Overall, potent therapeutic efficacy against breast cancer in mice was achieved due to effective intratumor and intracellular delivery of let‐7a with CNPs, as well as a synergistic effect between let‐7a and the chemotherapeutic, PTX, because the downregulation of KRAS protein by let‐7a enabled cancer cell sensitization to the chemotherapeutic agents.24 Here, KRAS is linked to breast cancer.