New targeted drug shows benefit against breast cancer in first phase III trial

A new type of targeted medicine has shown ‘remarkable’ benefits for patients with advanced breast cancer in a major phase III clinical trial. The drug capivasertib combined with hormone therapy doubled the time it took for cancer to progress in people with advanced forms of the most common type of breast cancer.

The findings, presented at the San Antonio Breast Cancer Symposium, establish capivasertib as a potential new treatment for people with oestrogen receptor (ER) positive, human epidermal growth factor receptor 2 (HER-2) negative breast cancer.

Capivasertib is a potential first-in-class drug that blocks activity of the cancer-driving protein molecule AKT. It was discovered by pharmaceutical company AstraZeneca following a programme of drug discovery research at The Institute of Cancer Research, London in collaboration with Astex Pharmaceuticals.

‘Effective across all patients treated in the trial’

The drug was found to be effective across all patients treated in the trial, including a group who had tumours with mutations in the AKT signalling pathway.

The international CAPItello-291 study is the first phase III trial of capivasertib to report findings and was led by researchers at The Institute of Cancer Research (ICR) and The Royal Marsden NHS Foundation Trust. It was sponsored and funded by AstraZeneca.

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The CAPItello-291 trial enrolled 708 women and men with an advanced form of ER-positive, HER-2 low or negative locally advanced or metastatic breast cancer.

Participants on the trial had seen their cancer recur or progress on standard hormone treatments, and the majority had also previously been treated with CDK4/6 inhibitors – drugs that block cancer cells from multiplying.

In current clinical practice, patients continue to receive fulvestrant hormone therapy, but this is often not effective, and many are left only with the option of chemotherapy, a treatment which can lead to debilitating side effects.

In the trial, adding capivasertib to fulvestrant hormone therapy doubled the median time to disease progression, from 3.6 months to 7.2 months. The treatment shrank tumours in 23 per cent of patients, compared with 12 per cent of patients who received fulvestrant hormone treatment plus a placebo.