Our group and others have identified an association between increased nonsynonymous tumor mutation burden (TMB) and response in patients with melanoma treated with CTLA-4 blockade (Snyder et al., 2014, Van Allen et al., 2015), NSCLCs treated with PD-1 blockade (Carbone et al., 2017, Rizvi et al., 2015, Rizvi et al., 2018), mismatch repair deficient tumors treated with PD-1 blockade (Le et al., 2017), and bladder cancers treated with PD-L1 blockade (Rosenberg et al., 2016). The gene discussed is CTLA4; the disease is melanoma.