Clinical case of the neoadjuvant treatment with nivolumab in a patient with microsatellite unstable (MSI-H) locally advanced gastric cancer.

Locally advanced gastric cancer (GC) is often managed by neoadjuvant chemotherapy and surgery; however, pathological complete responses to preoperative systemic treatment are rare. Some GCs are characterised by high-level microsatellite instability (MSI-H) and therefore are potentially sensitive to anti-PD1 (the programmed death 1) therapy. Neoadjuvant immune checkpoint blockade demonstrated promising results in a number of trials involving various categories of patients with cancer; therefore, we considered feasible to offer preoperative nivolumab to a patient with T3N1M0 MSI-H GC. The patient experienced a reduction of the tumour size and the analysis of surgical material revealed complete elimination of tumour cells. MSI-H status deserves to be considered in future trials on patients with GC.