摘要
Colorectal cancer(CRC)represents the second most common cancer in Europe with marked differences in prognosis and response to treatments.In the past years research showed emerging interest in genomic and immunologic fields.The clinical heterogeneity,that occurs during the pathogenesis of CRC,is driven by chromosomal alterations and defective function of DNA mismatch repair genes.CRC is classified in four consensus molecular subtypes(CMS)with different immunogenic characteristics and prognosis.CMS1 microsatellite instable(MSI)-like and CMS4,both characterized by high levels of immune infiltration,are recognized as the most immunogenic subtypes,even though functional characteristic leading to different prognosis are reported.In particular,MSI tumors have been identified as the best candidates for immunotherapy treatment and a number of studies have evaluated the efficacy of anti-programmed cell death ligand-1(PDL-1)and anti-cytotoxic T-lymphocyte-associated protein 4(CTLA4)in this setting.However,literature data show that the majority of patients with CRC have microsatellite stable(MSS)tumors and this status seems related to lower response to PDL-1/programmed cell death-1 or CTLA4 blockade.The aim of this paper is to investigate the role of immunotherapy in MSI and MSS CRC.
