Immunotherapy Approaches to Breast Cancer

Purpose of Review

Activating the immune system to eradicate breast cancer has emerged as a promising treatment strategy, and immune checkpoint inhibition has demonstrated activity in both advanced and early stage disease. Here we review recent clinical trial results of immunotherapy approaches to treat breast cancer.

Recent Findings

A number of trials of immune checkpoint inhibitors, both as monotherapy and in combination with other therapies, have been reported. While response rates with monotherapy in the advanced stage setting are relatively low, the durability of responses observed is remarkable. While PD-L1 positivity enriches for responders, it is not a consistent predictor of response. Response appears to correlate more strongly with tumor-infiltrating lymphocyte (TIL) density.

Summary

Immune checkpoint inhibition alone and in combination with chemotherapy appears well tolerated with manageable side effects. Treatment clearly benefits a subset of patients, and more precise biomarkers of response are needed.