Nicotinamide mononucleotide potentiates the anti-tumor efficacy of CAR-NK cell therapy targeting MSLN in ovarian cancer.

Chimeric antigen receptor-engineered NK cells targeting mesothelin (MSLN CAR-NK) have emerged as promising off-the-shelf immunotherapeutics for multiple malignancies. However, their clinical translation remains constrained by inefficient cytotoxic potency and limited persistence. This study investigated the therapeutic potential of nicotinamide mononucleotide (NMN), a metabolic modulator known to enhance immune cell functionality, in augmenting MSLN CAR-NK cell efficacy against ovarian cancer (OC). Through systematic evaluation, we found that NMN supplementation significantly enhanced CAR-NK cell activation marker expression (CD69, NKG2D), degranulation capacity (CD107a+ increased by 21.7 ± 1.1%), and cytokine production (IFN-γ elevated 1.3-fold). In addition, NMN treatment potentiated MSLN CAR-NK cell-mediated cytotoxicity against MSLN+ target cells, achieving 32.8 ± 1.4% specific lysis at an effector-to-target ratio of 25:1, while concurrently reducing cellular apoptosis compared with controls. Mechanistic interrogation via transcriptomic profiling revealed NMN-mediated modulation of PLC-γ phosphorylation cascades and mitochondrial redox homeostasis. Notably, NMN effectively counteracted tumor microenvironment-induced mitochondrial ROS accumulation (reduced by 25.1 ± 0.8% in OC-conditioned medium). Critically, in an OVCAR8-MSLN xenograft model, adoptive transfer of NMN-preconditioned CAR-NK cells led to superior tumor control, reduced proliferation (Ki67), diminished angiogenesis (CD31), and enhanced intratumoral CAR-NK infiltration compared with controls. These findings establish NMN as a clinically relevant adjuvant that augments CAR-NK cell efficacy through dual mechanisms: metabolic enhancement of effector functions and protection against microenvironmental oxidative suppression, thereby offering a translatable strategy to improve CAR-NK therapy for ovarian cancer.