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D. Potter

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    P1.01 - Poster Session with Presenters Present (ID 453)

    • Event: WCLC 2016
    • Type: Poster Presenters Present
    • Track: Epidemiology/Tobacco Control and Cessation/Prevention
    • Presentations: 1
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      P1.01-042 - Molecular Epidemiology of Programmed Cell Death 1-Ligand 1 (PD-L1) Protein Expression in Non-Small Cell Lung Cancer  (ID 4746)

      14:30 - 15:45  |  Author(s): D. Potter

      • Abstract

      Expression of programmed death-ligand 1 (PD-L1) in non-small cell lung cancer (NSCLC) patients might identify patients who would benefit from PD-L1 blocking antibodies. In a retrospective cohort of NSCLC patients, we characterized PD-L1 expression and other biomarkers to determine if PD-L1 expression is a prognostic biomarker and whether patient characteristics could be identified to determine those associated with high expression.

      This was a retrospective analysis of 136 NSCLC patients diagnosed between 1997 and 2015 with stage IIIB and IV disease and treated at Moffitt Cancer Center and affiliated institutions. All patients had at least 2 lines of standard of care chemotherapy and sufficient archival tumor tissue for PD-L1 testing by the Ventana SP263 validated assay and mutation status testing by targeted DNA sequencing with the TumorCare Panel. High PD-L1 expression was defined as ≥ 25% of tumor cells with membrane positivity for PD-L1 at any intensity above background staining. Statistical analyses were performed comparing PD-L1 expression by patient characteristics. Survival analyses were performed using Kaplan-Meier survival curves and the log-rank statistic. All statistical tests were two-sided; P-value of less than .05 was considered statistically significant.

      Of the 136 tissues tested for PD‐L1 expression, 116 (85.3%) were collected by surgical resection and 20 (14.7%) were collected by biopsy. Mean sample age was 7.2 years (SD=2.8 years). 82 of the 136 samples also underwent targeted DNA sequencing. In this patient cohort, 51.5% were male, 83.1% were ever smokers, 90.4% were White, 39% were stage IV at time of tissue collection, 71.3% had adenocarcinoma, 28.7% had four or more lines of therapy, and 24.2% had high-expression for PD‐L1. There were no statistically significant differences with respect to PD-L1 expression for patient characteristics, overall survival (OS), or progression-free survival (PFS). Additionally, there were no statistically significant differences with respect to PD-L1 expression by EGFR (WT/PD-L1<25% = 74.4% vs. WT/PD-L1≥ 25% = 88.5%), KRAS (WT/PD-L1<25% = 74.7% vs. WT/PD-L1≥ 25% = 69.2%), and ALK status (Neg/PD-L1<25% = 98.5% vs. Neg/PD-L1≥ 25% = 100%). However, mutation load (total number of non-synonymous mutations) was statistically significantly correlated with PD-L1 expression (correlation coefficient = 0.23; P = 0.03).

      In this study of NSCLC patients treated with 2 or more lines of standard of care chemotherapy, PD-L1 expression (high vs. low and as a continuous covariate) was not statistically significantly associated with OS or PFS. We did observe a novel positive correlation between PD-L1 expression and mutational load.