HIGH RESPONSE RATES WITH PEMBROLIZUMAB IN COMBINATION WITH RITUXIMAB IN PATIENTS WITH RELAPSED FOLLICULAR LYMPHOMA: INTERIM RESULTS OF AN ON OPEN‐LABEL, PHASE II STUDY. (June 2017) - Nastoupil, L.J.; Westin, J.; Fowler, N.; Fanale, M.; Samaniego, F.; Oki, Y.; Obi, C.; Cao, J.; Cheng, X.; Ma, M.; Wang, Z.; Chu, F.; et al.