Patients with non-small cell lung cancer (NSCLC) who were treated with anti-programmed cell death protein 1 (anti-PD-1) antibodies according to the results of programmed cell death ligand 1 (PD-L1) testing from endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) samples demonstrated similar outcomes as patients treated according to results of PD-L1 testing of conventional histologic specimens, according to the results of a retrospective study published in Chest.
Although pivotal clinical trials of anti-PD-1 antibodies relied on PD-L1 expression testing on surgical or tissue biopsy samples, the majority of decisions in practice are based on cytology specimens. Previous studies show that PD-L1 testing is feasible in more than 90% of samples obtained by EBUS-TBNA. The aim of this study was to determine if the outcomes of patients who were treated on the basis of their PD-L1 expression results differed according to technique of sample ascertainment.
The retrospective study included data from 145 patients with advanced NSCLC treated with nivolumab or pembrolizumab between 2016 and 2019 at a single center. Testing of PD-L1 was performed on samples from EBUS-TBNA among 31.7% of patients and from histologic samples among 68.3% of patients.
The median age of the cohort was 67 years, and 49% of patients were women. The majority of patients had metastatic disease and an Eastern Cooperative Oncology Group performance status of 0 or 1. More patients had nonsquamous histology in the EBUS-TBNA group at 89.1% compared with 64.7% in the histologic group (P =.003). Expression of PD-L1 by tumor proportion score was similar between the groups, with a score of at least 50% among 62.8% of patients.
Survival outcomes were similar between the groups. The median overall survival was 25.8 months in the EBUS-TBNA group and not yet reached in the histologic group among patients who received first-line anti-PD-1 therapy (hazard ratio [HR], 0.82; 95% CI, 0.34-1.95; P =.651). Median progression-free survival was 15.2 months and 11.9 months in the EBUS-TBNA and histologic groups, respectively (HR, 0.78; 95% CI, 0.35-1.73; P =.538).
Overall survival (HR, 0.82; 95% CI, 0.34-1.95) and progression-free survival (HR, 0.78; 95 %CI, 0.35-1.73) were also similar among patients who received anti-PD-1 therapy as second-line treatment.
No difference in survival was noted between the groups when adjusted for age, gender, disease stage, PD-L1 expression, histology, central nervous system metastases, or smoking status.
The authors concluded that “the outcomes of patients with advanced NSCLC treated with immune checkpoint inhibitors on the basis of PD-L1 expression in EBUS-TBNA samples are comparable to those of patients in whom PD-L1 expression was assessed in histological specimens.”
Tajarernmuang P, Ofiara L, Beaudoin S, Wang H, Benedetti A, Gonzalez A. Real-world outcomes of patients with advanced non-small cell lung cancer treated with anti-PD1 therapy on the basis of PD-L1 results in EBUS-TBNA vs. histological specimens. Chest. Published March 3, 2021. doi:10.1016/j.chest.2021.02.053