Nat. Rev. Clin. Oncol. 12, 621 (2015); published online 13 October 2015; 10.1038/nrclinonc.2015.178

In the version of this article originally published online and in print, nivolumab was incorrectly stated as targeting programmed cell death 1 ligand 1 (PD-L1), rather than programmed cell death protein 1 (PD-1). This error has now been corrected in the online HTML and PDF versions of the article.