One of the characteristics of tumour cells and tumour stroma cells is their secretion of the proteolytic enzymes such as cathepsins, which actively promote tumour growth and are therefore amenable as targets for targeted delivery of anti-cancer drugs. The invention is bio-molecular drug delivery system with a specific cathepsin-B inhibitor linked to a highly bio-compatible liposomal nano-carrier via lipid tail and which enables specific targeting of cathepsins in the tumour microenvironment, and therefore bringing the liposomomal nanocarrier containing the drug payload (eg.