Patient tumor bulk RNA-seq analysis of the pre-axi-cel treatment tumor microenvironment in large B cell lymphoma

We examined the tumor immune infiltrate and its relationship with clinical outcomes in patients with LBCL receiving Axicabtagene ciloleChimeric antigen receptor (CAR) T cell therapies have revolutionized B cell malignancy treatment, but many patients with large B cell lymphoma (LBCL) experience primary resistance or relapse. To uncover resistance mechanisms, we examined pre-infusion tumor biopsies and observed that increased immunoregulatory macrophages correlate with poor clinical responses. In murine models, CAR T cell-produced interferon-gamma (IFN-) upregulates inducible nitric oxide synthase (iNOS, NOS2) in immunoregulatory macrophages, impairing CAR T cell function. Proteomic profiling revealed that iNOS-expressing macrophages promote apoptosis and cell cycle arrest while downregulating protein synthesis machinery in CAR T cells. Metabolically, CAR T cells exhibit reduced glycolytic intermediates and altered tricarboxylic acid (TCA) cycle activity. Pharmacological inhibition of iNOS enhances CAR T cell treatment efficacy in vivo. Notably, elevated levels of iNOS+CD14+ monocytes in leukaphereses are associated with non-durable responses to CAR T cells. Targeting iNOS in immunoregulatory macrophages, potentially by modulating CAR T-produced IFN-, could improve LBCL outcomes.