Sequential delivery of an anticancer drug and combined immunomodulatory nanoparticles for efficient chemoimmunotherapy.

Chemoimmunotherapy combines chemotherapy based on anticancer drugs with immunotherapy based on immune activators to eliminate or inhibit the growth of cancer cells. In this study, water-insoluble paclitaxel (PTX) was dispersed in water using hyaluronic acid (HA) to generate a tumor-associated antigen in the tumor microenvironment. Cytosine-phosphate-guanosine oligodeoxynucleotides (CpG ODNs) were used to enhance the T helper (Th) 1 immune response. However, CpG ODNs also induced the secretion of interleukin-10 (IL-10) that reduces the Th1 response and enhances the T helper 2 (Th2) response. Therefore, RNA interference was used to downregulate IL-10 secretion from bone marrow-derived den-dritic cells (BMDCs). For the combined immunomodulation of BMDCs, we fabricated two types of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) containing CpG ODNs to activate BMDCs via Toll-like receptor 9 (CpG ODN-encapsulated PLGA NPs, PCNs) or a small interfering RNA to silence IL-10 (IL-10 small interfering RNA-encapsulated PLGA NPs, PINs). Treatment of BMDCs with both types of PLGA NPs increased the Th1/Th2 cytokine (IL-12/IL-10) expression ratio, which is important for the effective induction of an antitumor immune response. After primary injection with the HA/PTX complex, the tumor-associated antigen was generated and taken up by tumor-recruited BMDCs. After a secondary injection with immunomodulating PCNs and PINs, the BMDCs became activated and migrated to the tumor-draining lymph nodes. As a result, the combination of chemotherapy using the HA/PTX complex and immunotherapy using PCNs and PINs not only efficiently inhibited tumor growth but also increased the animal survival rate. Taken together, our results suggest that the sequential treatment of cancer cells with a chemotherapeutic agent and immunomodulatory nanomaterials represents a promising strategy for efficient cancer therapy.