The profound level of synergism resulting from this combination treatment, combined with the ability of eribulin to enhance STING and RIG-I/MDA-5 agonists in vitro and in vivo, provided the rationale for evaluations of these agents in a recurrent murine model of breast cancer where the combination of eribulin and a STING agonist showed improved antitumor efficacy compared to either agent alone. Here, STING1 is linked to breast cancer.