Why is Trastuzumab (Herceptin®) given after AC or AC->T and not during chemotherapy cycles?

A Clinical Drug Information Response for Patients and Healthcare Providers

Background Information

During review of breast cancer patient case, a discussion about Herceptin® being administered for HER2+ breast cancer was discussed with a healthcare provider.

I was tasked to determine why it would not be appropriate to give Herceptin® during AC or ACT chemotherapy cycles.

Clinical Response

AC/ACT includes Adriamycin® (doxorubicin) which is an anthracycline chemotherapy agent used as first line for breast cancer. Although effective, this drug induces prominent cardiotoxicity promoting cardiomyopathy in all patients.

Due to this side effect, doxorubicin has a life time cumulative exposure amount that is recorded and maintained in order to prevent cardiotoxicity.

The clinical issue with trastuzumab is the fact that this particular drug also contributes to the cardiotoxicity which can worsen cardiomyopathy.

It is strongly recommended by healthcare providers and oncology specialists to not administer concomitantly with doxorubicin. Therefore, Herceptin is often given only after successful completion of all chemotherapy cycles that include doxorubicin.

Trastuzumab (Herception®) Mechanism of Action


  1. Shord SS, Medina PJ. Chapter 104. Cancer Treatment and Chemotherapy. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey L. eds. Pharmacotherapy: A Pathophysiologic Approach, 9e. New York, NY: McGraw-Hill; 2014. http://accesspharmacy.mhmedical.com/content.aspx?bookid=689&Sectionid=48811497. Accessed August 04, 2016.