Dr. Tolaney Discusses Unmet Needs in ER+ Breast Cancer

Sara M. Tolaney, MD, MPH, instructor of medicine, Harvard Medical School, attending physician of medical oncology, Dana-Farber Cancer Institute, discusses unmet needs in the treatment of patients with estrogen receptor (ER)-positive breast cancer.

Tolaney says that clinicians do not currently know what to do with a patient with ER-positive breast cancer who has progressed on a CDK4/6 inhibitor. A lot of work that has been done in an attempt to understand the resistance mechanisms, but so far, there seems to be multiple different ways that a patient could become resistant. The patient could become resistant to the endocrine therapy or the CDK4/6 inhibitor, and it if is the CDK4/6 inhibitor, there are multiple potential causes as well. Another unanswered question is whether a patient should continue a CDK4/6 inhibitor beyond progression.

Sequencing is also a concern in this setting, as well as the protocol for patients who develop ESR1 mutations while on an aromatase inhibitor. It is complicated, and more work needs to be done, Tolaney says.