S7, a peptide antagonist of the IL-6 receptor, concentration-dependently inhibits IL-6 binding to its receptor. At 50 µM, S7 suppresses IL-6-triggered elevations in VEGF levels within C-33 A cervical cancer cells and RPMI-8226 B cell lymphocytes. It significantly reduces tumor volume in a C-33 A cervical cancer mouse xenograft model with IL-6 overexpression, following a dosage regimen of 50 mg/kg bi-daily. Moreover, when linked to cysteine on lipid nanoparticles (LNPs) encapsulating doxorubicin, S7 enhances glioma targeting and improves survival rates in a U251 glioblastoma mouse xenograft model.