Safety and antitumor activity of the anti-PD-1 antibody pembrolizumab in patients with recurrent carcinoma of the anal canal. - Ott, P. A.; Piha-Paul, S. A.; Munster, P.; Pishvaian, M. J.; van Brummelen, E. M. J.; Cohen, R. B.; Gomez-Roca, C.; Ejadi, S.; Stein, M.; Chan, E.; Simonelli, M.; Morosky, A.; et al. (Annals of Oncology, 2017)