Biomimetic black phosphorus nanosheets codeliver CDK9 and BRD4 inhibitors for gastric cancer targeted therapy

Combining the BRD4 and CDK9 inhibitors can trigger the significant down-regulation of the MYC oncogene as well as anti-apoptotic genes and induce tumor cell apoptosis by synergistically impairing RNA synthesis in cancer cells. However, the lack of tumor-targeting capacity and the different pharmacokinetic curves of these two inhibitors may impair the antitumor activity of simultaneous CDK9 and BRD4 inhibition. Herein, CDK9 inhibitor (CI) and BRD4 inhibitor (BI) were codelivered by macrophage membrane-encapsulated black phosphorus nanosheets (M@BP) for the treatment of gastric cancer (GC) via the high expression of BRD4 and CDK9. BP with prominent biocompatibility exhibited a high drug loading efficiency for both CI and BI and could efficiently decrease the expression of the MYC oncogene. More importantly, BP could also serve as a phototherapy agent collaborating with CDK9 and BRD4 inhibition for GC therapy upon near-infrared (NIR) irradiation. Furthermore, the introduction of a macrophage membrane endowed BP with tumor-targeting ability, which could simultaneously deliver CI and BI to tumor tissues. In a murine orthotopic GC model, M@BP could efficiently target and accumulate in the tumor tissues, exhibiting an excellent photothermal effect. The tumor growth monitoring demonstrated that the combination of CI and BI codelivered by M@BP significantly inhibited the tumor progress than the single inhibitors, and the inhibition effect could be further enhanced upon NIR irradiation. Taken together, M@BP with tumor-targeting capacity and high drug loading efficiency for CI and BI could efficiently block the activation of CDK9 and BRD4, exhibiting excellent antitumor activity under NIR irradiation without systemic toxicity in an orthotopic GC model. The combination of BRD4 and CDK9 inhibitors codelivered by M@BP can trigger the significant down-regulation of the MYC oncogene as well as anti-apoptotic genes and induce tumor cell apoptosis by synergistically impairing RNA synthesis in cancer cells.