Targeting HER2 in Breast Cancer

Debu Tripathy, MD, co-leader, Women's Cancer Program, University of Southern California Norris Comprehensive Cancer Center, discusses targeting HER2 in breast cancer.

Tripathy says that in early stage breast cancer, it is clear that HER2 targeting makes a big difference when treating patients. The only agent that has been tested in this space, Tripathy says, is trastuzumab, which may have a dual mode of action: blocking signaling that HER2 has with cell growth and recruiting the immune system.

Trastuzumab also has among the biggest impacts observed in breast cancer, cutting the risk of recurrence in half and risk of death by a third, Tripathy says.

Tripathy says that there is no such thing as a "magic bullet," though trastuzumab has a minimal toxicity profile. It is known that HER2 is in some ways involved in cardiac remodeling, which makes cardiac toxicity not all that surprising with HER2-targeted therapies. Fortunately, these events are rare and usually controllable.

Physicians have learned that mostly everybody with HER2+ cancer should be treated with trastuzumab and along with cardiac monitoring. The next step would be to find what drugs best pair with trastuzumab in order to make the agent more effective, Tripathy says.

Clinical Pearls

• Trastuzumab is the only HER2-targeting agent that has been tested in the early stage settings of breast cancer
• Trastuzumab cuts the risk of recurrence in half and the risk of death by a third
• Some cardiac toxicity occurs with trastuzumab
• Partnering other drugs with trastuzumab may make the agent more effective