Breast cancer is the most common cancer in the UK. One type of breast cancer is called HER2-positive. HER is a protein that is found in large amounts on the surface on some cancer cells where it stimulates their growth. HER2-positive breast cancer tends to grow faster than HER2-negative breast cancer. Treatment of early stage breast cancer usually involves surgery. Most patients will often receive some treatment (e.g. chemotherapy and radiotherapy) both before and after the surgery to improve the success rate of the treatment.
Trastuzumab emtansine is a cancer medicine that is already licensed for some specific types of advanced and metastatic HER2-positive breast cancer. Trastuzumab emtansine is a single intravenous medicine made up of two different products coupled together; trastuzumab (an antibody drug against HER2-positive cells), and emtansine (a cytotoxic chemotherapy). Trastuzumab works by recognising and attaching to the HER2 proteins, stimulating the immune system to kill the cancer cells. Emtansine acts by killing cancer cells when they attempt to grow. Trastuzumab emtansine is being developed as an additional cancer treatment given after the initial treatment for HER2-positive early breast cancer and when there is residual cancer remaining after surgery. If licensed, trastuzumab emtansine will offer additional treatment option for this patient group.
Olaparib belongs to a group of drugs called PARP enzyme inhibitors while bevacizumab is an anti-VEGF monoclonal antibody. Both drugs act in different but synergistic ways to kill tumour cells. It is thought that bevacizumab may increase the sensitivity of olaparib to killing the tumour cells. Olaparib administered orally as a monotherapy is already licensed as a maintenance therapy of advanced ovarian cancer. The addition of bevacizumab given by intravenous infusions may potentially improve treatment outcomes.