Durable response of immune checkpoint inhibitor for a patient with advanced gastric adenosquamous carcinoma

Gastric adenosquamous carcinoma (GASC) is an extremely rare malignancy of the stomach. It is generally diagnosed at an advanced stage and is associated with a poor prognosis. Notably, the standard treatments for GASC remain undetermined because of the condition's rarity. In this report, we present a patient diagnosed with advanced GASC with positive predictive biomarkers for immune checkpoint inhibitors (ICIs), who achieved a durable response through nivolumab monotherapy. We also review and discuss the management of GASC and possible roles of ICIs in gastric cancers.