Advancing cancer therapy with heptamethine carbocyanine dye-conjugated radionuclide drug Malignant tumors pose substantial treatment challenges due to their heterogeneity, metastatic potential, and therapeutic resistance, underscoring the urgent need for more effective treatment options. This study developed and characterized a novel radionuclide drug conjugate (RDC) employing a tumor-targeting heptamethine carbocyanine dye (DZ) for its high specificity and favorable safety profile.