Triple‑negative breast cancer (TNBC) is an aggressive disease with the capability of metastasizing quickly. However, treatment options for patients with TNBC still remain limited. CDK4/6 inhibitors have been approved by the U.S. Food and Drug Administration and are administered for the treatment of hormone receptor‑positive breast cancer subtypes, but not yet for TNBC. Although pre‑clinical research is being conducted on their efficacy in treating TNBC, acquired resistance to CDK4/6 inhibitors is now a growing clinical problem. One of the identified resistance mechanisms is through the IL‑6/STAT3 signaling pathway. In the present study, the CDK4/6 inhibitor, abemaciclib, was tested in combination with the IL‑6 inhibitor, bazedoxifene, on human (SUM159 and MDA‑MB‑231) and murine (4T1) TNBC cell lines. Both abemaciclib and bazedoxifene monotherapies inhibited cell cycle progression and cell viability, migration and invasion, and induced apoptosis; however, the combination treatment exerted a greater effect than either monotherapy. These findings support the concept of CDK4/6 and IL‑6 dual inhibition as a novel targeted therapy against TNBC.

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