Efficacy of immunotherapy in patients with locally advanced colorectal cancer and microsatellite instability: a case series

AIM : to assess the efficacy of immunotherapy in patients with locally advanced CRC and MSI. PATIENTS AND METHODS: three clinical cases of patients with locally advanced colorectal cancer and microsatellite instability are presented. RESULTS: all three patients experienced major clinical and radiological improvement shortly after the start of ICI treatment. The third patient developed a 2nd degree immune-mediated pneumonitis that necessitated hormonal therapy and ICI termination. This patient got a subsequent laparoscopic right colectomy which proved complete pathomorphologic response. Recurrent-free survival since the beginning of ICI treatment is 54, 30 and 18 months, respectively. CONCLUSION: patients with locally advanced CRC and MSI even in case of unresectability may benefit greatly after immunotherapy. This makes it crucial to evaluate the presence of MSI in this patients.