Fig. 4. Nanoparticle-based delivery systems carrying synergistic immunomodulatory drug combinations can sway the tumor microenvironment of 4T1 breast tumors from suppressive to permissive.

(A) Schematic description of the targeted drug nanocarrier used in our experiments. Also depicted are the chemical structures of the two compounds we encapsulated into the nanoparticles and the iRGD targeting ligand that we coupled to their surface. (B) Mice with established (d 10) 4T1 breast tumors were treated with 7×10¹³ liposomes (2 mg lipid) carrying 150 µg PI-3065 and 10 µg 7DW8-5, either alone or in combination, or with equivalent non-encapsulated drugs every three days. These graphs display absolute numbers of immune suppressor cells (top panel) and anti-tumor effector cells (lower panel) in 4T1 breast tumors after six treatments (day 26). The flow cytometry antibody panel used to phenotype these cells is the same as that described in Fig. 2D. (C) Progression of 4T1-ROR1 tumor growth following therapy. Every line represents one animal and each dot reflects tumor size, as determined by caliper measurements. Shown are eight animals per treatment group pooled from three independent experiments. (D) Overview graph displaying the average tumor volumes ± S.E.M. for each treatment regimen over time. (E) Graphs displaying absolute numbers of immune suppressor cells (top panel) and anti-tumor effector cells (lower panel) in 4T1 breast tumors that ultimately developed resistance and relapsed despite repeated PI-3065 + 7DW8-5 liposome infusions.