Programmed cell death 1 (PD-1) and its ligand 1 (PD-L1) are up-regulated in many cancers. The purpose of this study was to explore the relationship between PD-L1 expression and overall survival (OS) in HNSCC.
A retrospective study was conducted using data from pt medical records and analysis of archival tumor samples. Sample ages ranged from 8.2 to 227.5 months. Pts ≥18 years old diagnosed with HNSCC between 1989 and 2015 were selected. Demographic and tumor characteristics were compared by PD-L1 expression status. PD-L1 testing was performed using the Ventana PD-L1 SP263 assay. PD-L1 expression was scored separately using tumor cell (TC) and immune cell (IC) membrane staining and exploratory cut-offs of 1%, 5%, 10%, 25% and 50%. OS was calculated as the number of months from initial HNSCC diagnosis until death and estimated using the Kaplan–Meier method. The log-rank test was used to compare survival curves by PD-L1 status. PD-L1 status as a prognostic indicator of OS was further examined in Cox proportional hazards (PH) models.
We identified 214 HNSCC pts with data available for date of death/last follow-up and PD-L1 status. Mean (SD) tumor sample age was 93.3 (40.5) months. Mean (SD) pt age was 62.3 (13.4) years and 70% were male. The Table presents baseline characteristics by PD-L1 subgroup. Median OS was similar between PD-L1 high and low/negative pts classified using the TC ≥ 25%, IC ≥ 1%, and IC ≥ 25% cut-offs. However, median OS was 21.2 months longer in PD-L1 high versus low/negative pts (68.9 vs. 47.7 months, respectively; P=0.03) in analyses using the TC ≥ 1% cut-off. This latter relationship remained after adjusting for baseline covariates using Cox PH models.Table:
1049PD Baseline characteristics
|Characteristic||TC PD-L1 expression|
|High (≥25%)||Low/negative (|
PD-L1 high expression based on a TC ≥ 1% cut-off appears to be associated with improved OS in this sample of pts with HNSCC. A small number of samples and resulting low statistical power limited our ability to assess prognosis for TC ≥ 25% and IC ≥ 25%, yet OS was numerically higher among PD-L1 high pts in these subgroups.
Clinical trial identification
Legal entity responsible for the study
M. Stokes: Employment (Evidera) and research funding (Evidera). R. Wang: Employment (Evidera) and Stock ownership (Evidera). S. Wildsmith, H.K. Angell, C. Barker, J. Walker, P. Scorer, N. Shire: Employment (AstraZeneca) and Shareholder (AstraZeneca). M. Secrier: Employment (AstraZeneca) Corporate sponsored research (AstraZeneca) and Shareholder (AstraZeneca). M.C. Rebelatto: Employment (AstraZeneca/MedImmune) and Shareholder (AstraZeneca/MedImmune).