As many as 800 New Zealand women per year are diagnosed with HER2 positive breast cancer, a cancer that is generally more aggressive and has a poorer outcome than other types of breast cancer. The relatively new drug Herceptin offers these women a better chance of staying healthy for longer.
Until 2008, women with early stage breast cancer who might benefit from the drug had to pay up to about $70,000 themselves to get Herceptin for a year as it was previously only funded for 9 weeks treatment. But late in 2008 the government announced that 12 months of Herceptin would be fully funded for those with early stage breast cancer. This was a notable achievement and was the result of many women’s efforts, especially committee members of Breast Cancer Aotearoa Coalition. Herceptin Offers Hope
HER2 is Human Epidermal growth factor Receptor 2 and is one of the growth factors that are important for controlling cell growth. It is present in small amounts in normal breast cells and breast cancer.
HER2 positive (HER2+) breast tumours either have too many HER2 genes or produce large amounts of HER2 protein. The prognosis is poorer for the 25 to 30% of breast cancer patients who have such tumours – the cancer is more aggressive, growing more quickly and spreading more rapidly, there is a higher rate of recurrence and it is more invasive leading more often to metastases. Ten year survival rates are approximately 40%.
Recent research on trastuzamab (Herceptin) has offered hope for women with HER2+ breast cancer. Herceptin is a monoclonal antibody – a molecularly engineered antibody that resulted from early research on mice. It is a targeted treatment that works on the cancer not healthy tissue and for that reason has benefits over conventional chemotherapy.
Herceptin works in three ways:
- It binds to the HER2 proteins on the surface of the tumour cell and blocks signals for cell growth which may result in cancer cell death.
- When it binds to the HER2 proteins on the surface of the tumour cell, immune system cells within the body recognise it as a foreign object and attack, helping to more effectively kill the cancer cells.
- It can enhance the effectiveness of chemotherapy which attacks and damages the DNA in the nuclei of tumour cells and causes cancer cell death.
Generally the adverse effects of Herceptin are mild when compared with the toxic effects of chemotherapy. Side effects may include fever and chills, weakness, nausea, vomiting, cough, diarrhoea, and headaches, and are usually associated with the first dose and not subsequent doses. However, some women have experienced heart damage leading to congestive heart failure while on Herceptin. Recent research has found that most of the adverse cardiac effects of 12 months Herceptin treatment are treatable and reversible when Herceptin is not administered concurrently with anthracycline drugs. Results from recent clinical trials on Herceptin for early stage breast cancer have been received with enthusiasm by the medical profession and the breast cancer community. Four large adjuvant Herceptin trials have been reported on: NSABP B31, NCCTG Trial, BCIRG006 Trial and the HERA Trial. Each is slightly different and the follow-up is still relatively short. Overall, some 13,000 women, including women from New Zealand, participated in the four trials.
At 3 years, the studies suggested about 12 out of every 100 users of Herceptin, or about three out of every 100 breast cancer patients, would be helped by the drug to remain disease-free after three years.
Moving to life expectancy, after three years Herceptin improves the chances of survival from 91.7% to 94.3%. So the reduction in the death rate is indeed one-third (from 8.3% to 5.7%). But in less dramatic language, Herceptin keeps about three people out of every 100 alive after three years for those who take the drug. This amounts to less than one extra person per 100 among all breast cancer patients.” (From Herceptin will work wonders, not miracles, Gavyn Davies, 1/06/06, www.guardian.co.uk)
An additional smaller trial (FinHer) undertaken in Finland showed that just nine weeks of Herceptin improved disease-free survival at two-year follow-up. New Zealand women had the opportunity to join the SOLD trial, which compares 9 weeks treatment with 12 months.
Together the trials have shown that the benefit of Herceptin is independent of chemotherapy and patient characteristics (eg: age, tumour grade and node involvement).
Although there are questions over aspects of Herceptin treatment for early breast cancer, until such time as the questions are answered, New Zealand women have the burden lifted from their shoulders over how their Herceptin treatment will be funded, and an equitable regime is in place which does not depend on an individual’s ability to fund the drug themselves.