Scientists identify cause of resistance to ovarian and breast cancer drug

Scientists at the Institute of Cancer Research have identified a genetic mutation that causes cancer cells to become resistant to PARP inhibitors, such as olaparib, which are used to treat ovarian and breast cancers. 

This is a major discovery, as testing for this mutation could not only help to shape decisions on whether to begin treating the patient with PARP inhibitors, but also when to switch to alternative treatments.

PARP inhibitors are a relatively new type of drug, which are especially effective in women with BRCA mutations. However, over time, it is very common for cancer cells to develop resistance to these drugs. While women with ovarian cancer tend to respond well to initial treatment, the disease reoccurs in 70 – 90% of cases, making it very challenging to continue treating effectively. 

Study leader Professor Chris Lord, Professor of Cancer Genomics in the Breast Cancer Now Research Centre at the ICR, said:

“The evolution of cancers into drug resistant forms is a major challenge we face in getting cancer treatments to work. Studies like this can tell us how and why drug resistance occurs, and give us new ways of predicting the likely response to new-style targeted drugs.”

The researchers stress that further studies are now required to look for PARP1 mutations found in human patients, rather than those made artificially in the lab. 

However, it is exciting to think that in the future, this information could greatly improve patient survival by identifying the most appropriate treatment on a patient-specific basis. 

The research was funded by Cancer Research UK and Breast Cancer Now, and published in Nature Communications.