Schematic depiction of the proposed mechanisms of anti-PD-1 failure and efficacy of dual epigenetic targeting in R/R cHL. Simplified schematic depiction of selected key correlates of failure with DP as well as response to CDP treatment or R/R HL reported in the study by Nie and coauthors. cHL, classical Hodgkin lymphoma; FasL, Fas ligand; NK natural killer; PD-L1, programmed death protein 1 ligand 1.