Dr Hamilton on the Use of ADCs in Breast Cancer

Erika P. Hamilton, MD, director, Breast and Gynecologic Cancer Research, Sarah Cannon Research Institute, discusses the use and sequencing of antibody-drug conjugates (ADCs) in patients with hormone receptor (HR)–positive/HER2-negative and HER2-low breast cancer.

ADCs continue to shape the treatment arena for patients with breast cancer following the February 2023 FDA approval of sacituzumab govitecan-hziy (Trodelvy) for the treatment of patients with HR-positive, HER2-negative breast cancer and the August 2022 FDA approval of fam-trastuzumab deruxtecan-nxki (Enhertu) for the treatment of patients with unresectable or metastatic HER2-low breast cancer. The approvals of these paradigm-shifting agents are frequently discussed by experts in the breast cancer field, Hamilton begins, adding that multiple new ADCs are coming down the pike as well.

Sacituzumab govitecan is approved for both patients with triple-negative breast cancer and patients with HR-positive breast cancer, she explains. However, Hamilton shares that it is important to remember that patients with HR-positive disease should have exhausted their endocrine therapy options before receiving ADCs, which she refers to as “chemotherapy substitutes.” ADCs should not be given to patients in the upfront setting, as patients should still receive their endocrine therapies first, Hamilton emphasizes.

Once patients’ tumors have become endocrine resistant, it is important to begin considering chemotherapy as the next treatment option. In the confirmatory phase 3 TROPiCS-02 trial (NCT03901339), sacituzumab govitecan was evaluated in patients who had already received chemotherapy in the form of either capecitabine or paclitaxel, she expands. Although, it's important to know when to administer an ADC, whether it be sacituzumab govitecan or trastuzumab deruxtecan, it is just as important to remember to use other available treatments first, Hamilton explains.

ADCs across multiple breast cancer subtypes are proving to be a more effective treatment approach than chemotherapy, and in many cases, are easier for patients to tolerate as well, she concludes.