25% of monophosphoryl lipid A as adjuvant [227]. They reported higher anti-bFGF IgG titers and higher pulmonary metastasis inhibition in mice treated with monophosphoryl lipid A bFGF-loaded liposomes over cationic liposomes or a bFGF/Freund’s adjuvant mixture without

the toxicity associated with administration of free adjuvants. Selective depletion of tumor supporting cells represents another approach to cell-specific cancer therapy [228]. The tumor Inhibitors,research,lifescience,medical environment is enriched in tumor supporting cells among the tumor-associated macrophages that constitute a predominant inflammatory population involved both in resistance to therapy and metastasis [228]. Dichloromethylenediphosphonate (DMDP) liposomes induced macrophage depletion after intravenous Inhibitors,research,lifescience,medical injection in mice [229]. Intradermal injection of DMDP liposomes into the tissues surrounding melanoma or squamous cell carcinoma AZD9291 tumors led to a decrease in tumor-associated macrophages content and tumor rejection [230]. Ligand density was shown to influence both drug retention and target recognition. Zhang et al. demonstrated increase in liposome uptake in vitro as the ligand density was increased from 0% to 1, 3, and 5% demonstrating enhanced ligand recognition

[231]. However, increase of in vitro Inhibitors,research,lifescience,medical drug release as a function of DSPE-PEG-RGD ligand moiety has been reported by others [232]. Moreover, Saul et al. evidenced increase of nonspecific uptake in vitro with ligand density [233]. Consistent with their results, lower tumor accumulation of NGR (Asparagine-Glycine-Arginine) vasculature targeted liposomes has been evidenced in vivo with liposomes Inhibitors,research,lifescience,medical harboring 2.56% mole NGR-PEG-DSPE than 0.64% mole NGR-PEG-DSPE [234]. Altogether, these data suggest Inhibitors,research,lifescience,medical the use of the lowest targeting ligand density allowing target binding for effective anticancer therapy. 4. Liposomes for Combination Therapy The prevalence of drug resistance in cancer patients, both prior to treatment

and de novo [235, 236], fueled the application of drug combinations to treat cancer as an alternative to increased doses of chemotherapeutics associated with life threatening sideeffects [237–239]. Codelivery was well new illustrated in a study by Chen et al. [240]. Using LPH-NP (liposome-polycation-hyaluronic acid) nanoparticles targeted by postinsertion of DSPE-PEG-GC4 (scFv selected by phage display against ovarian tumors [241]), they codelivered 3 different siRNA and one miRNA and obtained a 80% decrease in tumor load after treatment. They simultaneously targeted proliferation pathways with Cmyc siRNA and miR34a miRNA [242, 243], apoptosis with MDM2 siRNA [244], and angiogenesis using VEGF siRNA [245].