CD274 and cancer: Between 2015 and 2017, the number of clinical trials using PD-1 and PD-L1 inhibitors has increased nearly 600%, from 215 trials to more than 1500.4 The market is expected to grow similarly, from $1 billion dollars in 2013 to $7 billion dollars in 2020.5 However, despite growing interest in checkpoint inhibitors,6,7,8,9,10 empirical analyses have quantified the use of these drugs only in certain tumor types.11 To our knowledge, there has been no empirical analysis of the potential use or benefit among all US patients with cancer.