New Antibody Slows Triple-Negative Breast Cancer Growth

Researchers at a leading cancer institute have developed an experimental antibody that targets triple-negative breast cancer, one of the deadliest forms of the disease. The antibody homes in on a specific protein on cancer cells, halting tumor growth and reactivating the body's immune defenses. These findings come from lab and animal tests conducted over the past year, with results shared this week.

Background

Triple-negative breast cancer makes up about 15 percent of all breast cancer cases. It lacks the three main receptors found in other types: estrogen, progesterone, and HER2. Without these targets, standard hormone therapies and HER2 drugs do not work. Patients often face rapid tumor growth, early spread to other organs like the lungs, and low survival rates. For those with metastatic disease, the five-year survival stands at just 12 percent.

This cancer hits younger women more often and women of African or Hispanic descent at higher rates. Treatment usually starts with chemotherapy, but many tumors resist it or return stronger. Doctors have turned to immunotherapy in recent years, using drugs like pembrolizumab to help the immune system spot and attack cancer cells. Still, not all patients respond, and the disease progresses quickly in many cases.

Over the last five years, new tools called antibody-drug conjugates have entered the picture. These are antibodies linked to chemotherapy drugs that deliver the poison directly to cancer cells. One such drug, sacituzumab govitecan, targets a protein called TROP-2, which sits on the surface of triple-negative cancer cells. Approved for later-stage use, it has helped thousands of patients worldwide. Now, work focuses on newer antibodies to attack TROP-2 even better and combine them with immune drugs from the start.

Key Details

The new antibody binds tightly to TROP-2, a protein that fuels fast cell division in tumors and helps cancer hide from immune cells. By blocking TROP-2, the antibody stops this growth signal and removes the shield, letting white blood cells swarm the tumor.

In lab dishes with human triple-negative cancer cells, the antibody shrank tumors that ignored standard chemo. When tested in mice with implanted human tumors, it slowed growth by half compared to untreated animals. Lung metastases, common in this cancer, dropped sharply—fewer spots formed, and existing ones shrank.

Tests on Resistant Cells

A big challenge with triple-negative cancer is resistance. Cells that survive initial chemo often spread faster. The antibody destroyed these tough cells in tests. It worked alone but paired well with existing immune drugs, clearing more tumors without extra side effects in animals.

Researchers grew tumors from patient samples in the lab. The antibody hit cells from different patients, suggesting broad action. No signs of harm to healthy cells appeared, as TROP-2 levels stay low there.

"This antibody turns the immune system back on against tumors that have learned to evade it," said Dr. Sara Tolaney, a breast cancer specialist who reviewed similar work. "Early results point to a real chance to improve survival."

Teams plan human trials soon, building on phase 3 data from related drugs. Sacituzumab govitecan with pembrolizumab already beat chemo in advanced patients, with progression-free survival of 11.2 months versus 7.8 months. Nearly 60 percent responded, and responses lasted 16.6 months on average.

What This Means

If human trials confirm these results, the antibody could move to first-line treatment for metastatic cases, especially those testing positive for PD-L1, a marker that predicts immune drug response. Right now, half of patients on standard chemo never reach second-line options like sacituzumab govitecan. Starting with this combo upfront could let more people benefit longer.

For early-stage patients, it might pair with neoadjuvant chemo to boost cure rates. Current standards mix chemo and immunotherapy, but over a third do not respond fully. Adding a TROP-2 blocker could fill that gap.

Broader use might cut reliance on harsh chemo alone. Antibody-drug conjugates like this one carry less chemo to the body, reducing nausea, hair loss, and fatigue for some. Over 60,000 breast cancer patients have used similar drugs safely across 50 countries.

Drug makers eye this as a backbone therapy. Other TROP-2 agents, like sacituzumab tirumotecan, test in trials at places like UCSF. One study checks it alone or with pembrolizumab against chemo. Another pairs avelumab with sacituzumab govitecan for inoperable tumors.

Patients with PD-L1-positive metastatic cancer stand to gain most first. Regulators may approve combos based on recent phase 3 wins, published in top journals. Survival gains could shift how doctors treat this fast-moving disease from day one.

Long-term, better tools mean fewer recurrences. Women facing diagnosis get more time with family and less fear of spread. Research now tests these in hormone-positive cancers too, expanding reach.