Triple drug combination effective in HER2-positive breast cancer

Italian researchers have shown that the effect of treating women before surgery with trastuzumab (Herceptin) and docetaxel for HER2-positive breast cancer is improved by adding another ‘Herceptin-like’ drug called pertuzumab.

Experts at the San Raffaele Cancer Centre in Milan found that adding pertuzumab to a woman’s treatment improved the rate at which her cancer completely disappeared by more than half after just four cycles (12 weeks) of treatment, compared with the treatment with just trastuzumab and docetaxel.

The phase II study – published in the Lancet Oncology – involved 417 previously untreated women with an aggressive type of early HER-2 positive disease.

About one in five women with breast cancer have HER2-positive disease, meaning that their tumour produces too much of the HER2 protein. Trastuzumab is a monoclonal antibody that blocks the cancer-causing activity of HER2. It’s a standard treatment for women with this type of breast cancer.

Pertuzumab is an experimental drug that also targets HER2, but in different way to trastuzumab.

Almost half (46 per cent) of women in the study who received the new triple combination before surgery had a pathological complete response – defined as complete absence of tumour cells in surgically removed breast tissue. This compared with 29 per cent of women given standard therapy.

The study also revealed that 17 per cent of women benefited from a combination of pertuzumab and trastuzumab without the addition of chemotherapy. That raises the possibility of a potential non-chemotherapy treatment for HER2-positive breast cancer patients in the future.

The study’s lead author, Luca Gianni, said the tumour response to the new triple combination is one of the highest reported to date, despite just a short treatment time. But he cautioned that further investigation is needed before a chemotherapy-free HER2 targeted therapy can be established.

The study also found that the new triple combination did not significantly increase side effects compared with the other regimens.

Dr Carlo Palmieri, a Cancer Research UK-funded breast cancer expert at Imperial College London, said: “This interesting study shows the benefits of using another HER2-directed treatment called pertuzumab alongside trastuzumab (Herceptin) in women with HER2-positive breast cancer.

“It’s particularly interesting that a small number of women on this study benefited from combination antibody treatment without chemotherapy. This holds the potential in the future for a possible non-chemotherapy treatment for HER2-positive breast cancer. But we”ll need to develop tests to pinpoint such women in the clinic.

“Further work will show if these impressive tumour responses translate into better survival rates. This will involve larger trials using pertuzumab with trastuzumab after surgery, not before as in this study.”

Copyright Press Association 2011