Multispecific Platinum(IV) Complex Deters Breast Cancer via Interposing Inflammation and Immunosuppression as an Inhibitor of COX‐2 and PD‐L1

Breast cancer (BC) is one of the most common malignancies in women and often accompanied by inflammatory processes. Cyclooxygenase‐2 (COX‐2) plays a vital role in the progression of BC, correlating with the expression of programmed death‐ligand 1 (PD‐L1). Overexpression of PD‐L1 contributes to the immune escape of cancer cells, and its blockade would stimulate anticancer immunity. Two multispecific platinum(IV) complexes DNP and NP were prepared using non‐steroidal antiinflammatory drug naproxen (NPX) as axial ligand(s) to inhibit the BC cells. DNP exhibited high cytotoxicity and antiinflammatory properties superior over NP, cisplatin and NPX; moreover, it displayed potent antitumor activity and almost no general toxicity in mice bearing triple‐negative breast cancer (TNBC). Mechanistic studies revealed that DNP could downregulate the expression of COX‐2 and PD‐L1 in vitro and vivo, inhibit the secretion of prostaglandin, reduce the expression of BC‐associated protein BRD4 and phosphorylation of extracellular signal‐regulated kinases 1/2 (Erk1/2), and block the oncogene c‐Myc in BC cells. These findings demonstrate that DNP is capable of intervening in inflammatory, immune, and metastatic processes of BC, thus presenting a new mechanism of action for anticancer platinum(IV) complexes. The multispecificity offers a special superiority for DNP to treat TNBC by combining chemotherapy and immunotherapy in one molecule. A platinum(IV) complex (DNP) modified by the non‐steroidal antiinflammatory drug naproxen downregulated the expression of cyclooxygenase‐2 (COX‐2) and programmed death‐ligand 1 (PD‐L1) in vitro and vivo, retarded the metastasis of breast cancer cells, and showed potent antitumor activity in cancer‐bearing mice. Suppression on inflammatory cytokines and immune checkpoint is the unique character of DNP as a drug candidate.