Magnetophoretic delivery of a tumor priming agent for chemotherapy of metastatic murine breast cancer

Tumor microenvironment (TME) is a significant physical barrier to effective delivery of chemotherapy into solid tumors. To overcome this challenge, tumors are pre-treated with an agent that reduces cellular and extracellular matrix densities prior to chemotherapy. However, it also comes with a concern that metastasis may increase due to the loss of protective containment. We hypothesize that timely priming at the early stage of primary tumors will help control metastasis. To test this, we primed orthotopic 4T1 breast tumors with a paclitaxel (PTX)-loaded iron oxide decorated poly(lactic-co-glycolic acid) nanoparticle composite (PTX@PINC), which can be quickly concentrated in target tissues with the aid of an external magnet, and monitored its effect on the delivery of subsequently administered NPs. Magnetic resonance imaging and optical whole-body imaging confirmed that PTX@PINC was efficiently delivered to tumors by the external magnet and help loosen the tumors to accommodate subsequently-delivered NPs....