Fig. 1. ‘Inside-out’ (serosa-to-mucosa) regression pattern of response seen in patients with colon and rectal cancer receiving botensilimab plus balstilimab in the neoadjuvant setting.

As shown, compared to traditional responses seen with chemotherapy, targeted therapy and/or radiation, the residual proportion of the tumor cells are all confined to the luminal surface with immunotherapy. This can be best described as a wave or tsunami of immune cells infiltration and subsequent cancer cell death.