cadonilimab + S-1

Cadonilimab + S-1 is a combination therapy consisting of **cadonilimab**, a novel tetravalent bispecific antibody targeting both PD-1 and CTLA-4 immune checkpoints, and **S-1**, an oral fluoropyrimidine chemotherapy agent. Cadonilimab functions with an Fc-null design that provides higher binding avidity in environments with high-density PD-1 and CTLA-4 expression, the ability to simultaneously bind different cells expressing PD-1 and CTLA-4, minimal antibody-dependent cellular cytotoxicity and phagocytosis, and reduced pro-inflammatory cytokine release (IL-6/IL-8). This dual targeting approach aims to enhance anti-tumor immune responses by blocking two distinct immunosuppressive pathways. S-1 is an oral fluoropyrimidine that combines tegafur (a prodrug of 5-fluorouracil) with two modulators that improve its efficacy and reduce gastrointestinal toxicity. It works by inhibiting DNA synthesis in rapidly dividing cancer cells. This combination therapy is being investigated in clinical trials for various advanced cancers, particularly in gastrointestinal malignancies, aiming for potential synergistic effects.