As cancer evolves during disease progression, tumors often develop mechanisms to evade the body’s immune response. A multitude of drugs targeting PD-1 and PD-L1—critical in T-cell recognition of a cell as foreign or self—are currently in development and have shown significant efficacy in subsets of patient cohorts with lung cancer and melanoma. The identification of markers that are capable of predicting responses to these drugs has only just begun.
Strategies for prediction employ:
All current strategies also have limitations due to the requirement of tissue. Evidence strongly suggests that sensitivity to immune checkpoint inhibitors and PD-L1 protein expression can increase with lines of systemic therapy. This supports the need for a real-time biopsy.
To identify patients who will most likely respond to immune checkpoint inhibitors, Epic Sciences has developed a number of tools, including a single cell PD-L1 IF assay. This test has pinpointed PD-L1+ patients in a variety of diseases, including lung, bladder, pancreatic, breast and prostate cancer. PD-L1+ CTCs have also identified worse outcomes in patients treated for lung cancer.