Based on the results of a previous trial, patients with advanced non-small cell lung cancer (aNSCLC) with PD-L1 expression between 50% and 100% who received immunotherapy as monotherapy had a higher chance of survival if their PD-L1 expression was 90% or higher. Researchers aimed to confirm this result with data collected from community oncology practices in the United States. With the help of a nationwide, de-identified longitudinal electronic health record-derived real-world database, investigators looked at the outcomes of patients with advanced non-small cell lung cancer (aNSCLC) who started on pembrolizumab monotherapy as first-line treatment and had PD-L1 expression of at least 50%. Very high PD-L1 expression is defined as greater than or equal to 90%, compared to high PD-L1 expression, defined as 50% to 89%. The primary endpoint was time to death from the start of pembrolizumab treatment, with censoring at the last point of care.

To fill in the gaps for the missing covariates, multiple imputations were employed. Kaplan-Meier curves and Cox proportional hazard regression models used inverse probability weighting (IPW) based on propensity scores to control for potential confounding. Patients diagnosed with atypical NSCLC treated with pembrolizumab monotherapy in the first line made up the cohort’s 1,952 members. The median age of the group was 73 (IQR: 65-80), 71% of the participants had a histology other than squamous, 94% had a smoking history, and 46% expressed very high levels of PD-L1. Very high PD-L1 expression was associated with a median overall survival of 15.84 months, and high PD-L1 expression was associated with a median overall survival of 12.72 months in the propensity score-weighted population. In addition, very high PD-L1 expression was linked to a reduced risk of death (IPW hazard ratio 0.79, 95% CI 0.69-0.91).

Patients with very high PD-L1 expression (≥90%) aNSCLC treated with first-line pembrolizumab in this large national US cohort had higher median survival than those with high PD-L1 expression (50% to 89%).