New research could pave the way for a targeted drug for lobular breast cancer

In new research published in Cancer Research, Professor Cathrin Brisken and her team found that a drug called a LOX inhibitor can slow the growth and spread of lobular breast cancer in the lab. 

The researchers, based at the Breast Cancer Now Toby Robins Research Centre at the Institute of Cancer Research, London, now hope to progress to clinical trials and develop a targeted treatment for lobular breast cancer. 

Invasive lobular breast cancer is a type of cancer that affects the cells of the lobules (milk-producing glands) of the breast. These cancers make up 15 out of every 100 breast cancers. Despite this, research into these cancers has historically been underfunded, and we know a lot less about them. 

Currently, there are no approved drugs that specifically target lobular breast cancer, and it is treated in much the same way as other types of breast cancer.  But we know that lobular tumours grow differently from other breast cancers, tend to spread differently, and have some distinct molecular features.

Lobular breast cancer is difficult to study in the lab, so Cathrin and her team used samples donated by people with lobular breast cancer to grow lobular tumours in mice. In doing so, they were able to accurately mimic the diversity of lobular tumours seen in people. 

Some lobular breast cancer cells also release an enzyme called LOX, which allows these cells to interact with surrounding proteins to increase tissue stiffness. And when this happens, it improves the ability of the cancer cells to grow and spread. 

In this study, they treated the tumours with a drug called a LOX inhibitor, which is already in early clinical trials for the treatment of a rare blood cancer called myelofibrosis. They found that lobular breast cancer cells rely on the same collagen fibres that contribute to myelofibrosis.

The drug was able to disrupt these interactions between lobular breast cancer cells and collagen fibres in their surrounding environment. Disrupting these interactions decreased tumour growth and spread. And the mice involved in the study tolerated the drug well, with minimal side effects.

Cathrin and her team also found increased activity in certain genes was closely linked to how well the tumour responded to the drug. In the future, this could be used to help doctors predict how people diagnosed with lobular breast cancer may respond to LOX inhibitor treatment.

Based on their findings, the researchers also think that high activity of the gene called JUN may help lobular breast cancers resist standard hormone therapy tamoxifen. The team believe that in the future, combining LOX inhibitors with standard hormone therapy currently used to treat lobular breast cancers could enhance the effectiveness of hormone therapy.

These exciting findings have the potential to make a big impact. And with future research, it could lead to the development of a new treatment that can specifically target lobular breast cancer. 

Because the team are proposing to repurpose a drug already being tested in clinical trials, we hope that this could accelerate its approval and provide a new treatment option for people living with lobular breast cancer.

And by creating models of lobular breast cancer in mice that more closely mimic the disease in people, this research has improved the tools we have to study lobular breast cancer, helping scientists around the world to better understand the disease.

This research comes at a very exciting time for us as we kickstart the lobular initiative, our new 5-year research programme into lobular breast cancer, which will invest £1 million in just the first year alone into this under funded research area.

We’re bringing together experts from across the Breast Cancer Now Toby Robins Research Centre at the Institute of Cancer Research, London, to find better treatments for lobular breast cancer.