A study from the University of Oklahoma shows that triple-negative breast cancer cells recruit immune cells called macrophages to secrete a nerve-growth protein, drawing nerve fibres into the tumour and fuelling its growth — and pointing to existing drugs that might interrupt the process.
Cancer’s relationship with the nervous system has become one of oncology’s more unexpected growth areas over the past decade, and a new study from the University of Oklahoma College of Medicine and the OU Health Stephenson Cancer Center adds a significant piece to that picture. Published in the journal Cell Death & Differentiation and reported on 17 August 2026, the research shows that triple-negative breast cancer — an aggressive subtype that lacks the three receptors (oestrogen, progesterone and HER2) targeted by most breast cancer drugs, and which therefore has fewer treatment options — actively recruits nerve fibres into tumours by manipulating the immune system rather than acting directly.
How tumours “call” nerves
The mechanism the researchers describe works through macrophages, immune cells that normally help the body identify and destroy abnormal or infected cells. Within triple-negative breast tumours, cancer cells appear to reprogramme nearby macrophages into releasing brain-derived neurotrophic factor, or BDNF — a protein best known for supporting the growth and survival of neurons in the brain and peripheral nervous system. Released within the tumour microenvironment, BDNF acts as a chemical beacon that draws in nerve fibres, a process called axonogenesis. Growing evidence in tumour biology links nerve infiltration of this kind to more aggressive cancer behaviour, and the Oklahoma team’s mouse-model experiments support that link directly: when researchers blocked BDNF signalling pharmacologically, nerve growth into the tumours was prevented and tumour growth itself slowed significantly.
The human data reinforce the mouse findings. Examining patient tumour samples, the researchers found that higher levels of both macrophages and BDNF within a tumour correlated with worse survival outcomes, suggesting the mechanism identified in mice is operating — and mattering clinically — in human disease as well. “Macrophages are the critical source for drawing nerves into the tumor,” said Dr Maureen Cox, one of the study’s researchers, in comments accompanying the release. “Although macrophages typically play a positive role in the body, they are facilitating a negative function in this scenario of breast cancer.”
A potentially fast route to the clinic
What distinguishes this finding from many basic-science cancer discoveries is the existence of drugs that already block BDNF signalling for other medical uses, chiefly in neurological and psychiatric contexts. Because these compounds have already been through safety testing and, in some cases, regulatory approval for other indications, the path from laboratory finding to clinical trial in cancer patients is considerably shorter than it would be for a therapy requiring an entirely new drug. The Oklahoma team has indicated it intends to extend the work into high-grade ovarian cancer, another aggressive tumour type in which nerve infiltration and poor prognosis frequently co-occur, to test whether the same macrophage–BDNF mechanism is at work there too.
Part of a broader pattern in tumour biology
The Oklahoma findings sit within a rapidly expanding body of work on what researchers increasingly call the tumour microenvironment — the mix of immune cells, blood vessels, connective tissue and, now, nerve fibres that surrounds and actively supports a cancer’s growth, rather than simply providing inert physical space for it. Similar nerve-recruitment mechanisms have been documented separately in pancreatic cancer, where nerve density in and around tumours has been linked to pain severity and poorer prognosis, and in prostate cancer, where nerve infiltration has been associated with more aggressive, treatment-resistant disease. What the macrophage–BDNF pathway adds to this picture is a specific, targetable molecular link between the immune system’s normal wound-healing behaviour and a tumour’s ability to recruit its own nerve supply — reframing macrophages, cells usually studied for their role in fighting infection, as unwitting accomplices in tumour progression when their signalling is co-opted in this way.
Why it matters
Triple-negative breast cancer accounts for a disproportionate share of breast cancer deaths relative to its incidence, precisely because it does not respond to the hormone- and HER2-targeted therapies that have transformed outcomes for other subtypes over the past two decades; chemotherapy and, more recently, immunotherapy remain the main options. A therapeutic strategy that targets the tumour’s interaction with its surrounding nerve and immune environment — rather than the cancer cells directly — represents a genuinely different angle of attack, one that could in principle be combined with existing chemotherapy or immunotherapy regimens rather than replacing them. It also adds further weight to the emerging field of cancer neuroscience described above. The finding carries particular relevance for Indian oncology: triple-negative disease is reported in several Indian clinical studies to occur at a higher proportion of overall breast cancer cases than in Western populations, and India’s breast cancer burden — now the country’s most commonly diagnosed cancer among women — makes any credible new therapeutic lead for its hardest-to-treat subtype directly relevant to Indian patients and oncologists, not merely of academic interest.
The caveats are the standard ones for early-stage cancer biology: the core causal mechanism has been demonstrated robustly in mice and correlated with outcomes in human tissue samples, but no clinical trial testing BDNF-blocking drugs specifically in breast cancer patients has yet been reported. Repurposing an existing drug class still requires dedicated oncology trials to establish safe dosing, efficacy and interaction with standard treatment before it can change clinical practice. For a disease with limited treatment options, however, a plausible, mechanistically grounded and potentially fast-track therapeutic lead is a genuinely welcome development.
– Rithvisha Kiran
Key facts
– Mechanism: triple-negative breast cancer cells reprogramme macrophages to secrete BDNF, drawing nerve fibres into tumours (axonogenesis)
– Blocking BDNF signalling in mouse models prevented nerve growth and slowed tumour growth
– Higher tumour macrophage/BDNF levels correlated with poorer survival in patient samples
– Published in Cell Death & Differentiation; research from University of Oklahoma College of Medicine/OU Health Stephenson Cancer Center; reported 17 August 2026
