PALOMA-3: Drug combination extends breast cancer control

Using a new drug in combination with a standard hormone treatment delays the progression of advanced breast cancer by more than twice as long as the standard treatment alone, a major clinical trial has found

"This new drug combination delayed the progression of the most common type of breast cancer by an average of five extra months"

Dr Nicholas Turner

The PALOMA-3 Phase III trial found that, in women with the most common form of breast cancer, tumours treated with a combination of palbociclib and the hormone treatment fulvestrant progressed after an average of 9.2 months. This compared with an average of 3.8 months with the hormone treatment alone.

Palbociclib is a ‘first-in-class’ drug that simultaneously blocks two proteins – CDK4 and CDK6, which are involved in cell division – in cancer cells. Because it is targeted at patients’ tumours, it causes less severe side-effects than traditional chemotherapy.

The trial was led by researchers at the ICR and The Royal Marsden, along with colleagues from 144 international research centres in 17 countries, and was funded by Pfizer. It enrolled 521 women with hormone-receptor-positive, HER2- negative breast cancer, which accounts for about 75 per cent of cases.

All women on the trial had seen their cancer get worse or relapse after first-line hormone therapy. The results of the trial were presented at the major American Society for Clinical Oncology conference in Chicago in June and published in the New England Journal of Medicine.

Study leader Dr Nicholas Turner, a Team Leader at the ICR and Consultant Medical Oncologist at The Royal Marsden, said: “We were delighted to show that this new drug combination delayed the progression of the most common type of breast cancer by an average of five extra months, compared with standard treatment on its own."

“It could help a lot of women to delay the moment when they start chemotherapy, which is effective but is often a difficult experience for women and their families to go through.”

9.2

months: median progression-free survival with palbociclib–fulvestrant combination

3.8

months: median progression-free survival with fulvestrant only