New Clones on the Block

Although immune checkpoint blockade (ICB) has yielded striking clinical responses in subsets of cancer patients, the mechanism of action is still unclear. In a recent issue of Nature Medicine, Yost et al., 2019 report that the T cell clones that dominate the intra-tumoral T cell landscape after ICB are distinct from those prior to treatment, a phenomenon referred to by the authors as “clonal replacement.”