CD274 and neoplasm: Pembrolizumab has also been approved in the US for patients with unresectable or metastatic, microsatellite instability-high (MSI-H) or mismatch repair-deficient (MMR) solid tumours, regardless of tumour site or histology, and Dr Rubin went on to consider whether PD-L1 inhibition could be attributed to the MSI-H phenotype, with data from ASCO 2015 [10] showing high rates of durable response in noncolorectal cancers with MMR deficiency.