New Drug Shows Promise for Hard-to-Treat Breast Cancer

Scientists have discovered that an existing drug could offer new hope for people living with lobular breast cancer, a type that's been overlooked for too long.

Researchers at The Institute of Cancer Research in London tested a drug called a LOX inhibitor on lobular breast cancer tumors grown in mice. The results were encouraging: the drug slowed both tumor growth and spread, and the mice tolerated it well with minimal side effects.

Lobular breast cancer makes up 15 out of every 100 breast cancer cases, but it's particularly tricky to treat. Unlike other breast cancers that form distinct masses, lobular tumors infiltrate surrounding tissue in single-file lines of cells. This makes them nearly invisible on clinical imaging and hard to measure, which means patients are often excluded from clinical trials.

Right now, there are no approved drugs specifically targeting this disease. Patients receive the same treatments as those with other breast cancers, even though lobular tumors grow and spread differently.

The research team discovered that lobular breast cancer cells release an enzyme called LOX, which stiffens surrounding tissue and helps cancer cells grow and spread. The cells travel along collagen fibers like highways, using them to move through the body.

The LOX inhibitor drug disrupts this process by blocking the interaction between cancer cells and those supportive collagen fibers. What makes this particularly exciting is that the drug is already in early clinical trials for a rare blood cancer called myelofibrosis, which could speed up its path to helping breast cancer patients.

The team also found that combining the LOX inhibitor with standard hormone therapy like tamoxifen could make existing treatments work better. They identified a gene called JUN that may help predict which patients will respond best to the drug.

Creating accurate models of lobular breast cancer has been challenging, but this team succeeded by placing tumor cells inside mouse milk ducts. This breakthrough gives scientists worldwide better tools to study the disease.

The Ripple Effect

Almost 20 years ago, researchers at the same institute discovered that the LOX enzyme drives cancer spread. In 2017, another team there designed the first drug to target it. Now, this latest research brings that decades-long effort full circle, potentially opening doors for thousands of patients.

Professor Cathrin Brisken, who leads the research team, acknowledges the long road ahead but remains optimistic. Her team is currently applying for funding to launch a clinical trial with 91 patients.

Dr. Renee Flaherty, who worked on the study, says the lobular breast cancer research community and patient advocates have driven her throughout this challenging work. Their dedication and patience are finally yielding results.

After years of being difficult to see, difficult to study, and difficult to treat, lobular breast cancer is finally getting the attention it deserves.