Glaucoma Medicines Could Be Repurposed for Cancer

Scientists have uncovered weaknesses in some cancer cells that could make them susceptible to a group of drugs currently used to treat glaucoma.

The weaknesses have been found in breast cancer, melanoma and acute myeloid leukaemia, and the findings pave the way for future clinical trials of these drugs to treat a wide range of cancers.

When cancer cells spread around the body, they cause advanced disease that is hard to treat. These aggressive cells rely on a molecule called Rho kinase (ROCK).

Blocking ROCK

ROCK keeps the scaffolding of cells tense, making the cells contract and become round. In cancer cells, this generates force for the cells to squeeze through tissue.

A team from The Institute of Cancer Research, London, set out to find markers that could be used to identify which cancers would respond well to drugs that block ROCK – drugs which are already in use on the NHS to treat the eye condition, glaucoma.

In the eyes, the network of cells through which fluid drains is a mesh also controlled by ROCK – when the mesh is too tense and tightly packed, fluid builds up and causes pressure. ROCK inhibitors relax this mesh and enable fluid to drain.

The study received funding from The Institute of Cancer Research (ICR), which is a charity as well as a research institute, Breast Cancer Now, Barts Charity, Cancer Research UK, Worldwide Cancer Research, and UK Research and Innovation (UKRI).

Identifying the pattern in cells that respond

In research published in the journal iScience, the team, working in the Breast Cancer Now Toby Robins Research Centre at the ICR, used a publicly available drug sensitivity database. The database compiles previous studies of hundreds of cells from a wide range of cancers, stating how they respond to specific drugs.

All cancer types in the database had some cell populations that did respond to the inhibitors, and some that did not. The team analysed this data to identify patterns between the cells that responded to ROCK inhibitors. They then validated these patterns in experiments in the lab, in tumour samples from patients and in studies in mice.

In the database, epithelial solid tumours – such as breast cancer – that responded to ROCK inhibitors had a particular gene that was not working as it should, called E-Cadherin.

In non-epithelial solid tumours – such as melanoma – the database showed that cells that respond to ROCK inhibitors tend to have a more rounded shape, and high activity of a signalling pathway that drives tumour growth, spread and inflammation, called NFKB.

The team then tested whether similar markers would apply to blood cancers. In the database, acute myeloid leukaemia (AML) cells that responded well to ROCK had a specific subset of gene alterations.

In all tumour types, cancer cells that responded better to ROCK inhibitors were always the ones with more genes that regulate the cell’s identity and how it divides.

The researchers hope that, in the future, a biopsy of a patient’s cancer showing these specific genes, a rounded cell shape, or aggressive cells found within the invasive border area or the tumour, will indicate that ROCK inhibitors would work well for the patient. They hope that since these drugs are already used to treat glaucoma, clinical trials for patients with cancer can begin soon.

'A shared weakness of aggressive cancer cells'

Professor Victoria Sanz Moreno, Professor of Cancer Cell and Metastasis Biology at The Institute of Cancer Research, London and lead author, said:

“Some cancers are particularly aggressive, and once they spread they become very hard to treat. Catching these aggressive cancers and preventing their ability to move around the body is really crucial to our mission to keep more people living well with cancer.

“Our research has identified a shared weakness of aggressive cancer cells that could be targeted across many cancer types, wherever they originate in the body.

“We confirmed our findings in aggressive cancers such as breast cancer, melanoma, and a type of blood cancer called acute myeloid leukaemia, but we believe this molecular fingerprint of cancer cells likely to die after treatment applies to many more cancer types.

“It’s reassuring to know that a treatment already exists – a drug currently being used safely in some patients could be adapted to treat these cancers. This is a testament to discovery science, understanding the fundamental principles of the biology of a cancer cell and its ecosystem and how investing in that knowledge can ultimately translate into real benefits for patients.”

'A specific pattern of features'

Jaume Barcelo, Postdoctoral Research Fellow at The Institute of Cancer Research, London, now based at the Barts Cancer Institute at Queen Mary University of London, and first author of the study, said:

“While it’s been known that aggressive cancer cells may rely on the ROCK molecule, and successful drugs targeting ROCK are used to treat patients with other conditions, until now we haven’t known which cancer patients are likely to respond to the drugs.

“Our study has identified a specific pattern of features that is consistent across many cancer types, and that can be used to match the right patients to this treatment. 

“The next stage for this research will be to test how these drugs that inhibit ROCK work in combination with other treatments, to maximise the benefit for patients. As ROCK inhibitors are already approved to treat glaucoma, I hope that our findings can be used to progress the drugs into clinical trials to treat cancer in the near future.”

Dr Simon Vincent, chief scientific officer at Breast Cancer Now said: 

"With around 11,500 women tragically dying from breast cancer every year in the UK, research like this is vital to finding more effective treatment options. 

“This study helps to lay the foundation for understanding who among those with certain cancers, including breast cancer, might benefit most from existing drugs. Finding new uses for existing treatments, which we know people can safely take, is easier and faster than developing new cancer drugs from scratch.  

“It’s encouraging that these drugs may be especially effective in targeting cancer cells that are more likely to spread and resist treatment. 

"While this research is still at an early stage and clinical trials are needed, it’s an important step towards more personalised breast cancer treatments in the future." 

Reference: Barcelo J, Teigen Y, Martin JAJ, et al. Pan-cancer analysis reveals Rho kinase addiction as a vulnerability of de-differentiated cancer cells. iScience. 2026;29(6). doi: 10.1016/j.isci.2026.116031

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