Pharmacogenetics

Using genetic information to predict effectiveness of breat cancer treatment

Overview

Our researchers have been studying the effects of genetic changes in how women respond to certain drugs used to treat breast cancer. It has been found that genetic changes in a particular gene can indicate if women are less likely to respond to a hormone treatment called tamoxifen, the most important treatment for breast cancer over the past 30 years.

Problem

Tamoxifen is one of the most widely used and effective treatments for women with breast cancer. However up to a third of women do not respond to this medication. It has been found that variants in the CYP2D6 gene have been shown to affect how tamoxifen is converted to its active metabolite called endoxifen.

More recently a different type of hormonal treatment for breast cancer called aromatase inhibitors have increased in use instead of tamoxifen.

What we have achieved to date

We are keen to use genetic information to work out whether tamoxifen or aromatase inhibitors will be the most effective for individual women to treat their breast cancer.

Variants in the CYP2D6 gene have been shown to affect how tamoxifen is converted to it’s active metabolite called endoxifen. Our researchers have worked alongside colleagues in Dundee to study the relationship between carrying variants in the gene and taking other medications including serotonin reuptake inhibitors, commonly prescribed to patients with breast cancer and adherence.

Our data indicates that individuals predicted to have reduced CYP2D6 activity either due to genetic variants in CYP2D6 or through co-medication are less likely to respond to tamoxifen treatment.

Over the past three years multiple studies have been reported in this complex area, but at the moment it is still unclear how strong the relationship between these genetic variants and tamoxifen is. We are working with an international consortium to try to unravel the pharmacogenetics of tamoxifen.

What we aim to achieve

Our recent research funded by The Breast Cancer Research Campaign has identified variants in the aromatase gene which may be important in predicting which patients respond to aromatase inhibitors. We hope to develop this work to establish the most effective treatment regimens for patients with breast cancer.

We have also developed genetic testing services available to doctors treating patients with different types of cancer to ensure that they can choose the most effective treatments.