P1.01-18 Immunosenescence Correlates with Progression upon PD-(L)-1 Blockade (IO) in Advanced Non-Small Cell Lung Cancer (aNSCLC) Patients

Immunosenescence is a progressive remodeling of immune functions with a multifactorial etiology (i.e. aging, chronic inflammation, cancer). Although a CD28-CD57+KLRG1+ phenotype on peripheral T-lymphocytes is a potential hallmark of immunosenescence, the characterization of such phenotype in IO-treated NSCLC patients and the correlation with clinical characteristics and benefit from immunotherapy are unknown. A senescent immune phenotype (SIP) defined as a percentage of circulating CD8+CD28-CD57+KLRG1+ T-lymphocytes was assessed by flow cytometry (FC) on fresh blood samples from IO-treated aNSCLC patients (03/2017–04/2018). A log-rank maximization method was used to identify a SIP cut-off level and dichotomize patients accordingly. The objective was to correlate SIP with clinical characteristics and RECIST response by univariate logistic regression analysis. 39 aNSCLC patients were evaluable for SIP before IO: 38% ≥ 65 years, 87% non-squamous, 38% KRAS mutated, 54% with PD-L1 expression ≥1%, 13% chemotherapy naïve. Among 30 patients evaluable for IO response, 53% had progression (PD), 27% stability (SD), 20% partial response (PR). Median PFS was 1.9 months (95% CI 1.5; 2.5). OS was not calculated due to the short follow-up [6 months (95% CI 4-11)]. SIP (% CD28-CD57+KLRG1+) median value on circulating CD8+ lymphocytes was 15.26% (min 1.87%, max 56.28%). Overall, 13 (33%) of 39 patients had >22.25% CD8+ lymphocytes with a CD28-CD57+KLRG1+ phenotype, being classified as SIP+. SIP status did not correlate with age, IO-baseline patients’ characteristics or chemotherapy exposure. Among patients evaluable for IO response, only 1 (10%) of 10 SIP+ experienced disease control (PR/SD), compared to 13 (65%) of 20 SIP- patients; similarly, PD rate was significantly higher in SIP+ compared to SIP- patients (90% vs 35%, p=0.007) (Figure). Immunosenescence, monitored by FC measurement of 3 surface molecules on circulating CD8 + lymphocytes, is observed in 33% of aNSCLC patients, is independent of age and correlates with lower IO disease control rate.