B Cells and Tumor Immunometabolism: Emerging Insights into Immune Regulation and Therapeutic Resistance.

Cancer progression and therapeutic resistance are shaped by reciprocal dynamic interactions between malignant cells and the metabolically altered tumor microenvironment (TME). Tumor-associated hypoxia, glucose and amino acid competition, extracellular acidity, lactate accumulation, adenosine, prostaglandin E2 (PGE2) and other metabolic signals can remodel immune cell function and determine whether inflammation is tumoricidal or tumor-supportive. Although B lymphocytes have traditionally been viewed as antibody-producing cells, tumor-infiltrating B (TIL-B) cells comprise functionally heterogeneous populations that can act as antigen-presenting cells, cytokine and chemokine producers, antibody-secreting cells, cytotoxic effectors, regulatory B cells (Bregs) and organizers of tertiary lymphoid structures (TLSs). Their functional state is strongly influenced by the metabolic and spatial context in which they reside. This review focuses on the intersection of B cell biology and tumor immunometabolism, emphasizing how hypoxia, lactate, nutrient limitation, adenosine, PGE2, kynurenine and B cell-derived γ-aminobutyric acid (GABA) may shape B cell states and their interactions with myeloid and lymphoid cells. We discuss how metabolically conditioned Bregs and immunoglobulin (Ig)A-skewed humoral responses can contribute to immune suppression, whereas metabolically competent antigen-presenting, IgG-biased and TLS-associated B cell responses may support effective anti-tumor immunity. Importantly, the effects are tumor type- and context-dependent: B cell/TLS signatures are associated with favorable outcomes in several breast, lung and other solid tumors, whereas B cell-centered immune landscapes can be suppressed or neutral in pancreatic cancer and IgA-dominated responses may be unfavorable in selected malignancies. We further examine how these states may influence sensitivity or resistance to immune checkpoint blockade, chemotherapy, radiotherapy and cellular therapies. Finally, we highlight B cell metabolic pathways as potential therapeutic entry points and identify priorities for spatial metabolomics and prospective interventional studies.