How Lung Cancer Hijacks the Brain’s Own Wiring to Spread and Survive

When lung cancer spreads to the brain, it does something far more cunning than simply invading new territory. A comprehensive review published in Medical Oncology argues that the disease exploits the brain’s own neural and immune circuitry, turning the organ’s protective machinery into an accomplice of tumor growth. The review, led by Zhanhai Wei and Jingyi Zhou of Southeast University in Nanjing, together with colleagues, weaves together hundreds of studies into a single framework showing how tumor cells, neurons, glial cells, and immune elements engage in a dynamic, reciprocal dialogue that drives every stage of brain metastasis. The authors contend that understanding this neuro–immune–tumor network as an integrated system, rather than as separate neural or immune pathways, could finally unlock the therapeutic strategies that patients with lung cancer brain metastasis so desperately need.

Brain metastasis is one of the most feared complications of lung cancer. Both non–small cell lung cancer and small cell lung cancer have a pronounced tendency to seed the central nervous system, and once tumors establish themselves behind the blood–brain barrier, prognosis deteriorates sharply and treatment options narrow. Tyrosine kinase inhibitors and immune checkpoint inhibitors have improved outcomes for some patients, but the brain environment remains a formidable sanctuary where drugs penetrate poorly and immune responses are blunted. The review’s central premise is that this therapeutic failure is not accidental: the brain microenvironment actively reshapes itself around the tumor, and the tumor in turn reprograms the brain.

To organize this complexity, the authors adopt a stage-specific, spatiotemporal framework with three phases. The early phase centers on blood–brain barrier disruption and initial colonization, when circulating tumor cells arrive at the cerebral vasculature and begin negotiating their way into neural tissue. The intermediate phase involves extensive microenvironmental remodeling, during which immunosuppressive niches form and glial cells are co-opted. The late phase is characterized by stabilization, in which sustained neuro–tumor interactions lock the metastasis into a self-reinforcing state. This staging matters clinically, the authors argue, because each phase presents distinct therapeutic windows during which particular molecular hubs become vulnerable.

Among the most prominent pathways highlighted is the brain-derived neurotrophic factor, or BDNF, and its receptor TrkB. BDNF is normally a caretaker of neuronal survival and synaptic plasticity, but lung adenocarcinomas that express the full-length TrkB variant have been associated with brain metastasis, and BDNF levels correlate with immune infiltration patterns in lung adenocarcinoma. In effect, tumor cells appear to borrow the brain’s own survival signals. Related work in other cancers reinforces the pattern: pancreatic cancer models have revealed a feedforward loop in which β2-adrenergic signaling stimulates neurotrophin production, and TNF receptor 2 signaling has been shown to elevate BDNF in a TrkB-dependent manner. The review prioritizes BDNF–TrkB signaling as a hub molecule with emerging translational relevance, while candidly noting that direct validation in lung cancer brain metastasis models remains limited for some branches of this axis.

Adrenergic signaling forms a second major pillar. Stress hormones such as norepinephrine and epinephrine, acting through β2-adrenergic receptors, have long been implicated in lung cancer biology, influencing vascular endothelial growth factor signaling and cooperating with nicotinic acetylcholine receptors in ways that promote tumor progression. Because beta-blockers are already widely used in cardiovascular medicine, the β-adrenergic pathway represents one of the most immediately druggable nodes in the neuro–immune–tumor network. The review suggests that repurposing efforts and carefully designed clinical trials could test whether adrenergic modulation, alone or in combination with existing oncology regimens, might slow the establishment or progression of brain lesions.

Glial cells emerge as perhaps the most versatile players in the story. Astrocytes, the star-shaped support cells that maintain the blood–brain barrier and regulate neurotransmitter levels, can be subverted by tumor cells through several mechanisms. One landmark finding summarized in the review involves carcinoma–astrocyte gap junctions, through which tumor cells transfer the second messenger cGAMP into astrocytes, triggering interferon and TNF-α signaling that supports tumor survival and chemotherapy resistance. In lung cancer specifically, astrocyte-derived interleukin-11 has been shown to upregulate PD-L1 on EGFR-mutated tumor cells, promoting immune escape, while astrocyte-induced activation of metabotropic glutamate receptor 1 stabilizes EGFR signaling in metastatic cells. Small cell lung cancer, meanwhile, appears to mimic brain developmental programs in its dialogue with astrocytes, and has even been shown to form functional synapses with neurons, a finding that underscores how deeply tumor cells can integrate into neural circuitry.

