Impact of Patient Characteristics, Prior Therapy, and Sample Type on Tumor Cell Programmed Cell Death Ligand 1 Expression in Patients with Advanced NSCLC Screened for the ATLANTIC Study

Abstract

Introduction: We evaluated the impact of patient characteristics, sample types, and prior non-immunotherapy treatment on tumor cell (TC) programmed cell death ligand 1 (PD-L1) expression using samples from patients with advanced NSCLC.

Methods: Patients (N = 1590) screened for the ATLANTIC study submitted a recently acquired (≤3 months) or archival (>3 months to >3 years old) tumor sample for PD-L1 assessment using the VENTANA PD-L1 (SP263) Assay with a cutoff of ≥25% of TCs expressing PD-L1 (TC ≥25%). Samples were acquired either before or after the two or more treatment regimens required for study entry and sample age varied among patients. A subset of patients (n = 123) provided both recent and archival samples.

Results: A total of 517 of 1590 (32.5%) patients had TC greater than or equal to 25%: prevalence was greater in smokers versus nonsmokers (p = 0.0005) and those with EGFR- versus EGFR+ tumors (p = 0.0002); these effects were independent. Prevalence of TC greater than or equal to 25% was increased in recent metastatic versus primary (p = 0.005) and recent versus archival (p = 0.039) samples. Chemotherapy or radiotherapy, but not tyrosine kinase inhibition, before sampling was associated with significantly increased PD-L1 prevalence. PD-L1 status (TC ≥25% cutoff) remained unchanged in 74.0% of patients with recent and archival samples; where PD-L1 status changed, it was more likely to increase than decrease over time or with intervening treatment.

Conclusions: Several factors potentially impact PD-L1 TC greater than or equal to 25% prevalence in advanced NSCLC; however, no characteristic can be considered a surrogate for PD-L1 expression. Fresh biopsy may provide more accurate assessment of current tumoral PD-L1 expression where a low/negative result is seen in an archival sample, especially if the patient has received intervening therapy.

Keywords: Diagnostic test; Immunohistochemistry; Immunotherapy; NSCLC; Programmed cell death ligand 1.