Dual checkpoint blockade for microsatellite instability-high colorectal cancer
Metastatic colorectal cancer with microsatellite instability-high or mismatch repair-deficient status represents a distinct tumour subtype that accounts for around 5% of total colorectal cancer cases. Although standard chemotherapy has some efficacy in this subtype, immune checkpoint inhibition has shown promising activity, primarily due to the high tumour mutational burden and increased expression of tumour-specific neoantigens.1 Despite the progress of immunotherapy in microsatellite instability-high or mismatch repair-deficient colorectal cancer, only around 40% of patients have durable clinical responses with single-agent PD-1 blockade.