Efficacy and safety results from IMblaze370, a randomised Phase III study comparing atezolizumab+cobimetinib and atezolizumab monotherapy vs regorafenib in chemotherapy-refractory metastatic colorectal cancer

Background: Patients with chemotherapy-refractory microsatellite stable (MSS) metastatic colorectal cancer (CRC) are a population with limited treatment options and relatively short survival. Atezolizumab (an anti–PD-L1 mAb) inhibits the binding of PD-L1 to its receptors PD-1 and B7.1, leading to the re-invigoration of tumour-specific T-cell immunity. Cobimetinib inhibits MEK1/MEK2 in the MAPK pathway, and blocking the MAPK pathway has been shown to favourably alter the tumour, tumour microenvironment and T-cell responses to promote anti-tumour immune activity.