Immunotherapy in NK/T-Cell Lymphoma: Mechanisms, Clinical Evidence, Resistance, and Emerging Multimodal Strategies

Natural killer/T-cell lymphoma (NKTCL) is a rare and aggressive Epstein–Barr virus (EBV)-associated lymphoma characterized by intrinsic chemoresistance and an immunosuppressive tumor immune microenvironment (TIME). EBV-driven immune dysregulation provides a biological rationale for immunotherapy. This review summarizes current advances in immunotherapeutic strategies for NKTCL, integrating molecular mechanisms, clinical evidence, and resistance mechanisms within the context of TIME remodeling and immune reprogramming. We synthesize evidence from clinical trials, translational studies, and preclinical investigations evaluating immune checkpoint inhibitors, antibody-based therapies, adoptive cellular therapies, immune engagers, EBV-directed immunotherapies, and multimodal combination strategies in NKTCL. Among these strategies, PD-1/PD-L1 inhibitors are the most extensively studied immunotherapies in NKTCL and demonstrate clinically meaningful activity across different clinical settings. However, therapeutic responses remain heterogeneous, and primary or acquired resistance is common, driven by EBV-associated immune suppression, defective antigen presentation, metabolic reprogramming, and multi-checkpoint co-expression. Beyond immune checkpoint blockade, emerging approaches—including dual-checkpoint inhibition, epigenetic and metabolic combinations, antibody–drug conjugates, EBV-specific cytotoxic T lymphocytes, chimeric antigen receptor (CAR)-based platforms, immune engagers, and EBV vaccines—have shown encouraging signals in early-phase studies. Increasing evidence also supports multimodal strategies integrating immunotherapy with radiotherapy and other immune-modulatory interventions to enhance immune reprogramming and improve response durability. Overall, immunotherapy has substantially expanded the therapeutic landscape of NKTCL but remains constrained by complex EBV–TIME interactions and interpatient heterogeneity. Future progress will rely on biologically informed patient stratification, rational multimodal combination strategies, and integration of innovative immune platforms to establish a durable, immune-reprogramming-centered treatment paradigm for EBV-driven NKTCL.