Efficacy of anti‐PD1 therapy in extranodal NK/T cell lymphoma: A matched cohort analysis from the LYSA - Amira Marouf; Sammara Chaubard; Raphaël Liévin; Jean‐Marie Michot; Nicolas Molinari; Julien Rossignol; Doriane Cavalieri; Camille Golfier; Olivier Allangba; Laure Philippe; Benoît Tessoulin; Adrien Chauchet; et al. (HemaSphere)