Octahedral iodide Mo ₆ cluster complex bearing thiosulfate ligands: a dual chemotherapeutic and radiodynamic agent for advanced cancer therapy

Cancer treatment faces significant challenges due to tumor heterogeneity, drug resistance, and the limited efficacy of single-agent therapies, driving the search for novel therapeutic approaches. The water-soluble molybdenum cluster complex Na₅Cs₃[{Mo₆I₈}(S₂O₃)₆]·3H₂O, developed in this study, represents a unique compound that combines a strong chemotherapeutic effect, achieved through the controlled release of sulfur-containing gas-signaling molecules (H₂S and SO₂) during hydrolysis, with a radiodynamic effect, enabled by the ability of the cluster to generate singlet oxygen (¹O₂) under X-rays. The results of <i>in vitro</i> experiments confirmed significant cytostatic effects on cancer cells, while <i>in vivo</i> studies using Nu/J mice xenografted with HeLa tumors showed substantial tumor growth inhibition when the cluster was administered subcutaneously in combination with X-ray irradiation. Overall, the dual functionality of the cluster, along with the slow release and prolonged retention of the complex in tumor tissues, makes it a highly promising candidate for advanced cancer treatment strategies, particularly when integrated with conventional radiotherapy.