New targeted drug shows benefit against breast cancer in first phase III trial
Image: False coloured scanning electron micrograph of a breast cancer cell from a cultured cell line. Credit: Anne Weston, Francis Crick Institute (CC BY-NC 4.0)
The first phase III trial to report findings on a new type of targeted medicine has produced remarkable results. A combination of the drug capivasertib and hormone therapy was effective for all 708 people in the international CAPItello-291 trial, many of whom had seen their cancer recur or progress following standard hormone treatments.
Outside of clinical trials, chemotherapy is currently the only effective option for these patients, but it can cause debilitating side effects. The trial was led by Professor Nicholas Turner, Professor of Molecular Oncology at the ICR and both Consultant Medical Oncologist and Head of the Ralph Lauren Centre for Breast Cancer Research at The Royal Marsden.
Capivasertib works by blocking the activity of a protein kinase called AKT, which stimulates cell growth. Including capivasertib in the treatment doubled the time it took for the participants’ cancer to progress, extending the median time to disease progression from 3.6 months to 7.2 months. In addition, the combined treatment led to tumour shrinkage in 23 per cent of the participants, compared with 12 per cent of those receiving hormone treatment plus a placebo.
All of the participants had locally advanced or metastatic breast cancer that was positive for oestrogen receptor (ER+) and low or negative for human epidermal growth factor receptor 2 (HER2). However, the treatment was most effective for the 41 per cent of people whose cancers also had genetic alterations to the AKT signalling pathway. These alterations can promote cancer and increase treatment resistance. Among these patients, those who received the combination treatment had a median progression-free survival of 7.3 months while 29 per cent saw their tumours shrink.
These results are particularly exciting because ICR research was fundamental to the discovery of capivasertib. The team behind the CAPItello-291 study is hopeful that capivasertib combined with hormone therapy will become a new treatment option for people with certain types of breast cancer.