Microglia, the brain’s resident immune cells, occupy an ambivalent position in this network. On one hand, they can polarize toward an immunosuppressive, tumor-supporting state: lung cancer-derived exosomal cargo, including the long non-coding RNA LINC00482 and specific microRNAs, has been shown to drive M2-like microglial polarization that facilitates metastasis, and nicotine exposure can suppress innate immune function through microglial reprogramming. On the other hand, studies in breast cancer models have demonstrated that microglia can also promote anti-tumor immunity and suppress brain metastasis, suggesting that these cells are not inherently pro-tumor but rather context-dependent arbiters whose behavior is shaped by the signals they receive. The review emphasizes that flipping microglial polarization back toward an anti-tumor state, for example by targeting the HSP47–collagen axis, has already shown promise in preclinical work by restoring anti-tumor immunity.

Neurotransmitters themselves are conscripted into the metastatic program. Glutamate, the brain’s principal excitatory transmitter, has been linked to metabolic adaptation in lung cancer: dysregulation of the glutamate transporter SLC1A1 propels cystine uptake for glutathione synthesis, buffering tumor cells against oxidative stress, and glutamate can blunt the cell-killing activity of neutrophils in the tumor microenvironment. GABA signaling has been implicated in the metabolic reprogramming that supports brain metastasis in non–small cell lung cancer, while serotonin receptor 3C has been proposed as a prognostic biomarker in lung cancer. Dopamine signaling adds further nuance, with dopamine receptor D1 activity suppressing proliferation, EGFR activation, and PD-L1 expression in lung cancer cells, and the truncated DARPP-32 isoform promoting resistance to molecular targeted therapy in EGFR-mutated adenocarcinoma. Each of these transmitter systems represents a potential pharmacological handle, and several corresponding drugs already exist for neuropsychiatric indications.

The translational implications extend beyond individual drug targets to the design of clinical trials and biomarkers. The authors argue that because the neuro–immune–tumor network is context-dependent, with hub molecules varying by disease stage, histological subtype, and driver mutation, future studies should pursue combinatorial strategies that pair neural modulation with immune modulation. They also highlight the growing power of single-cell and spatial transcriptomics, which have begun to map the cellular architecture of lung cancer brain metastases in unprecedented detail, revealing distinct tumor architectures, immune landscapes, and region-specific plasticity. Such datasets, combined with organoid models and CRISPR-based screening platforms, could identify which patients are most likely to benefit from targeting specific neuro–immune axes, and could define biomarkers such as BDNF levels, serotonin receptor expression, or microglial polarization signatures to guide treatment selection.

What makes this review particularly striking is its intellectual honesty. The authors repeatedly acknowledge that direct validation in lung cancer brain metastasis remains limited for several of the pathways they discuss, and that much of the supporting evidence derives from related cancers or from in vitro and animal models. Yet the convergence of evidence across tumor types, from glioblastoma’s remodeling of neural circuits to breast cancer’s exploitation of neural signaling for meningeal spread, suggests that the principles are general even when the molecular details differ. If the framework holds up under clinical scrutiny, the implications are profound: the brain would no longer be viewed as a passive battlefield where lung cancer metastases simply hide from therapy, but as an active participant whose neural signals and immune architecture can be therapeutically redirected. In that vision, drugs that quiet stress signaling, block aberrant neurotrophic loops, reprogram glial cells, and restore immune surveillance could be combined with existing targeted and immunotherapies to finally turn the tide against one of cancer’s most devastating complications.

Subject of Research: Neuro–immune crosstalk mechanisms driving lung cancer brain metastasis and their therapeutic targeting

Article Title: Neuro–immune crosstalk in lung cancer brain metastasis: mechanisms, therapeutic targets, and translational opportunities

Article References: Wei, Z., Zhou, J., Mo, W., & Zhang, H. (2026). Neuro–immune crosstalk in lung cancer brain metastasis: mechanisms, therapeutic targets, and translational opportunities. Medical Oncology, 43(10), Article 260. https://doi.org/10.1007/s12032-026-03366-8

Image Credits: AI Generated

DOI: 10.1007/s12032-026-03366-8

Keywords: lung cancer, brain metastasis, neuro–immune crosstalk, BDNF–TrkB signaling, adrenergic signaling, astrocytes, microglia, neurotransmitters, tumor microenvironment, immunosuppression, therapeutic targets, translational oncology