A five year follow up US trial on women receiving trastuzumab (Herceptin) in combination chemotherapy for early-stage breast cancer showed that the risk of congestive heart failure did not increase with time.
The findings of the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-3 trial, which was funded by the National Cancer Institute, were presented by researchers from Pittsburgh University to the 43rd annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago this week.
Herceptin is one of a new class of cancer fighting drugs called monoclonal antibodies and is made by drug company Genentech. It is used to treat patients with HER-2 positive breast cancer, characterized by abnormally high levels of the HER2/neu protein.
Heart damage is the most significant side effect of Herceptin, occurring in around 5 per cent of patients, and women with existing heart conditions cannot take it.
Some women stopped taking Herceptin,fearing that the risk increased in the long term. However, this study shows that not to be the case. The risk in the long term is the same as the risk that is there from the beginning, suggesting that a patient taking the drug is either susceptible to heart problems or they are not.
Using the findings of the trial, the research team have developed a prediction model that will help oncologists assess the risk of heart failure in individual patients before treating them with Herceptin and chemotherapy.
Dr Priya Rastogi, who is assistant professor at the University of Pittsburgh School of Medicine and assistant director of medical affairs, NSABP, and presented the study, said that:
“The information we obtained from this study is essential to understanding women’s risks for congestive heart failure associated with adding Herceptin to combination chemotherapy for breast cancer treatment.”
“We’re encouraged that we found no increase in heart failure risks long-term and now are able to use this knowledge to individualize women’s treatment based on their specific cardiac risk factors,” she added.
Rastogi and colleagues assessed the cardiac side effects in 1,850 women with HER-2 positive breast cancer over a five year period. The women were randomly assigned to a Herceptin group or a control group.
The control group underwent four cycles of a standard combination chemotherapy regimen, doxorubicin and cyclophosphamide followed by paclitaxel. The Herceptin group was treated with four cycles of doxorubicin and cyclophosphamide followed by paclitaxel and Herceptin.
They compared the incidence of congestive heart failure between the two groups at 3 and 5 years of follow up using a Multiple Gated Acquisition scan (MUGA scan) which shows a moving image of the beating heart. This helped the researchers assess the health of cardiac ventricles non-invasively.
The results showed that:
- Herceptin provides a clear benefit for women with HER-2 positive breast cancer.
- However, at the 3-year follow up, the incidence of congestive heart failure was greater in the Herceptin group than the control group (4.1 per cent versus 0.8 per cent).
- But, at the 5-year follow up, the incidence of congestive heart failure was unchanged (3.8 per cent in the Herceptin group, 0.9 per cent in the control).
The researchers then developed a prediction model to assess the likely risk of congestive heart failure to patients who are considering adding Herceptin to their combination chemotherapy treatment. The model takes into account blood pressure, age and data on heart function at the start of treatment.
Rastogi said they hope the model “will help to individualize care for women in terms of choice of Herceptin-containing treatment regimens based on their personal risk and benefits”.
The US Food and Drug Administration approved Herceptin for the treatment of advanced breast cancer in 1998.
The National Cancer Institute estimates that this year in the US, 178,000 women and 2,000 men will be diagnosed with breast cancer and over 40,000 women and 450 men will die of the disease. It is the most commonly diagnosed cancer in women and the second leading cause of cancer-related death in women in the US.
Lymph-node positive breast cancer accounts for about 30 per cent of cases, and between 20 and 30 per cent of these tumours overexpress the HER-2 protein, which Herceptin targets.
Written by: Catharine Paddock
Writer: Medical News Today