In a case-based discussion, moderator Adam M. Brufsky, MD, PhD, describes a 40-year-old woman with a 2 cm mass in her left breast and a single 2 cm metastatic liver lesion. A biopsy of the left breast reveals the tumor is estrogen receptor (ER)-positive and HER2-positive. A biopsy of the liver indicates that it is HER2-positive and ER-negative.

The majority of the panel agrees that a combination regimen of docetaxel, trastuzumab, and pertuzumab (THP) is ideal for this scenario. Joyce A. O’Shaughnessy, MD, suggests that carboplatin should also be administered, since it appears to be oligometastatic disease that could be amenable to a curative therapeutic strategy. Moreover, the addition of a DNA damaging agent, like carboplatin, appears to be beneficial in the setting of ER-negative disease, O’Shaughnessy notes.

Depending on the response to the combination therapy, a hepatic metastasectomy could be performed following the completion of treatment, believes Hope S. Rugo, MD. An optimal strategy may include treatment with the 4-drug combination followed by docetaxel plus trastuzumab or trastuzumab plus pertuzumab with an assessment of the metastatic site at 6 to 12 months, suggests Brufsky. At this point, if the lesion is still present, metastasectomy is a reasonable option.