A drug used to treat lung cancer could offer a new targeted therapy for thousands of breast cancer patients, research has shown.
Institute of Cancer Research scientists have established that lung cancer drug crizotinib can kill breast cancer cells that have a particular genetic defect.
Estimates show roughly 7,150 women in the UK are diagnosed every year with breast tumours that are E-cadherin defective.
However, there are not any current treatments which target the E-cadherin-defective breast tumours specifically and there is very little known about what weaknesses exist in these types of cancer cell.
E-cadherin defects occur in more than 13% of all breast cancer cases, and are seen in up to 90% of all lobular breast cancers, which occur in the areas of the breast that produce milk.
The new research, which is published in the journal Cancer Discovery, saw scientists test 80 small-molecule inhibitors to see if any of these drugs caused cancer cells with a defective E-cadherin gene to die.
They used synthetic lethality, which exploits two key genes that cancer cells need to survive. Where one of these two genes does not function properly due to a mutation, blocking the other with a drug has a synthetic lethal effect, causing the cancer cell to die.
They found the most significant synthetic lethality was demonstrated by crizotinib, one of a class of drugs known as ROS1 inhibitors, which killed the E-cadherin defective breast tumour cells and left normal cells relatively unaffected.
A second phase trial is now ongoing on the treatment and researchers hope it will become the second targeted breast cancer drug to use synthetic lethality.