Four-year survival with nivolumab in patients with previously treated advanced non-small-cell lung cancer: a pooled analysis. - Antonia, Scott J; Borghaei, Hossein; Ramalingam, Suresh S; Horn, Leora; De Castro Carpeño, Javier; Pluzanski, Adam; Burgio, Marco A; Garassino, Marina; Chow, Laura Q M; Gettinger, Scott; Crinò, Lucio; Planchard, David; et al. (Lancet Oncology, 2019)