Abstract
Immunomodulation treatment using anti-programmed cell death protein 1 antibody is a very promising treatment for various types of advanced cancers, including melanoma, non-small cell lung cancer, and renal cell carcinoma. However, the therapeutic effects on early cancers are still unknown. We experienced 2 cases of early gastric cancers coexisting advanced melanomas. In both cases, early gastric cancers did not respond to nivolumab. Both early gastric cancers did not express programed death ligand 1. It was speculated that immunotolerance was not fully established responsible for nivolumab in early gastric cancer, and for this reason, nivolumab could not shrink these tumors. We experienced 2 cases of early gastric cancer, where PD-L1 was negative, not responding to nivolumab.