Efficacy of PD-1 or PD-L1 inhibitors and PD-L1 expression status in cancer

Cancer cells can attack the immune system through programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1), giving them high value as therapeutic targets.

Cancer cells can attack the immune system through programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1), giving them high value as therapeutic targets. Even as patients who test positive for PD-L1 expression tend to do better with PD-1 or PD-L1 antibodies than they do with standard therapy, there also have been many cases in which patients who are negative for PD-L1 or who test at low levels still benefit from drugs like avelumab, atezolizumab, and nivolumab. To gauge the efficacy of these and other blocking agents compared with conventional drugs, researchers in China launched a meta-analysis of eight randomized controlled trials. The studies collectively included 2,254 enrollees who tested positive for PD-L1 expression and 1,920 who tested negative. Regardless of status, treatment with PD-1 or PD-L1 inhibitors was correlated with significantly prolonged overall survival. The primary benefit was a 34% lower risk of death in the PD-L1 positive group and a 20% reduction in the PD-L1 negative group. Because the antibodies appear to improve outcomes in both PD-L1 positive and negative patients, the investigators conclude that PD-L1 expression by itself it not enough to determine which patients should undergo PD-1 or PD-L1 blockade therapy.