5 Important Advances in Breast Cancer Treatment

Trodelvy (sacituzumab govitecan-hzly) was approved by the FDA in April to treat metastatic triple-negative breast cancer. It is called triple-negative because the cancer cells lack estrogen and progesterone receptors and the human epidermal growth factor receptor 2 (HER2) protein. Roughly 15% of breast cancers are triple-negative breast cancers, and they are more commonly diagnosed in women younger than 40. Triple-negative breast cancer is aggressive and is more likely to be diagnosed at a later stage than breast cancers with the receptors it lacks.

Trodelvy, which is administered intravenously, was approved to treat metastatic triple-negative breast cancer that has not responded to standard chemotherapy. The drug is an antibody-drug conjugate, which works like a smart bomb, says David Riseberg, M.D., chief of medical oncology and hematology at Mercy Medical Center in Baltimore. Antibody-drug conjugates are agents that combine antibodies and chemotherapy agents. With Trodelvy, it is the antibody’s job to recognize the trophoblast cell-surface antigen 2 — Trop-2, for short — receptor on the surface of triple-negative breast cancer cells. When that happens, it delivers a topoisomerase inhibitor that is toxic to the cancer cell. This approach of pairing recognition with a chemotherapy agent means the treatment is more precisely directed than chemotherapy alone.

In the ASCENT study that led to Trodelvy’s approval, a third of patients responded to the treatment as measured by overall response rate. “This is generally better than what would be expected in patients with triple-negative breast cancer who were previously treated with prior chemotherapy agents,” says Shannon Puhalla, M.D., a medical oncologist at the UPMC Hillman Cancer Center in Pittsburgh. However, Trodelvy was approved with a boxed warning about severe neutropenia and diarrhea. The commercial prospects for Trodelvy—and the antibody-drug conjugates in general— are bright judging by Gilead’s recent $21 billion acquisition of Immunomedics, the company that developed Trodelvy.