This Breast Cancer Hijacks Immune Cells to Grow Its Own Nerve Supply

Doctors have known for years that many solid tumors contain dense networks of nerves. What they haven't known is how those nerves get there in the first place. A new study finds that one of the most aggressive forms of breast cancer recruits immune cells meant to fight it, and turns them into a tool that draws nerves into the tumor instead.

The Key Fact

KEY FACT
When researchers blocked BDNF signaling with a drug in mouse trials, nerves failed to infiltrate the tumor and its growth dropped significantly.

Why This Matters

Triple-negative breast cancer is one of the hardest breast cancer types to treat because it lacks the three receptors most standard therapies target: estrogen, progesterone and HER2. Treatment therefore relies mainly on chemotherapy and immunotherapy, with few other options, which makes any new therapeutic target valuable for patients who often run out of conventional treatments. This discovery offers a genuinely different target: rather than attacking the cancer cells themselves, it suggests cutting the chemical signal they use to recruit nerves that help them grow, resist treatment and potentially spread. It joins a broader picture emerging around how tumors reprogram immune or environmental elements around them in their own favor, similar to an earlier study showing how high blood sugar helps cancer cells build a sugary shield that hides them from the immune system. The finding carries extra weight because the team didn't stop at mouse experiments. They also analyzed data from real patients and found that tumors with higher levels of macrophages and BDNF were associated with worse survival, suggesting the same mechanism may hold true in humans, not just in lab models.

What Happened

Researcher Maureen Cox, an assistant professor of microbiology and immunology at the OU College of Medicine and a research member of OU Health Stephenson Cancer Center, led a team investigating how nerves enter tumors in the first place. They found that tumors recruit macrophages, immune cells that normally fight infection and help wounds heal, and convert them, once inside the tumor, into a source of brain-derived neurotrophic factor, or BDNF, a protein best known for helping nerve cells grow in the brain. Here, it acts as a chemical beacon that draws nearby nerves into the tumor rather than leaving it alone. Cox says macrophages, despite their normally beneficial role in the body, are performing a distinctly harmful function in this setting.

How It Works

To test the idea, the team used a drug already available on the market to block BDNF signaling in mouse models of triple-negative breast cancer. The blockade kept nerves from infiltrating the tumor, and its growth dropped significantly as a result. Cox suspects the nerves that do infiltrate tumors are immunosuppressive, meaning preventing their entry in the first place could give the immune system a better shot at attacking the tumor on its own, rather than relying solely on outside drugs to do the work. Other evidence suggests these nerves might also encourage the growth of blood vessels that feed the tumor oxygen and nutrients, or give cancer cells an actual physical route to crawl along and spread elsewhere in the body, two separate pathways Cox plans to test individually.

What Happens Next

Cox plans to further investigate the precise mechanism by which nerves help tumors grow, whether by stimulating blood vessel growth or enabling cancer cells to spread. Her team also intends to test the same intervention in high-grade ovarian cancer, another disease that is similarly difficult to treat and shares triple-negative breast cancer's shortage of good treatment options. Her stated goal is to reactivate the body's own anti-tumor immunity rather than relying solely on attacking the tumor from outside.

Takeaway

The discovery doesn't hand doctors a ready-made treatment, but it does reframe the target: instead of chasing the cancer cells themselves, it may be enough to cut the chemical signal those cells use to call in reinforcements from the nervous system, a shift that still needs an actual human trial to confirm.