AND/OR A NA-SALT OF N-13-CIS-RETINOYL CYSTEIC ACID METHYL ESTER. A PHARMACEUTICAL COMPOSITION COMPRISING SUCH A DDS. METHODS FOR PREPARATION OF SUCH A DDS AND SUCH A PHARMACEUTICAL COMPOSITION. USE OF SUCH A DDS AND PHARMACEUTICAL COMPOSITION FOR TREATMENT OF CANCER. FIGURE 1