Currently, clinically approved drugs to treat breast cancer such as Doxil are relatively stable in circulation; however, drug transfer from the nanocarrier to breast cancer cells remains particularly problematic. This is in part attributed to the fact that DDSs of this size (~100nm in diameter) require pegylation to achieve optimal circulation times in vivo, which negatively influences cellular uptake of these systems. One solution to this problem involves making liposomes smaller in size. For example, other clinically approved liposome-based drugs

such as DaunoXome Inhibitors,research,lifescience,medical PHA-739358 concentration currently used to treat Kaposi’s sarcoma do not need to be pegylated as a result of their small size reported to be ~45nm in diameter [34]. An additional advantage that smaller DDS may have over their larger counterparts also involves their ability to potentially penetrate deeper into the tumor microenvironment [35]. However, it remains controversial Inhibitors,research,lifescience,medical as such small systems are potentially limited in their ability to deliver an effective dose of the drug to tumor tissue. Thus, several groups are currently

working on improved formulations Inhibitors,research,lifescience,medical that retain adequate circulation times in vivo, yet more efficiently deliver their encapsulated cargo without having to necessarily reduce the overall size of the nanocarrier. Many of these systems have been reported here and include formulations designed to release encapsulated cytotoxic agents at elevated temperatures and/or improve colocalization between the drug and breast cancer cells Inhibitors,research,lifescience,medical through targeting ligand addition. It is worth noting that liposomal formulations involving both targeting ligand incorporation as well as pegylation can be particularly challenging as the presence of the PEG moiety has the ability to potentially negatively influence receptor/ligand recognition [3]. Nonetheless, the systems

reported here or similar formulations may in fact be commonly used clinically in the near future in order to more effectively Inhibitors,research,lifescience,medical treat breast cancer. Acknowledgments This work was Edoxaban supported by funds generously provided by West Texas A&M University, as well as additional support from the Killgore Research Center through the Research Enhancement and Killgore Research grant program at West Texas A&M University.
Ever since Paul Ehrlich introduced the concept of the “magic bullet”—that is, the combination of an agent conferring selectivity towards a disease-causing organism with a therapeutic agent—scientists have worked towards achieving this vision. One way to achieve selectivity towards certain disease states was to develop a prodrug that would be administered in its inactive and nontoxic form but would be metabolized to its active form once it reached the diseased organ.