Combination of attenuated Salmonella carrying PD-1 siRNA with nifuroxazide for colon cancer therapy.

Colon cancer is a member of malignant tumors in the digestive system. Traditional treatment strategies are ineffective and improving the treatment of colon cancer is an urgent need. Targeting programmed cell death-1 (PD-1) by monoclonal antibodies has shown some therapeutic effectiveness and has advantages. Additionally, the Stat3 inhibitor nifuroxazide was employed to promote the antitumor activity. Here, we hypothesized that combining nifuroxazide with PD-1 small interfering RNA carried by attenuated Salmonella would exert a synergistic antitumor effect on colon cancer. Indeed, treatment with this combination effectively inhibited the development of colon cancer in mice and improved the survival rate. These two novel anticancer agents worked synergistically to elicit potent antitumor immunity and achieve improved therapeutic efficacy. The underlying mechanisms are mainly involved with immune regulation and cell apoptosis. This study provides a previous framework for combining this Stat3 inhibitor with RNAi designed to block immune checkpoint signaling for cancer therapy.