Cancer Immunotherapy Trials Not Immune from Imprecise Selection of Patients

Arguably, no drug class has more radically and rapidly altered the management of non–small-cell lung cancer (NSCLC) than inhibitors of the interaction between programmed death 1 (PD-1) and its ligand PD-L1. By impeding this negative regulatory signal for T-cell response, PD-1 and PD-L1 inhibitors result in longer survival than does chemotherapy among patients with previously treated NSCLC.¹⁴ In this issue of the Journal, Carbone and colleagues report on a trial that compared the PD-1 inhibitor nivolumab with chemotherapy as first-line treatment for advanced NSCLC in a population of patients selected on the basis of PD-L1 expression level.⁵ Progression-free survival . . .