Gene Test Predicts Chemotherapy Response in Breast Cancer Patients

A new study from Karolinska Institutet shows that gene analysis of breast cancer tumours can identify patients who do not benefit from chemotherapy given before surgery.

The findings, published in the journal Nature Communications, could in the long term contribute to more personalised treatment.

The study included 179 patients with hormone dependent, HER2 negative breast cancer who took part in the Swedish PREDIX LumB trial.

Before surgery, all patients received both treatments, but in different sequences. They were given either chemotherapy followed by hormone blocking therapy together with the drug palbociclib, which slows the division of cancer cells, or the reverse sequence.

When the researchers analysed the results, they found that the treatments led to similar reductions in tumour size overall. Survival was also similar regardless of whether treatment started with chemotherapy or with palbociclib and hormone blocking therapy.

Not all tumours responded to chemotherapy. At the same time, the analyses showed that there was a subgroup of tumours with a poorer response to chemotherapy but a better response to palbociclib in combination with hormone‑blocking therapy.

To understand why some tumours did not respond to chemotherapy, the researchers analysed tumour gene expression, how active different genes are in the tumour, in tissue samples taken before treatment started.

Based on these analyses, they developed a model called CDKPredX, which can identify tumours that respond poorly to chemotherapy but better to palbociclib combined with hormone blocking therapy.

“Today, we lack reliable ways to determine in advance which patients will actually benefit from chemotherapy before surgery,” said Alexios Matikas, a researcher involved in the study.

The study was conducted as part of the Swedish PREDIX LumB trial, which focuses on optimizing treatment sequences for breast cancer patients.