TUGETHER

The TUGETHER Clinical Trial

TUGETHER aims to find out if adding tucatinib and pembrolizumab to the usual treatment given to people with advanced HER2-positive breast cancer slows down the growth of the cancer.

In HER2-positive breast cancer, there are too many HER2 receptors on the surface of the cancer cell. Having too many receptors can cause the breast cancer cells to grow and divide very quickly. Anti-HER2 medicines (such as trastuzumab) slow or stop the growth of cancer cells by attaching to the HER2 receptor proteins on the surface of cancer cells and blocking the growth signals.

Trastuzumab will be used in this study together with tucatinib, which works in a different way to trastuzumab. Tucatinib gets inside the breast cancer cells and blocks the signals that are sent by the HER2 receptors. These two treatments complement each other to gain better control over the cancer cells.

Pembrolizumab helps the immune system work against cancer by stopping a protein called PD-L1 (programmed cell death 1). The PD-L1 protein attaches to the surface of certain immune cells called T-cells, so the T-cells cannot find and kill cancer cells. Blocking PD-L1 can enable the immune system to find and kill cancer cells.

Increased levels of PD-L1 are referred to as “PD-L1 positive” and low levels of PD-L1 are referred to as “PD-L1 negative”. A sample of the tumour tissue provided at the start of the study will show if the cancer is PD-L1 positive or PD-L1 negative.

Chemotherapy is also usually given with anti-HER2 treatment. This can have significant short and long-term side effects. The researchers would also like to find out if a new treatment program without chemotherapy is effective in treating the cancer with less side effects.

All people taking part in TUGETHER will receive tucatinib, trastuzumab and pembrolizumab.

The TUGETHER trial will involve 16 sites in Australia, is open to both men and women, and will enrol 50 participants on the study.

Professor Sherene Loi is the Study Chair for the TUGETHER clinical trial.