Nat. Med. 24, 1441–1448 (2018).

Immune checkpoint inhibitors (ICIs) have been shown to be more effective in individuals with elevated levels of the protein known as programmed death-ligand 1 (PD-L1) or high levels of mutations in their tumors. However, it is difficult to obtain tissue for analysis of these factors from potential recipients of this therapy.

Scientists from the United States and China developed a blood-based assay to measure mutation levels in tumors and performed retrospective analysis of two large randomized clinical trials. They showed that the levels of tumor mutations in patients with non-small-cell lung cancer who did not respond to first-line treatment could predict which of these patients responded to the ICI atezolizumab (an anti-PD-L1 drug).

The study shows that a high level of tumor mutation is a clinically actionable biomarker for ICI in this type of cancer.