Case Report: Two cases of pathologic complete response after upfront chemoimmunotherapy for initially unresectable gastric cancer.

Gastric cancer causes considerable morbidity and mortality. Chemoimmunotherapy has improved survival in the metastatic setting and pathologic complete response (pCR) for those with resectable disease. However, the ability of chemoimmunotherapy to convert locally advanced unresectable into resectable disease, or to lead to a pCR in this setting, is not known. Here we describe two cases of patients who were initially diagnosed with unresectable and incurable gastric cancer who, after receiving upfront chemoimmunotherapy, were converted to resectable disease, received curative surgery, and demonstrated a pCR. Both patients had microsatellite stable, HER2-negative gastric cancers with a combined positive PD-L1 score of greater than or equal to 10. Both experienced an immunotherapy-related adverse event and are currently on surveillance. These cases highlight the importance of reassessing candidacy for surgical resection among those with a good clinical response to upfront treatment, and the growing role of chemoimmunotherapy in the treatment of incurable and curable gastric cancer.