Immune Therapeutics in the Treatment of Advanced Gastric and Esophageal Cancer

Systemic chemotherapy is the mainstay of therapy in patients with advanced gastric and esophageal cancer, but has multiple drawbacks including lack of durable efficacy and dose limited toxicities. Recent clinical trials data on the efficacy of immune therapy in this patient group have shed light on its potential as an alternative treatment option. Checkpoint inhibitors, specifically the anti-PD-1/PD-L1 inhibitors, seem to be beneficial for a subgroup of patients with advanced gastric or esophageal cancer who have progressed on multiple systemic chemotherapies. As clinical trials results mature, it will become apparent whether checkpoint inhibitors are effective in other treatment settings such as in first-line therapy or adjuvant therapy. Although the toxicity of checkpoint inhibitors is generally unpredictable, they tend to be more manageable and better tolerated than the toxicities of systemic chemotherapy. Furthermore, recent research in molecular subtyping of esophageal and gastric cancer are paving way for better treatment response prediction and patient selection for checkpoint inhibitor therapies. Compared to checkpoint inhibitors, other types of immune therapies such as cancer vaccines, and adoptive cell therapies have yet to be proven effective in esophageal and gastric cancer and are further away from clinical use. Immune therapy seems poised to take a firm position as part of the therapeutic armamentarium for advanced gastric and esophageal cancer and future clinical trials will show the extent of its application in different treatment settings in this patient population.