Immunotherapy for breast cancer
Breast cancer remains a significant threat to the health and wellness of women in the United States, accounting for 30% of all new cancer diagnoses and almost 41,000 deaths annually(1). Although advances in early detection and therapy have resulted in a 38% decrease in the breast cancer death rate, almost all patients who develop metastatic disease will succumb to it. These sobering data illustrate a critical need for innovative approaches to breast cancer therapy that reduce relapse and death due to this disease. In recent years, accumulating data support a key role for the immune system in determining both response to standard therapy and long-term survival in breast cancer patients. Both these data and the striking clinical success of immune checkpoint antagonists across multiple solid tumors have re-ignited interest in immune-based strategies for breast cancer treatment and prevention.
Immunotherapy is revolutionizing the management of multiple solid tumors, and early data have revealed the clinical activity of PD-1/PD-L1 antagonists in small numbers of metastatic breast cancer patients. Clinical activity appears more likely if the tumor is triple negative, PD-L1+, and/or harbors higher levels of TILs. Responses to atezolizumab and pembrolizumab appear to be durable in metastatic triple negative breast cancer (TNBC),suggesting these agents may transform the lives of responding patients. Current clinical efforts are focused on developing immunotherapy combinations that convert non-responders to responders, deepen those responses that do occur, and surmount acquired resistance to immunotherapy. Identifying biomarkers that can predict the potential for response to single agent immunotherapy, identify the best immunotherapy combinations for a particular patient, and guide salvage immunotherapy in patients with progressive disease are high prioritiesfor clinical development. Smart clinical trialstesting rational immunotherapy combinations that include robust biomarker evaluations will accelerate clinical progress, moving us closer to effective immunotherapy for almost all breast cancer patients.