Gastric cancer (GC) is the fourth leading cause of
cancer-related deaths worldwide. Under the
standard of care,
patients with advanced GC (AGC) have a median
survival time of approximately 12–15 months. With the emergence of
immunotherapy as a key
therapeutic strategy in
medical oncology, relevant changes are expected in the systemic
treatment of GC. In the phase III ATTRACTION-2 trial,
nivolumab, a monoclonal anti-
programmed cell death 1 (PD-1) antibody, as a third- or later-line
treatment improved overall
survival (OS) compared with placebo in
patients with AGC. Furthermore,
nivolumab in combination with
5-fluorouracil and
platinum as a first-line
treatment improved OS in
patients with
human epidermal growth factor receptor-2 (HER2)-negative AGC in the global phase III CheckMate-649 study. Another anti-PD-1 antibody, pembrolizumab, in combination with
trastuzumab and cytotoxic
chemotherapy as a first-line
treatment, significantly improved the overall response rate in
patients with HER2-positive AGC. Therefore,
immune checkpoint inhibitors (ICIs) are essential components of the current
treatment of GC. Subsequent
treatments after ICI combination
therapy, such as ICI rechallenge or combination
therapy with agents having other modes of action, are being actively investigated to date. On the basis of the success of
immunotherapy in the
treatment of AGC, various clinical trials are underway to apply this
therapeutic strategy in the perioperative and postoperative settings for
patients with early GC. This
review describes recent progress in
immunotherapy and potential
immunotherapy biomarkers for GC.